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Home My WebLink About20200739.tiffLloyd Sisson 115 -kV Transmission Line Project Use by Special Review and 1041 Application Packet, Weld County, Colorado November 14, 2019 Submitted to: Submitted by: Weld County Planning and Zoning Department of Planning Services 1555 N. 17th Ave. Greeley. CO 80631 TRI-STATE Generation and Transmission Association. Inc. A Touchstone:. Energy%Ctx*penttlye 1100 W 116th Ave. Westminster. CO 80234 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application TABLES Table 1: Keota—Lloyd Sisson Comparative Data 9 Table 2: Transmission Line Characteristics 28 Table 3: Project Schedule 49 Table 4: Common Sources of Magnetic Fields 56 Table 5: General Routing Objectives 61 Table 6: Typical Construction Personnel and Equipment —Transmission Line 63 Table 7: Weight of Construction Vehicles 64 Table 8: Threatened or Endangered Species in Weld County 69 Table 9: Soil Shrink/Swell Classes 73 Table 10: Soil Erodibility Classes 73 FIGURES Figure 1: Study Area 3 Figure 2: Alternatives . 7 Figure 3: Plot Plan —Lloyd Sisson Substation 15 Figure 4A: Vicinity Map —Farmland 17 Figure 4B: Vicinity Map —Soils 19 Figure 5A: Typical Structure Type -115 -kV Wood H -Frame 29 Figure 5B Possible Structure Type 115kV Steel H -Frame 31 Figure 6: Typical Structure Type -115 -kV Steel Three -Pole Angle Structure 33 Figure 7: Possible Structure Type —Steel Monopole 35 Figure 8: Possible Structure Type —Angle Steel Monopole 37 Figure 9: Soil Shrink/Swell Potential (Linear Extensibility) 45 Figure 10: Land Cover 51 Figure 11: Land Use 53 Figure 12: Water Resources 67 Figure 13A Soil Erodibility by Water 75 Figure 13B: Soil Erodibility by Wind 77 APPENDICES Appendix A: Preliminary Drainage Report —Lloyd Sisson Substation Appendix B- Tri-State Position Statement on EMF Health Effects Appendix C: Environmental Protection Measures for Construction Projects Appendix D: NRCS Soils Reports Appendix E. USR Questionnaire Appendix F: Landowner Tables and Affidavit of Surface Owners Appendix G: Certificate of Conveyances and Statement of Taxes Appendix H: Letter of Authorization u Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application LIST OF ACRONYMS AND ABBREVIATIONS A APLIC APP BMP CDPHE CFR CPW CR dBA EMF EPM FAA FPD High West IGA kV mG MW MVA NESC NRCS NRHP PM,a Project PUC R ROW RUA S T Tri-State USFWS USR Agricultural (Zone District) Avian Power Line Interaction Committee Avian Protection Plan Best Management Practice Colorado Department of Public Health and Environment Code of Federal Regulations Colorado Parks and Wildlife County Road decibels electromagnetic fields Environmental Protection Measures Federal Aviation Administration Fire Protection District High West Energy, Inc. Intergovernmental Agreement kilovolt milligauss megawatts megavolt ampere National Electrical Safety Code Natural Resources Conservation Service National Register of Historic Places particulate matter smaller than 10 micrometers in diameter Lloyd Sisson 115kV Transmission Line Project (Colorado) Public Utilities Commission Range Right-of-way Regional Urbanization Area Section Township Tri-State Generation and Transmission Association. Inc. U.S. Fish and Wildlife Service Use by Special Review ui Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application PROJECT DESCRIPTION (SATISFIES 21-3-330.C.1.A-G) INTRODUCTION This document is being submitted by Tri-State Generation and Transmission Association, Inc. (Tri-State) to request review of the proposed Lloyd Sisson 115 -kV Transmission Line Project (Project) under the provisions of the Weld County 1041 process_ This submittal includes the purpose and need and description of the proposed Project. which is situated on privately owned property in Weld County. Who is Tri-State? Tri-State is a wholesale electric power supplier owned by the 42 electric cooperatives and public power districts (the "Member Systems") that it serves. Tri-State generates and transports electricity to its member systems throughout a 200.000 -square -mile service territory across Colorado, Nebraska. New Mexico, and Wyoming. Tri-State was founded in 1952 and today supplies power for approximately 1.5 million consumers in the four states. Tri-State serves its member systems through a combination of owned base load, intermediate. and peaking power plants that use coal and natural gas as their primary fuels. supplemented by purchased power, federal hydroelectricity allocations, and renewable energy The Cooperative Difference Electric cooperatives are private. not -for-profit utilities owned and governed by the members they serve. Electric cooperatives bridge the vast expanse of rural America to energize residencesfarms, ranches. businesses, and communities that have organized cooperatively and accept the responsibility for delivering safe. affordable. and reliable power. PROJECT DESCRIPTION Tri-State is proposing to construct a new transmission line and substation, called the Lloyd Sisson 115 -kV Transmission Line Project, to establish a new delivery point for its Member System. High West Energy. Inc. (High West). The Project will be located in rural Weld County, west of Grover. Colorado. and is primarily intended to serve the growing oil and gas development in the area, as well as transferred load from the nearby Wayne Child and Pine Bluffs substations. The project will include the following components (Figure 1): • A new 115/34.5 -kilovolt (kV) substation located west of the town of Grover called the Lloyd Sisson Substation. • Approximately 20 miles of 115 -kV transmission line from Tri-States existing Keota Substation to the proposed Lloyd Sisson Substation. • Construction staging areas located at the existing Keota Substation and the proposed Lloyd Sisson Substation used for the duration of construction to store equipment and stage construction (Figure 1). The staging areas will have two construction trailers. multiple storage containers, and other associated equipment. 1 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application High West will construct distribution lines (<115-kv, and as defined in Section 23.1.90 of Weld County Code) out of the substation, not included as part of this Project. and a use allowed by right in the Agricultural Zone District. The substation and transmission line construction is expected to begin in early summer 2020 and the facilities are expected to be in-service by first quarter 2021. The proposed transmission line will be approximately 20 miles in length and located entirely on private lands. The new 115 -kV transmission line will be constructed out of wood and self -weathering steel. The right-of-way (ROW) will be 100 -feet -wide. PURPOSE AND NEED Tri-State is a regional, wholesale electric power supplier owned by the Member Systems that it serves Tri-State is obligated to provide reliable. efficient, cost -based. wholesale power to these Member Systems, who in turn provide retail electric service to their end -use member -consumers. High West. one of Tri-State's Member Systems, has received formal requests for service for several large industrial loads. These load requests include up to12 megawatts (MW) for oil and gas production facilities. The current load in the areas is 6.5 MW sourced from the Wayne Child Substation. The existing 34.5 -kV distribution service cannot accommodate these new loads. The new Lloyd Sisson Substation would also be used to provide back-up service to the Wayne Child and Pine Bluffs Substation. This service would improve system losses and provide voltage support to the area. SUPPORTING INFORMATION Supplemental information provided along with this permit application is provided in eight appendices as listed below This information is provided as required in the Use by Special Review Procedural Guide Appendix A: Appendix B Appendix C: Appendix D: Appendix E• Appendix F: Appendix G: Appendix H. 2 Preliminary Drainage Report —Lloyd Sisson Substation Tri-State Position Statement on EMF Health Effects Environmental Protection Measures for Construction Projects NRCS Soils Report USR Questionnaire Landowner Tables and Affidavit of Owners Certificate of Conveyances and Statement of Taxes Letter of Authorization Eagle Rock Ranch Conservation Easement a CsQ J7 coon%- P n b i 9 0 Oy County Road 128 •0 C O Western High Plains. Easement Arapaho and Roosevelt National Forests County County Road 114 County Road 118 uunty Road 120 Pawnee National Grassland NI Ioi kJ O7 County Road 112 Lloyd Sisson 115kV Delivery Point Sib Land County Road 110 �r c 0 0 U aunty Road 110 County Road 126 County Road 124 County Road 108 County Road 106 i- .3/4 ii GRP Weld, CO (08123) County Road 120 County Road 83 U Greater Pawnee Easement County "WALE I Laramie Ave .1. Grover County Road 112 Keota County Road 114 County Road 110 Keota - Rcdbox Tri-State Generation acid Transmission Uoyd Sisson Delivery Point Project Figure I: Study Area city A Station • TnState Line Line - Substation Service IUSFSI Federal Land Land Transmission GST - Tri-State G& T Other Utility Organization Line Transmission — Transmission I Project Forest Other State Non -Governmental ■ 0 Project ll/tl.srwlE N r I 1 1 Man 2 05 I mtg., . nal Mae I.. they annr a f h } i 4:741_ J tt Coffins Wesley Ili IS; 31 t4.10 ~Ac .1•4, i.41. m• wMroducuturdate.tuprdiwwnD/Map,tMXD,aficaft.rc..t ri SmvyAr.a_. loydi non mad Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application ALTERNATIVES TO THE PROPOSED PROJECT Transmission System Alternatives Three electrical system alternatives were evaluated to address the need for the Project. Alternative A: No Action Taking no action would result in no power delivery to Tri-State's Member and their customers. The No Action Alternative does not meet the need of the Project and would require oil and gas operators to -self- generate" to meet their power needs and to obtain the accompanying air permits to do so. Alternative B. New 345/115 -kV Substation Tri-State evaluated an alternative that included construction of a 345/115 -kV substation located near the proposed load that would tap the existing 345 -kV transmission line, rather than the Keota Substation. This alternative would have required a larger substation and less transmission line construction However. in order to accommodate the proposed loads and also provide back-up service to the Wayne Child and Pine Bluffs Substation, this alternative would have required redundant 345/115 -kV transformers. Single outage contingency analyses determined that the use of only a single transformer could have resulted in a four week outage. which would not have been acceptable for Tri-State, its Member, or their customers. For cost and reliability reasons, this alternative was eliminated from further consideration. Alternative C. New Substation and 115 -kV Transmission Line Connection This alternative would involve the construction of approximately 20 miles of 115 -kV transmission line and a new substation. Alternative C would provide the necessary power to reliably serve oil and gas facilities in the area. as requested by Member customers. The preferred system alternative is Alternative C. Alternative C meets the Project's purpose and need and provides a cost-effective. secure. and reliable source of power for Tri-States Member and their customers. Transmission Line Routing Alternatives The process used to identify alternative locations for the transmission line began with delineating the Study Area. The general location for the substation site and the transmission line were initially identified based on the location of the oil and gas facilities/load. existing infrastructure (transmission lines and substations). and Federal land. The locations of these features heavily influenced the area of consideration for the Project. A summary of the Project alternatives is provided in Figure 2 and summarized in Table 1. Preliminary routes were identified along the existing transmission line (Tri-State's 345 -kV Keota—CO/WY State Line), county roads, and field/parcel lines (Figure 2). The existing transmission line, which runs northwest out of the Keota Substation. presented an opportunity for routing. although the corridor crosses the Pawnee National Grasslands (PNG) and a Federal permitting process would pose a risk to the Project schedule. An alternative route was identified that avoids the PNG while staying along the 345 -kV line. but it adds a considerable amount of angles to the line and boxes in one landowner. The site for the Lloyd Sisson Substation was selected based on the proximity to the oil and gas loads, the existing 345 -kV line and the willingness of the landowner to sell the parcel to Tri-State for the substation. 5 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application Keota-Lloyd Sisson Alternative 1 Alternative 1 (Figure 2) makes use of the existing utility corridor between the Keota Substation and County Road 77. At County Road 77. the route diverts from the 345 -kV line and runs along the west side of County Road 77 for approximately 5.5 miles where it turns west for 3 miles to meet rejoin the existing 345 -kV transmission line corridor. It again follows the corridor for 4 miles before continuing back to the east to the Lloyd Sisson Substation site. This route makes the most use of the existing 345 -kV transmission line corridor and consolidates disturbance to the extent possible without crossing Federal lands. However. a landowner that owns nearly 5 miles of the route was not in favor of the Project. Additionally. this alternative would require crossing a series of ponds and wetlands associated with Little Crow Creek. It would also encroach on a 200' buffer around a permitted oil and gas well The route would come within 150 feet of an occupied residence on the west side of County Road 77. Keota—Lloyd Sisson Alternative 2 Alternative 2 was developed to consider a route that would allow for a connection to an existing distribution substation owned by High West on County Road 126. This route goes north out of the Keota Substation and follows the existing Cedar Creek—Keensburg transmission line for 1 mile where it diverts to the northwest to follow County Road 87 for 3 miles. It then turns west along property lines before turning north for 4.5 miles. It runs north for an additional 3 miles before turning to the west again for 4 miles partially along County Road 130 before turning into the Lloyd Sisson Substation site. This route has the greatest amount of angles and would create a new transmission line corridor less than 5 miles from the existing corridor. which outweighs the marginal benefit of connecting to the existing distribution substation_ Keota—Lloyd Sisson Preferred Route The Preferred route (Figure 2) follows Alternative 1for approximately 9 miles. It diverts from Alternative 1 by crossing to the east side of CR 77 south of CR 114 to avoid a home. It stays on the east side of CR 77 for five miles and then instead of continuing all of the way back west to the existing 345 -kV corridor, it turns north just west of County Road 75. It then continues north and west along property lines into the Lloyd Sisson Substation site. This route follows the existing 345 -kV corridor for approximately 7 miles. It avoids the PNG and Federal permitting. It also reduces the amount of transmission line on a landowner that is not in favor of the Project (reduced from 5 miles to 1 mile compared to Alternative 1). This alternative was selected as the Preferred Route because it consolidates disturbance to the existing corridor, minimizes impacts to a disapproving landowner, avoids an oil and gas well. avoids a home, and avoids crossing a series of ponds and wetlands Where the route occurs adjacent to County Road 77, Tri-State would prefer to construct the transmission line directly adjacent to the County Road right-of-way to minimize impacts to agricultural crops: however. coordination with the pipeline construction in the area dictates a greater separation in this case 6 n C C Eagle Rock Ranch Conservation Easement County Road I lb Western High Plains Easement Arapaho and Roosevelt National Forests V ■ C County Road 124 Pawnee National Grassland • ■ V c cC r� c 1U • Slb Land County Road 130 ■ • ■ ■ ■ 1 ■ ■ ¢ • • • • • County Road 1.12 ■ • C• ounay4tuad 126 ■ ..tat■■■■■■■■■t: ■ ■ • • ■ ■ • ircc ■ ■ O • • C roily R,,..d I I.i T C U • ■ ■ • • County Road 124 ■ • County Road 83 . . I. ■ ■ t Cou tp Iy Rio id 116 r'. • r ■ C • • ■ • • • aunty Road 110 Nis F) County Road 108 County Road 106 GRP Weld, CO (08123) ■ ■ ■ ■ • ■ n c 72. 4 v County Road 120 ■ • ■ • ■ 1. it tom, Ave Grover ■ • ■ ■ • • • v 0 I'V ■ ■ ■ • • • • C C U • • County Road 122 Keota County Road 93 County Road 118 County Road 110 Greater Pawnee Easement Cuts lty A 01 -a. a U 1 CC c 3 O U County Road 114 Keota - Redbox C:. County Road 112 I County Road 97 jut ..mcn•Pat+vfpcor.4eouors,Vocact,LndtE-•LI. 1v,CS uuvUP Maps\MXOiO*t Il.tu•c,I.41 ake•raatnu Lioycs uo'.r-ud Tri-State Generation And Transmission Lloyd Sisson Delivery Point Project Figure 2:Alternatives City 4 Station Transmission - Tri-State Line Line Substation Service (USFS) Federal Land Land Transmission 1 2 ',IATI (.t - t - Tri-State - Other Utility Oiganitadlun Alternatives Line ,ii.: G&T -a Transmission Project Forest Other Slate Non -Governmental Preferred Alternative Alternative 174714i v M7 Transmission • ■ ■ • IN ■ N J 1 ..I -IIIIr 1 F Oft a 0 1 -skint itit o ey G:" aid Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application Table 1: Keota-Lloyd Sisson Comparative Data Comparative Criteria Alternative 1 Alternative 2 Preferred Route Engineering Factors Overall length (miles) 19.45 20.98 19.78 Miles adjacent to linear features —e roads. 16 (transmission and roads) 6.5 (roads) 13 (transmission and roads) g transmission and distribution lines Number of transmission line angles 5 11 8 Number of wetland/water crossings (from preliminary data) 3 3 2 Oil and Gas and Industrial Factors Oil and gas wells within 200 feet 1 0 0 Jurisdiction/Land Use Factors Center pivots within 75 feet 1 2 1 Residences and Other Structures Residences within 75-200 feet of centerline 1 0 0 Total residences within 500 feet of centerline 2 0 2 Number of landowners 17 19 26 Miles of landowners in opposition 5 NA* 1 *Landowners on this route were not contacted. PUBLIC OUTREACH Tri-State and our contractor, Western States Land Services, contacted landowners along the Preferred Route and Alternative 1 per ownership information derived from Weld County property records_ This contact has been in various forms including project introduction phone calls; project introduction and access permission letter mailings; and project introduction and access permission meetings with landowners. Landowner contacts began in June 2018 and are on -going. 9 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application USE BY SPECIAL REVIEW APPLICATION CHAPTER 23, ARTICLE II, DIVISION 4 OF THE WELD COUNTY CODE 23-2-240. DESIGN STANDARDS. A. An applicant for a Use by Special Review shall demonstrate compliance with the following design standards in the application and shall continue to meet these standards if approved for DEVELOPMENT. 1. Adequate water service in terms of quality, quantity and dependability is available to the site to serve the USES permitted. Not applicable. The use being permitted includes a transmission line and substation, which do not require water service. Bottled water will be used at the staging areas. 2. Adequate sewer service is available to the site to serve the USES permitted. Not applicable. The use being permitted includes a transmission line and substation, which do not require sewer service Portable toilets will be used during construction. 3. If soil conditions on the site are such that they present moderate or severe limitations to the construction of STRUCTURES or facilities proposed for the site, the applicant has demonstrated how much limitations can and will be mitigated. Nearly all of the soils along the transmission right-of-way (91%) and the substation have low shrink/swell potential as described in Section 23-2-260 and shown in associated Figure 9. The majority of the soils (77%) are not limited for structures. However. Tri-State will perform geotechnical studies at the substation site. The geotechnical study will identify the structural characteristics of the soil and provide recommendations for construction of foundations within the soils. Appendix D includes a soil report prepared by the Natural Resources Conservation Service (NRCS). See also Section 21 -3 -330.B.15 —Hydrologic, Atmospheric, Geologic, Pedologic. Biotic, Visual. and Noise Impacts. 4. Adequate fire protection measures are available on the site for the STRUCTURES and facilities permitted. The proposed transmission line and substation are designed with overhead ground wires and grounded towers to protect the system from becoming damaged by lightning. See Section 21-3- 330.B.5.g—Hazards and Emergency Procedures for additional fire protection measures. 5. USES shall comply with the following stormwater management standards: a. Stormwater retention facilities shall be provided on site, which are designed to retain the stormwater runoff from the fully developed site from a one -hundred -year storm or as otherwise required by the Department of Public Works. In the case of a LIVESTOCK CONFINEMENT OPERATION (L.C.O.), wastewater collection, conveyance and retention facilities shall be designed and constructed in accordance with the Confined Animal Feeding Operation Control Regulations (5 CCR 1002-19). A range of measures to ensure that the Project does not impact water quality. among other things, is listed in Appendix C, and prior to construction, a Storm Water Permit for 11 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application Construction Activities would be acquired from the Colorado Department of Public Health and Environment (CDPHE). The Storm Water Management Plan prepared as part of the Storm Water Permit will include the use of sediment control measures. covering of exposed soils,. and other established Best Management Practices (BMP) that will control runoff. See Sections 21 -3 -330.B.12 —Air and Water Pollution Impacts and Control Alternatives. Air Pollution Impact and Control. and 21-3-330.B.16 Surface and Subsurface Drainage. b. The drainage facilities shall be designed to release the retained water at a quantity and rate not to exceed the quantity and rate of a five-year storm falling on the UNDEVELOPED site. There would be no alteration in the pattern or intensity of surface drainage as a result of construction or operation of the transmission line. Drainage from the substation would be directed towards a detention pond located on the substation property (Figure 3). A Preliminary Drainage Report is included in Appendix A. a Final Report will be prepared and submitted to Public Works for approval prior to construction. 6. All parking and vehicle storage shall be provided on the site; parking shall not be permitted within any public right-of-way. An adequate parking area shall be provided to meet the parking needs of employees, company vehicles, visitors and customers. During construction, all vehicles would be parked at the staging areas at the Keota and Lloyd Sisson Substations. No parking areas would be constructed. No parking would occur within any public right-of-way. Only a small portion of the transmission line right-of-way would be disturbed for vehicle access. See Section 21-3-330. B.2. b —Access to the Project Area. 7. The USE shall comply with all the SETBACK and OFFSET requirements of the zone district. The entire Project is within the A (Agricultural) Zone District. The minimum setback in the A zone is 20 feet. and the minimum offset is 3 feet. or 1 foot for each 3 feet of building height. as defined in Section 23-3-50 of the Weld County Code. The transmission and substation structures proposed as part of this project comply with the County setback and offset requirements. 8. The access shall be located and designed to be safe; ingress and egress shall not present a safety hazard to the traveling public or to the vehicle accessing the property. For USES generating high traffic volumes and large number of large, slow -accelerating vehicles, acceleration and deceleration lanes may be required to mitigate a potential traffic hazard. No adverse effects on county roads are anticipated. An access road would be created off of CR 130 for the Lloyd Sisson Substation and staging area (Figure 1).Tri-State will submit Access Road Permit applications and will comply with all County design standards. All mobile construction equipment would be certified to operate on Interstate highways. There may be short periods of time when traffic would be halted on county roads to allow construction vehicles to enter and exit the construction areas No improvements to roads in Weld County would be required. See Section 21-3-330.B 7 —Natural and Socioeconomic Environmental Impacts from Construction of the Electric Transmission Line. 12 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application 9. New accesses to public rights -of -way shall be constructed using the following as minimum standards: a. Size of drainage structure —twelve (12) inches in diameter. b. Length of drainage structure —twenty (20) feet. c. Depth of cover over pipe —twelve (12) inches. d. Width of access —fifteen (15) feet. e. Maximum grade of access —fifteen percent (15%). f. Flare radius —twenty (20) feet. g. Depth of surfacing —four (4) inches. Standards exceeding these minimums may be required depending on the type and volume of vehicles generated by the type of USE proposed. An access road would be created off county roads for the substation and staging area. as described above. The access road would be 25 feet -wide with a minimum inside flare radius of 50 feet. The road would be designed with a 6 inch section of modified Class 5 road base. Tri-State will submit Access Road Permit applications and will comply with all County design standards. 10. Buffering or SCREENING of the proposed USE from ADJACENT properties may be required in order to make the determination that the proposed USE is compatible with the surrounding uses. Buffering or SCREENING may be accomplished through a combination of berming, landscaping and fencing. The proposed use (electric transmission) and the proposed structures (utility poles and substation structures) are compatible with the other uses and structures within and adjacent to the Agricultural Zone district. This zone district contains existing electric transmission and distribution lines. existing substations, and oil and gas development, making their appearance and operation balanced with the surrounding uses. 11. Uses by Special Review in the A (Agricultural) Zone District shall be located on the least prime soils on the property in question unless the applicant can demonstrate why such a location would be impractical or infeasible. One soil type (157 acres) along the transmission line is designated as Farmland of Statewide Importance (Figures 4A and 4B). Two soil types (16 4 acres) are designated as Prime Farmland. if irrigated. However, placement of the transmission line structures would not preclude the use of farmland under the suspended transmission line, only a small portion of the soils in the 100 -foot right-of-way would be disturbed for the Project (approximately 2 5 acres of permanent disturbance for the transmission line), and the portion of the line crossing Prime Farmland coincides with the colocation with the existing transmission line corridor. Additionally. transmission structures will be designed to accommodate agricultural operations. to the extent feasible. based on discussions with the landowners. The 7.5 -acre substation site is considered Farmland of Statewide Importance (Figures 4A and 4B), but is only a small subdivision of a larger 627 -acre parcel that continues to be farmed. See Section 21 -3 -330.B.15 —Hydrologic. Atmospheric, Geologic. Pedologic. Biotic. Visual, and Noise Impacts. 13 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application B. If the Special Review Permit for a MAJOR FACILITY OF A PUBLIC UTILITY OR PUBLIC AGENCY is approved, the Planning Commission shall arrange for the Department of Planning Services to record the appropriate Facilities Plan, Utility Line or Selected Route Map with the County Clerk and Recorder. (Weld County Codification Ordinance 2000-1) Noted. 14 v Slb Land' —'S Eagle Rock Ranch Conservation Easement Lloyd Si son 11 De ery P Count Road 120 Arapaho and Roosevelt National Forests Pawnee Natlonol Grassland Cl I 44 I NF 0l County Road 130 County R County Road 110 C U County Road 102 1 County Road 106 a GRP Weld. CO (011123) County Road 126 County Road 124 County Road 106 e i-� K GreaterP�aw.nee Ea t' County Ro 'County Road 114 a: • County Road III 09N �F 6 I W \re t, z I: I\ U 1 Chalk FilaljJ iUN oUVV County Road 112 County Road I 09N 60W Tri-State Generation .in,, Transmission Uoyd Sisson Delivery Point Project Figure 4A:Viclnity Map - Farmland Residences * transmission) A Station _ Transmission (within -Tri-State Line Line Transmission Substation Service (USFS) Federal Land Land of statewide farmland farmland if irrigated farmland if irrigated -STILTS GAT halt mile or -Tri-State -Other Line and OaT Transmission Utility — w Project j • Project Forest Other State Non -Governmental Organization Section Township/Range Farmland Class Farmland importance Not prime Prime Prime protected j.4 4 TM O. ---1 Iola Jill, -4 N r I 1 Miles 2 Ilya m• 4i S I •' IliylonYMsy Clkayellne I Jna... 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Aluno7 A.0. -..,AL - run ua.ua•u• II 11p 70 amp w •lnaq.ueant " •I \I 21 1I r AA I - ..__ 1 1 & 0' $ ge o 21 1ulod l�: pa . -- MI79 cl silos - deW A3lup!A:g1 aln2ld »aloid Wulod ksaAllaa uossl5 p4ol1 UOISSIl iSUe.11 uouvaauaD a)ens-u1 2 to s o r a .0 0 0t• r G, r off Atun°J a as°3 1 AO , 10 tr .. ri r, �_ Of I PQoH .1 Aluno7 o b O. V -+ Sit uo SIS pAoll Will y�Ypa as03 u01loAAaruo] if 301j 30103pue N I loo U . I. 1: 14 " II a'r a . z- •t i� Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application 23-2-250. OPERATION STANDARDS. An applicant for a Special Review Permit shall demonstrate conformance with the following operation standards in the Special Review Permit application to the extent that the standards affect location, layout and design of the Use by Special Review prior to construction and operation. Once operational, the operation of the USES permitted shall conform to these standards. A. The operation of the USES shall comply with the noise standards enumerated in Section 25-12-101, C.R.S. The Project would be constructed and maintained in accordance with Colorado Revised Statutes 25- 12-101 et seq. (Noise Abatement) and Article IX, Section 14-9-10 et seq of the Weld County Code. Audible noise levels are expected to be below 50 dBA (allowed in the more stringent standard for Residential Areas) at the edge of the 115 -kV right-of-way and measured 25 feet from the substation property line, See Section 21-3-330.B 15 Hydrologic. Atmospheric. Geologic. Pedologic. Biotic, Visual, and Noise Impacts. B. The operation of the USES shall comply with the air quality regulations promulgated by the Colorado Air Quality Control Commission. Construction of the Project is not expected to contribute negatively to the air quality status in the area. There would be no long-term air quality effects associated with routine operation and maintenance of the proposed transmission line and substation. See Section 21 -3 -330.B.12 —Air and Water Pollution Impacts and Control Alternatives. Air Pollution Impact and Control. C. The operation of the USES shall comply with the water quality regulations promulgated by the Colorado Water Quality Control Commission. There would be no direct impacts to water quality associated with the regular operation or maintenance of the transmission line and substation_ See Section 21 -3 -330.B.12 —Air and Water Pollution Impacts and Control Alternatives, Air Pollution Impact and Control. D. The USES shall comply with the following lighting standards: 1. Sources of light, including light from high -temperature processes such as combustion or welding, shall be shielded so that light rays will not shine directly onto ADJACENT properties where such would cause a nuisance or interfere with the USE on the ADJACENT properties; and No lighting would be required for transmission line structures. Lighting will be installed throughout the substation yard and mounted on the exterior of the electric equipment enclosure, pointing inward and downward. Lights are generally only on in emergency situations when maintenance is required during low light conditions. Substation lighting would not cause a nuisance on adjacent properties. 2. Neither direct nor reflected light from any light source may create a traffic hazard to operators of motor vehicles on PUBLIC or private STREETS and no colored lights may be used which may be confused with or construed as traffic control devices. No lighting would be required for transmission line structures. Lighting will be installed throughout the substation yard and mounted on the exteriors of the electric equipment enclosures. pointing 21 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application inward and downward. Lights are generally only on in emergency situations when maintenance is required during low light conditions_ Substation lighting would not cause a traffic hazard on county roads and no colored lights would be used. E. The USES shall not emit heat so as to raise the temperature of the air more than five degrees (5°) Fahrenheit at or beyond the LOT line. The proposed transmission line and substation would not raise the temperature of the air more than five (5°) degrees Fahrenheit at or beyond the lot line See Section 21-3-330.B 5 g —Hazards and Emergency Procedures, F. Property shall be maintained in such a manner that grasses and weeds are not permitted to grow taller than twelve (12) inches. In no event shall the property owner allow the growth of NOXIOUS WEEDS. Tri-State's Environmental Protection Measures for Construction Projects (Appendix C) contains a description of revegetation and noxious weed control. Undeveloped areas of the right-of-way and substation site would be reclaimed to previous conditions and noxious weeds would be treated. G. Any off -site and on -site improvements agreement shall be made in conformance with the County policy on collateral for improvements, as well as in conformance with Section 12-5-10 et. Seq. and the Engineering and Construction Standards in Appendix 12-A. If required. Tri-State will enter into a Road Maintenance Agreement with Weld County for construction of the Project. 23-2-260. APPLICATION REQUIREMENTS. A. The purpose of the application is to give the petitioner an opportunity to demonstrate through written and graphic information how the proposal complies with the standards of this Chapter. The following supporting documents shall be submitted as a part of the application except for those items determined by the Director of Planning Services, in writing, or the Board of County Commissioners, on the record, to be unnecessary to a decision on the application: 1. A statement which explains that the proposal is consistent with Chapter 22 of this Code and any other applicable code provision or ordinance in effect. The Weld County Code, Chapter 22, Comprehensive Plan, has been reviewed and the proposed project is consistent with the intent of the Comprehensive Plan, including Land Use. Environmental Resources. and Natural Resources. See Section 21 -3 -330.B.7 —Natural and Socioeconomic Environmental Impacts from Construction of the Electric Transmission Line 2. A statement which explains that the proposal is consistent with the intent of the district in which the USE is located. The Project is located in unincorporated Weld County. within the Agricultural Zone District. Major facilities of public utilities are uses that are allowed by special review within the Agricultural Zone District. See Section 21-3-330.B.5 a —Present Use and Zoning. 22 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application 3. A statement which explains that the USES which would be permitted will be compatible with the existing surrounding land USES. The area is largely used for agricultural purposes. oil and gas development, and rural residences. There is an existing transmission line corridor in the area that generally parallels the proposed transmission line. Placement of the transmission line structures would not preclude the use of farmland under the suspended transmission line, and only a small portion of the right-of-way would be disturbed Transmission structures will be designed to accommodate agricultural operations, to the extent feasible, based on discussions with the landowners. This Project would be compatible with the existing surrounding land uses See Section 21-3-330.B.5.m—Existing Land Uses of All Properties Adjacent to Parcel. 4. A statement which explains that the USES which would be permitted will be compatible with the future DEVELOPMENT of the surrounding area as permitted by the existing zone and with future DEVELOPMENT as projected by Chapter 22 of this Code and any other applicable code provision or ordinances in effect, or the adopted MASTER PLANS of affected municipalities. This use is consistent with the future development of the surrounding area as permitted by the existing zoning and as projected by Chapter 22 of this Code. See Section 21-3-330.B.5.a— Present Use and Zoning The substation and transmission line is located in unincorporated Weld County in the Agricultural zone The substation will provide an additional source from which electric distribution service will be provided. As such, it is not only consistent with future development, but is part of the infrastructure that would support such development. 5. A statement which explains that the application complies with Article V and Article IX of this Chapter if the proposal is located within any Overlay District Area identified by maps officially adopted by the COUNTY. The Project does not occur within any Overlay District Area identified by the County. 6. A statement which explains that if the USE is proposed to be located in the A (Agricultural) Zone District, the applicant has demonstrated a diligent effort has been made to conserve prime agricultural land in the locational decision for the proposed USE. One soil type (157 acres) along the transmission line is designated as Farmland of Statewide Importance (Figures 4A and 4B). Two soil types (16.4 acres) are designated as Prime Farmland. if irrigated. However. placement of the transmission line structures would not preclude the use of farmland under the suspended transmission line, only a small portion of the soils in the 100 -foot right-of-way would be disturbed for the Project (approximately 2.5 acres of permanent disturbance for the transmission line), and the portion of the line crossing Prime Farmland coincides with the colocation with the existing transmission line. Additionally. transmission structures will be designed to accommodate agricultural operations, to the extent feasible, based on discussions with the landowners. The 7.5 -acre substation site is considered Farmland of Statewide Importance (Figures 4A and 4B). but is only a small subdivision of a larger 627 -acre parcel that continues to be farmed. 23 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application 7. A statement which explains that there is adequate provision for the protection of the health, safety and welfare of the inhabitants of the NEIGHBORHOOD and the COUNTY. All Tri-State electric facilities are designed, constructed. operated, and maintained to meet or exceed all applicable standards of design and performance set forth in the National Electrical Safety Code (NESC 2012). See also Section 21-3-330.B.5.g—Hazards and Emergency Procedures. B. The following general information shall be submitted: 1. Name, address and telephone number of the applicants. Tri-State Generation and Transmission Association. Inc. Attention: Selina Koler Address: 1100 West 116th Ave Westminster. CO 80234 Phone Number: 303-254-3720 2. Name and address of the fee owners of the property proposed for the Use by Special Review if different from above. Substation Parcel: Lloyd Farms 66732 County Road 87 Grover. CO 80729 An Authorization Form from Loyd Farms is included as Appendix H. 3. Legal description of the property under consideration. These legal descriptions are approximate and will be replaced by the final legal descriptions following completion of land survey work for the Project. They are also subject to change within the same ownership based on engineering design. Existing Keota The south half of the Southeast quarter of Section 17, Township 9 Substation/Staging Area North. Range 61 West. of the 6t'' Prime Meridian (PM), Weld County, Colorado. 24 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application Lloyd Sisson Substation A tract of land, situated in the SE1/4 SE1/4 of Section 11, Township 11 North, Range 63 West, 6th Principal Meridian, Weld County. Colorado, more particularly described as follows: Beginning at a Point which is also the Southeast corner of said Section 11 from which the East 1/4 Corner of said Section 11 bears N01 ° 11'51 "W 2638.15 feet Thence S89°15'18"W 615.00 feet along the South line of said Section 11: Thence N01 °11'51 "W 530.00 feet: Transmission Line Easement—Keota to Lloyd Sisson Thence N89"15'18"E 615.00 feet to a point on the East line of Said Section 11; Thence S011 1151 "E 530.00 feet along said East line to the Southeast Corner of said Section 11 and the Point of Beginning. An easement one hundred (100) feet wide within the approximate limits of the identified portions of the following Sections, all located in Weld County, Colorado: Township 9 North, Range 61 West, 6th P.M.: W '/2 & SE 17, NE 20. NE 18. S '/z & NW 7 Township 9 North Range 62 West. 6th P.M. N'/2 12, SW 1, W'/2& SE 2. NE 3 Township 10 North, Range 62 West, 6th P.M.: S '/2 34. E '/2 & NW 33. W '/2 28, NE 32. E '/2 29, W'/2 21, W'/2 16. W '/z 9. W'/24 Township 11 North, Range 62 West, 6th P.M.: W '/2 33. N '/2 32. NI/231, W1/230, W 'A2 19. SW 18 Township 11 North, Range 63 West, 6th P.M.: S'/213,E114.SE11 4. Total acreage of the parcel under consideration. The surface area for the newly constructed transmission line structures and substation on private land would total approximately 10 acres (7.5 acres for the Lloyd Sisson Substation, and 2.5 acres for permanent transmission structures). 5. Existing land USE of the parcel under consideration. The Project would take place on private land. Land uses on the parcels in the Project area include agricultural production. electric transmission, oil and gas production and storage. as well as residential uses. The parcel for the substation includes a pipeline owned by Summit Midstream (999 18' Street, Denver. CO 80202). 6. Existing land USES of all properties ADJACENT to said parcel. The parcels adjacent to the line include agricultural property. residential use. and oil and gas development. There are existing electric transmission and pipelines on the properties as well. There are two residences within 500 feet, and seven residences within % mile of the transmission 25 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application line. There are no residences directly adjacent to the Lloyd Sisson Substation, but one residence is located one mile to the east. 7. Present zone and overlay zones, if appropriate. The Project does not occur within any overlay zones 8. Signatures of the applicant and fee owners or their authorized legal agent. See Use by Special Review (USR) Application Form. 9. A certified list of the names, addresses and the corresponding Parcel Identification Numbers assigned by the County Assessor of the owners of property (the surface estate) within five hundred (500) feet of the property subject to the application. The source of such list shall be the records of the County Assessor, or an ownership update from a title or abstract company or attorney derived from such records, or from the records of the County Clerk and Recorder. If the list was assembled from the records of the County Assessor, the applicant shall certify that such list was assembled within thirty (30) days of the application submission date. See Section 21-3-330.B 2.a -Surface Property Owners and Appendix F 10. The written certification required by Section 24-65.5-103.3, C.R.S., if applicable. Such certification may be submitted on the date of the initial public hearing referred to in Section 24-65.5-103(1), C.R.S. To date, no written certification is applicable 11. The applicant shall provide the Department of Planning Services with a certificate from the County Treasurer showing no delinquent taxes for the parcel area. See Appendix G 12. Proposed LANDSCAPE plans. A formal landscape plan is not provided. as no landscaping would be done along the transmission line or at the substation. Areas disturbed during construction of the Project would be reseeded in coordination with the landowners and their current land use. 13. The applicant shall submit to the Department of Planning Services a copy of an agreement with the mineral owners associated with the subject property. Such agreement shall stipulate that the oil and gas activities on the subject property have been adequately incorporated into the design of the site, OR shall provide written evidence that an adequate attempt has been made to mitigate the concerns of the mineral owners on the subject property. Tri-State has identified mineral owners on the substation property and intends to comply with Section 24-65.51-103. Colorado Revised Statutes. The Mineral Interests requirement is not applicable to electric transmission line projects per Section 24-65 51-103. Colorado Revised Statutes. 14. The applicant shall submit signed copy of the notice of inquiry form demonstrating that the IGA municipality does not wish to annex if required by the IGA. Not applicable 26 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application 15. A proposed plan for installation of desired signs following the standards set forth in Chapter 23, Article IV, Division 2. No new signage is planned. 16. A certificate of conveyance form provided by the Department of Planning Services and completed by a Title Insurance or Abstract Company. Tri-State will not acquire fee title to the properties over which the proposed transmission line crosses. Tri-State will acquire easement interests in support of the transmission line. Tri-State will own the parcel for the Lloyd Sisson Substation A Certificate of Conveyance form is provided in Appendix G. C. A detailed description of the proposed operation and USE shall be supplied. Details for the following items, when applicable, are required: 1. Type of USE for which the application is being made. The proposed use includes approximately 20 miles of transmission line one new substation, and the use of staging areas at the existing Keota and proposed Lloyd Sisson Substations (see Figure 1). The surface area for the newly constructed transmission line structures and substation would total approximately 10 acres (7.5 acres for substation and 2.5 acres for structure locations along the transmission line). 2. Proximity of the proposed USE to residential STRUCTURES. There are two residences within 500 feet of the Preferred transmission line route. There are no residences adjacent to the Lloyd Sisson Substation. but one located approximately 1 mile to the east There are seven residences within '/2 mile of the transmission line route- See Section 21-3- 330.B.5.m—Existing Land Uses of All Properties Adjacent to Parcel. 3. The number of shifts to be worked and the maximum number of employees. One 10 -hour shift per day (5-7 days per week) would be worked during construction: the facilities would be monitored remotely during operation. The maximum number of construction workers at any one time would be approximately 50. See Section 21 -3 -330,B.7 —Natural and Socioeconomic Environmental Impacts from Construction of the Electric Transmission Line and Substations. 4. The maximum number of users, patrons, members, buyers or other visitors that the use by special review facility is designed to accommodate at any one (1) time. Not applicable. 5. Types and maximum numbers of animals to be concentrated on the site at any one (1) time. Not applicable. 6. Types and numbers of operating and processing equipment to be utilized. The 20 miles of transmission line would consist of approximately 110-130 structures (Table 2). The structures would be a mixture of wood and steel pole construction (Figures 5 through 8) spaced approximately 700-1.000 feet apart. The transmission line would have three conductors (single -circuit configuration). an overhead optical ground wire for internal Tri-State 27 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application communications, and one shield wire. Steel transmission poles would be set in concrete foundations. Table 2: Transmission Line Characteristics Characteristic 230 -kV Voltage 115 -kV Total Length (approximate) 20 miles Right -of -Way Width 100 feet Typical Structure Type Primarily wood pole H -frames. some steel single poles on concrete foundations, some three -pole steel angle structures. and some guyed wood angle structures Span Between Structures: Typical Range 700-1,000 Number of Structures per Mile: With Typical Range 5 to 9 Height of Structures: Typical Range 60-95 feet above ground Minimum Ground Clearance Beneath Conductor 28 feet Minimum Ground Clearance Beneath Conductor Over Roads 28 feet Circuit Configuration Variable Conductor Type and Size (circular mils) 795 kcmil, 1.108 diameter, 26/7. ACSR. Drake" Shieldwire Types and Size (inches) One 48 fiber optical ground wire, approximately 0.547 inch in diameter: and one 3/8" EHS. 7 strand ground wire 28 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application Figure 5A: Typical Structure Type -115 -kV Wood H -Frame 1 5 50 ' LI I1 0 75 el) I 6 00 10 00 15 50 61 00 27 75 — 0- 0 cf 00 Embedment 70 00 29 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application Figure 5B: Possible Structure Type-115kV Steel H -Frame U D _ U a 100-115' • 31 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application Figure 6: Typical Structure Type -115 -kV Steel Three -Pole Angle Structure 59 0 220 47C n S s8 O 0 33 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application Figure 7: Possible Structure Type —Steel Monopole 9. 7' 90'-100' p. SLIP ,. ow! ('F REQ.()) suy f CP2 35 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application Figure 8: Possible Structure Type —Angle Steel Monopole 93'- 01:' i r8' SLAP JOINT (IF RfO'D) r• 7 8' GP2 iH 37 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application 7. Type, number and USES of the proposed STRUCTURES to be erected. Approximately 110-130 transmission line structures would be used to transmit electricity over the 115 -kV transmission lines See the Project Description for additional information. 8. Type, size, weight and frequency of vehicular traffic and access routes that will be utilized. See Section 21 -3 -330.B.7 —Natural and Socioeconomic Environmental Impacts from Construction of the Electric Transmission Line, Transportation Impacts. 9. Domestic sewage facilities. Not applicable. 10. Size of stockpile, storage or waste areas to be utilized. Enclosed containment would be provided for all trash. All construction waste. including trash and litter. garbage. other solid waste. petroleum products, and other potentially hazardous materials would be removed from the site and transported to a disposal facility authorized to accept such materials. There would be no significant amount of hazardous materials stored in the Project area. See Section 21-3-330 B 5.g —Hazards and Emergency Procedures 11. Method and time schedule of removal or disposal of debris, JUNK and other wastes associated with the proposed USE. Enclosed containment would be provided for all trash. All construction waste. including trash and litter. garbage. other solid waste, petroleum products. and other potentially hazardous materials would be removed from the site and transported to a disposal facility authorized to accept such materials. See Section 21-3-330. B.5.g—Hazards and Emergency Procedures. 12. A time table showing the periods of time required for the construction of the operation. Construction is proposed to begin in summer 2020 and the facilities in-service by first quarter 2021. See Section 21-3-330.B.5.f—Projected Development Schedule. 13. Proposed LANDSCAPE plans. A formal landscape plan is not provided. as no landscaping would be done along the transmission lines or at the substation site. Areas disturbed during construction of the Project would be reseeded in coordination with the landowners and their current land use 14. Reclamation procedures to be employed as stages of the operation are phased out or upon cessation of the Use by Special Review activity. Tri-State's Environmental Protection Measures (EPM) for Construction Projects, included as Appendix C. addresses site reclamation of disturbed areas under standard BR -2. 15. A statement delineating the need for the proposed USE. As described in the Purpose and Need section, Tri-State's Member cooperative, High West. is required to deliver electrical power to oil and gas facilities in the area in order for them to operate. 39 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application 16. A description of the proposed fire protection measures. As discussed in Section 21-3-330.B.5.g—Hazards and Emergency Procedures, the conductors are supported by insulators mounted on grounded poles to prevent arcing (which could start a fire). Tri-State prohibits storage of flammables, construction of flammable structures. and other activities that have the potential to cause or provide fuel for fires on its easements and rights -of - way. There are no explosive substances associated with the proposed transmission line or substation. All Tri-State electric facilities are designed, constructed. operated, and maintained to meet or exceed all applicable standards of design and performance set forth in the NESC. The proposed line is designed with overhead ground wires and grounded towers to keep the system from becoming damaged by lightning. 17. Such additional information as may be required by the Department of Planning Services, the Planning Commission or the Board of County Commissioners in order to determine that the application meets the requirements of this Chapter and the policies of Chapter 22 of this Code. Noted. D. Special Review Permit Plan Map. 1. The map shall be delineated on reproducible material approved by the Department of Planning Services. Noted 2. The dimensions of the map shall be thirty-six (36) inches wide by twenty-four (24) inches high. Noted 3. The Special Review Permit Plan Map shall include certificates for the property owner's signature, the Planning Commission, the Board of County Commissioners and the Clerk to the Board. The required content of the certificates is available from the Department of Planning Services. Noted. 4. Vicinity Map. A vicinity map shall be drawn on the Use by Special Review Permit Plan Map. a. The scale of the vicinity map shall be one (1) inch equals two thousand (2,000) feet or at another suitable scale if approved by the Department of Planning Services. The scale of the Vicinity Map is 1 inch = 8000 feet See Vicinity Maps (Figures 4A and 4B). b. The vicinity map shall delineate all of the required information within a one-half (Y) mile radius of the property proposed for the Use by Special Review. c. The following information shall be shown on the vicinity map: 1) Section, Township and range. Noted See Vicinity Maps (Figures 4A and 4B). 2) Scale and north arrow. Noted_ See Vicinity Maps (Figures 4A and 4B). 40 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application 3) Outline of the perimeter of the parcel proposed for the Use by Special Review. Noted. See Vicinity Maps (Figures 4A and 4B). 4) The general classifications and distribution of soils over the parcel under consideration. Soil classification names and agricultural capability classifications must be noted in the legend. Noted. See Vicinity Map (Figures 4A and 4B). 5) Locations and names of all roads, irrigation ditches and water features. Noted. See Vicinity Maps (Figures 4A and 4B) 6) Location of all residences within a one -half -mile radius, existing and proposed accesses to the property proposed for the Use by Special Review, any abutting subdivision outlines and names, and the boundaries of any ADJACENT municipality. See Vicinity Map (Figures 4A and 4B) for residences and Plot Plan for access (Figure 3). 7) Any other relevant information within a one -half -mile distance of the perimeter property proposed for the Use by Special Review as may be reasonably required by the COUNTY to meet the intent and purpose of this Chapter.5. Plot Plan. A plot plan of the Use by Special Review area shall be drawn on the Special Review Permit Plan Map. a. The scale of the plot plan shall be one inch (1") equals one hundred feet (100') or at another suitable scale if approved by the Department of Planning Services. The scale of the Plot Plans is 1.' =100' See Plot Plan (Figure 3) b. The plot plan shall outline the Boundaries of the parcel being considered for the Use by Special Review. Noted See Plot Plan (Figure 3) c. The plot plan shall include the location and identification of all of the following items which exist within a two -hundred -foot radius of the boundaries of the Use by Special Review area. as well as within the area itself; it shall also include the proposed features and STRUCTURES of the Use by Special Review: See Plot Plan (Figure 3) 1) All public rights -of -way of record (including names). 2) All existing and proposed STRUCTURES. 3) All utility easements or rights -of -way for telephone, gas, electric, water and sewer lines. 4) Irrigation ditches. 5) Adjacent property lines and respective owners' names (may be shown on vicinity map instead). 6) All hydrographic features including streams, rivers, ponds and reservoirs (including names). Not applicable 41 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application 7) Topography at two -foot contour intervals or at intervals as determined necessary by the Department of Planning Services. Noted 8) Location of areas of moderate or severe soil limitations as defined by the Natural Resources Conservation Service or by a soil survey and study prepared by a soils engineer or scientist for the USES and associated STRUCTURES proposed for the parcel. Nearly all (91%) of the soils along the transmission right-of-way and the substation have low shrink/swell potential (Figure 9). The majority (77%) of the soils are not limited for structures. 9) Location and design of stormwater management devices or STRUCTURES. Stormwater management devices will be developed with detailed design and a stormwater management plan prepared for the Lloyd Sisson Substation. See Preliminary Drainage Plan (Appendix A). 10) Complete traffic circulation and parking plan showing locations and sizes. Not applicable 11) Location, amount, size and type of any proposed LANDSCAPE material, including fencing, walls, berms or other SCREENING. Not applicable 12) Location of any flood hazard, GEOLOGIC HAZARD or mineral resource areas. No parts of the Project are located within the 100 -year floodplain or a geologic hazard area. 13) The location of any sign requiring zoning approval. Distances from property lines shall be indicated. Not applicable 14) Such additional information as may be reasonably required by the Department of Planning Services, the Planning Commission or the Board of County Commissioners in order to determine that the application meets the requirements of this Chapter, the policies of Chapter 22 of this Code and any other applicable code provision or ordinance in effect. All relevant requirements noted See Plot Plan (Figure 3). 42 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application E. Supporting Documents. The following supporting documents shall be submitted as part of the application: 1. Where an authorized legal agent signs the application for the fee owners, a letter granting power of attorney to the agent from the owners must be provided. Tri-State is serving as the authorized legal agent for the fee owner of the property proposed for the Lloyd Sisson Substation (Appendix H). 2. Proof that a water supply will be available which is adequate in terms of quantity, quality and dependability (e.g., a well permit or letter from a water district). Not applicable 3. Copy of the deed or legal instrument by which the applicant obtained an interest in the property under consideration. Easements would be secured prior to construction. 4. A noise report, unless waived by the Department of Planning Services, documenting the methods to be utilized to meet the applicable noise standard. Not applicable. 5. A soil report of the site prepared by the Natural Resource Conservation Service or by a soils engineer or scientist. In those instances when the soil report indicates the existence of moderate or severe soil limitations for the USES proposed, the applicant shall detail the methods to be employed to mitigate the limitations. Nearly all of the soils along the transmission line and at the substation have low shrink/swell potential (Figure 9). The majority of the soils are not limited for structures. However, in order to identify and mitigate any concerns associated with the soils at the substation site, Tri-State will perform a geotechnical soils study. The study will identify the structural characteristics of the soil and provide recommendations for construction of foundations. Appendix D includes a soil report prepared by the NRCS. 6. If applicable, an Improvements Agreement executed by the applicant. This agreement shall be in accordance with the County policy and documents for collateral for improvements. Not applicable 7. For a RESIDENTIAL THERAPEUTIC CENTER, submittal of a report demonstrating the need for the facility; data about the background, experience and financial capacity of the proposed operator; applicable licenses; and analysis of the impact of the facility to the area and any other information relevant to evaluating the compatibility of the proposed facility. The County may waive or modify these requirements, particularly if there is a risk of harm to the future occupants (e.g., case of a domestic violence shelter). Not applicable. 43 Eagle Rock Ranch Conservation Easement County Road 121 Western High Plains 1 aiement Arapaho and Roosevelt National Forests Pawnee National Grassland Ni- In.t Lloyd on 115kv ry Point 1 1 1 1 t 1 1 1 1 1 a 516' Land County Road 11.1 iiiii a aorecoatortWpdumLLaidi€ ,cydSsionDRMtp. "•w-.: O..&Nut O star InamNry_Ibtdkwa rid 3! Road 102 1 1 1 1 1 1 1 1 1 1 1 County Road 126 County Road 106 GRP Weld, CO (0812 3) County Road 120 a Ave C U Keota County Road 122 a z u County Road 118 County Road 110 County Road 1 c 0 0 U I4 Greater Pawnee Easement County R,,:.. CUrnik bluffs County Road I I I Keota - Redbox Tri-State Generation .: •' Transmission Lloyd Sisson Delivery Point Project Figure 9: Linear Extensibility AStation Transmission OdT Govemmental / • Tri-State Line Line - Transmission Substation Service (USFS) Federal Land Land Swell Potential - 3.000000 • 10.000000 • Tri-State Other Line — Transmission utility Project t 1 Project Forest Other State Non. Organization Soil Shink 1.500000 3.000001 N St p ..... tauioi. r ,., . ,u, .. M. I I Miles in / ..• Ira {tpdai.d Upaai.d I . ,.... •..0 i•p„ • St K al MM I tmy inns r}E ! J r.. .......i.,{I- Al . I Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application AREAS AND ACTIVITIES OF STATE INTEREST APPLICATION REQUIREMENTS 21-3-330. APPLICATION SUBMITTAL REQUIREMENTS. 21 -3 -330.A —Application Requirements for a Major Facility of a Public Utility These submittal requirements apply to this application for a development permit for a major facility of a public utility approximately 20 miles of 115 -kV transmission line, one new substation (and staging area). and the use of a staging area at an existing substation. 21-3-330.B SUBMITTAL REQUIREMENTS 21 -3 -330.B.1 —Map Requirements 21-3-330.B.1.a—Name and Acreage of Proposed Use The proposed use (Lloyd Sisson 115kV Transmission Line Project) includes approximately 20 miles of 115 -kV transmission lines that would connect the existing Keota Substation to a new substation called Lloyd Sisson (see Figure 1 ). The surface area for the newly constructed transmission line structures and substation would total approximately 10 acres (7.5 acres for the substation and 2.5 acres for structure locations along the transmission line). The Project also includes a construction staging areas used for the duration of construction to store equipment and stage construction located off of County Road 89 at the existing Keota Substation and at the proposed Lloyd Sisson Substation site. The staging areas will have two construction trailers, multiple storage containers. and other associated equipment. 21-3-330.B 1.b. d —Map Requirements All map requirements, including scale as approved by Weld County, have been met. 21-3-330.B.1.c—Applicants and Consultants Applicant: Tri-State Generation and Transmission Attention: Selina Koler Address: 1100 W 116th Ave Westminster. CO 80234 Phone Number: 303-254-3720 Surveyor. Nicholas E Barrett. PLS#38037 Del -Mont Consultants, Inc 125 Colorado Avenue Montrose. CO 81401 Phone Number: 970-249-2251 Engineer Tri-State Generation and Transmission Civil Engineer, Transmission Line Address• 1100 W. 116Th Ave Westminster. CO 80234 Attention: Charlie Fung Phone Number: 720-872-7209 47 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application 21-3-330.B.2 Title Information 21-3-330.B 2.a -Surface Property Owners The names and addresses of all owners of surface property within 1,320 feet of the substation and within 500 feet of the centerline of the proposed transmission corridor are provided in Appendix G. 21-3-330. B.2. b —Access to the Project Area Right-of-way agreements will include 100 -foot easements purchased from landowners along the transmission alignment Tri-State would acquire easements for the transmission lines prior to construction Only a small portion of the transmission line right-of-way would be disturbed for structure installation and vehicle access. The majority of the proposed right-of-way can be accessed from existing county roads (Figure 2) and via cross-country travel. Where construction of new roads is required to gain access to sites where the poles would be erected. Tri-State will design the roads to minimize impacts to resources while allowing access by construction and maintenance vehicles. Existing access to the Keota Substation would be used to access the staging area. A new access road would be required off of County Road 130 for the Lloyd Sisson Substation. Tri-State will submit Access Road Permit applications where required and will comply with all County design standards. 21-3-330 B 2 c —Real Property Interests The names and addresses of all owners of surface property or holders of interest of property that would be physically disturbed or crossed by the Project were obtained from the Weld County Assessor's Office and are presented in Appendix G. 21-3-330.B 2.d —Mineral Interests Tri-State has identified mineral owners on the substation property and intends to comply with Section 24- 65.51-103, Colorado Revised Statutes. The Mineral Interests requirement is not applicable to electric transmission line projects per Section 24-65.51-103. Colorado Revised Statutes. 21-3-330.B.3 Application Submittal Requirements 21-3-330.B 3 a —c —Map Requirements Figures 4A and 4B. the Vicinity Maps. will be provided to Weld County in a reproducible format. if requested. This map includes a vicinity view of Project at a scale of 1 = 8000 feet. The permit map is consistent with the requirements of Section 21-3-330.B.3 and the relevant subsections thereof. 21-3-330.B 3.d Vicinity Map The Vicinity Map is provided in Figures 4A and 4B. 21 -3 -330.B.4 —Plot Plan The Plot Plan is shown on Figure 3 at a scale of 1:100. 48 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application 21-3-330. B.5 —Other Information 21-3-330.B.5.a—Present Use and Zoning The Project is located in unincorporated Weld County and is zoned Agricultural. This zoning is intended to provide areas for the conduct of agricultural activities and activities related to and agricultural production without interference of other incompatible land uses. Land use in the Project vicinity is primarily agricultural, residential, and energy development (oil and gas facilities). Land cover in the Project area is primarily grassland, weeds, and herbaceous vegetation (Figure 10). Existing land use is presented in Figure 11 21-3-330. B. 5. b —d —Map Extent Figure 1 illustrates all existing transmission lines of 115 -kV or greater within two miles of the Project site. 21-3-330.B.5.e—Type of Facility The Project would involve construction of approximately 20 miles of new 115 -kV transmission line originating at the Keota Substation and terminating at the new Lloyd Sisson Substation. High West would construct the distribution lines (<115 -kV), which are considered a use allowed by right in the Agricultural Zone District. and not included in this permit application. The new transmission lines would be constructed on wood and steel structures within a 100 -foot right-of-way. The transmission line would consist of approximately 110-130 structures. with conductors and phase wires, a shield wire, and an optical ground wire for internal Tri-State communications. The project will also include a new substation located on lands to be owned by Tri-State The Lloyd Sisson Substation is designed as a single 115 -kV bay to a dual voltage 34.5 -12.47 -kV distribution bank with four feeders at each distribution voltage. Ultimately the substation is laid out for a future four breaker 115 -kV ring bus and an additional eight feeders of distribution. The initial build out will consist of (4) 115 - kV switches, (1) 115 -kV circuit switcher, a 115/34.5 -kV 30/40/50 megavolt ampere (MVA) transformer, a 34.5/12.47 -kV transformer along with distribution voltage switches. meters and electrical equipment Site preparation at the substation will include grading, fencing, grounding, and construction foundations. The Project also includes a construction staging area used for the duration of construction to store equipment and stage construction located at the existing Keota Substation and at the proposed Lloyd Sisson Substation. The staging areas will have two construction trailers on -site for approximately 11 months. multiple storage containers. and other associated equipment. 21-3-330. B. 5.f —Projected Development Schedule A project schedule is presented in Table 3. Table 3: Project Schedule Milestone Date Weld County Permit Granted 1Q 2020 Easement Acquisition 1Q -2Q 2020 Construction Begins Summer 2020 In Service 1O 2021 49 N i County Road 128 County Road 124 s a ¢ T yd Sisson u 115kV cry Point p County Road 120 3 O U County Road 108 County Road Si 'f w a i C C O V NF•10a t County Road 69 County Road 112 County Road 110 1 1 p County Road 102 1 1 I 1 1 I I I t I --MS ♦C c 0 c U Co u.Tt ¢ V i ounry Road 126 County Road IOC R. ad 106 y -ate 0 m v 'o K CC O V County Road 115 County Road 110 County Road 14 r t County Road 122 al.2mIC AV,• Ave 41 County Road 99 County Road 130 County Road 112 n I Ktota • Rcdbox a Uri -State Generation and Transmission Lloyd Sisson Delivery Point Project Figure 10: Land Cover A Station - Tri-State Transmission Line - Tri-State ORT Transmission Line - Other Utility Project Transmission Line Project Substation National Land Cover Data (2016) Open Water 1 Developed. Open Space Developed. Low Intensity IIIII Developed, Medium Intensity UM Developed, High Intensity Barren Land (Rock/Send/Clay) it Deciduous Forest Mixed Forest _ Shrub/Scrub Grassland/Herbaceous 2 Pasture/Hay S Cultivated Crops Woody Wetlands Emergent Herbaceous Wetlands GITR1.4TATS WT 0 • rwW ti i I Miles 2 Cdliris Glade, f a ut.°w.e u Ler. i i r.• : -i :)*I atilt ht, LV. wanton ..040-0 ...�w.E•• Ury osonoP .a..M%U,O4I ...L II j.r.CCon r LIaydS.no. r.a I ogle Rock Rana. Conservation Easement County Road 129 c� 0 v 4 Western Hrgll Plains Easement Pawnee National Grassland Arupoho and Roosevelt National Forests i.oun't oad 109 tit in.1 tC U County Road 124 Land Doau•m•n NWT \h4Itorc4aono•.' ;?.M&ot\MX0\04µ.11 tucl\ttl l_L✓.c•Ju \ brc$ na mid County Road 132 County Road 130 County Road 114 County Road Ito Road 102 County Road 126 County Road County Road 106 vtC GRP Weld, CO (08123) Ccunty Road 120 County Road 122 County Road 110 County Road p o C C c Coun ad ISO c U County Road I Keota m - Redbox Tn-St.lti., Gem. r.tti ,c, .IN ! Trans 11111 s1 un Lloyd Sisson Delivery Point Project Figure I I: Land Use AStation - Tri-State Transmission Line - Tn-State OIL T Transmission Line -Other Utility - ei Project Transmission Line E Project Substation Forest Service (USFS) Other Federal Land State Land Non-Oovernmental Organization Land Use Agricultural ii1 Exempt net Industrial Real State ®TRI,STATE GAT:, - Miles 0, I 2 uw... _ UVJ.uro Iy,ZL1fV N Rtiiond My ' it.etlne 1 , g a . Qtall s FPrt r,-nfl nI. O —1.- , Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application 21-3-330.B 5.q —Hazards and Emergency Procedures The purpose of the proposed Project is to transform and transmit electricity. The greatest danger from a transmission line is direct contact with electrical conductors. Accordingly, extreme caution must be exercised when operating high -profile vehicles and equipment near the Project facilities. The conductors are supported by insulators mounted on grounded poles to prevent arcing (which could start a fire). Tri- State prohibits storage of flammables. construction of flammable structures. and other activities that have the potential to cause or provide fuel for fires on its easements and rights -of -way. There are no explosive substances associated with the proposed transmission lines or substations. All Tri-State electric facilities are designed. constructed, operated, and maintained to meet or exceed all applicable standards of design and performance set forth in the NESC (NESC 2012). Post -construction, the proposed transmission line and substation would be unmanned and controlled remotely by Tri-State. The proposed line is designed with overhead ground wires and grounded towers to protect the system from becoming damaged by lightning. Transmission line poles and conductors occasionally may be hit by lightning: therefore, the area near towers and other tall objects (e.g.. trees) should be avoided during thunderstorms. Electric fields are caused by voltage on an object, such as the voltage on conductors connected to an energized substation. Magnetic fields are produced when an electrical current flows through a conductor. EMF extends outward from transmission line conductors and decreases rapidly with distance from the transmission line. This concept of prudent avoidance was considered in the siting. proposed construction. and operation of this facility. The levels of EMF for the proposed transmission line are expected to be well below 150 milligauss (mG), as required by the Colorado Public Utilities Commission (PUC) (Rules 3206(e) and (f)). Typical levels at the edge of the 115 -kV right-of-way are between 10 and 20 mG These levels are similar to magnetic fields generated by common household appliances. power tools, and office equipment (Table 4). The Colorado PUC requires a utility to include the concept of prudent avoidance with respect to planning, siting, construction, and operation of transmission facilities. Prudent avoidance is the striking of a reasonable balance between the potential health effects of exposure to magnetic fields and the cost and impacts of mitigation of such exposure. by taking steps to reduce the exposure at reasonable or modest cost. Such steps might include, but are not limited to: (1) Design alternatives considering the spatial arrangement of phasing of conductors: (2) Routing lines to limit exposures to areas of concentrated population and group facilities such as schools and hospitals. (3) Installing higher structures; (4) Widening right-of-way corridors; and (5) Burial of lines. This Project maintains suitable distances from sensitive group receptors like schools and hospitals. 55 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application Table 4: Common Sources of Magnetic Fields Sources of Magnetic Fields (mG)* Distance from source 6" 1' 2' 4' Distance from source 6" 1' 2' 4' Office Sources AIR CLEANERS Lowest Median Highest COPY MACHINES Workshop Sources BATTERY CHARGERS 110 20 3 - Lowest 180 35 5 1 Median 250 50 8 2 Highest DRILLS Lowest Median Highest FAX MACHINES Lowest Median Highest FLUORESCENT LIGHTS 4 90 200 4 6 9 2 2 20 40 1 7 13 3 30 50 2 3 4 Lowest 1 Median 4 Highest POWER SAWS Lowest Median Highest Lowest Median Highest 100 150 200 50 200 1000 20 30 40 9 40 300 3 4 6 1 5 40 4 SEr ELECTRIC SCREWDRIVERS (while charging) 20 - - - Lowest 40 6 2 - Median 100 30 8 4 Highest ELECTRIC PENCIL SHARPENERS Lowest 20 8 Median 200 70 Highest 300 90 5 20 2 30 30 VIDEO DISPLAY TERMINALS (see page 48) (PCs with color monitors)** Lowest Median Highest 7 14 20 2 5 6 1 2 3 Bathroom Sources HAIR DRYERS Lowest 1 Median 300 1 Highest 700 70 10 1 ELECTRIC SHAVERS Lowest Median Highest 4 - 100 20 600 100 10 1 Distance from source 1' 2' 4' Living/Family Room Sources CEILING FANS Lowest Median 3 Highest 50 6 1 WINDOW AIR CONDITIONERS Lowest Median Highest COLOR TELEVISIONS** Lowest Median Highest 3 1 20 6 4 7 2 20 8 4 56 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application Table 4: Common Sources of Magnetic Fields, continued Sources of Magnetic Fields (mG)* Distance from source 6" 1' 2' 4' Distance from source 6" V 2' 4' Kitchen Sources BLENDERS Lowest Median Highest CAN OPENERS 30 5 70 10 100 20 Kitchen Sources ELECTRIC OVENS - - Lowest 2 - Median 3 - Highest ELECTRIC RANGES Lowest Median Highest COFFEE MAKERS 4 9 20 1 4 5 1 AMEND 500 40 3 - Lowest 600 150 20 2 Median 1500 300 30 4 Highest REFRIGERATORS Lowest Media n Highest DISHWASHERS 4 7 10 1 20 - 30 8 2 200 30 9 6 - - Lowest - - Median - - Highest TOASTERS Lowest Median Highest FOOD PROCESSORS 2 2 1 40 20 10 10 10 6 2 - Lowest 20 10 4 — Median 100 30 7 1 Highest Lowest Media n Highest 20 30 130 GARBAGE DISPOSALS 5 6 2 20 3 Lowest 60 Median 80 Highest 100 MICROWAVE OVENS*** 8 10 20 1 2 3 Lowest Median Highest MIXERS 100 1 200 4 300 200 1 10 2 30 20 Lowest Median Highest 30 5 100 10 1 600 100 10 5 10 3 20 7 Bedroom Sources DIGITAL CLOCK**** Lowest Median High 1 8 2 1 ANALOG CLOCKS (conventional clockface)**** Lowest Median Highest 1 15 2 30 5 3 BABY MONITOR (unit nearest child) Lowest 4 Median 6 Highest 15 1 2 57 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application Table 4: Common Sources of Magnetic Fields, continued Sources of Magnetic Fields (mG) Distance from source 6" 1 2' 4' Distance from source 6" 1' 2' 4' Laundry/Utility Sources ELECTRIC CLOTHES DRYERS Lowest Median Highest 10 WASHING MACHINES Lowest 4 1 Median 20 Highest 100 IRONS Lowest Median Highest Laundry/Utility Sources PORTABLE HEATERS - - Lonest - - Median - - Highest 7 1 30 6 6 1 8 1 20 3 5 1 100 20 4 150 40 8 1 VACUUM CLEANERS Lowest Median Highest 100 20 4 300 60 10 1 700 200 50 10 SEWING MACHINES Home sewing machines can produce magnetic fields of 12 mG at chest level and 5 mG at head level. Magnetic fields as high as 35 mG at chest level and 215 mG at knee level have been measured from industrial sewing machine models (Sobel. 19941. Source EMF In Your Environment, U.S. Environmental Protection Agency, 1992. • Dash (-) means that the magnetic field at this distance from the operating appliance could not be distinguished from background measurements taken before the appliance had been turned on • • Some appliances produce both 60 -Hz and higher frequency fields. For example. televisions and computer screens produce fields at 10.000-30,000 Hz i10-30 kHz) as well as 60 -Hz fields. • • • Microwave ovens produce 60 -Hz fields of several hundred rnilligauss, but they also create microwave energy inside the appliance that is at a much higher frequency (about 2 45 billion hertz) We are shielded from the higher frequency fields but not from the 60 -Hz fields. • • • • Most digital clocks have low magnetic fields. In some analog clocks. however. higher magnetic fields are produced by the motor that dines the hands. In the above table, the clocks are electrically powered using alternating current. as are all the appliances described rn these tables Source. National Institutes of Health (2002) 58 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application Numerous scientific studies have been conducted to better understand whether there is a possibility that EMF causes disease. The consensus of scientists familiar with these studies is that no significant risk to humans from long-term exposure to EMF has been established. Tri-State remains sensitive to the EMF issue and responds promptly and accurately to inquiries with currently available information. As corporate policy. Tri-State has adopted programs to ensure that its electric facilities are designed, constructed, and operated to minimize, to the extent prudent and practicable. the level of EMF that is created. Tri-States position statement on EMF health effects is included as Appendix B. Environmental Hazards Enclosed containment would be provided for all trash. All construction waste, including trash and litter, garbage. other solid waste. petroleum products. and other potentially hazardous materials would be removed from the site and transported to a disposal facility authorized to accept such materials. There would be no significant amount of hazardous materials stored in the Project area. Construction. operation, and maintenance activities would comply with all applicable federal. state. and local laws and regulations regarding the use of hazardous substances. The only hazardous chemicals expected to be used on site are those found in diesel fuel. gasoline, coolant (ethylene glycol), and lubricants in machinery. Hazardous materials would not be drained onto the ground or into streams or drainage areas. In its contract with the construction contractor, Tri-State would specify that it will hold a required pre -construction meeting with the contractor to ensure all applicable laws and Tri-State's procedures would be followed. Tri-State's Project Environmental Protection Measures for Construction Projects are attached as Appendix C Although the transmission lines would be inspected annually. emergencies may occur_ If there were an issue, appropriate field crews and engineering personnel would be notified by telephone or radio and they would undertake the required procedures to correct the problem and restore facilities to normal operations. 21-3-330 B.5.h—Name, Address. and Telephone of Applicant Tri-State Generation and Transmission. Inc. Attention: Selina Koler Address: 1100 West 116th Ave. Westminster, CO 80234 Phone Number 303-254-3720 21-3-330.B5 i—Name and Address of the Fee Owners of the Property Tri-State will own the property for the Lloyd Sisson Substation. It will acquire easements for the transmission line right-of-way. A list of property owners is provided in Appendix F. 59 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application 21-3-330. B. 5.1 Legal Description of the Property under Consideration Existing Keota Substation/Staging Area The south half of the Southeast quarter of Section 17, Township 9 North, Range 61 West, of the 6"' Prime Meridian (PM), Weld County, Colorado. Transmission Line Easement An easement one hundred (100) feet wide within the approximate limits of the identified portions of the following Sections, all located in Weld County, Colorado: Township 9 North, Range 61 West. 6t P.M.: W'/2 & SE 17, NE 20. NE 18, S '/2 & NW 7 Township 9 North, Range 62 West, 6th P.M.: N'/2 12, SW 1. W'/2& SE 2, NE 3 Township 10 North. Range 62 West, 6th P.M.: S '/2 34, E '/2 & NW 33. W % 28, NE 32.E '/2 29, W1/2 21. W/2 16, W % 9, W1/2 4 Township 11 North, Range 62 West. air P.M.: W'/2 33, N'/2 32, N'/2 31, W'/2 30, W'/2 19, SW 18 Township 11 North, Range 63 West. 6th P.M.: S'/2 13, E'/2 14. SE 11 Lloyd Sisson Substation A tract of land. situated in the SE'/4SE1/4 of Section 11, Township 11 North. Range 63 West. 6th Principal Meridian. Weld County, Colorado, more particularly described as follows: Beginning at a Point which is also the Southeast corner of said Section 11 from which the East 1/4 Corner of said Section 11 bears N01 11'51"W 2638.15 feet: Thence S89°15'18"W 615.00 feet along the South line of said Section 11; Thence N01 °11'51 "W 530.00 feet, Thence N89°15'18"E 615.00 feet to a point on the East line of Said Section 11; Thence S01 °11'51 "E 530.00 feet along said East line to the Southeast Corner of said Section 11 and the Point of Beginning. These legal descriptions are approximate and will be replaced by the final legal descriptions following completion of land survey work for the Project. They are also subject to change within the same ownership based on engineering design. 21-3-330.B.5.k—Total Acreage of the Parcel. Right -of -Way or Corridor under Consideration The surface area for the newly constructed transmission line structures and substation on private land would total approximately 10 acres. 21-3-330. B.5.l—Existing Land Use The Project would take place on private land. Land uses near the Project area include agricultural production. electric transmission. oil and gas production and storage. as well as residential uses. 60 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application 21-3-330.B.5.m—Existing Land Uses of All Properties Adjacent to Parcel The Project is located in unincorporated Weld County and is zoned Agricultural. The parcels that would be crossed by the line include agricultural property. residential use, and oil and gas development. There is an existing transmission line on some of the properties as well. There are two residences within 500 feet of the preferred transmission line route. and seven residences within 1/2 mile. There are no residences directly adjacent to the Lloyd Sisson Substation. but one residence 1 mile to the east. 21-3-330. B.5. n —Present Zone and Overlay Zones The Project is not within any Overlay Zones. 21-3-330.B.5.o-Signatures of the Applicant and Fee Owners or Their Authorized Legal Agent See USR Application Form. 21 -3 -330.B.6 —Natural and Socioeconomic Environmental Constraints Affecting Site Selection and Construction The general location for the substation site and the transmission line were initially identified based on the location of the load (oil and gas facilities), existing infrastructure (transmission lines and substations). and Federal land (Pawnee National Grasslands). General routing objectives are provided in Table 5 below. but primarily included the following considerations: • Agricultural uses (e.g., center pivots, crops) • Land ownership (e.g.. Federal) • Length following existing linear features • Number of residences in proximity • Engineering factors (e.g., transmission line crossings and angles) • Property lines • Proximity to wells and other oil and gas facilities Table 5: General Routing Objectives Land Use Objectives Avoid oil and gas flare and vent facilities by 75 feet for height clearance Avoid gas and water wells by 200 feet Parallel existing transmission lines where possible, while maintaining appropriate clearance Minimize number of transmission line crossings Favor routing transmission line through areas with existing and future land uses that are compatible with transmission lines such as industrial, commercial, and agricultural grazing Minimize areas with existing and future land uses that are less compatible such as residential developments. agricultural crops. and high density land use Where they exist and are not constrained by crowding. parallel existing linear corridors (roads and transmission lines) Minimize proximity to occupied structures and other buildings Minimize proximity to homes and buildings, and other industrial structures such as oil and gas wells, so that the ROW is kept clear of existing structures Minimize impacts to agriculture/crop lands Transportation Objectives Favor paralleling existing state highways and county and local roads where possible 61 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application Table 5: General Routing Objectives Land Cover Objectives Transmission line spans are approximately 700 feet to 1000 feet: therefore, avoid surface water or other land features such as ditches that are greater than 1000 feet in width that cannot be spanned Minimize impacts to sensitive resources that exist in wetlands by spanning wetlands or routing around wetlands or through careful pole placement Existing Utility Infrastructure Objectives Assess feasibility of routing along existing transmission and distribution lines and existing pipelines Cultural and Historic Resources Objectives Avoid potential degradation of National Register of Historic Places (NRHP)-listed sites by routing transmission line away from such sites Avoid routing transmission line within identified sites Biological Resources Objectives Reduce potential impacts to sensitive species habitat Minimize impacts to avian species by avoiding nesting areas Based on the comparative analysis and landowner input. the preferred route was selected. The preferred route minimizes impacts to residences and current land use. Impacts to agricultural lands would be minimized by designing structures to accommodate agricultural operations, to the extent feasible, based on discussions with the landowners. Placement of the transmission line structures would not preclude the use of farmland under the suspended transmission line. and only a small portion of the right-of-way would be disturbed 21-3-330.B.7 Natural and Socioeconomic Environmental Impacts from Construction of the Electric Transmission Line (satisfies 21-3-330.C.2.a) Land Use Land use along the proposed transmission line route would be minimally impacted and would continue to include agriculture. residential use. and oil and gas activities. The Weld County Code, Chapter 22. Comprehensive Plan, has been reviewed and the proposed transmission line and substation are consistent with the intent of the Comprehensive Plan. including land use, environmental resourcesand natural resources. The proposed transmission line and substation would be located in an area that is zoned Agricultural. Although the transmission line is not an agricultural use, it is a land use commonly located in agricultural areas and does not conflict with the goals outlined in the Comprehensive Plan. Careful site planning would be developed with only a localized loss of agricultural land quality. Ground disturbance generally would be limited to an area of approximately 235 square feet around each pole (-15 feet x 15 feet). The route crosses one parcel that has an active center pivot, but Tri-State is working with the landowner to design the structures to span the pivot and minimize impacts to the system The long-term presence of the existing transmission line and continued agricultural, residential, and oil and gas development in the area provide an example of the complementary nature of the uses_ 62 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application Transportation Impacts 'satisfies 21-3-330.C.2.g) A daily average of 36 construction workers would be employed during the course of the approximately 11 - month construction period. The maximum number of construction workers at any one time would be approximately 50: however, the workers would likely be dispersed along the right-of-way and at the substation. Table 6 lists the personnel and equipment for each phase of construction. Table 7 lists the weight of construction vehicles. After construction. the Project would generate infrequent trips to the transmission line and substation during operation: the line would be inspected annually and occasionally for maintenance. No adverse effects on county roads are anticipated. Tri-State would work with the Weld County Public Works Department to determine the appropriate access to the construction area. All mobile construction equipment would be certified to operate on Interstate highways. There may be short periods of time when traffic would be halted on County Roads to allow construction vehicles to enter and exit the construction area. No improvements to Weld County roads would be required. Table 6: Typical Construction Personnel and Equipment —Transmission Line Activity Number of Persons Equipment Duration of Construction Trips (Average) Substation 6 -12 6-12 pickup trucks 4 concrete trucks 1 flatbed 18 wheeler 16 weeks 3 weeks 1 month 4-6 roundtrips per day 2 -10 roundtrips per day 1-2 roundtrips per day Foundations 8 1 pressure digger 4-5 concrete trucks 3-4 pickup trucks 1 tractor/trailer 2 flatbed trailers 1 loader 1 mobile crane 1-2 dump trucks 5 weeks 1 round trip per week 4-5 round trips per day 12-16 round trips per day 4-6 round trips per day 1 round trip per day 1 round trip per day 1 roundtrip per day 4-6 round trips per day Structure Assembly and Erection 25-30 3-4 bucket trucks 3 digger derricks 1 boom truck 2 mobile crane 6 pickup trucks 3 flatbed trailers 2-3 tractor/trailers 8 weeks 3-4 round trips per day 3 round trips per day 1 round trip per day 2 round trips per week 20 round trips per day 1 round trip per day 8-12 round trips per day Wire Installation 25-30 6 pickup trucks 2 drum pullers 2 tensioners 3 bucket trucks 1 helicopter (maybe needed) 8 weeks 20 round trips per day 2 round trips per week 2 round trips per week 3 round trips per day Cleanup 8 1 bobcat 5-6 pickups 4 weeks 1 round trip per day 20 round trips per day Totals 33-38 N/A 22 weeks 30 average/45 max 63 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application Table 7: Weight of Construction Vehicles Type of Vehicle Weight (Ibs) Pickup Truck 7,000 Bucket Truck 60,000 Boom Truck 47,000 Pressure Digger 33,000 Front-end Loader 43.000 Backhoe 420 15.000 Concrete Truck (with 10 cubic yard load) 66,000 Tractor Trailer 80,000 Bobcat 4,200 Material Truck 7,000 Drum Puller Tensioner 4,500 empty / 20.600 with reel Socioeconomic Impacts (satisfies 21-3-330.C.2.g and 21-3-330.C.3.a; The communities nearest to the Project area are Grover and Hereford. Larger nearby cities include Cheyenne and Fort Collins. It is anticipated that the Project would have a small beneficial impact to the local economies of these towns and the larger metropolitan cities. Construction contractors, regardless of origin, would likely spend some money in these communities for fuel, food, or other supplies. During the construction period, the local economy may see a small influx of dollars and a small increase in sales tax revenue. The footprints of the proposed structures and the 7.5 -acre substation site would be the only land removed from current use. Land between the transmission structures would remain available for farming. grazing. or other operations that do not interfere with safe and reliable operation of the transmission line The Project area is located within District 1 of the Weld County Sheriffs Department and is within the jurisdiction of the Pawnee Fire Protection District (FPD). Public roads are maintained by the Weld County Department of Public Works. The nearest hospital to the north side of the Project area is in Cheyenne (Cheyenne Regional Medical Center) and the nearest hospital to the southern side of the Project area is in the City of Fort Collins (Poudre Valley Hospital). None of these services is expected to be affected. unless emergency situations occur. There are no adverse socioeconomic impacts associated with the Project. The Project would generate additional tax revenue for Weld County. This Project is not inconsistent with the Economic Development Goals and Policies described in the Weld County Comprehensive Plan (Weld County 2008). Discussion of Impacts on Additional Resources Including Significant Environmentally Sensitive Factors (satisfies 21-3-330.C.2c and 21-3-330.C.2e) Vegetation Including Marshlands and Wetlands The Project area is characterized by agricultural lands, oil and gas development. and residential use. The surrounding vegetation is primarily disturbed grassland. Permanent removal of vegetation would occur at structure sites and at the substation. Construction would occur primarily in areas that have been previously disturbed, and impacts to native vegetation communities are expected to be minimal. Most access would be overland or along existing roads and minimal vegetation would be disturbed from roads. 64 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application Surveys for noxious weeds were conducted along the transmission line route and at the substation site in the summer of 2019. Two state -listed noxious weeds were found, Canada thistle (Cirsium arvense) and cheatgrass (Bromus tectorum), in nine locations (5.72 acres). Wavyleaf thistle (Cirsium undulatum) was also found in numerous locations along the right-of-way: while it is comparable to many listed noxious weeds, it is a native species on the shortgrass prairie and tends to occur in small numbers and not in dense stands like Canada thistle. Tri-State will treat all existing noxious weed infestations that will be disturbed prior to construction to prevent further spread Surveys were also conducted for wetlands and other waters. Eight wetlands (3.19 acres) were formally delineated within the right-of-way. Four wetlands were riverine wetlands occurring with active stream channels, one wetland was an emergent wetland located in a swale feature, and three features were playa wetlands (naturally occurring, shallow, depressional wetlands that are typically round in shape). Two streams were mapped during the August surveys (Crow Creek and an unnamed tributary to Crow Creek) as well as two unnamed ponds which were isolated within the landscape. No drainages or wetlands would be permanently impacted by the transmission line or substation. Transmission line structures would not be placed in wetlands and access roads would be routed around wetlands. to the extent feasible. Any impacts to wetlands or stream crossings during construction would be temporary and all disturbances would be reclaimed. Figure 12 presents a map of water resources within the Project area. Wildlife and Critical Wildlife Habitat The Project area is likely to support a variety of common wildlife such as coyote. fox. skunk, rabbits. and various birds. There is no designated critical wildlife habitat in the vicinity of the project although suitable habitat may exist for the state -listed Western burrowing owl in two black -tailed prairie dog colonies that were detected during 2019 surveys Four raptor nests were found within 0.5 mile of the Project and were found to be inactive. One active nest was found outside the 0.5 mile buffer area (Swainson's hawk). Prior to construction. Tri-State will conduct additional surveys for migratory birds and Western Burrowing Owls (in prairie dog towns in the vicinity of the transmission line and substation). If any nests for migratory birds or any listed species are found, appropriate construction timing limitations will be enforced. as feasible, according to Colorado Parks and Wildlife (CPW) recommendations. Where timing limitations or setback cannot be applied due to timing constraints, other alternative mitigation measures would be considered and vetted with CPW. If any federally -listed species are found. Tri-State will consult with the U.S. Fish and Wildlife Service (USFWS) regarding avoidance and mitigation. To preclude avian electrocutions and minimize collision risk, Tri-State would incorporate Avian Protection Plan (APP) recommendations developed by the Avian Power Line Interaction Committee (APLIC 2006) and the APP guidelines (APLIC and USFWS 2005) to protect birds on power lines. as well as NESC- specified electric conductor clearances. Additionally. Tri-State contracted with EDM International. Inc to conduct an Avian Collision Risk Assessment for the route and will install flight diverters on all segments of the transmission line determined to be at high risk for collisions (primarily around ponds and wetlands). Project impacts to wildlife are expected to be minimal and limited to temporary disturbance from construction activities. 65 Lloyd Sisson 115kv Delivery Point County Road 130 -1 " I.-...al.ty Road 128 CountCcd y Road t 24� (WIZ Ly� Gi uunty Pawnee National Grassland 516 vL nd Notional Forests CC.al \�� \ _ N1 1 04 County Road 114 ounty Road I10 t County Road 118 County Road 108 • hc.rcrt Pan1`.1•plorcicotto,c•I•eacn.lar.f.F'.-1loy SS .wrOnMap.tMXD.plcufi.'cnlgl i Watt•0.uo.acct_Lloydti.on rvd • `aunty Road 122 Coon Road 118 W County Road 110 r}• County Road I County Codnty Road 11 t \_ t✓ Tri-State Generation and Transmission Uoyd Sisson Delivery Point Project Figure I2:Water Resources A Station Transmission - Tri-State Line - Tri-State Transmission Line Substation Wetlands I Wetlands Service (USFS) Federal Land Land a a OtT Project Project Surveyed Hydrology Forest Other State Non -Governmental Organization lill 91`] 0.4/S .'r -. 1...th•....a, i I 1 Miles 19 It' try•ma t iIWiMi• N 0.95 .11 *, h.it lay. rn /_,. rat Reg, ...IPlop Cheyenne 111 0 YTYY IaWrt} C. i 1 „k, p -t. �r a t dins u Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application Special Status Species Federal and state -listed threatened or endangered species that occur in the Project area are listed in Table 8. Table 8: Threatened or Endangered Species in Weld County Common Name Scientific Name Federal Status State Status Birds Mexican Spotted Owl Strix occidentalis lucida Threatened Threatened Whooping Crane Grus Americana Endangered Endangered Least Tern Sterna antillarum Endangered Endangered Piping Plover Charadrius melodus Threatened Threatened Western Burrowing Owl Athene cunicularia Threatened Bald Eagle Haliaeetus leucocephalus Special Concern Plains Sharp -tailed Grouse Tympanuchus phasianellus jamesii Endangered Ferruginous Hawk Buteo regahs Special Concern Mountain Plover Charadrius montanus Special Concern Mammals Preble's Meadow Jumping Mouse Zapus hudsonius preblei Threatened Threatened Swift Fox Vulpes velox Special Concern Plants Ute Ladies' -tresses orchid Spiranthes diluvialis Threatened Western Prairie Fringed Orchid Platanthera praeclara Threatened Source: USFWS 2019 The Mexican Spotted Owl is known to occur in the southwestern U.S. with the main populations inhabiting Arizona and New Mexico. The Mexican Spotted Owl prefers canyon habitat consisting of mixed -conifer, pine -oak, and riparian forest This habitat is not present in the Project area. Therefore, Mexican Spotted Owls are unlikely to be impacted by the Project. The Least Tern and Piping Plover are typically found near water. Terns are fish eaters and prefer to nest on sandy or pebbly beaches around lakes and reservoirs, or on sandbars consisting of sandy soils in river channels. Piping Plovers feed on a variety of beach -dwelling invertebrates and nest on sandy lakeshore beaches. sandbars within riverbeds. or even sandy wetland pastures. Given the lack of water and the intense agricultural land use. these species are not expected to occur in the Project area. The Whooping Crane is a rare North American bird with the largest population migrating between the Arkansas National Wildlife Refuge and the Wood Buffalo National Park. Whooping cranes are listed by the USFWS for Weld County as a potentially impacted species due the potential depletion of the Platte River Basin. The USFWS considers projects with less than 0.1 acre-foot per year of depletion to be de minimis exceptions for water -related activities in the Platte River Basin. The proposed Project may use 69 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application water for dust abatement activities during construction: however, water use will be below the de minimis threshold for depletion. No impacts to Whooping cranes are anticipated for this Project. The Preble's meadow jumping mouse is a federally threatened species. This species inhabits riparian areas and adjacent uplands. Preferred riparian habitat includes mixed vegetation types where dense herbaceous or woody vegetation occurs near the ground level Presence of this species in the Project area is highly unlikely There is no designated critical habitat for Preble's meadow jumping mouse in Weld County. The Ute ladies' -tresses orchid is a federally threatened plant species associated with floodplains and wet meadows. Suitable habitat for this species may exist within the Project area: however, as there would be no disturbance to wetlands as part of the Project, no impacts would occur. The Western prairie fringed orchid is a federally threatened plant species that does not occur in Colorado, but water related activities or uses in the Platte River Basin may affect this species in Nebraska. The proposed Project will use a very limited amount of water: therefore. no impacts to this species are expected. Although Bald and Golden Eagles are not federally listed species under the Endangered Species Act. they have federal protections under the Bald and Golden Eagle Protection Act and the Migratory Bird Treaty Act. Eagles are found throughout the continuous U.S. and Alaska, and occupy a very wide range of habitat. For nesting, they most frequently use cliffs but will also nest in trees. Pre -construction surveys would be conducted for raptors to identify any active nests and appropriate timing restrictions would be implemented to avoid impacts to the Bald and Golden Eagles The Plains Sharp -tailed Grouse is listed as endangered in Colorado. The bird formerly nested over much of the northern two-thirds of the eastern prairie, but the present population consists of only a few hundred birds in Douglas County (CPW 2010). No impacts to Plains Sharp -tailed Grouse are expected. The project area is considered overall range for swift fox. which is a state -species of special concern. As with other terrestrial mammal species in the area, impacts to swift fox are expected to be minimal and primarily consist of temporary disturbance from construction activities. Swift fox could be temporarily displaced during construction. but animals in the area are likely habituated to human activity due to residential development, agriculture, and oil and gas activities_ The Mountain Plover is a state -species of special concern and occurs in Weld County. More than half of the world's population nests in the state. east of the Project area in the Pawnee National Grasslands. Mountain plovers inhabit prairie grasslands. arid plains and fields. Nesting areas include grasslands grazed by prairie dogs and cattle, and overgrazed tallgrass and fallow fields. Surveys will be conducted prior to construction in areas identified as suitable habitat. If any nests are found, appropriate construction timing limitations will be implemented to avoid impacts to the Mountain Plover. The Western Burrowing Owl is a state -threatened species and could occur in the Project area. In northeastern Colorado. burrowing owls are typically associated with prairie dog colonies. Burrowing owls can excavate their own burrows. but they usually depend on burrows that have been started by colonially burrowing mammals. especially ground squirrels and prairie dogs. Pre -construction surveys will be 70 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application conducted in prairie dog towns. If Western burrowing owls are encountered, timing restrictions will be implemented to avoid impacts to this species. The Ferruginous Hawk is a state -species of special concern in Colorado. and occurs year-round in the state. It is a common winter resident on the eastern plains in open grasslands and shrub steppe communities. Ferruginous Hawks nest in flat. rolling or rugged terrain in open areas. cliffs or rock outcrops, or isolated trees in grasslands. Pre -construction surveys will be conducted for raptors and if nests are encountered construction timing will be implemented to avoid impacts to this species_ Unique Areas of Geologic, Historic, or Archaeological Importance Tri-State conducted a Class I archaeological database search of the Project area, as well as a Class III pedestrian survey on properties where survey permission was granted. Four new cultural resources and one previously recorded resource were found. All sites are recommended as not eligible for listing into the National Register of Historic Places and no further management is necessary. There are no areas of geologic importance in the vicinity of the project. Vested Water Rights The Project would have no impacts on vested water rights Construction water and water to suppress dust during construction activities would be trucked into the area. 21 -3 -330.B.8 —Long -Term Effects upon Physical and Socioeconomic Development The proposed Project would not have any adverse effects on physical or socioeconomic development of the area. 21 -3 -330.B.9 —Mitigation of Adverse Impacts and Maximization of Positive Impacts Efforts would be made so the contour of the land and natural drainage patterns along the right-of-way are not disturbed. If land contours and drainage patterns are disturbed, efforts would be made to restore any negative effects. Because Weld County has a semi -arid climate. revegetation can be difficult. As a result, disturbances to land surrounding the construction area would be minimized. All practical efforts would be made to re-establish native vegetation in the disturbed area. Tri-State's Environmental Protection Measures for Construction Projects, included as Appendix C. addresses site reclamation of disturbed areas. 21 -3 -330.B.10 —Non -Structural Alternatives There are no non-structural alternatives that would accomplish the purpose and need for the transmission lines and overall Project. If the Project is not constructed, Tri-State and its Member's customers would be required to move their facilities or self -generate. 21 -3 -330.B.11 -Structural Alternatives Transmission routing alternatives were considered in addition to the Preferred route. These alternatives are discussed in more detail in the Alternatives to the Proposed Project section (page 5). 71 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application 21 -3 -330.B.12 —Air and Water Pollution Impacts and Control Alternatives Air Pollution Impact and Control (satisfies 21-3-330.C 2.d) Construction would last approximately 11 months. Construction activities associated with the proposed transmission line and substation would generate less than significant amounts of particulate matter from soil disturbances and diesel -powered equipment. and less than significant amounts of carbon monoxide and the precursor pollutants to ozone formation from tailpipe emissions. Any air pollutants generated would be widely dispersed across the Project area, short term in duration, and minimized by the small scale of construction operations for the substation, and excavating foundations for transmission structures. Air pollutants also would be minimized through implementation of dust suppression and proper vehicle maintenance. Therefore. Project construction is not expected to impact the air quality status in the area. There would be no long-term air quality effects associated with routine operation and maintenance of the proposed transmission lines and substations. Once construction activities have been completed. but before vegetation has been re-established, some minor amount of additional dust could occur. The generation of dust would be monitored by Tri-State. and the appropriate action would be taken to control the dust and ensure that potential wind erosion is minimized. Portions of Weld County, near the Front Range cities, are designated as "non -attainment" with the 8 -hour federal ozone standard. However, the Project is in an attainment area for all measured pollutants. including particulate matter smaller than 10 micrometers in diameter (PM10). No air emissions would result from operation of the transmission line or substation. Water Pollution Impacts and Control There would be no direct impacts to water quality associated with regular operation or maintenance of the transmission line and substation. Drainage from the substation would be directed towards a detention pond located on the property. A Preliminary Drainage Report for the Lloyd Sisson Substation is included as Appendix A Prior to construction. a Storm Water Permit for Construction Activities would be acquired from the CDPH 21 -3 -330.B.13 —Design Alternatives: Access, Landscaping, and Architecture Access to the Project construction area would primarily be provided by existing roads and the right-of-way along the transmission line. Where construction of new roads is required to gain access to sites where the poles would be erected. Tri-State will design the roads to minimize impacts to resources while allowing access by construction and maintenance vehicles. The access roads would not require architectural or landscape treatments. 21 -3 -330.B.14 —New or Upgraded Services New or upgraded services are not applicable to, and not required for this Project 21 -3 -330.B.15 —Hydrologic, Atmospheric, Geologic, Pedologic, Biotic, Visual, and Noise Impacts Biotic and atmospheric impacts are described above. 72 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application Hydrologic Construction and maintenance of the transmission line and substation would not measurably impact surface water or groundwater quality. Additionally. there would be no long-term impacts to hydrology as a result of construction or operation of the Project. Project would not impact hydrologic flow of either surface water or groundwater. nor would it affect groundwater recharge Prior to construction. a Storm Water Permit for Construction Activities would be acquired from the CDPHE, where required_ Minimal water would be used during Project construction. Water for construction purposes, including concrete foundations and dust control. would be brought in from off -site sources by a construction water provider. The source of the construction water would be from either a private well owned by the construction water company or from a municipality. No existing water rights would be impacted, and there would be no long-term use of water No water would be required for the operation of the transmission line or substation Geologic Construction and operation of the electric transmission lines and substations would not alter the geology of the Project area. The Project does not occur within a Geologic Hazard Area. Pedoloqic Appendix D includes a complete list of the soil map units that occur on the right-of-way and at the substation. Figure 9 shows the linear extensibility, or soil shrink/swell potential. Shrink/swell potential of a soil is based on the change in length of an unconfined clod as moisture content is decreased from a moist to a dry state. The classes of shrink/swell potential are shown in Table 9. The majority of the soils in the right-of-way have low shrink/swell potential. Table 9: Soil Shrink/Swell Classes Class Value Low 0-3% Moderate 3-6% High 6-9% Very high > 9% Figure 13A shows the soil erodibility based on factor K within the Project area. The factor K is a measurement of the soil's susceptibility to sheet and rill erosion by water: it is calculated as a function of an average diameter of the soil particles. Factor K is one of six factors used in the Revised Universal Soil Loss Equation to predict annual rate of soil loss in tons per acre per year Factor K values range from 0.02 to 0.69. with higher values indicating higher losses. For the purpose of this report. soil K factors would be classified based on Table 10_ Table 10: Soil Erodibility Classes Class Factor K Value Low 0.05-0 2 Moderate 0.21-0.4 High > 0.4 73 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application According to the NRCS Soil Survey of the Northern Part of Weld County (Appendix D), the majority of the soils, including those found at the substation have moderate erodibility. Soil erodibility by wind is shown on Figure 13B Soils that are highly erodible by wind occur throughout the Project area, EPMs described in Appendix C are expected to mitigate impacts. There are no data sources available that evaluate subsidence hazard in the area. However, there are no mines in the vicinity of the Project, which may increase the risk of soil subsidence. Numerous soil types along the transmission line are designated as Farmlands of Statewide Importance. However, placement of the transmission line support structures would not preclude the use of farmland under the suspended transmission line. Approximately 16 4 acres of the right-of-way is considered Prime Farmland, if Irrigated. There is approximately 157 acres of Farmlands of Statewide Importance on the 100 -foot right-of-way (Figure 4A). However. only a small portion of the soils in the right-of-way would be disturbed for the Project (approximately 2.5 acres of permanent disturbance). The entire Lloyd Sisson Substation site is considered Farmland of Statewide Importance. The Project would not adversely affect any of the soil types within the Study Area. Construction of the project would cause some localized soil compaction and increase the potential for soil erosion. Long-term effects associated with soil erosion and compaction would be minimized or negated though use of EPMs (Appendix C). Noise The Project would be constructed and maintained in accordance with Colorado Revised Statutes 25-12- 101 et seq. (Noise Abatement) and Article IX, Section 14-9-10 et seq. of the Weld County Code. Audible noise levels are expected to be between 40 and 50 dBA (roughly comparable to a conversation in the home) at the edge of the 100 -foot right-of-way in normal conditions. Noise from the substation would be below 50 dBA measured 25 feet from the property line, as required by the Colorado Public Utilities Commission (PUC) (Section 3206 (f) (II)). Visual The Project is not expected to significantly affect the aesthetics of the area. There is extensive oil and gas development in the area, as well as an existing electric transmission line. 21 -3 -330.B.16 -Surface and Subsurface Drainage Subsurface drainage would not be impacted by the proposed transmission line. There would be no alteration in the pattern or intensity of surface drainage as a result of construction or operation of the transmission line. Drainage from the substation would be directed towards a detention pond located on the substation property. A Preliminary Drainage Report is included as Appendix A_ A range of measures ensuring the Project does not impact water quality is listed in Appendix C: prior to construction. a Storm Water Permit for Construction Activities would be acquired from CDPHE. where required. 74 Eagle Rock Ranch Con servatlon Easement County Road I £8 aw I Western High Plain Ease Mete! Arapaho and Roosevelt National Forests Pownee National Grassland U County R e ae e u ad 124 yd Sisson 115kV Del ery Point ty Road U County Road 132 County Road 130 1 ii 1 1 1 1 4 n 124 s County Road 120 Jotancnt ?.t 1two re least a- 'oA.nt,laWtFw.L bay d$ Is, r'Dl,Mgt•M%6'.011,►g tthiUa Wn.-Fomt-4t dor:ntornue Slb Land. County Road I 1 4 S 1 County Road 126 .NP Weld, CO 108113) 4 3 County Road 122 amie Ave $totAve to County Road Ile County Road 110 s C V County Road 114 Coon a.e't 130 P. U t I a County Road 112 \ MOP Ca Keota • Redbox Tri-State Generation and Transmission Lloyd Sisson Delivery Point Project Figure I 3a: Soil Erodibility - Water A Station • Tri-State Transmission Line - Tri-State OAT • Project Transmission Line Project Substation i Forest Service (USFS) T Other Federal Land State Land Non -Governmental Organization Soil Erodibility - Water N/A NM Low to Moderate Erodibility M. Moderate to High Erodibility .TRc.STAT! ctt►T „S • 1.41.4. I4 i.t {v1t.WS 44..44.. 0 0.5 I I Mort UNJt.: Upt.s.J I Regional Map he,Ci 'tllilt! 111 Jr la ILt r• NY County I- n a:e r. Eagle Rock Ranch Conservation Easement Count, Road I20 Aropoho and Roosevelt National Forests Pawnee Notional Grassland ii .104 County Road 124 Docs..nt Pam:'Fatto•elconorctP-oc„ntU_.pealhoa,tr.CP5500 Gec«gUc•nryPo,,r,a.1 k(6tOeu-cYwcttl y l le_ WM&ailially_Urdia nand County Road 132 County Road 130 51b Land, Count Road 114 unty Road 110 Road 102 County Road 126 County, Ro 124 County Road 10i. County Road 106 GRP Weld, CO (0d 113) County Road 120 —Laramie Ave County Road 122 Stot •Ajre Keota County Road 110 ounty Road 114 Keota - Redbox et CC Greater Pawnee Easement County na• I lu County Road I12 V Tri-State Generation ant Transmission Lloyd Sisson Delivery Point Project Figure 13b: Soil Erodibility - Wind A Station Transnvsslon - Tn-State Line - Tri-State Trails miss ion Lim - Substation Service (USFS) Federal Land Land Susceptibility to High Susceptibility to Low Susceptibility WT -ay.,— cu. .. —a IGte w..-- — — OAT Project Project Forest Other State Non -Governmental Organization WA High Moderate Moderate F QTR!-l7Te►7R • WindErosionOroup r 0 as I N I I Miles 2 I Itettena Map iv 0 Cheyenne ewer 1 •' a F60 �- a r-sliiretlsr .I . I I Ni plait$ tauint Cdbns 4� to Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application REFERENCES APLIC (Avian Power Line Interaction Committee (APLIC). 2006. Suggested Practices for Avian Protection on Power Lines: The State of the Art in 2006. Edison Electric Institute/Raptor Research Foundation. Washington, D.C. 207 pp. APLIC and USFWS (Avian Power Line Interaction Committee and U.S. Fish and Wildlife Service). 2005. Avian Protection Plan (APP) Guidelines. April CPW (Colorado Parks and Wildlife). 2011. Black -footed Ferret (Mustela nigripes)—Species Profile. Available online: http.//wildlife.state.co.us/WildlifeSpecies/SpeciesOfConcern/Mammals/Pages/BlackfootedFerret.a spx. Last updated November 30, 2011. . 2010. Plains Sharp -tailed Grouse (Tympanuchus phasianellus jamesr)—Species Profile. Available online: http://wildlife.state.co.us/WildlifeSpecies/Profiles/Birds/Pages/SharptailGrouse.aspx. Last updated July 16, 2010. NAIP (Natural Agriculture Imagery Program) 2005. Base Map Data. NESC (National Electrical Safety Code). 2012. 2012 National Electric Safety Code. National Hydrography Dataset 2006. Surface Water Data. National Landcover Dataset. 2001. Land Cover Data. NRCS (Natural Resources Conservation Service). 2019. Soils Data. NRCS (Natural Resources Conservation Service). 2019. Custom Soil Resource Report for Weld County Colorado. Southern Part Accessed at: http://websoilsurvey. nres.usda.gov/app/WebSoilSurvey.aspx in August 2. 2019. National Institutes of Health_ 2002. Electric and Magnetic Fields Associated with the Use of Electric Power. Questions and Answers. June. U.S. Fish and Wildlife Service (USFWS). Information, Planning. and Conservation System (IPAC). Accessed at http://ecos fws gov/ipac/ in November. 2019. Weld County 2008. 2008 Weld County Comprehensive Plan. Adopted November 24, 2008 Chapter 22 of the Weld County Code. Wyoming Game and Fish Department. 2011. Threatened. Endangered. and Nongame Bird and Mammal Investigations, Annual Completion Report, Period Covered: 15 April 201 to 14 April 2011. Available online: http://gf.state.wy.us/web2011/Departments/ Wildlife/pdfs/JCR NONGAMEACR 20110001023.pdf. August. 79 Lloyd Sisson 115kV Transmission Line Project Weld County USR and 1041 Application Appendix A: Preliminary Drainage Report Lloyd Sisson Substation TRI-STATE GENERATION & TRANSMISSION, INC. LLOYD SISSON SUBSTATION DRAINAGE REPORT October 23, 2019 Prepared by: P\4€ — — a - OM O- Me a — - e - e -- _ a•— IS SS DEL-MONT CONSULTANTS, INC. ENGINEERING • SURVEYING 125 Colorado Ave. • Montrose, CO 81401 • (970) 249-2251 • (970) 249-2342 FAX www.del-mont.com • servicemdel-mont_com Lloyd Sisson Substation Drainage Report TRI-STATE GENERATION & TRANSMISSION, INC. LLOYD SISSON SUBSTATION DRAINAGE REPORT ENGINEER'S CERTIFICATION I hereby certify that this drainage report for the drainage design of the Lloyd Sisson Substation was prepared by me (or under my direct supervision) in accordance with the provisions of the Weld County Engineering and Construction Guidelines for the owners thereof. I understand that the County does not and will not assume liability for drainage facilities designed by others, including the designs presented in this report. David Schieldt Registered Professional Engineer State of Colorado No. 47195 COUNTY ACCEPTANCE This report has been reviewed and found to be in general compliance with the Weld County Engineering and Construction Guidelines. The accuracy and validity of the engineering design, details, dimensions, quantities, and concepts in this report remains the sole responsibility of the professional engineer whose stamp and signature appear hereon: Accepted by: County Engineer Date Lloyd Sisson Substatioi Drainage Report TABLE OF CONTENTS 1.0 General Location and Description 1.1 Site Location 1.2 Site Description 2.0 Drainage Basins and Sub -Basins 2.1 Existing Drainage Sub -Basins 2.2 Proposed Drainage Sub -Basins 3.0 Drainage Design Criteria 3.1 Methodology 3.2 Land Cover Hydrologic Properties 3.3 Weighted Design Values 4.0 Drainage Facility Design 4.1 Historical Drainage 4.2 Proposed Drainage 5.0 Conclusions 5.1 Drainage Concept 5.2 Compliance with the Weld County Code 6.0 References Appendix A — Appendix B — Appendix C Appendix D Site Maps & Design Drawings NRCS Soils Report - Site Specific Physical Design Properties - SWMM Modeling Results == Lloyd Sisson Substation Drainage Report 1-1 1-1 1-1 2-1 2-1 2-1 3-1 3-1 3-1 3-1 4-1 4-1 4-1 5-1 5-1 5-1 6-1 1.0 General Location and Description Tri-State Generation and Transmission (TSGT) in coordination with Del -Mont Consultants, Inc. (DMC) is in the process of designing a new substation yard. The scope of work includes the construction of the substation yard. driveway, detention pond and swales, installation of new perimeter and property fence; and the addition of high voltage electrical equipment and facilities. The purpose of this report is to present the findings from the hydrologic and hydraulic analyses that were performed on the existing property as well as present the results from a detailed analysis performed on the proposed improvements to the property. 1.1 Site Location The proposed substation yard is located on a 7.5 -acre parcel owned by TSGT, situated in the SE 1/4 of Section 11. Township 11 North, Range 63 West, 6th Principal Meridian in Weld County, Colorado. The substation site is accessed from County Road 130 approximately 430' west of County Road 71. 1.2 Site Description The site naturally drains from northwest to southeast and is currently covered in native grasses. weeds; and agricultural crops. There are currently no features on the site to provide water quality or quantity treatment for discharge from the site. Site layout details will be discussed in more detail in Section 2. There are currently no developments on or near the site. No wetlands are present on the site and the site is not located within a floodplain. P\ic, Lloyd Sisson Substation Drainage Report 1-1 2.0 Drainage Basins and Sub -Basins The property functions overall as one drainage basin flowing to the east, towards the intersection of CR130 and CR71, ultimately ending up in Little Crow Creek. Proposed conditions produce several smaller sub -basins and will be discussed in detail in the following sections. 2.1 Existing Drainage Sub -Basins The existing site is comprised of one overall drainage basin: Existing Site. The entire property discharges southeasterly. A map illustrating the delineation of the existing property can be found in Appendix A. There is currently no development present on the neighboring properties located to the north and west of the substation. Table 2-1 presents the existing basin and its corresponding acreage. Table 2-1: Existing Basin Acreages Sub -Basin Total Area (Acres) Existing Site 7.5 2.2 Proposed Drainage Sub -Basins The proposed conditions will produce several different sub -basins. The proposed site is divided into three different sub -basins: Sub -Yard. West Area. and East Area. A map illustrating the delineation of the sub -basins can be found in Appendix A. The Sub -Yard contains the majority of the entrance driveway. the substation yard that is scheduled to be built. and the detention pond. The Western Area and Eastern Areas contain swales that will route any run-on from the neighboring property around the substation site. returning to historical discharge patterns. Table 2-2 presents the proposed sub -basins, their corresponding acreages. and their percentage of the overall site. Table 2-2: Proposed Sub -Basin Acreages Sub -Basin Total (Acres) Area % of Total Area Sub -Yard 2.32 31% West Area 2.00 27% East Area 3.16 42% P\ 1 Lloyd Sisson Substation Drainage Report 2-1 3.0 Drainage Design Criteria 3.1 Methodology The hydrologic/hydraulic analysis of the site was performed using the Autodesk Storm and Sanitary analysis utilizing the SWMM engine platform model for a 10 -year, 1 -hour rainfall event of 1.38 total inches and a 100 -year. 1 -hour rainfall event of 2.82 total inches. The Curve Number method of determining rainfall losses due to infiltration was used. Runoff for all site conditions was computed for both the 10 -year and 100 -year. 1 -hour storms Rainfall depths were obtained for the region from NOAA Atlas 14. Volume 8, Version 2 and rainfall distribution curves were developed using a 1 -hour rainfall distribution. Modeling results are presented in Appendix D. The Urban Drainage Detention Basin Design Workbook was utilized to determine the required water quality capture volume (WQCV) and to design the outlet structure. The spreadsheets/worksheets can be found in Appendix C and are discussed in more detail in Section 4.0. Soil data was obtained from a USDA Soils Report and gives a hydrologic soil group B for the site. The soils report is included in Appendix B. The described methods/tools used in the analysis. are in accordance with Weld County's Engineering and Construction Guidelines. 3.2 Land Cover Hydrologic Properties Curve numbers and corresponding Manning's N values. for hydrologic soil group B. were assigned to the various land cover types found on the project. both existing and proposed. and are presented in Table 3-1. Table 3-1: Land Cover Hydrologic Properties Land Cover Type Curve Number Manning's N Pasture or Range Land, Fair Condition (Existing Site) 69 0.15 Open Graded Aggregate Topping Over Compacted Base (Substation Yard) 85 0.024 Compacted Base Material (Driveways) 85 0.024 Pavement/Concrete 98 0.015 3.3 Weighted Design Values Utilizing the land cover hydrologic properties presented above. a weighted curve number and Manning's N value was calculated for each of the sub -basins, presented in Section 2.0 to be used for analysis. Table 3-2 presents the weighted design values for existing conditions and Table 3-3 presents the weighted design values for proposed conditions. Detailed calculations can be found in Appendix C. !1 Lloyd Sisson Substation Drainage Report 3-1 Table 3-2: Existing Sub -Basin Weighted Design Values Sub -Basin Total Area (Acres) Weighted Manning's N Weighted Curve Number Existing Site 7.48 0.144 69 8 Table 3-3: Proposed Sub -Basin Weighted Design Values Sub -Basin Total (Acres) Area Weighted Manning's N Weighted Curve Number Sub -Yard 2.32 0.050 88.1 West Area 2.00 0.145 69.7 East Area 3.16 0.137 70.7 ,k P Lloyd Sisson Substation Drainage Report 4.0 Drainage Facility Design 4.1 Historical Drainage Per Weld County requirements. the historical discharge rate from the 10 year — 1 -hour storm shall be utilized to determine the allowable discharge from the detention pond for the 100 year — 1 -hour storm for the proposed improvements. Values presented in Table 3-2 were used in the model to calculate a historical discharge rate for the existing property. Table 4-1 presents the discharge rate for the existing property for both the 10 -year and 100 -year 1 - hour storm events as well as a theoretical discharge for the proposed substation basin based on percentage of the total acreage. This flow rate for the Sub basin is the target flow rate to be used to design the proposed pond and outlet structure. Table 4-1: Existing Property Discharge Values Sub -Basin 10 -Year Discharge (CFS) 100 -Year Discharge (CFS) Existing Site 2.24 8.07 Sub (31% of Total) 0.69* 2.50 *Design flow rate for discharge pond for 100 -year event. 4.2 Proposed Drainage Values presented in Table 3-3 were utilized in the model to calculate the runoff for the proposed conditions. The Urban Drainage Detention Basin Design Workbook was utilized to determine the WQCV in conjunction with the model to size the detention pond. Once the pond was sized. the Urban Drainage Detention Basin Design Workbook was utilized to estimate required orifice sizes in the outlet structure to provide water quality treatment. The model was then used to verify all design elements of the pond and the outlet structure to ensure the pond not only retained the correct WQCV but to also discharge at or less than the required 10 -year historic discharge rate presented in Table 4-1 as well as drain the pond in less than the allowable time per State Requirements. The spreadsheet showing the detailed calculations can be found in Appendix C. The design of the outlet structure is detailed in the grading drawings. The proposed detention pond was designed to provide water quality treatment as well as detain the 100 -year storm event for the ultimate buildout of the yard while maintaining the required 1 -foot of freeboard prior to passing through the overflow weir. The proposed detention pond stage -storage curve is presented in Table 4-2. Table 4-2: Detention Pond Stage -Storage Table Elevation Surface Area (Sq. Ft.) 5242.61 0 5243.0 947 5244.0 11,502 5245.0 14,485 5246.0 17,736 4-1 Lloyd Sisson Substation Drainage Report The model of the proposed site conditions was utilized to calculate discharge flow rates from the outlet structure in order to size the pond discharge culvert. Table 4-3 presents the hydraulic capacity of the culvert and the required capacity to discharge flow from the outlet structure for both the 10 -year and 100 -year events. A larger pipe than needed was selected to reduce the amount of discharge the emergency weir will need to carry in the event of large back-to-back storms. The design of the driveway culvert was also analyzed to pass the flow from the west basin to the southeast corner of the property. Detailed design of the pipes is provided in Appendix A. Table 4-3: Outlet Pipe Hydraulic Capacity (100 -year event) Drainage Feature Pipe Diameter (in) Total Capacity (cfs) Required Flow Capacity (cfs) Remaining Capacity (cfs) Pond Outlet 12 2.18 0.20 1.98 Driveway Culvert 15 3.96 1.82 2.14 Table 4-4 presents the discharge rates for the proposed sub -basins for both the 10 -year and 100 -year 1 -hour storm events prior to detention. This discharge value represents the flow rate that the pond is receiving. The discharge from the pond and other basins (total discharge from site) is summarized in Table 5-1. Table 4-4: Proposed Sub -Basin Discharge Values (Pre -Detention) Sub -Basin 10 -Year Discharge (CFS) 100 -Year Discharge (CFS) Sub -Yard 5.33 12.68 West Area 0.20 1.82 East Area 0.57 3.15 Utilizing the flow rates presented above, the model was utilized to analyze the flow path of water through the piping and pond system. With the installation of the outlet structure. the pond was designed to pass both the 10 -year and 100 -year events. treat the required WQCV. and slowly release the water in the required length of time after the end of an event set forth by the County/State. The entire substation yard drains to the pond and the discharge rate leaving the pond is presented in Table 5-1. Pond drain down curves for both storm events are found in Appendix C. The intercept swale routing water around the northern end of the substation was also analyzed for adequate capacity. The contributing areas to the swales are native land. The contributing area to the north swale is approximately 10 acres. The capacity of the north swale as designed is approximately 24 cfs. The area would generate approximately 10.7 cfs for the 100 -year event. Required channel capacity is 1.33xflow rate or approximately 14.3 cfs. The capacity of the swale is adequate and can easily pass the 100 -year flow rate. meeting County regulations. nk,44:6,7, Lloyd Sisson Substation Drainage Report 4-2 5.0 Conclusions 5.1 Drainage Concept The drainage design has been prepared using sound engineering judgement and practices and will provide an effective means of controlling runoff on the project site as well as protect the site from damage. The design has been completed according to Weld County Standards and will result in no downstream impacts to any people or structures. Historic flow paths, discharge rates. and water quality have been maintained or improved. 5.2 Compliance with the Weld County Code Per Weld County requirements, the historical discharge rate from the 10 -year — 1 -hour storm shall be utilized to determine the allowable discharge rate for the 100 -year 1 -hour storm for the proposed improvements. To demonstrate compliance with this requirement. both the existing and proposed conditions were combined into one overall sub -basin. Table 5-1 presents the overall discharge rates for the overall basin as well as the individual basins. Table 5-1: Overall Sub -Basin Discharge Values (Post Detention) Basin 10 -Year (CFS) Discharge 100 -Year Discharge (CFS) Existing Proposed Existing Proposed Sub -Yard (Pond Outlet) 2 24 0.08 8.07 0.20* West Area 0.20 1.82 East Area 0.57 3.15 Total 2.24 0.85 8.07 5.17 *Discharge from the pond discharge structure is less than the required 10 -year flow rate of 0.69 cfs The pond outlet structure was sized according to County Standards so that the proposed condition 100 -year discharge rate is less than the required discharge rate from the 10 -year, 1 -hour storm event, resulting in compliance with County requirements. The detention pond was also sized according to County requirements to treat the WQCV. detain the 100 -year event. maintain 1 foot of freeboard, and maintain historical discharge patterns resulting in no downstream impacts. The emergency overflow weir has been designed according to County requirements and sizing calculations can be found in Appendix C. Weir details can be found in the grading/drainage design drawings. Inspections of the pond and outlet structure will be conducted by the owner on an annual basis as well as after large storm events. If deficiencies are identified or if maintenance is required. maintenance of the outlet structure will be performed by the owner of the property in an effort to return the structure to its original level of functionality. Maintenance may involve cleaning of sediment and debris from the facility. maintaining vegetation growth around the structure. and performing any additional maintenance required. �-- Lloyd Sisson Substation Drainage Report 5-1 6.0 References NOAA Atlas 14, Volume 8, Precipitation -Frequency Atlas of the United States. U.S. Department of Commerce, 2013. U nited States Department of Agriculture Natural Resources Conservation Service. Web Soil Survey U rban Drainage and Flood Control District. Detention Basin Design Workbook. Version 3.07. February 2017. U rban Drainage and Flood Control District. Urban Storm Drainage Criteria Manual. Volume 1-3, June 2001. Weld County Engineering and Construction Guidelines, April 2012, Updated July 2017 PN,Lloyd Sisson Substation Drainage Report 6-1 Appendix A Site Maps & Design Drawings ` Lloyd Sisson Substation Drainage Report Summery Runoff Tables hating Oe*4A Pan Contributing Area Runoff Peak 10-wa. (Ron, Runoff Peak 100yIw (Rom Wes) (ch) (C) I 1411 2. 74 R.07 Po -Poet Dear Pan, contttbutft Mae Rune? Peak t0-wa bent Ronan Peak 10OTw hunt Wes) Ice) (ch) 1 1.48 0RS s.11 7 7.)) 5.1) A.Y EXISTING max cOM011N LxtstsaC •ITERMLONI( CONIOu* oilOPOSI 0 CAW RI "NOPOSLD 'IDEA CONtOUR PROPOSED MTLRW(Oat( ctfITO,I° PROPOSED ORAINACL I LONI NI PROPOSED LOT 'LOW ARROW t t R Ir a I i L e C c m .4. : I- 7.) j pa; u•1) I! 'q ] i o I t ; 1 4 ii DRAINAGE BASIN DELINEATION I ROBS Appendix B NRCS Soils Report El\ir Lloyd Sisson Substation Drainage Report USDA United States an Department of Agriculture N RCS Natural Resources Conservation Service A product of the National Cooperative Soil Survey. a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations. and local participants Custom Soil Resource Report for Weld County, Colorado, Northern Part Lloyd Sisson Substation October 1 . 2019 Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists. urban planners. community officials, engineers. developers, builders. and home buyers. Also. conservationists. teachers, students, and specialists in recreation. waste disposal. and pollution control can use the surveys to help them understand, protect. or enhance the environment. Various land use regulations of Federal. State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm. local. and wider area planning. onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/ portal/rims/main/soils/health!) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (https //offices.sc.egov.usda.gov/locator/app?agency=nres) or your NRCS State Soil Scientist (http://www.nres.usda. gov/wps/portal/nres/detail/soils/contactus/? cid=nrcs142p2_053951). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations. and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey. the site for official soil survey information. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race. color. national origin, age. disability, and where applicable. sex. marital status. familial status, parental status. religion. sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require 2 alternative means for communication of program information (Braille. large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA. Director. Office of Civil Rights, 1400 Independence Avenue, S.W.. Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (T0D). USDA is an equal opportunity provider and employer. 3 Contents Preface 2 How Soil Surveys Are Made 5 Soil Map 8 Soil Map 9 Legend 10 Map Unit Legend 11 Map Unit Descriptions 11 Weld County. Colorado. Northern Part 13 4 —Ascalon fine sandy loam, 0 to 6 percent slopes 13 References 15 4 How Soil Surveys Are Made Soil surveys are made to provide information about the soils and miscellaneous areas in a specific area. They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, and shape of the slopes: the general pattern of drainage; the kinds of crops and native plants. and the kinds of bedrock. They observed and described many soil profiles. A soil profile is the sequence of natural layers. or horizons, in a soil. The profile extends from the surface down into the unconsolidated material in which the soil formed or from the surface down to bedrock. The unconsolidated material is devoid of roots and other living organisms and has not been changed by other biological activity. Currently. soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAs are geographically associated land resource units that share common characteristics related to physiography, geology, climate. water resources. soils, biological resources, and land uses (USDA. 2006). Soil survey areas typically consist of parts of one or more MLRA. The soils and miscellaneous areas in a survey area occur in an orderly pattern that is related to the geology landforms, relief. climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform. By observing the soils and miscellaneous areas in the survey area and relating their position to specific segments of the landform. a soil scientist develops a concept. or model, of how they were formed. Thus, during mapping, this model enables the soil scientist to predict with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape. Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soil map. however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations. supplemented by an understanding of the soil -vegetation -landscape relationship. are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries. Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color, texture. size and shape of soil aggregates, kind and amount of rock fragments. distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to taxonomic classes (units). Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States. is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil 5 Custom Soil Resource Report scientists classified and named the soils in the survey area. they compared the individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research. The objective of soil mapping is not to delineate pure map unit components: the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of soil components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such landforms and landform segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, onsite investigation is needed to define and locate the soils and miscellaneous areas. Soil scientists make many field observations in the process of producing a soil map. The frequency of observation is dependent upon several factors. including scale of mapping. intensity of mapping. design of map units, complexity of the landscape. and experience of the soil scientist. Observations are made to test and refine the soil -landscape model and predictions and to verify the classification of the soils at specific locations. Once the soil -landscape model is refined. a significantly smaller number of measurements of individual soil properties are made and recorded. These measurements may include field measurements. such as those for color, depth to bedrock. and texture. and laboratory measurements, such as those for content of sand, silt, clay. salt, and other components. Properties of each soil typically vary from one point to another across the landscape. Observations for map unit components are aggregated to develop ranges of characteristics for the components. The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties. While a soil survey is in progress. samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Soil scientists interpret the data from these analyses and tests as well as the field -observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils are field tested through observation of the soils in different uses and under different levels of management. Some interpretations are modified to fit local conditions. and some new interpretations are developed to meet local needs. Data are assembled from other sources. such as research information. production records. and field experience of specialists. For example. data on crop yields under defined levels of management are assembled from farm records and from field or plot experiments on the same kinds of soil. Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over long periods of time, but they are not predictable from year to year. For example, soil scientists can predict with a fairly high degree of accuracy that a given soil will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the soil on a specific date. After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and 6 Custom Soil Resource Report identified each as a specific map unit. Aerial photographs show trees. buildings, fields. roads, and rivers. all of which help in locating boundaries accurately. 7 Soil Map The soil map section includes the soil map for the defined area of interest. a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. 8 Custom Soil Resource Report Soil Map 40° 55' 58' N 40° 5S 45" N 550320 59310 I 5140 x090 r'7 i .r r a i rrYJ b ` 191. 551000 l l l 561000 561080 56112O Map Scale: 1:2,850 if printed on A landscape (11" x 8.5") sheet. 0 40 80 160 Meters 240 Feet 0 100 200 400 600 Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 551240 551240 551360 551420 in N 9 40° 5S 45' N Custom Soil Resource Report MAP LEGEND Area of Interest (AOl) Area of Interest (AO') Soils Soil Map Unit Polygons ..s Soil Map Unit Lines Soil Map Unit Points Special Point Features v Blowout C4 X 0 elb • 0 0 0 V a 4 0 Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot 0 7 A ow Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation +-4-+ Rails Interstate Highways US Routes Major Roads Local Roads Background a Aerial Photography 10 MAP INFORMATION The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection. should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Weld County, Colorado, Northern Part Survey Area Data. Version 14, Sep 13, 2019 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Oct 22, 2014 Oct 2, 2017 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Custom Soil Resource Report Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 4 Ascalon fine sandy loam, 0 to 6 percent slopes 32.0 100.0% Totals for Area of Interest 32.0 100.0'/0 Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions. along with the maps. can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely. if ever. can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit. and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar. components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed. and consequently they are not mentioned in the descriptions. especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned. however, onsite investigation is needed to define and locate the soils and miscellaneous areas. 11 Custom Soil Resource Report An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition. thickness. and arrangement. Soils of one series can differ in texture of the surface layer, slope. stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences. a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example. Alpha silt loam. 0 to 2 percent slopes. is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations. or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha -Beta complex, 0 to 6 percent slopes. is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha -Beta association. 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas. or it can be made up of all of them. Alpha and Beta soils. 0 to 2 percent slopes. is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. 12 Custom Soil Resource Report Weld County, Colorado, Northern Part 4 Ascalon fine sandy loam, 0 to 6 percent slopes Map Unit Setting National map unit symbol: 2t1p5 Elevation: 4,550 to 6,050 feet Mean annual precipitation: 12 to 17 inches Mean annual air temperature: 46 to 54 degrees F Frost -free period: 135 to 160 days Farmland classification: Farmland of statewide importance Map Unit Composition Ascalon and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions. and transects of the mapunit. Description of Ascalon Setting Landforrn. I nterfluves Landforrn position (two-dimensional): Backslope, summit Landform position (three-dimensional): Interfluve Down -slope shape: Linear Across -slope shape: Linear Parent material: Wind -reworked alluvium and/or calcareous sandy eolian deposits Typical profile Ap - 0 to 7 inches: fine sandy loam Bt1 - 7 to 13 inches: sandy clay loam Bt2 - 13 to 18 inches: sandy clay loam Bk - 18 to 48 inches sandy loam C - 48 to 80 inches: sandy loam Properties and qualities Slope: 0 to 6 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat) Moderately high to high (0.60 to 6.00 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Calcium carbonate, maximum in profile: 10 percent Salinity, maximum in profile: Nonsaline (0.1 to 1.9 mmhos/cm) Sodium adsorption ratio, maximum in profile: 1.0 Available water storage in profile: Moderate (about 6.8 inches) Interpretive groups Land capability classification (irrigated): 3e Land capability classification (nonirrigated): 4e Hydrologic Soil Group: B Ecological site: Sandy Plains (R067BY024CO) Hydric soil rating: No 13 Custom Soil Resource Report Minor Components Olnest Percent of map unit: 8 percent Landform. Interfluves Landform position (two-dimensional): Backslope Landform position (three-dimensional): Side slope Down -slope shape: Linear Across -slope shape: Linear Ecological site: Sandy Plains (R067BY024CO) Hydric soil rating: No Otero Percent of map unit: 7 percent Landform. Interfluves Landform position (two-dimensional): Footslope Landform position (three-dimensional): Base slope Down -slope shape: Linear Across -slope shape: Linear Ecological site: Sandy Plains (R067BY024CO) Hydric soil rating: No References American Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition. American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00. Cowardin. L.M., V. Carter. F.C. Golet. and E.T. LaRoe. 1979. Classification of wetlands and deep -water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31. Federal Register. July 13. 1994. Changes in hydric soils of the United States. Federal Register. September 18. 2002. Hydric soils of the United States. Hurt. G.W., and L.M. Vasilas, editors. Version 6.0. 2006. Field indicators of hydric soils in the United States. National Research Council. 1995. Wetlands: Characteristics and boundaries. Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/ nres/detail/national/soilsi?cid=nres142p2_054262 Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http:// www.nres.usda.gov/wps/portal/nres/detail/national/soils/?cid=nres142p2_053577 Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture; Natural Resources Conservation Service. http:// www.nres.usda.gov/wps/portal/nres/detail/national/soils/?cid=nres142p2_053580 Tiner. R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control. Wetlands Section. United States Army Corps of Engineers. Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1. United States Department of Agriculture, Natural Resources Conservation Service. National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ home/?cid=nrcs142p2_053374 United States Department of Agriculture. Natural Resources Conservation Service. National range and pasture handbook. http://www.nres.usda.gov/wps/portal/nres/ detail/national/landuse/rangepasture/?cid=stelprdb1043084 15 Custom Soil Resource Report United States Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430 -VI. http://www.nrcs.usda.gov/wps/portal/ nres/detail/soils/scientists/?cid=nres142p2_054242 United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296. http://www.nres.usda.gov/wps/portal/nres/detail/national/soils/? cid=nrcs142p2_053624 United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. http:// www.nres.usda.gov/lnternet/FSE_DOCUMENTS/nres142p2_052290.pdf 16 Appendix C Site Specific Physical Design Properties v- Lloyd Sisson Substation Drainage Report Lloyd Sisson Substation Drainage Design Existing Conditions Total Area Area Name (sf) (acres) Flow Length Width (A/L) Slope (%) Existing Site 325950 7.48 500 651.9 1 land Cover Type Curve Number Mannings N 0 -Store Pervious Pasture or Range Land, Fair Condition 69 0.15 0.15 Open Graded Aggregate Topping Over Compacted Base 85 0.024 0.1 Compacted Base Material 85 0.024 0.05 Pavement/Concrete 98 0.015 0.05 Roughness Coefficient and Curve Number Analysis Existing Site Description County Roads Native Total Area (ac) Weighted Manning's'n' Weighted Curve Number Dstore Pervious (in) Total Area (ac) 037 7.11 7.48 0.144 69.79 0.15 Manning's'n' 0.024 0.15 sum Weighted A!n 0.0088 1.0672 1.0760 0.143803405 CN A`CN 85 31.2798 69 490.9201 522.2000 69.78686915 Lloyd Sisson Substation Drainage Design Proposed Conditions Total Area Area Name (sf) (acres) Flow Length Width (A/L) Slope (%) Sub Yard & Pond West East 101059.2 87120 137649.6 232 2.VV 3._6 150 500 673.728 174.24 275.2992 1.2 1.00 1.00 Land Cover Type Curve Number Mannings N D -Store Pervious Pasture or Range Land, Fair Condition 69 0.15 0.15 Open Graded Aggregate Topping Over Compacted Base 85 0.024 - Compacted Base Material 85 0.024 0 0'5 Pavement/Concrete 98 0.015 0.05 Roughness Coefficient and Curve Number Analysis Sub -Yard & Pond Description Substation Yard/Driveway Pond Area Total Area (ac) Weighted Manning's'n' Weighted Curve Number Dstore Pervious (in) Total Area (ac) _ =3 2.32 0.050 88.12 0.10 Mannin['s'n' 0.024 0.15 sum Weighted Mn 0.0441 0.0723 0.1164 0.050176689 CN 85 100 A• N 156.2314 48.1983 204.4298 88.11627244 West Area Description Driveway/County Roads Native Total Area (ac) Weighted Manning's 'n' Weighted Curve Number Dstore Pervious (in) Total Area (ac) 0.08 1.92 2.00 0.145 69.67 0.15 Mannine's'n' 0.024 0.15 sum Weighted Mn 0.0020 0.2874 0.2894 0.144706612 85 69 A•CN 7.1419 132.2025 139.3444 69.67217631 East Area Description veway/County Roads \a• -ye Total Area (ac) Weighted Manning's'n' Weighted Curve Number Dstore Pervious (in) Total Area (act 0.33 2.83 3.16 0.137 70.68 0.15 Mannin 's'n' 0.024 0.15 sum Weighted Mn 0.0079 0.4244 0.4323 0.13680772 85 69 A•CN 28.1226 195.2111 223.3337 70.6752101 DETENTION BASIN STAGE -STORAGE TABLE BUILDER UD-Detention, Version 3.07 (February 2017) Pm)act: LOW 51aon S bstek a Sarin ID: Debitbn Pond Ernie Tm.. Ca11Ypi ratan (Rdadaon Pond) Requsd Vaunt Catalan= Sand BPS Type • Watershed Area • Watershed Length • Watershed Scope • WrrMsd Nrpernowrae • F4roraN• gldrobpc Sal Dnaap A • Pon./a98 44'.0341400 Sal Gasp B a Prcrapr MaJMOc Sal Group GD • Owed W0CV D. Tao • EOB 277 760 0012 52.00% 0.0% 1000% 00% Co Loudon tr 14. Radd Depths • claw bawd Warr Sally Canute Wee 010011 • Ewa U. Rat Wra LELRVI 2 -ye Rand Sloane (PI • 067 n.) • Syr Rue Vdara (P1 • I.11 n.) • I0. v Ranoll V r1a (P1 • 1.76 n.) • 2Syc Ruh Volume (PI • 1.82 n.) • 504r Rana Vlelene (PI a 22 n.) • Kea Rue Mine (PI • 257 n.1 • 'mat RuwN Wawa (P1 a 175 n.l • %Ro.ede 2•Fr Doreen Wane • Awn Sc Delude Wno • Apppaeae t0.n Da.ea. Vdnte a seenamae 2540 Deena Nine a tapo+ae 5o4r Detrdbn Van • lane a ate 1004. Detention Volume • Slap -Swage Cakaletion areal Wrens DVOC) • Zane 2 Wee a 100Wr - 2re 11. Sao ear. 3 Sing. Wane IOpatal l • Tmd Deana ban Wme • heel Sedapa V ns 85V) • Seal 50340.0 DePaa 96O) • Tod Aeead► Dm.eaa Dadra 04..) • Dada of Tooth Channel Mc:) • Staved laud. Chanel (5. c) a Sheens d Lee Bwa Sides (S-., ) • Ban LsaplAbWWN Row 1R w) • and Unary nee Al,1 • SuWpe Wtee Length 1L„) • Swamps Wes Wrap tWnJ • Deal of Ban Fba Oita.) • Leah d Ban Floor 11..• owl • War d Ban Flow 11,,.0.1 • Ares d Ban Fba (41,0) • Wiser d lase Flea N„0,.)• Dan d Mn Bat IFIwJ • Lerch or tan Ban 0..,,J • We of It.. Barn (1/10...J hen d Per. Ban LA..,J Von d Mt Ban N...,.) Cabala Total Oast Wane 01.") • CAC 0.129 0.077 0.106 0.151 0340 0.707 0766 0.820 0066 OWN 0.130 0.175 0.197 0.233 /acre leat acre acne/ an anal acrHeat manna ata<+nl t is Overran IJr Paplaon 053 1.11 IS 1.62 210 alt 176 ethos echo nots inches lichen ads awls Dan Increment • OS Sane cal Top of Miaopod 0m 076 Lan let Writ 60 )rit viral Peen ern aa» 0 947 Alen (acel 0.000 0.022 Nidns ir` 175 0.034 /7N 115@ 0.261 6.291 0146 279 14,485 17.735 0.733 0.407 10402 0.446 75,517 0515 3J9 19095- Pond LID Ddadion.dem. Ban 1012019. I 2.16 MA DETENTION BASIN STAGE -STORAGE TABLE BUILDER UD-Detention. Vereton 3.07 (February 2017) S 3 003 :a: .v•{tn In, — 4.. tic ^ C 630 3315 10 210 S 030 0003 t o, 203 ICS RI 300 —4nl.aal —V*j .lr III 2133 3 615 0410 Drs 0 000 000 IflS • Pod AD Delentbnnlint Ban 10117019. 11 16 MA Detention Basin Outlet Structure Design ;JO -Detention, Version 3.07 {February 2017) Project: Lloyd Sisson Substation Basin ID: Detention Pond ".S" kvocv ONE roixurraxr Pooa ZONE ) :ore: -ZONE 1 Dore I HO ce ncts Example Zone Configuration (Retention Pond) .aorwr WOKE User Input: Orifice at Underdrain Outlet (typically used to drain WQCV in a Filtration BMP) Underdrain Orifice Invert Depth = Underdrain Onfice Diameter = N/A N/A Zone 1 (WQCV) tone 2 (100 -year) Zone 3 Stage (ft) Zone Volume (ac -ft) Outlet Type 0 86 0.041 Ohdice Plate 1 71 0 192 weir&Pipe (Circular) ft (distance below the filtration media surface) inches 0.233 Total Calculated Parameters for Underdrain Underdrain Orifice Area = N/A ft' Underdrain Orifice Centroid = N/A feet User Input: Orifice Plate with one or more orifices or Elliptical Slot Weir (typically used to drain WQCV and/or EURV in a sedimentation 8MP) ft (relative to basin bottom at Stage = 0 ft) ft (relative to basin bottom at Stage = 0 ft) inches sq. inches (diameter = 11/16 inch) Invert of Lowest Orifice = Depth at top of Zone using Orifice Plate = Orifice Plate: Orifice Vertical Spacing = Orifice Plate: Orifice Area per Row = 0.00 2.00 6.00 0.36 User Input- Stage and Total Area of Each Orifice Row (numbered from lowest to highest) Stage of Orifice Centrist (ft) Orifice Area (sq- inches) Stage of Orifice Centrist (ft) Orifice Area (sq. inches) Calculated Parameters for Plate WQ Onfke Area per Row = Ellipt cal Half -Width = Elliptical Slot Centroid = Elliptical Slot Area = 2.500E-03 N/A N/A N/A feet feet ft' Row 1 (required) Row 2 (optional) Row 3 (optional) Row 4 (optional) Row S (optional) Row 6 (optional) Row 7 (optional) Row 8 (optional) 0.00 0.50 1.00 1.50 0.36 0.36 0.36 0.36 Row 9 (optional) Row 10 (optional) Row 11 (optional) Row 12 (optional) Row 13 (optional) Row 14 (optional) Row 15 (optional) Row 16 (optional) User Input: Vertical Orifice (Circular or Rectangular) Invert of Vertical Orifice = Depth at top of Zone using Vertical Orifice = Vertical Orifice Diameter = Not Selected Not Selected N/A N/A N/A ft (relative to basin bottom at Stage = 0 ft) ft (relative to basin bottom at Stage = 0 ft) inches Calculated Parameters for Vert cal Orifice Vertical Orifice Area Vertical Orifice Centroid = Not Selected Not Selected N/A N/A ft' feet User Input: Overflow Weir (Dropbox) and Grate (Flat or Sloped) Overflow Weir Front Edge Height. Ho = Overflow Weir Front Edge Length = Overflow Weir Slope = Horiz. Length of Weir Sides = Overflow Grate Open Area % _ Debris Clogging 34 = Zone 2 Weir Not Selected 2.00 4.00 0.00 0.00 70% 50% ft (relative to basin bottom at Stage = 0 f) feet H:V (enter zero for flat grate) feet %, grate open area/total area User Input: Outlet Pipe w/ Row Restriction Mate (Circular Orifice, Restrictor Plate, or Rectangular Orifice) Depth to Invert of Outlet Pipe = Circular Orifice Diameter = Zone 2 Circular Not Selected User Input: Emergency Spillway (Rectangular or Trapezoidal) Spillway Invert Stage= Spillway Crest Length = Spillway End Slopes = Freeboard above Max Water Surface = ft (distance below basin bottom at Stage = 0 ft) inches ft (relative to basin bottom at Stage = 0 ft) feet H:V feet Calculated Parameters for Overflow Weir Height of Grate Upper Edge. H, = Over Flow Weir Slope Length = Grate Open Area / 100-yr Orifice Area = Overflow Grate Open Area w/o Debris = Overflow Grate Open Area w/ Debris = Zone 2 Weir Not Selected 2.00 0.00 0.00 0.00 feet feet should be > 4 ft' ft2 Calculated Parameters for Outlet Pipe w/ Flow Restriction Plate Outlet Orifice Area = Outlet Orifice Centroid = Half -Central Angle of Restrictor Plate on Pipe = Zone 2 Circular Not Selected N/A N/A Calculated Parameters for Spillway Spillway Design Flow Depth= Stage at Top of Freeboard = Basin Area at Top of Freeboard feet feet acres ft2 feet radians Routed Hydrograph Results Design Storm Return Penod One -Hour Rainfall Depth jn) _ Calculated Runoff Volume (acre -ft) _ OPTIONAL Overnde Runoff Volume (acre -11) _ Inflow Hydrograph Volume (acre -ft) = Predevelopment Unit Peak Flow. q (cfs/ace) Predevelopment Peak Q (cfs) _ Peak Inflow 0 (cfs) _ Peak Outflow 0 (cfs) _ Ratio Peak Outflow to Predevelopment Q Structure Controlling Flow Max Velocity through Grate 1 (fps) Max Velocity through Grate 2 (fis) Tune to Drain 97% of Inflow Volume (hours) Time to Drain 99% of Inflow Volume (hours) Maximum Ponding Depth (ft) = Area at Maximum Ponding Depth (acres) _ Maximum Volume Stored (acre -R) WQCV EURV 2 Year 5 Year 10 Year 25 Year 50 Year 100 Year 500 Year 0.53 1.07 0.83 1.11 1.38 1.82 2.20 2.63 3.78 0.041 0.I29 0.073 0.106 0.151 0.240 0.307 0.3% 0.620 0.040 0.129 0.073 0.105 0.150 0.239 0.306 0 395 0.620 0.00 0.00 0.01 0.02 0.18 0 67 0.99 1 41 2.41 0.0 0.0 0.0 0 0 0.4 1 5 2.3 3 3 5.6 0.8 2.4 1.4 1.9 2.7 4.3 5.5 7.1 11.1 0.0 0.0 0.0 00 0.0 0.0 0.1 0.6 3.4 N/A N/A N/A 0.7 0.1 0 0 0.0 0.2 0.6 Plate Plate Plate Plate Plate Plate Plate Overflow Grate 1 Overflow Grate 1 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A 38 77 S5 68 83 107 >120 >120 >120 40 81 59 72 89 >120 >120 >120 >120 0.83 1.30 1.04 1.20 1.38 1.70 1.93 2.12 2.42 0.13 0.24 0.18 0 22 0 26 0.28 0.30 0.31 0.33 0.037 0 122 0.070 0 099 0 145 0 229 0.297 0.358 0.455 Detention Basin Outlet Structure Design UD-Detention, Version 3.07 (February 2017) 12 10 6 4 2 0 SOYA IN SOOYR OUT 100YR IN — LOOM out SOYR IN — Sorg OUT 1SYR IN - EYR OUT — tam IN - • - UN%OUT SW IN STR OUT 1VR IN - - - TS OUT EURV — FM OUT ••wOcv w woty OUT 0.1 1 TIME [hi] 10 3 — Sao* 25 —in —SOYR —nfl — IOYR —sYR _1nR 2 , —CUM? —Wgcv 1 0-5 0.1 1 10 DRAIN TIME (hr) 100 User Area [ft"2j Interpolated Area (ft^2j Summary Area [ft"2) Volume (ft"3j • • 41.• • Summary Volume [ft"3) Outflow [cfs) • - 41 • • Summary Outflow Ws' 200 PONOING DEPTH N 5 -A -VD Chart Axis Override X-axis Len Y -Axis Right Y-AYis minimum bound maximum bound 2.50 3.00 25.00 20-00 15.00 I 10.00 t7 5.00 0.00 4.00 Detention Basin Outlet Structure Design Out`low Hydr:,graph Workbook F%.ena're Storm Inflow Hydrographs UD-Detention, Version 3.07 (February 2017) the uses can override the calculated inflow hydrographs horn this workbook with inflow hydrographs developed in a separate program Time Interval 4 62 mm Hydrograph Constant 1082 SOURCE WORKBOOK WORKBOOK WORKBOOK WORKBOOK WORKBOOK WORKBOOK WORKBOOK WORKBOOK WORKBOOK TIME WQCV (cfsJ EURV kis) 2 Year (cfsJ 5 Year Ws) 10 Year (ds' 25 Year (cfs) 50 Year (cfsJ 100 Year (cis) 500 year (cfsJ 0 00:00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.04:37 0.00 000 000 0.00 0.00 0.00 o.00 a00 o.00 0:09:14 0.00 0.00 0.00 000 0.00 0.00 000 000 0.00 0:13:52 0.04 0.11 0.06 0.09 0.13 0.20 0.25 0.32 0.49 018:29 009 029 0.17 0.24 0.33 052 067 0.86 133 0.23.06 0.24 074 0.42 061 086 1.35 172 720 3.42 0'27:43 0.65 203 1.17 1.67 2 35 3.71 4 72 6.06 9.39 0:32:20 0 75 2 37 1 35 194 2 74 4 34 5 55 7.15 11.14 036:58 0 71 2 25 1.28 1 84 2.61 4 13 518 6 81 10.63 0.41:35 064 204 1 16 1 67 2 37 3.76 4.81 6.20 9.68 0:46:12 0.56 181 103 148 210 3.34 4.28 5.52 8.64 0:50:49 0.48 1 54 0.87 1 26 1 79 2.86 3 67 4 75 7.46 0:55:26 0.47 1.35 0.76 L10 1.57 2.50 3.21 415 6.50 1.00:04 0.38 112 0.69 099 1 42 2 26 290 3.75 5.89 1 04 41 0.30 0.99 0.56 080 1 15 1.R5 238 308 4 86 1:09:18 0.24 080 0.44 0 65 0.93 1.50 1 93 2 51 3 97 1.13:55 0.17 0 59 0.33 0 48 0.70 1.13 1 47 : 91 3 05 1:18:32 0 12 0.43 0 23 0.34 0.50 0 83 108 : 41 2 21 1:23:10 0.09 0.32 0.17 0 26 0.37 0.61 0. 79 1 03 1.65 1:27:47 0.07 0.25 0.14 0.20 0.29 0.48 0.61 0.80 1.28 132:24 0.06 0.21 011 017 0.24 0.39 0.51 0.66 105 1.37:01 005 018 010 014 0.21 0.33 0.43 0.56 0.89 1.41:38 0.05 0.16 0.09 0.13 0.18 0.29 038 0.49 0.78 1.46:16 0.04 0 14 0.08 0.11 0.16 0.27 034 0.45 0.70 1:50:53 0.04 0 13 0.07 0 11 0 15 0.25 0 32 0 41 0.65 1.55:30 0.03 0 10 0.05 008 0 11 0 18 0 23 0.30 0.48 2:00:07 0.02 007 0.04 006 008 0.13 017 022 0.35 2:04:44 0.02 0.05 0.03 0.04 0.06 0.10 012 0.16 0.26 2:09:22 0.01 0.04 0.02 0.03 0.04 007 009 0.12 0.19 2.13:59 0 01 0.03 0.01 0.02 0.03 0.05 0.06 0.08 0.13 2:18:36 0.01 0.02 0.01 0.01 0.02 0.04 0.05 0.06 0.10 2.23:13 0.00 001 0.01 0.01 0.01 0.02 003 0.04 0.07 2.27:50 0.00 0.01 0.00 0.01 0.01 0.02 0 02 0.03 004 2:32:28 0.00 000 000 000 0.01 0 01 o o: 0.02 0.03 2:37:05 0.00 000 0.00 000 0.00 0.00 001 0 01 0.01 2:41:42 000 000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2.46:19 0.00 000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2.50.56 0.00 0.00 000 000 0.00 0.00 000 0.00 0.00 2.55:34 0.00 000 000 0.00 0.00 000 000 0.00 0.00 3 00.11 0.00 000 000 000 000 0.00 000 000 000 3:04:48 0.00 0.00 0.00 000 000 0.00 000 0.00 0.00 3.09:25 coo o.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3.14:02 0.00 0.00 0.00 0.00 000 0.00 000 0.00 0.00 3:18:40 0.00 000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3 23:17 0.00 0.00 0.00 0.00 000 0.00 000 000 0.00 3 27 54 000 000 0.00 000 0.00 0.00 000 0.00 0.00 3,32:31 0.00 000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3 37.08 0.00 000 0.00 0.00 0.00 0.00 000 0.00 0.00 3 41.46 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 000 3.46:23 0.00 000 0.00 0.00 0.00 0.00 000 0.00 0.00 3.51.00 0.00 000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3.55.37 0.00 0.00 0.00 0.00 0.00 0.00 000 000 0.00 4'00:14 0.00 000 0.00 0.00 0.00 0.00 000 0.00 0.00 4 04 52 0.00 000 0.00 000 0.00 0.00 000 0.00 0.00 4 09 29 0.00 0.00 0.00 0.00 0.00 0.00 000 0.00 0.00 4 14:06 000 000 0.00 0.00 0.00 0.00 003 0.01 000 4 18 43 0.00 000 000 000 0.00 0.00 0.00 000 0.00 4 23.20 0.00 300 0.00 000 0.00 0.00 000 000 0.00 4.2758 0.00 000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4 32:35 0.00 000 0.00 0.00 0.00 0.00 000 0.00 0.00 4:37.12 0.00 000 0.00 000 0.00 0.00 0.00 0.00 0.00 4-41 49 0.00 000 0.00 000 0.00 0.00 000 0.00 000 4 46 26 0.00 000 0.00 000 0.00 0.00 0.00 0.00 0.00 4.51 04 0.00 000 0.00 000 0.00 000 0.00 0.00 0.00 4.55.41 0.00 000 0.00 000 000 GOO 000 0.00 0.00 5:00:18 0.00 000 000 000 0.00 0.00 000 0.00 0.00 504:55 0.00 000 0.00 000 0.00 0.00 000 0.00 0.00 509' 32 0.00 000 0.00 0.00 0.00 000 0.00 000 0.00 5.14.10 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 5:18:47 0.00 000 0.00 0.00 0.00 0.00 000 0.00 0.00 5.23 24 0.00 0.00 0.00 0.00 0.00 0.00 000 0.00 0.00 5:28:01 0.00 0.00 0.00 000 000 000 000 000 0.00 5 32 38 0.00 000 0.00 0.00 0.00 0.00 0.00 000 000 Detention Basin Outlet Structure Design UD-Detention. Version 3.07 (February 2017) Summary Stage -Area -Volume -Discharge Relationships The user can create a summary S -A -V -D by entering the desired stage increments and the remainder of the table will populate automatically. The user should graphically compare the summary S -A -V -D table to the full S -A -V -D table in the chart to confirm it captures all key transition points. Stage - StorageOWlow Otscrligtion SUP I^ AM 'h V' Arta (ion! Vahwre Volume TOW For best results, include rho stages of all grade slope changes le.g ISV and Floor from the S -A -V table on Sheet 'Basin'. Also include the inverts of all outlets le.g vertical orifice, overflow grate, and spillway where applicable). Lloyd Sisson Substation Calculated by: David Schieldt Trapezoidal Broad -Crested Weir Sizing Francis Weir Equation: Q=2/3 Cl bV2g H^(3/2) Solve For b: b=Q/(2/3 C1 V2g H^(3/2) ) Variable Input Units Discharge Rate (0) 12.7 cfs Disharge Coefficient (C1) 0.5 Weir Height (H) 0.5 ft Garvity Constant (g) 32.2 ft/s^2 Width of Weir (b) - Required ft Width of Weir (b) - Provided 15.00 ft Date: 10-08-2019 Appendix D SWMM Modeling Results Lloyd Sisson Substation Drainage Report Lloyd Sisson Substation 10 -Year Event Project Description File Name Project Options Flow Units Elevation Type Hydrology Method EPA SWMM Infiltration Method Link Routing Method Enable Overflow Ponding at Nodes Skip Steady State Analysis Time Periods Analysis Options 19095 Lloyd Sisson SubstationSPF CFS Elevation EPA SWMM SCS Curve Number Kinematic Wave YES NO Start Analysis On Aug 21, 2018 00:00:00 End Analysis On Aug 25, 2018 00:00:00 Start Reporting On Aug 21, 2018 00:00:00 Antecedent Dry Days 0 days Runoff (Dry Weather) Time Step 0 01:00:00 days hh:mm:ss Runoff (Wet Weather) Time Step 0 00:05:00 days hh:mm:ss Reporting Time Step 0 00:05:00 days hh:mm:ss Routing Time Step 30 seconds Number of Elements Qty Rain Gages 1 Subbasins 4 Nodes 6 Junctions 4 Outfalls ........... 1 Flow Diversions 0 Inlets 0 Storage Nodes 1 Links 8 Channels 1 Pipes 2 Pumps 0 Onfices 4 Weirs 1 Outlets 0 Pollutants 0 Land Uses 0 Rainfall Details SN Rain Gage Data Data Source Rainfall ID Source ID Type 1 Rain Gage -01 Time Series 10-YR 1 -HR Cumulative Rain Units inches State County Return Rainfall Rainfall Period Depth Distribution (years) (inches) 0.00 Uoyd Sisson Substation 10 -Year Event Subbasin Summary SN Subbasin ID Area Impervious Area (ac) 1 East 3.16 2 Existing 7.48 3 SubYard&Ponc 2.32 4 West 2.00 (%) 6.00 10.00 52.00 3.00 Weighted Average Equivalent Impervious Curve Slope Width Area Number Manning's Roughness 70.70 69.80 88.10 69.70 (%) 1.0000 1.0000 1.2000 1.0000 (ft) 275.00 652.00 1673.00 175.00 0.0150 0.0150 0.0150 0.0150 Pervious Total Total Total Total Peak Area Rainfall Infiltration Runoff Runoff Runoff Manning's Volume Roughness 0.1430 0.1440 0.0500 0.1430 Time of Concentration (in) (in) (in) (ac -in) (cfs) (days hh:mm:ss) 1.38 1.38 1.38 1.38 1.1710 1.1260 0.3800 1.2190 0.16 0.21 0.97 0.12 0.52 1.55 2.25 0.23 0.57 2.24 5.33 0.20 0 00:41:06 0 00:40:10 0 00:03:53 0 00:41:45 Lloyd Sisson Substation 10 -Year Event Node Summary SN Element Element ID Type 1 N.ChanEnd 2 N.ChanStart 3 OutletBoxlnvOut 4 OutletPipe 5 SE Corner 6 SissonPond Junction Junction Junction Junction Outfall Storage Node Invert Elevation (ft) Ground/Rim (Max) Elevation Initial Surcharge Ponded Peak Max HGL Water Elevation Area Inflow Elevation Elevation Attained (ft) (ft) 5073.15 6.00 0.00 5074.00 6.00 0.00 5242.02 5246.00 0.00 5241.87 5070.00 0.00 5241.00 5242.61 5246.00 0.00 (ft) (ft') (cfs) (ft) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.08 0.00 0.08 3.02 0.00 5.33 5073.50 5074.00 5242.15 5242.00 6058.00 5244.13 Max Surcharge Depth Attained (it) 0.00 0.00 0.00 0.00 Min Freeboard Attained (ft) 1.50 1.50 3.85 0.87 Time of Total Total Time Peak Flooded Flooded Flooding Volume Occurrence (days hh:mm) (ac -in) (min) 0 00:00 0 00:00 0 00:00 0 00:00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Lloyd Sisson Substation 10 -Year Event Link Summary SN Element Element From To (Outlet) ID Type (inlet) Node Node 1 link -02 Pipe OutleiPipe SE Corner 2 OutletPipe Pipe OutlegoxlnvOut OutletPipe 3 N.ChannelContreolhng Channel N.ChanStart N.ChanEnd 4 Ortce-01 5 Orifice -02 6 Orifice -03 7 Onfice04 8 Weir -01 Orifice SissonPond OutieffimclnvOut Orifice SissonPond Out etBarinvOut Orifice SissonPond OutletBoxlnvout Orifice SissonPond OutietBarinvOut Weir SissonPond OutletBonlnvOut Length Inlet Outlet Average Diameter or Mann ing's Peak Design Flow Peak Flow/ Peak Flow Peak Flow Peak Flow Total Time Reported Invert Invert Slope Height Roughness Flow Capacity Design Flow Velocity Depth Depth/ Surcharged Condition Elevation Elevation Ratio Total Depth Ratio ft) (ft) ft) r6) 1287.35 5067.89 30.00 5242.02 100.00 5074.00 5242.61 6058.00 -76.9100 5241.87 0.5000 5073.50 0.5000 5242.02 5242.61 5242.02 5242.61 5242.02 524261 5242.02 5242.61 5242.02 (n) 0.000 12.000 18.000 0.750 0.750 0.750 1.375 cis 0.0150 0.08 0.0150 0.08 0.0320 OW 0.02 0.02 0.01 0.03 0.00 cis) 0.00 2.18 23.91 (ftisec) (ft) 0.00 OW 0.04 1.31 0.00 OW 0.00 0.13 0.00 0.00 0.13 0.00 (min) 0.00 0.00 CalouPated 0.00 Lloyd Sisson Substation 10 -Year Event Subbasin Hydrology Subbasin : East Input Data Area (ac) 3.16 Impervious Area (%) 6.00 Weighted Curve Number 70.70 Conductivity (in/hr) 0.1500 Drying Time (days) 7.00 Average Slope (%) 1.0000 Equivalent Width (ft) 275.00 Impervious Area Manning's Roughness 0.0150 Pervious Area Manning's Roughness 0.1430 Curb & Gutter Length (ft) 0.00 Rain Gage ID Rain Gage -01 Composite Curve Number Soil/Surface Description Area Soil Curve (acres) Group Number Composite Area & Weighted CN Subbasin Runoff Results 3.16 - 70.70 3.16 7070 Total Rainfall (in) ....... 1.38 Total Runon (in) 0.00 Total Evaporation (in) 0.0000 Total Infiltration (in) 1.1710 Total Runoff (in) 0.16 Peak Runoff (cfs) 0.57 Weighted Curve Number 70.70 Time of Concentration (days hh:mm:ss) 0 00:41:06 n 8 8 Runoff (cfs) 00p 00 2002 PN0N0N0w0w00(,�0w 0 000 000000 (J� ON A 8 8 O N A iii W N0 N A ai OW N Q7 W A *tit Q1 to [J1 N O'1Eg 07 ydeJBoJpAH JJouna ti � a 3 CD N O 8 0 0 0 0 0 0 0 0 0 -+ N W lJ1 T V CO (D Rainfall (in/hr) N N N N N N N N - N W A Ul O V CO fD N N W A U1 Q1 V O lD 3se3 : uiseggnS Lloyd Sisson Substation 10 -Year Event Subbasin : Existing Input Data Area (ac) 7.48 Impervious Area (%) 10.00 Weighted Curve Number 69.80 Conductivity (in/hr) 0.1500 Drying Time (days) 7.00 Average Slope (%) 1.0000 Equivalent Width (ft) 652.00 Impervious Area Manning's Roughness 0.0150 Pervious Area Manning's Roughness 0.1440 Curb & Gutter Length (ft) 0.00 Rain Gage ID Rain Gage -01 Composite Curve Number Area Soil Curve Soil/Surface Description (acres) Group Number 7.48 - 69.80 Composite Area & Weighted CN 7.48 69.80 Subbasin Runoff Results Total Rainfall (in) 1.38 Total Runon (in) 0.00 Total Evaporation (in) 0.0000 Total Infiltration (in) 1.1260 Total Runoff (in) 021 Peak Runoff (cfs) 2.24 Weighted Curve Number 69.80 Time of Concentration (days hh:mm:ss) 0 00:40:10 Lloyd Sisson Substation 10 -Year Event Subbasin : Existing Rainfall Intensity Graph Rainfall (in/hr) u Ct 0 c 3.1 3 2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 21 2 19 1.8 17 1.6 1.5 14 1.3 1.2 11 1 0.9 0.8 07 0.6 0.5 0.4 03 0.2 01 2.4 2.3 2.2 2.1 2 1.9 1.8 1.7 16 1.5 14 13 12 11 1 09 0.8 0.7 0.6 0.5 04 03 02 01 0 5 10 15 20 25 30 35 40 45 50 Time (hrs) 5 10 15 20 25 30 40 60 65 70 75 80 90 0 Runoff Hydrograph 45 50 55 Time (hrs) 70 75 80 85 90 95 Lloyd Sisson Substation 10 -Year Event Subbasin : SubYard&Pond Input Data Area (ac) 2.32 Impervious Area (%) 52.00 Weighted Curve Number 88.10 Conductivity (in/hr) 0.1500 Drying Time (days) 7.00 Average Slope (%) 1.2000 Equivalent Width (ft) 1673.00 Impervious Area Manning's Roughness . 0.0150 Pervious Area Manning's Roughness 0.0500 Curb & Gutter Length (ft) 0.00 Rain Gage ID Rain Gage -01 Composite Curve Number Area Soil Curve Soil/Surface Description (acres) Group Number 2.32 - 88.10 Composite Area & Weighted CN 2.32 88.10 Subbasin Runoff Results Total Rainfall (in) 1.38 Total Runon (in) 0.00 Total Evaporation cm) 0.0000 Total Infiltration (in) 0.3800 Total Runoff (in) 0.97 Peak Runoff (cfs) 5.33 Weighted Curve Number 88 10 Time of Concentration (days hh:mm:ss) 0 00:03:53 Lloyd Sisson Substation 10 -Year Event Subbasin : SubYard&Pond R ahfaHH Irlterlilty Ti apt a 3 2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 21 19 L 1.8 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 01 5.4 52 5 4.8 4.6 4.4 4.2 4 3.8 3.6 3.4 3.2 3 2.8 26 24 22 18 1.6 1.4 12 1 0.8 0.6 0.4 0.2 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 Time (hrs) Runoff Hydrograph 1n 25 4r 45 5rj Tune (lir; 65 70 75 80 85 Lloyd Sisson Substation 10 -Year Event Subbasin : West Input Data Area (ac) 2.00 Impervious Area (%) 3.00 Weighted Curve Number 69.70 Conductivity (in/hr) 0.1500 Drying Time (days) 7.00 Average Slope (%) 1.0000 Equivalent Width (ft) 175.00 Impervious Area Manning's Roughness 0.0150 Pervious Area Manning's Roughness 0.1430 Curb & Gutter Length (ft) 0.00 Rain Gage ID Rain Gage -01 Composite Curve Number Area Soil Curve Soil/Surface Description (acres) Group Number 2.00 - 69.70 Composite Area & Weighted CN 2.00 69.70 Subbasin Runoff Results Total Rainfall (in) 1.38 Total Runon (in) 0.00 Total Evaporation (in) 0.0000 Total Infiltration (in) 1.2190 Total Runoff (in) 0.12 Peak Runoff (cfs) 0.20 Weighted Curve Number 69.70 Time of Concentration (days hh:mm:ss) 0 00:41:45 Lloyd Sisson Substation 10 -Year Event Subbasin : West Rainfall Intensity Graph C m c m Et 3.1 3 2.9 2.8 2.7 26 2.5 24 2.3 2.2 2.1 2 1.9 1.8 1.7 1.6 1.5 1A 13 1.2 1.1 1 0.9 0.8 07 06 05 0.4 0.3 0.2 01 0 5 10 15 0.21 _ 0.2 0 19 0.18 - 0.17 0.16 - 0.15 0.14 0.13 012 0.11 0.1 - 0.09 0.08 0.07 0.06 0.05 0.04 0.03 002 0.01 45 50 Time (hrs) Runoff Hydrograph 70 75 80 85 5 10 15 40 45 50 Time (hrs) 70 75 Lloyd Sisson Substation 10 -Year Event Junction Input SN Element Invert Ground/Rim Ground/Rim Initial Initial Surcharge Surcharge Ponded Minimum ID Elevation (Max) (Max) Water Water Elevation Depth Area Pipe Elevation Offset Elevation Depth Cover (ft) (ft) (ft) (ft) (ft) (ft) (ft) (ft') (in) 1 N.ChanEnd 5073.15 6.00 -5067.15 0.00 -5073.15 0.00 -6.00 0.00 0.00 2 N.ChanStart 5074.00 6.00 -5068.00 0.00 -5074.00 0.00 -6.00 0.00 0.00 3 OutletBoxlnvOut 5242.02 5246.00 3.98 0.00 -5242.02 0.00 -5246.00 0.00 0.00 4 OutletPipe 5241.87 5070.00 -171.87 0.00 -5241.87 0.00 -5070.00 0.00 0.00 Lloyd Sisson Substation 10 -Year Event Junction Results SN Element ID 1 N.ChanEnd 2 N.ChanStart 3 OutletBoxlnvOut 4 OutletPipe Peak Peak Max HGL Max HGL Max Inflow Lateral Elevation Depth Surcharge Inflow Attained Attained Depth Attained (cfs) (cfs) (ft) (ft) (ft) 0.00 0.00 0.08 0.08 0.00 0.00 0.00 0.00 5073.50 5074.00 5242.15 5242.00 0.35 0.00 0.13 0.13 0.00 0.00 0.00 0.00 Min Freeboard Attained (ft) 1.50 1.50 3.85 0.87 Average HGL Elevation Attained (ft) 5073.50 5074.00 5242.08 5241.93 Average HGL Time of Time of Total Total Time Depth Max HGL Peak Flooded Flooded Attained Occurrence Flooding Volume Occurrence (ft) (days hh:mm) (days hh:mm) (ac -in) (min) 0.35 0.00 0.06 0.06 0 00:00 0 00:00 0 01:13 0 01:13 0 00:00 0 00:00 0 00:00 0 00:00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 000 Lloyd Sisson Substation 10 -Year Event Channel Input SN Element ID 1 N.ChannelControlling Length Inlet Inlet Outlet Outlet Total Average Shape Invert Invert Invert Invert Drop Slope Elevation Offset Elevation Offset (ft) (ft) (ft) (ft) (ft) (ft) (%) 100.00 5074.00 0.00 5073.50 0.35 0.50 0.5000 Triangular Height Width Manning's Entrance Exit/Bend Additional Initial Flap Roughness Losses Losses Losses Flow Gate (ft) (ft) (cfs) 1.500 12.000 0.0320 0.5000 0.5000 0.0000 0.00 No Lloyd Sisson Substation 10 -Year Event Channel Results SN Element ID Peak Time of Design Flow Peak Flow/ Peak Flow Travel Peak Flow Peak Flow Total Time Froude Reported Flow Peak Flow Capacity Design Flow Velocity Time Depth Depth/ Surcharged Number Condition Occurrence Ratio Total Depth Ratio (cfs) (days hh:mm) (cfs) 1 N.ChannelControlling 0 00 0 00:00 23.91 (fUsec) (min) (ft) 000 000 0.00 (min) 0.00 0 00 Lloyd Sisson Substation 10 -Year Event Pipe Input SN Element Length Inlet Inlet Outlet Outlet Total Average Pipe Pipe Pipe Manning's Entrance Exit/Bend Additional Initial Flap ID Invert Invert Invert Invert Drop Slope Shape Diameter or Width Roughness Losses Losses Losses Flow Gate Elevation Offset Elevation Offset Height (ft) (ft) (ft) (ft) (ft) (ft) (%) (in) (in) (cfs) 1 Link -02 1287.35 5067.89 -173.98 6058.00 817.00 -990.11 -76.9100 Dummy 0.000 0.000 0.0150 0.5000 0.5000 0.0000 0.00 No 2 OutletPipe 30.00 5242.02 0.00 5241.87 0.00 0.15 0.5000 CIRCULAR 12.000 12.000 0.0150 0.5000 0.5000 0.0000 0.00 No Lloyd Sisson Substation 10 -Year Event Pipe Results SN Element Peak Time of Design Flow Peak Flow/ Peak Flow Travel Peak Flow Peak Flow Total Time Froude Reported ID Flow Peak Flow Capacity Design Flow Velocity Time Depth Depth/ Surcharged Number Condition Occurrence Ratio Total Depth Ratio (cfs) (days hh:mm) (cfs) (ft/sec) (min) (ft) (min) 1 Link -02 2 OutletPipe 0.08 0 01:13 0.08 0 01:13 0.00 0.00 0.00 0.00 0.00 0.00 2.18 0.04 1.31 0.38 0.13 0.13 0.00 Calculated Lloyd Sisson Substation 10 -Year Event Storage Nodes Storage Node : SissonPond Input Data Invert Elevation (ft) 5242.61 Max (Rim) Elevation (ft) 5246.00 Max (Rim) Offset (ft) 3.39 Initial Water Elevation (ft) 0.00 Initial Water Depth (ft) -5242.61 Ponded Area (ft2) 0.00 Evaporation Loss 0 00 Storage Area Volume Curves Storage Curve : Lloyd Sisson Pond Stage Storage Storage Area Volume (ft) (ft') (ft') 0 0 0.000 0.39 947 184.67 1.39 11502 6409.17 2.39 14485 19402.67 3.39 17736 35513.17 Lloyd Sisson Substation 10 -Year Event 3.4 3.3 3.2 3.1 3 2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2 1.9 1.8 C 1.7 C t!) 1.6 1.5 1.4 1.3 12 1.1 1 0.9 0.8 Storage Area Volume Curves Storage Volume Or) 0 5.000 10.000 15.000 2 0.00 0 25,000 30.000 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 r J t. 35.000 -3.4 C- 4. 0 r 2.000 4.000 6.000 8.000 10,000 12.000 14,000 16.000 Stomage Area (fti Storage Area — Storage Volume I 3.3 3.2 3.1 3 2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2 '1.9 1.8 1.7 1.6 1.5 -1.4 -1.3 -1.2 1.1 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 Lloyd Sisson Substation 10 -Year Event Storage Node : SissonPond (continued) Outflow Weirs Outflow Orifices SN Element Weir ID Type Flap Gate 1 Weir -01 Rectangular No SN Element Orifice ID Type Crest Elevation (ft) Crest Length Offset (ft) (ft) 5244.94 2.33 4.00 Orifice Flap Shape Gate Circular Rectangular Orifice Diameter (in) Orifice Height (in) Weir Total Discharge Height Coefficient (ft) 1.00 3.33 Rectangular Orifice Orifice Orifice Invert Coefficient Width Elevation (in) (ft) 1 Orifice -01 Side 2 Orifice -02 Side 3 Orifice -03 Side 4 Orifice -04 Side Output Summary Results CIRCULAR No CIRCULAR No CIRCULAR No CIRCULAR No Peak Inflow (cfs) 5.33 Peak Lateral Inflow (cis) 5.33 Peak Outflow (cfs) 0.08 Peak Exfiltration Flow Rate (cfm) 0.00 Max HGL Elevation Attained (ft) 5244.13 Max HGL Depth Attained (ft) 1.52 Average HGL Elevation Attained (ft) 5243.20 Average HGL Depth Attained (ft) 0.59 Time of Max HGL Occurrence (days hh:mm) 0 01:13 Total Exfiltration Volume (1000 -ft) 0.000 Total Flooded Volume (ac -in) 0 Total Time Flooded (min) 0 Total Retention Time (sec) 0.00 0.75 0.75 0.75 1.38 5242.28 5242.78 5243.28 5243.78 0.61 0.61 0.61 0.61 Lloyd Sisson 10 -Year Pond Draindown Curve � - iteptli 10Cv • SssonPorta 119005 LIuyd Station Substation 2U14-10-06 11 06 ter) I t{1 125 050 0 :5 J00 _ I0 :'0 w 40 50 lime (his) e0 70 60 YO Lloyd Sisson Substation 100 -Year Event Project Description File Name 19095 Lloyd Sisson Substation SPF Project Options Flow Units CFS Elevation Type Elevation Hydrology Method EPA SWMM EPA SWMM Infiltration Method SCS Curve Number Link Routing Method Kinematic Wave Enable Overflow Ponding at Nodes YES Skip Steady State Analysis Time Periods NO Analysis Options Start Analysis On Aug 21, 2018 00:00:00 End Analysis On Aug 25. 2018 00:00:00 Start Reporting On Aug 21. 2018 00:00:00 Antecedent Dry Days 0 days Runoff (Dry Weather) Time Step 0 01:00:00 days hh:mm:ss Runoff (Wet Weather) Time Step 0 00:05:00 days hh:mm:ss Reporting Time Step 0 00:05:00 days hh:mm:ss Routing Time Step 30 seconds Number of Elements Qty Rain Gages 1 Subbasins 4 Nodes 6 Junctions 4 Outfalls 1 Flow Diversions 0 Inlets 0 Storage Nodes 1 Links 8 Channels 1 Pipes 2 Pumps 0 Orifices 4 Weiss 1 Outlets 0 Pollutants 0 Land Uses 0 Rainfall Details SN Rain Gage Data Data Source Rainfall ID Source ID Type 1 Rain Gage -01 Time Series 100-YR 1 -HR Cumulative Rain Units inches State County Return Rainfall Rainfall Period Depth Distribution (years) (inches) 0.00 Lloyd Sisson Substation 100 -Year Event Subbasin Summary SN Subbasin ID Area Impervious Area (ac) (%) Weighted Average Equivalent Impervious Curve Slope Width Area Number Manning's Roughness (%) (ft) Pervious Area Manning's Roughness Total Total Total Rainfall Infiltration Runoff Total Peak Runoff Runoff Volume Time of Concentration (in) (in) (in) (ac -in) (cfs) (days hh:mm:ss) 1 East 3.16 2 Existing 7.48 3 SubYard&Pont 2.32 4 West 2.00 6.00 10.00 52.00 3.00 70.70 1 0000 69.80 1.0000 88.10 1.2000 69.70 1 0000 275.00 652.00 1673.00 175.00 0.0150 0.0150 0.0150 0.0150 0.1430 0.1440 0.0500 0 1430 2.82 2.82 2.82 2.82 1.8510 1.7960 0.4910 1.9440 0.92 0.98 2.30 0.82 2.91 7.30 5.33 1.65 3.15 8.07 12.68 1.82 0 00:30:52 0 00:30:10 0 00:02:55 0 00:31:21 Lloyd Sisson Substation 100 -Year Event Node Summary SN Element Element ID Type 1 N.ChanEnd 2 N.ChanStart 3 OutletBoxlnvOut 4 OutletPipe 5 SE Corner 6 SissonPond Junction Junction Junction Junction Outfall Storage Node Invert Elevation (ft) Ground/Rim (Max) Elevation Initial Surcharge Ponded Peak Max HGL Water Elevation Area Inflow Elevation Elevation Attained (ft) (ft) 5073.15 6.00 0.00 5074.00 6.00 0.00 5242.02 5246.00 0.00 5241.87 5070.00 0.00 5241.00 5242.61 5246 00 0.00 (ft) (ft2) (cfs) (ft) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.20 0.00 0.20 13.02 0.00 12.68 5073.50 5074.00 5242.23 5242.08 6058.00 5244.97 Max Surcharge Depth Attained (ft) 0.00 0.00 0.00 0.00 Min Freeboard Attained (ft) 1.50 1.50 3.77 0.79 Time of Total Total Time Peak Flooded Flooded Flooding Volume Occurrence (days hh:mm) (ac -in) (min) 0 00:00 0 00:00 0 00:00 0 00:00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Lloyd Sisson Substation 100 -Year Event Link Summary SN Element ID Element From Type (Inlet) Node 1 Link -02 Pipe 2 OutietPipe Pipe 3 N.ChannelConholling Channel 4 Orifice -01 5 Orifice -02 6 Orifice -03 7 Orifice -04 8 Weir -01 Once Orifice Orifice Orifice 111kir OutietPipe OutldBoodnvOut N.ChanStart SissonPond SissonPond SissonPond SissonPond SissonPond To (Outlet) Length Inlet Outlet Average Diameter or Manning's Peak Design Flow Peak Flow/ Peak Flow Peak Flow Peak Bow Total Time Reported Node Invert Invert Slope Height Roughness Flow Capacity Design Flow Velocity Depth Depthl Surcharged Condition Elevation Elevation Ratio Total Depth Ratio ft) SE Corner 1287.35 OutletPipe 30.00 N.ChanEnd 100.00 OutietBodnvOut OutletBo InvOut OutletBo lnvOut OutietBoxinvOut OutletBoxinvOut 5067.89 6058.00 -76.9100 5242.02 5241.87 0.5000 5074.00 5073.50 0.5000 5242.61 5242.02 5242.61 5242.02 5242.61 5242.02 524261 5242.02 5242.61 5242.02 n) 0.000 12000 18.000 0.750 0.750 0.750 1.375 cfs) 0.0150 0.20 0.0150 0.20 0.0320 0.00 0.02 0.02 0.02 0.05 0.09 cfs) 0.00 2.18 23.91 0.00 0.09 0.00 ft/sec) (ft) 0.00 1.74 0.00 0.00 0.21 0.00 0.00 0.21 0.00 (nin) 0.00 0.00 Calculated 0.00 Lloyd Sisson Substation 100 -Year Event Subbasin Hydrology Subbasin : East Input Data Area (ac) 3.16 Impervious Area (%) 6.00 Weighted Curve Number 70.70 Conductivity (in/hr) 0.1500 Drying Time (days) 7.00 Average Slope (%) 1.0000 Equivalent Width (ft) 275.00 Impervious Area Manning's Roughness 0.0150 Pervious Area Manning's Roughness 0.1430 Curb & Gutter Length (ft) 0.00 Rain Gage ID Rain Gage -01 Composite Curve Number Area Soil Curve Soil/Surface Description (acres) Group Number 3.16 - 7070 Composite Area & Weighted CN 3.16 70.70 Subbasin Runoff Results Total Rainfall (in) 2.82 Total Runon (in) 0.00 Total Evaporation (in) 0.0000 Total Infiltration (in) 1.8510 Total Runoff (in) 0.92 Peak Runoff (cfs) 3.15 Weighted Curve Number 70.70 Time of Concentration (days hh:mm:ss) 0 00:30:52 Lloyd Sisson Substation 100 -Year Event Subbasin : East Rainfall Intensity Graph 6.2 6 5.8 5.6 5.4 5.2 5 4.8 4.6 4.4 4.2 4 3.8 3.6 3.4 3.2 3 2.8 2.6 2.4 2.2 2 1.8 1.6 14 1.2 1 0.8 06 0.4 0.2 34 32 3 2.8 2.6 2.4 2.2 2 U, 7.5 18 zlz 0 c 1.6 1.4 1.2 0.8 0.6 0.4 0.2 5 10 15 20 25 40 45 50 Time (hrs) Runoff Hydrograph 65 70 75 80 85 90 95 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 Time (hrs) Lloyd Sisson Substation 100 -Year Event Subbasin : Existing Input Data Area (ac) 7.48 Impervious Area (%) 10.00 Weighted Curve Number 69.80 Conductivity (in/hr) 0.1500 Drying Time (days) 7.00 Average Slope (%) 1.0000 Equivalent Width (ft) 652.00 Impervious Area Manning's Roughness 0.0150 Pervious Area Manning's Roughness . 0.1440 Curb & Gutter Length (ft) 0.00 Rain Gage ID Rain Gage -01 Composite Curve Number Area Soil Curve Soil/Surface Description (acres) Group Number 7.48 - 69.80 Composite Area & Weighted CN 7.48 69.80 Subbasin Runoff Results Total Rainfall (in) 2.82 Total Runon (in) 0.00 Total Evaporation (in) 0.0000 Total Infiltration (in) 1.7960 Total Runoff (in) 0.98 Peak Runoff (cfs) 8.07 Weighted Curve Number 69.80 Time of Concentration (days hh:mm:ss) 0 00:30:10 Lloyd Sisson Substation 100 -Year Event 2.5 Subbasin : Existing Rainfall Intensity Graph 7 6.5 6 55 5 45 2 1.5 0.5 8.5 8 75 7 6.5 6 55 5 4.5 35 3 25 2 15 05 5 10 15 40 45 50 55 Time (hrs) Runoff Hydrograph 70 75 0 5 10 15 20 25 30 35 40 45 50 55 60 Time (hrs) 70 75 80 85 90 Lloyd Sisson Substation 100 -Year Event Subbasin : SubYard&Pond Input Data Area (ac) 2.32 Impervious Area (%) 52.00 Weighted Curve Number 88.10 Conductivity (in/hr) 0.1500 Drying Time (days) 7.00 Average Slope (%) 1.2000 Equivalent Width (ft) 1673.00 Impervious Area Manning's Roughness 0.0150 Pervious Area Manning's Roughness 0.0500 Curb & Gutter Length (ft) 0.00 Rain Gage ID Rain Gage -01 Composite Curve Number Area Soil Curve Soil/Surface Descnption (acres) Group Number 2.32 - 88.10 Composite Area & Weighted CN 2.32 88.10 Subbasin Runoff Results Total Rainfall (in) 2.82 Total Runon (in) 0,00 Total Evaporation (in) 0.0000 Total Infiltration (in) 0.4910 Total Runoff (in) 2.30 Peak Runoff (cfs) 12.68 Weighted Curve Number 88.10 Time of Concentration (days hh:mm:ss) 0 00:02:55 Lloyd Sisson Substation 100 -Year Event Subbasin : SubYard&Pond Rainfall Intensity Graph 7 6.5 6 r5 r� 4.5 Rainfall (in/hr) 3.5 3 25 15 05 0 5 10 15 20 115 _ 13 12.5 12 11.5 11 10,5 10 95 9 8.5 8 75 7 6.5 6 5.5 5 4.5 4 3.5 3- 2.5 2 1.5 1 0.5 - 35 40 45 50 Time (hrs) Runoff Hydrograph 65 70 75 0 5 10 15 20 35 40 45 50 55 Time (hrs) 70 75 80 85 90 95 Lloyd Sisson Substation 100 -Year Event Subbasin : West Input Data Area (ac) 2.00 Impervious Area (%) 3.00 Weighted Curve Number 69.70 Conductivity (in/hr) 0.1500 Drying Time (days) 7.00 Average Slope (%) 1.0000 Equivalent Width (ft) 175.00 Impervious Area Manning's Roughness 0.0150 Pervious Area Manning's Roughness 0.1430 Curb & Gutter Length (ft) 0.00 Rain Gage ID Rain Gage -01 Composite Curve Number Area Soil Curve Soil/Surface Description (acres) Group Number 2.00 - 69.70 Composite Area & Weighted CN 2.00 69.70 Subbasin Runoff Results Total Rainfall (in) 2.82 Total Runon (in) 0.00 Total Evaporation (in) 0.0000 Total Infiltration (in) 1.9440 Total Runoff (in) 0.82 Peak Runoff (cfs) 1.82 Weighted Curve Number 69.70 Time of Concentration (days hh:mm:ss) 0 00:31:21 Lloyd Sisson Substation 100 -Year Event 2.5 Subbasin : West Rainfall Intensity Graph 7 65 6 55 5 4.5 2 1.5 0.5 L M- 0 c Cr 1.9 1.8 1.7 16 1.5 1.4 1.3 1.2 11 1 0.9 0.8 0.7 0.6 0.5 04 0.3 02 01 0 5 10 15 25 30 40 45 50 Time (hrs) Runoff Hydrograph 75 0 5 10 15 20 25 40 45 50 Time (hrs) 70 75 Lloyd Sisson Substation 100 -Year Event Junction Input SN Element Invert Ground/Rim Ground/Rim Initial Initial Surcharge Surcharge Ponded Minimum ID Elevation (Max) (Max) Water Water Elevation Depth Area Pipe Elevation Offset Elevation Depth Cover (ft) (ft) (ft) (ft) (ft) (ft) (ft) (ft2) (in) 1 N.ChanEnd 5073.15 6.00 -5067.15 0.00 -5073.15 0.00 -6.00 0.00 0.00 2 N.ChanStart 5074.00 6.00 -5068.00 0.00 -5074.00 0.00 -6.00 0.00 0.00 3 OutletBoxlnvOut 5242.02 5246.00 3.98 0.00 -5242.02 0.00 -5246.00 0.00 0.00 4 OutletPipe 5241.87 5070.00 -171.87 0.00 -5241.87 0.00 -5070 00 0.00 0.00 Lloyd Sisson Substation 100 -Year Event Junction Results SN Element Peak ID Inflow 1 N.ChanEnd 2 N.ChanStart 3 OutletBoxlnvOut 4 OutletPipe Peak Lateral Inflow Max HGL Elevation Attained Max HGL Depth Attained (cfs) (ds) (ft) (ft) 0.00 0.00 0.20 0.20 0.00 0.00 0.00 0.00 5073.50 5074.00 5242.23 5242.08 0.35 0.00 0.21 0.21 Max Surcharge Depth Attained Min Freeboard Attained Average HGL Average HGL Elevation Depth Attained Attained (ft) (ft) (ft) 0.00 0.00 0.00 0.00 1.50 1.50 3.77 0.79 5073.50 5074.00 5242.12 5241.97 Time of Max HGL Occurrence Time of Total Total Time Peak Flooded Flooded Flooding Volume Occurrence (ft) (days hh:mm) (days hh:mm) (ac -in) 0.35 0.00 010 010 0 00:00 0 00:00 0 01:10 0 01:10 0 00:00 0 00:00 0 00:00 0 00:00 0.00 0.00 0.00 0.00 (min) 0.00 0.00 0.00 0.00 Lloyd Sisson Substation 100 -Year Event Channel Input SN Element ID Length Inlet Inlet Outlet Outlet Total Average Shape Height Width Manning's Entrance Exit/Bend Additional Initial Flap Invert Invert Invert Invert Drop Slope Roughness Losses Losses Losses Flow Gate Elevation Offset Elevation Offset (ft) (ft) (ft) (ft) (ft) (ft) (%) (ft) (ft) (cfs) 1 N.ChannelControlling 100.00 5074.00 0.00 5073.50 0.35 0.50 0.5000 Triangular 1.500 12.000 0.0320 0.5000 0.5000 0.0000 0.00 No Lloyd Sisson Substation 100 -Year Event Channel Results SN Element ID 1 N.ChannelControlling Peak Flow Time of Peak Flow Occurrence Design Flow Peak Flow/ Capacity Design Flow Ratio (cfs) (days hh:mm) (cfs) 0.00 0 00:00 Peak Flow Travel Peak Flow Peak Flow Total Time Froude Reported Velocity Time Depth Depth/ Surcharged Number Condition Total Depth Ratio (ft/sec) (min) (H) 23.91 0.00 0.00 (min) 0.00 0.00 0.00 Lloyd Sisson Substation 100 -Year Event Pipe Input SN Element Length Inlet ID Invert Elevation (ft) (ft) Inlet Outlet Outlet Invert Invert Invert Offset Elevation Offset (ft) (ft) (ft) 1 Link -02 1287.35 5067.89 -173 98 6058.00 817.00 2 OutletPipe 30.00 5242.02 0.00 5241.87 0.00 Total Average Pipe Pipe Pipe Manning's Entrance Exit/Bend Additional Initial Flap Drop Slope Shape Diameter or Width Roughness Losses Losses Losses Flow Gate Height (ft) (%) (in) (in) (cfs) -990.11 -76.9100 Dummy 0.000 0.000 0.0150 0.5000 0.5000 0.0000 0.00 No 0.15 0.5000 CIRCULAR 12.000 12.000 0.0150 0.5000 0.5000 0.0000 0.00 No Lloyd Sisson Substation 100 -Year Event Pipe Results SN Element Peak Time of Design Flow Peak Flow/ Peak Flow Travel Peak Flow Peak Flow Total Time Froude Reported ID Flow Peak Flow Capacity Design Flow Velocity Time Depth Depth/ Surcharged Number Condition Occurrence Ratio Total Depth Ratio (cfs) (days hh:mm) (cfs) (ft/sec) (min) (ft) (min) 1 Link -02 0.20 0 01:10 0.00 0.00 0.00 0.00 0.00 0.00 2 OutletPipe 0.20 0 01:10 2.18 0.09 1.74 0.29 0.21 0.21 0.00 Calculated Lloyd Sisson Substation 100 -Year Event Storage Nodes Storage Node : SissonPond Input Data Invert Elevation (ft) 5242.61 Max (Rim) Elevation (ft) 5246.00 Max (Rim) Offset (ft) 3.39 Initial Water Elevation (ft) 0.00 Initial Water Depth (ft) -5242.61 Ponded Area (ft') 0.00 Evaporation Loss ... 0.00 Storage Area Volume Curves Storage Curve Lloyd Sisson Pond Stage Storage Storage Area Volume (ft) (ft') (ft') 0 0 0.000 0.39 947 184.67 1.39 11502 6409.17 2.39 14485 19402.67 3.39 17736 35513.17 Lloyd Sisson Substation 100 -Year Event 3.4 3.3 3.2 3.1 3 2.9 2.8 2.7 0 Storage Area Volume Curves Storage Volume (ft3) 5,000 10,000 15,000 20,000 25,000 30,000 35,000 2.6 - 2.5 2.4 2.3 2.2 2.1 2 1.9 1.4 1.3 1.2 1.1 -_ 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 r I- i J- 0 2,000 4.000 6.00 MM 10.000 Storage Area (ft2) 12.000 14,000 16.000 - Storage Area - Storage Volume I 3.4 -3.3 3.2 3.1 3 2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 Lloyd Sisson Substation 100 -Year Event Storage Node : SissonPond (continued) Outflow Weirs SN Element Weir Flap Crest Crest Length Weir Total Discharge ID Type Gate Elevation Offset Height Coefficient (ft) (ft) (ft) (ft) Outflow Orifices 1 Weir -01 Rectangular No 5244.94 2.33 4.00 1.00 3.33 SN Element Orifice Orifice Flap Circular Rectangular Rectangular Orifice Orifice ID Type Shape Gate Orifice Orifice Orifice Invert Coefficient Diameter Height Width Elevation (in) (in) (in) (ft) 1 Orifice -01 Side 2 Orifice -02 Side 3 Orifice -03 Side 4 Orifice -04 Side Output Summary Results CIRCULAR No CIRCULAR No CIRCULAR No CIRCULAR No Peak Inflow (cfs) 12.68 Peak Lateral Inflow (cfs) 12.68 Peak Outflow (cfs) 0.20 Peak Exfiltration Flow Rate (cfm) 0.00 Max HGL Elevation Attained (ft) 5244.97 Max HGL Depth Attained (ft) 236 Average HGL Elevation Attained (ft) 5243.82 Average HGL Depth Attained (ft) 1.21 Time of Max HGL Occurrence (days hh:mm) 0 01:10 Total Exfiltration Volume (1000 -ft') 0.000 Total Flooded Volume (ac -in) 0 Total Time Flooded (min) 0 Total Retention Time (sec) 0.00 0.75 0.75 0.75 1.38 5242.28 5242.78 5243.28 5243.78 0.61 0.61 0.61 0.61 Lloyd Sisson 100 -Year Pond Draindown Curve zs 2.0 15 I to 0.5 00 10 50 Time (Ws) 60 711 SITE cto HEREFORD GROVER VICINITY MAP N.T.S. TRI STAT E Generation and Transmission Association, Inc. Lloyd Sisson Substation Construction of a New Substation including Grading, Drainage, and Surface Improvements Weld County, Colorado Construction Plans prepared in cooperation with: I rA L..1lr DEL-MONT CONSULTANTS, INC. ENGINEERING V SURVEYING I25 Colorado Ava ♦ Morton. CO 81401 t (970) 2497231 V (970) 2492342 FAX went oal motif mm V aorviceOdoltroM com t F 1 LLOYD SISSON SUBSTATION COVER SHEET h Lnw � p q �o u o? tkg zz Ida I I s I i e I f a } 4 5 I F 3 440d 10/13(10 Ore Si I42 -A-01-001 QENERAL NOTES; t 1 t i 1 THE OWNI N (TSGT)) WILL PROVIDE THE CONTRACTOR tin DOCUMENTATION NCC(SSART 10 RECOVER THE SURVEY MORAINES TO ESTABLISH HORIZONTAL AND VERTICAL CONTROL THE CONTRACTOR is RESPONSIBLE FOR COORDINATION Of CONSTRUCTION STALING W11H TN[ RESIDENT PROJECT REPRESENTATIVE 2. THE CONTRACTOR SHALL SCntOuit WORK SUCH THAT THE DURATION OF IMPACT TO ADJACENT PuBI.C ROAD% AND RIGHTS -OF -WAY IS MINIMIZED TABLE OF ESTIMATED QUANTITIES 3 THE CONTRACTOR R R(SPONSBLE FOR INSWITNG THAI M PERSONNEL MO SUBCONTRACIOR PERSONNEL. ARt AWARE Of PROPER Wirt PROCEDURES UNIT NO MO MI NIL[ ARO OESClrTON OF CON67RUCTXIN ASAMILV WTI NO OF UNITS U.0 V AS-CONITRUCTEO NO OE UNITS 4 . 1H( CONTRACTOR IS RESPONSIBLE TOR OBTAINING ALL. STIR NECESSARY TOR CONSTRUCTION I Y -T TORO •' Era NO %IOC.S t M OIIMI IXAICe Oro CoaI*4CTON AR/II N•! CY D S THE CONTRACTOR SHALL POONA, THE OWNER OF ONLY WORD ACIMTIE5 AND THIS I Y•7 ES(wTIOR (W -SIN a1AN) OD M R( -N(0 OM 00.9111. P OM(IND AM nSI) 7• CV LOCATIONS IN GENERAL DAILY PLANNING SHALL INCLUDE A DISCUSSION 01 SPECIFIC SAFETY MEASURES TO BE TAKEN DURING THE ] Y"] Krpl, INIOCI••. A10 COIrKI 11RMINY[NT ••]• CY DAY'S WORK • II -I 0RA0( P16C(S) ARD c01rACT LIMING WWK1 MO •V• -SWAG WTIW (YARD. 0•FRRIAY • POLO WORSTW ICtOK AIKWI T•p0! 5Y 6. THE CONTRACTOR SMALL COOPERATE WITH THE OWNER ARO THE TESTING LABORATORY TO FACILITATE OWNER'S 5 Y-) EYWYWTP COYPKt(0, HX)1/l[II, N PLACE (COtlt[R N IRK[ yams[) •11] N MWAG(MEM AND QUALITY CONTROL OF THE PROJECT CONSTRUCTION • Y-• MAORI AIID sow •" mat POOPED DAN S 641 STIRS ETARD MEIN COW*C1(0. COCA R W PAC 1.7• CT 7 THE CNIL YORKs CONTRACTOR SMALL BE RESPONSIBLE FOR PROVIDING HIS OWN PROJECT OFFICE. TOILET 7 r-7 WPM ANO •61Ai1 !' iHCR wMAG 001013:0•11 (ARO AREA) WYPT7n ARK[ F•1 n FACILITIES ANO KL OTHER NECESSARY BLALOINGS OR SHELTERS. THE OWNER WILL NO! PROVIDE ANY FACTORS TO TIN R Y-• WW1 SO ...rm.!. Tr NOT COMES Cue s MX STIRS (O CM ANA) LOW CtIII COMRIIL W A to 154 Cf CONTRACTOR DURING CONSTRUCTION ALL FACILITIES ANO SERVICES FOR THE RESIDENT PROJECT REPRCS(NTAIIVE(RPR) SHALL BE PRONGED BY THE CML WORKS CONTRACTOR AND SHALL BE • Y-• t• DIAW um HAKE NM )-WRAC MCuiItV VOL WMPt(n. MAKE (MASLOW% PM10) 11)7 J SUBSIDIARY TO THE VARIOUS END ITEMS ON THIS PROJECT THE CONTRACTOR SHALL PROVIDE LOCKABLE AND 10 M -t0 ]0 CNW Ufa GAT( (7-+5• POI GATES). CWWtc1E. N RACE I L1 SEPARATE OFFICE SPACE FOR THE RPR, FAX MACNNE WITH SUPPLIES AM) DEDICATED SERVICE. COPY MACHINE AND SUPPERS, Of FICE DISK, f,LING CABINETS, ORATING TABLE. MEETING TABLE. CHAIRS. ENTRANCE STEPS. II N-'' 3' OMAN Lam WA WE COMPLETE. N RAG I W MR CONO17K1MNG/HEATING MO IN50( TOILET TORSI FACILITIES SHALL BE MAINTAINED W WORKING CONDITION a M-17 • Sky •-51AAND FIELD TIKE. COCCI. W PEACE Im• V BY THE CONTRACTOR Al ALL TIMES is M-1] V KIPOMRD TRENCH OMW, CONtAR, W RACE )7O J 6 TM CONTRACTOR'S PRWI CT MANAGER SHALL ATTEND ALL SCHEDULED ROUTINE PROGRESS MEETINGS DURING !• M -+M Er Ap•M1IOYt(p IR[ACH DRNL COMPUTE III RAC[ 1115 J ILTE DURATION Of Int PROJECT- AND PROVIDE UPDATED SCHEDULES AS REQUESTED. *WILY PROGRESS MEETINGS ARE MANDATORY Is to- it Ms ORMW O.RET N•EMW', corn. W RAC( 1 LA TO M•1• IF •(WO•c10 CONCAVE PO( tOK•1, COMO FERRO IMO NCt10RI COOLER. W PLACE 40 V 9 ME CONTRACTOR SHALT BE RESPONSIBLI ION IOCAi1NG AND MµKING ALL EXISTING UNDLIIGROUNO UTILITIES AND STRUCTURES THE CONTRACTOR TALI BE REQUIRED TO WORK WITH ALL DUE CAUTION IN THE AREAS Of 17 M-11 IF IRWORL[D COCKER PW COO (N0 CECIL COrt[l(. W PVC( ! EA 'HE LOCATED UNDERGROUND UTILITIES IN ORDER TO AVOID DAMAGING SAIO UTILITIES IN THE. EVENT Of UTILITY 1• Y-1• Or • S. POCK POMP Kt eaICHPAAl1 R DAME OJtIALLR OtIM1KW LORD [WTREY OttltOW). COYPAII. Ni RACE TIT IN !IMAGE, THE CONTRACTOR SMALL Bt R(SPONSIHLL TOR INITIATING MMLDMI( REPAIRS AND NOTIFICATION OF .1( PROPER A{/TIORII I[5 AND SERE PROVIOI R$ TO r•TE1 wan 0(nNtW Pare MALI STRUCea. COMSgTL N PIACI 1 Ls 70 M•f0 V TIC OTACME ItiOTODCT ORJVLOR Twat. CITATIRETE. W MACE I L1 ID THE CONTRACTOR SAME SUBMIT HIS CONSTNUCIOM WORK SCHEDULE TO Tnl OWNER PROTECTING HIS UPCOMING WORK FOR 111E NEXT THREE WEEKS THE OWNER SHALL REVIEW TEAS PLAN WEEKLT WITH THE I1 To Pi Y S DOOM MWGAl DWMOL. COrRiTi. N PIACI T„ J CONTRACTOR SO THAT EVERYONE 5 AWARE Of UPCOMING C0NSTRUCTON EVENTS. 73 WP -21 WIGS Ptc(WRt CSO(0 SMOOTH CDOt[II W PLACI _ 1117 CT 11 THE CONTRACTOR SHALL MAINTAIN A CLEAN AND SAFE CONSTRUCTION WORK AREA THE CONTRACTOR SHALL 71 N•I WONG / tilt ICSt0REttil I AC PERFORM CLEAN-UP OPERATIONS ON A ONLY BASS 7• Is 110101 C➢MIICL at IMIALLATKW AND WIMTIMMC/ Ip oat. O ICAO 1 LS 12 THE CONTRACTOR STALL HMI SuffTCIENT (OUEHMENT AND PERSONNEL ON SITE 10 ACCOMPLISH EFFICIENT AND » •-T IORIEAIOy I a 6 PROMPT CONSTRUCTION Of THE VARIOUS WORK ITEMS INCLUDING WORK ON MORE THAN ONE WORK ITEM 1* 0.1 D(rORKRATOM T L) SIMULTANEOUSLY. 11 NO TRENCHES W OR DIRECTLY ADJACENT TO OPERATIONAL PAVEMENT SHALL REMAIN OPEN OV(4NIGH] OR WHEN THE CONTRACTOR FINISHES WORK FOR THE OAT M TIN AREA TRENCHES NOT BACKFILLEO SHALL BE COVERED WITH STEEL PLATES TO ALLOW FOR SAFE PASSAGES BY VEHICLES ACROSS THE TRENCH. 'F APPROVED BY THE OWNER 1• THE CONTRACTOR SNAIL BE RESPONSIBLE TOR REPAIR 01 ANY DAMAGE TO LISTING FACILITIES NOT DESIGNATED FOR RECONSTRUCTION OR REPLACEMENT, Al HIS EXPENSE IS DAMAGE ID EXISTING MOMENTS DUE TO MOVING OR USAGE Of HEAVY EQUIPMENT ON NHL TRANSPORT OF MATERIALS TO 04 ON THE SITE SHALL 0( REPAIRED TO EQUAL OR BETTOR OuAITY or It1C CONTRACTOR At IRS EXPENSE 16 THE CONTRACTOR SHELL BE RESPONSIBLE TOR •VMIDIATE REPAIR OT APO ()IMAGE TO UNDERGROUND CABLES ENCOUNTERED 11.µL ABOVE GROUND AND GROUND LEVEL ELECTRICAL RELATED APPURTENANCES DE TIGHTS. CABLE BOXES. CABLE AND/CA DUCT MARKERS, TELEPHONE PEDESTALS. Utility POLES. CONDUIT. ETC ) SHALT BE PROTECTED AT ALL IMES ANT DAMAGE DONE TO SAID APPURTENANCES BY THE CONTRACTOR SMALL B( REPAIRED TO LIKE QUALITY AT THE CONTRACTOR'S EXPENSE Int REPAIRS SHALL M. PERFORMED TO THE SATISFACTION OF THE OWNER'S PROJECT ONAGER, AND AMY RESPONSIBLE UTILITY PROVIDER TB.CONSIRLICTK)N WORKERS WILL 1901 BE ALLOWED TO ESTABLISH OVERNIGHT RESIDENCE ON THE PREMISES ALL CONSTRUCTION WORKERS SHALL LEAVE THE CONSTRUCTION SITE AT THE ENO OF THEIR WORK PERIOD 19.WORK CANNOT COMMENCE UNTIL PFMQAII I7ATION NQTF4; - . w • w N • LLOYD SISSON SUBSTATION GENERAL NOTES AND CIVIL CONSTRUCTION QUANTITIES Mr- STATE CENERA TION & TRANSMISSION ASSOCIATION, INCORPORATED I ' ' L i - , • H •• ■ I I 4 S I 1 I 10 APPROPRIATE GRADING SHALL BE DONE AROUND EACH ENO Of CULVERTS AND HEADWALLS TO INSURE THAT RUNOFF 15 PROPERLY CHANNELED INTO AND OUT Of THE CULVERTS I CONDOONS Of THE PROJECT AREA UPON COMPLETION Of THE JOB SMALL BE AS GOOD AS OR BETTER THAN 191 THE CONTRACTOR'S StORMMTHE TER MANAGEMENT PERIMETER CONTROLS INCLUDING STABILI/ED THE CONDITIONS PRIOR 70 STARTING WORK, IN ADDITION 10 THE WORK ITEMS LISTED CONSTRUCTION ENTRANCE AND DISCHARGE ii POINT CONTROLS ARE IN PLACE THE GRADES AND SLOPES TOR THE CONSTRUCTION REPRESENTED IN THESE PLANS ARE NECESSARY TO PROVIDE FOR THE PROPER DRAINAGE AND ORATE 01 114E SITE CONTRACTOR SHALL PROVO( TOR 2 THE PROJECT AKA SHALL BE FREE OT ANY CONTRACTOR STOCKPILE MATERIALS UPON COMPLETION OF THE 197 ALL SAFETY EQUIPMENT TOR PERSONNEL ANO CONSTRUCTION EQUIPMENT K IN PLACE AND OPERABLE ACCuRATE AND CONSISTENT MEASUREMENT Of ELEVATIONS TO ACHIEVE Int GRADES NOTED IN THESE PLANS JOB UNLESS OTHERWISE DIRECTED BY int OWNER 20A COUPLET( PROJECT SCHEDULE 5 10 BE Suslt(D WITHIN 10 DAYS Of NOIICI TO PROMO 12 NIP RAP MATERIAL AND PLACEMENT SHALL BE W COWS MINCE WITH MGT SPECIFICATIONS 3 UPON COMPLETION Of THE PROJECT. ML OT list HAUL ROUTES SHALL BE PROPERLY CLEANED TO PREVENT 21 THE CONTRACTOR S RESPONSIBLE FOR THE LOCATION AND RESTRICTIONS FOR SERVICING AND MAINTAINING 1.) CONTRACTOR SHAH REMOVE TOPSOIL IN AREAS DESIGNATED BY TSGT AS STOCKPILE LOCATOILS PRIOR TO SLREON OVI'ANDOR CAUSE BROUGHT HBACK TO RIO NORMAL CONDITIONREGuLR I REI E ALL TEMPORARY AREAS HAUL ROUTES EQUIPMENT AND DISPOSAL. OF uSED LUBRICANTS. ETC STOCKPILING MATERIALS OTHER THAN TOPSOIL RAD OE NEMOV O AND BACK LI ORIGINAL IN TL OR BE 17IR Alt Nui1Cp SHALL W GRADED SMOOTH SEEDING %/NL1 BE APPLIED AS INCIDENTAL 14 (ROSTON CONTROL BLANKETS SHALL BE WINTERS CHHOICI BO, w/ MOOtCRALABLE JUTE NURNG, OR • tot JOB TRAILER ALL OF THE CONSTRUCTION EQUIPMENT, µ AW E T FACILITIES TEMPORARILY PLACED ON 5,•I FNFIANIEWS ANEi GRA' Jf ROWS APPROVED EQUAL. H FOR PROJECT THE .t SHALL BE REMOVED FROM Sill. 1 N CONTRACTOR SHALL AK PRECAUTIONS 10 MOO DAMAGING EXISTING PAVEMENT THAT MUST REMAIN IN SERVICE GAIAAGE MUST 8E REPAIRED At THE CONTRACTOR'S CAPERS( JOPSOli NOTES, 5 AM PROPERTIES BELONGING 10 THE OWNER STALL 6E RETURNED TO THC OWNER CSTRI-STATE aM MNnwC llac. T�w /��awmth �YMe ap'lwvW.e 1100W 116th Ave. P. 0. Box 33695 Denver, Colorado 80233 303-451-6111 2 DESIGN CONTOURS AND SPOT ELEVATIONS SHAWN PT PLANS REPRESENT FINAL FINISHED SURFACE ELEVATORS 1 ORGANIC MATERIAL S PRESENT IN TM TOP 6" OF THE SIT( THIS MATERIAL IS NOT CONSIDERED 10 BE 6 PROPER DRAINAGE (NO LOCALIZED PONONG) SHALL BE MAINTAINED PRIOR TO. DURING MO MIER UNLESS OTHERWISE NOTED ACCEPTABLE AS STRUCTLMAL EMBANKMENT EARTHEN MATERIAL WITH ORGANIC CONTAMINATION SHALL BC MOI•LI/ATION CONSIDERED TOPSOIL 3. ESTIMATED QUANTITIES OF EXCAVATOR AND EMBANKMENT IN THESE PLANS WERE CALCULATED BASED ON THE TOPSOIL MATERIAL REMOVED FROM THE CONSTRUCTION AREAS ON THE SITE SHALL BE SIOCKPILID ON^SITE 7 DEMOBILIZATION SHALL BE DONE TO THE SATISFACTION or THE OWNER REMOVAL Dr 6' OF TOPSOIL WITH AN ASSUMED SETTLEMENT OF 1 01[ 7 FOR RE -USE N TOPSOIL PLACEMENT AFTER OVERALL GRADING IS COMPLETE EXCESS TOPSOIL MATERµ 4. QLANDERS OF EXCAVATION ANO EMBANKMENT TO EN MEASURED MO PAID TOR WILL BE BASED ON THE PLAN REMAINING AFTER CONSTRUCTION SMALL BE SPREAD OVER BORROW AREAS ON -SITE OR HAULED OFF B OPERATORS O $HELL N DONE ECIA MANNER THAT WILL HE CAUSE ANY nNCONONITHTO SOE QUANTDIES ON THIS SHEET THE METHOD OF COMPUTATION FOR QUANTITIES- WAS BASED ON A PR15MO10AL OPERATORS OR THE CONTINUED [ONSiRtlC 1104 OF THE OTHER APPURTENANCES ON THE SITE VOLUMETRIC COMPUTATION VALIDATED THROUGH AVERAGE ENO AREA Of CROSS SECTIONS WITH ALLOWANCE FOR 3 TOPSOIL SHALL BE REMOVED TO A MINIMUM DEPTH OF 6- IN Ina NEW YARD AREA, FENCE APRONS. POND 9 ANT DAMAGE 10 PROPERTIES DURING DEMOBILIZATION SHALL BE REPAIRED AND PAID FOR AT THE MATERIAL DEFORMATION THROUGH THE PROCESS OE EXCAVATION AND PLACEMENT BERM AREA. AND ACCESS DRNTWAYs THE CONTRACTOR SHALL VEINY WITH THE OWNER THAT THE EXPOSED CONTRACTOR'S EXPENSE MATERIAL PS AN ACCEPTABLE %VOGNAD( AS NECESSARY AND DIRECTED 8Y THE OWNER, THE CONTRACTOR 5 EXCAVATED ROCK (6' PAMPER AND GREATER) MAY Of USED ONLY IN LOWER LEVELS OR OUTER PORTIONS Of SHALL REMOVE ADDITIONAL WATERT& 10 ESTABLISH AN ACCEPTABLE SUBGRADE SURFACE TO SAFETY REGULATORS SHALL 8E OBSERVED AT ALL TIMES DURING DEMOBT. MAtION FILLS, NO1 LIKELY TO RECENT TRAFFIC. SUBJECT TO THE OWNER'S APPROVAL THE MAAIYUM ALLOWABLE SIZE DE MATERMl. IN 111E TOP C Of SUBGRADE IS C DIAMETER II ha COST ION DEMOBILIZATION SHAFT BI CONSIDERED SUBSIDIARY TO lilt PAT ITEM TOR MOBILIZATION 6 EARTHEN EMBANKMENTS AND TRENCH BACKFILL NULL BE PLACED TN ACCORDANCE WITH TSGT SPECIFICATIONS 1 SOIL MATERIAL, OTHER THAN TOPSOIL, F0UNO UNFIT FOR USE IN THE CONSTRUCTION OE EMBANKMENTS SMALL BE REMOVED PROM THE SITE Al THE CONTRACTOR'S EXMNSt B EXPOSED SUBGRACt SNAG. at SCARiFRD AND NtCOMPACTEO TO THE DEPTH REOuTREMLNIS IN THE SOILS REPORT. IMP 6-, PNOR ID BtGDNING PLACEMENT DT EMBANKMENT MATS µD BASE MATERIAL RECOMPACTION SHALL COMPLY WITH THE COMPACTION REQUIREMENTS N THE SOILS REPORT 9 . OVERALL EXCAVATION ANO EXCAVATION Of THE DETENTION POND ARE INCLUDED IN Int UNCLASSIFIED EXCAVATION QUANTITY _•MGW WI 19/7.3/I9_ IIHi• 5I142 A-01 002 i Contra Point Table I I I I I I I NodP01n1CO•1 Nertn•p East")I I I I I I I 1 1 $001 CPI 1W10..N 77N1.).0 '!'Ten Sl5jlo _ _ f I • I ....• I I ]007 Ch 1 'IWO/ ■0 33070■1 M I i 1 5007 00■ INKY 71 =N., 75 d r t( 10 I NOB EN 'WHIM 17 UMW 11 r 1• ' Y _ - ' ` )N N' 1 N. 45 • I COUNTY ROAD 71 II I, I �� I 'I � / I - Wit A ON ��t1 C•0•�1 II I• I II i I I I I I { I I I I ; I �� ,. I ,} I �. N. -M kar cc I I I. I . 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I I ,,, MOW TO/77/10 BASELINE AS NECESSARY TO PROVIDE 'OR CLEAR LINES Of SIGHT AND To PROTECT THE coNTROt rOR THE DURATION or 1HEPROJECI 2 SURVEYOR STRATI SET THE CONTROL, POINTS OU/SIM THE - — — — SWIICHYARO SECURITY FENCE IN-THE-fIEtO, ANO RCPOR7 - ._.----------------------------- — — — — Ser15'u1r 411.00' I COUNTY ROAD 130 -- I � � I — — — — — \ / I .....• Ow SI I,a-A-of-oos • •—. •—I--•— . -- • AND REINSENS TO THE OWNER'S -•I• —• •- '- / L,CCODED TECHons ._ —. _ . AUTHORIZED TECHNICAL REPRESENTATM (OATR) I I 'PRELIMINARY r 7 I I eo(a •••-•••D. • e' IC MTh• t0 WNW. snow 1 C 1 KC intMIAIO I.x OESans S11q.a.01.0.' WE 511 IOC. M••1M• 0.. a• r WTI. • 1 %roar. Kt 4%alatytUN Si.4 Intl F 41 -A -DI -011 PIS %t) t-40sWIOiI Cio/MI ' a .0 It NUNS Off' - IJO Control Point Toble Point 1 Cp III Notihirq Emu"; Lam FPI .W 1a 10 110118•1 ea 1001 CPI 1W101 a0 110»a. XI 1001 173 111180 PI 1)011.1 n SWIM- IS 1,004 W %Will. IP SON of .114334 P. 1101101110 I L _ NOTE tea If -MO O. • a' f. WON • I. 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PROPSR7t ILNCL ONANAGE ftowtwE MAC n feel 4A 0 r.1D •1 J0 0 40 PIOPOIIO ONVEwe• Cairtirl 1' I S I i 1 l a a 0 4 r• I Substation • n so h Nh1 tq� Asoct 2v w6 v- uo 51 S i s 1 A A' J.41731'0 IW 51141A-OI .004 i I l 1 S I I j 5800. • LEGEND 7L 4117 2 n EXISTING INDEX CONTOUR EXISTING INTERMEDIATE CONTOUR PROPOSED INDEX CONTOUR PROPOSED INTERMEDIATE CONTOUR PROPOSED DRAINAGE ELOWLt4E PROPOSED SUBSTATION f !NCI PROPOSED PROPERTv 'No PROPOSED BRIM t04.. PROPOSED DRAINAGE ILO* ARROW PROPOSED DRAINA& ILOW ARROW PROPOSED ADS N17 PERT SUB- ORMN PIPE PROPOSED ADS NI2 SUB -DRAIN PIPE PROPOSED RIPRAP G 4727 1' rt \\\ C 4644 Scat nA el M4104 Dosnma n 44.89 K 46 661 S24B S IA.•s. 11004 M -W P4A SPICRCAT01I W 10 p1 OW '011•ADXEN OEOR4*XL .404c (4A4R1 INN pa A44Np4W IYVn4EN1 7 151 47 47 IE N A 40.01 a of • 4 . 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N.. 51142--A-OI-006 t 4 I a I y£ 3 6 era LEGEND O0STING wax CONTOUR Ex*TdG INIEiwEDMtE CONTDurr PROPOSED POE z CONTOUR PROPOSED INTERMEDMIE CONTOUR PROPOSED DRAM & PEOWEwE PIOPOSED SuBS1A1'a0N PENCE CRISING r ENC1 ileaor lase n N.1 f r0 0 M4e $240 0 MOO. E»f •1121 COUNTY ROAD 130 rwOr C<%MC PC tL00 4Peb «Palsied r tapir. 4040 '10 1 U V. W ti U 0 x a 1 C I 57 R 3f a a11N141.nM "Cl a lir S LV4 f:)...--..-....'".'"- *0 W, 11 iii IS' CWu • *Cr '• dM5 2 CO% V F U n U R h 0*00 0+50 1+00 52.5 5240 • - 1 +50 I I i J E I I I I w • I Uoyd Sisson Substation 1 I a t 2 1 } LU I-. • T Q ` M1 x.nor $— Ms — ;$s � ot1 � P O1.n y: Alt _ .10/21f+9 S1142 A 01 007 3 e j 3 I a 4 0 Sc::- n s.r: I i I 5230 5245 5740 5750 5745 5240 5250 OIr..1:C0- 1•••1144 V fa I 71 00 1..-11•, 44 L4 _ A 414 41 Ka*Yla 4I C fti %l*sf • pf..1910D' [Y.-i7M.I Oll it 4.14040:) 531 9p Val Si too a yl 014 ., 41 50 40 30 20 0 0 0 70 30 40 50 DJ 19 6; YO Yard Section 1-1 • • Sr.; p•4 •rv( N '00 110 170 '30 '40 '50 '60 110 160 140 100 TO 170 730 240 750 760 11O45 7: S I1 08 4...•144.9 �n •4I•w•, N... • Y:,,4, A•.IIY•,. 'L C41Y-. ',45 vu:-•• ,- tool SO .0 10 -70 -10 0 0 70 30 40 50 SO 10 60 90 100 '10 120 130 •40 '50 Yard Section 2-2 fI. .41 IV l4. -u.. .4 014.-1100 a•-17.4 r4� • 11 d _ 160 F 10 160 190 200 2'O 120 730 740 .I; lil.,)1 t4 I'... 1:44 .01“,11,11:4 ••• 110 ,G 5230 tic MENCd J.A•• Cv1101 ASSL1 11 OO CF.IKS JfMC1 311.1.4-41-nlo 5245 ��. 5243 5240 50 •40 30 10 0 0 '0 70 30 40 50 60 10 60 90 100 I15 110 130 140 150 160 '10 160 1/0 200 210 770 2305x•0 Yen! Section 3.3 . •:o kat n*VI 70 40 5230 5245 5240 • ` .• Al:'. .. 111.1 h13 • A C SIM A 410..1 • :OW 750 •.. ry 5250 52.5 5240 760 710 0 409 Yri A •D1 ,1. Hn r.-4 •04I•.u140 110..514 a. Or. •\I Oq C- 5JM 4G 5250 5245 5240 40 -10 -10 10 0 10 20 30 40 SO S0 1J 60 90 'CO 113 110 110 140 150 160 110 160 '90 200 210 220 730 240 250 260 110 760 1011 3041 110 320 330 340 150 360 310 300 J60 400 410 470 430 440 I 1 S d $ I I I a • • a I S LLOYD SISSON SUBSTAT70N Fb a T Q twa,- IEt i 161 ej e- O 6 T Mow 012 3t10_ $1142 A 01 008 41. 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Iluui1 illlnlllluuTJJi HuiHh!tfl'1IIllllull I1ll1dJI111 i1li[III111uftJ Ill1Illl1 TYPICAL DRIVEWAY SECTION NTS CRIXSpK GIRO 3109664 1I' ME9 (9(R •45TM1AtCM OCTALS - 11 011(26) I IM,Iµ Clout*I SCAInf'T. %I PI AM) PCCOW4C1 EIPOSEO (P15t•PAr SIACRAOt - IIMCtNE51 2 91100104 PEI 5P(CM(AION 06100,1 Prim AGCAECATL. t IABRC INS1AluliCk NOTES. 1 LAY MARY IN IRCACM PRO* 10 P:ACEMCNT 01 AGGREGATE } AR FABRIC 10 COIPACIED skint MATERIEL ALONG 1RCACI, •WERE NECESSARY OVERLAP AhOIWNC PIECES A AIl•4tW Of I- 09 PER MWIRKIORCR'S RELONMCNOAION 3 NStAL: PERfMRAT EO PPt 10 0IS{N GAMS FAIN P(WORAIOAIS Pts 0(141 4 RCCRERL 10 MSCN SiII(ACE CRAMS MA IL(VAIONS Si,.. Ik• CRuSntD AGCAICAIC PER SP(CACATORS PM /a 10 W1M WATERS,. vNMi - -O NP 9AC{EU ,M(N[n RON I-1�}• Ch.5,(0. *A5NC0 AOCRCGIE +IPI SA • I: J I,VMI SVYiIATOM tin SUREACC UCWCM SIC OLTMLt 1M(st PSIS NON-NOWA GCOTLAIAE IABRC ENVELOPE (MIRE, 1101. OR APPROVED EOWNCNI) SEE MSIALLA,ON NOTES f E e I I d PCRE064110 ADS M -r} CORSUGAILO EPICROR AMP SM001P 114101104 1 1065 M)/- PERIgOIOM AT 6. OC ROTATE RoI M lIEACI, Wet, TIM, SA MOLA[ 6(IMSEN 1PI ROM CO PEW 0RAIOM I5 Al Nit 601104 (MI PLANS ION PIPE WE) TYPICAL PERFORATED TRENCH DRAIN DETAIL NIS SISSTAIION YARD SOREKE S(CtO. SEC EE1ML5 M[st PLANS -1 RA1011 ON -Silt slaCCI 002202 Wt inAL AS NECESSARY 10 9.140.10. PR 114.401 (DLPNN waif) PER SPECIIICATCN 001001 3C IIYA) 4M M- 1} PIP( TYPICAL SOLID UNDERDRAIN DRAIN DETAIL NTS AOMAS Ir (cast MG01C0 CLASS S 114[ MAItRS [ALL MGCMEII TOt 0 LM13ACC KR SPCC4GLION 05,01} 6 SELECT BACPILL WRRS PER SPECRCATIOM 06 100' r (I) RCP PPI. SIC YARR5 SEE PIAN DRIVEWAY CULVERT SECTION NTS -I c I, Jin O 2t X00 O WU 6 fri En 81 la "etee J yr P W {p IN Q 1 o �No 401m= ° b T - A R O ILL • Era ' 0028 00 ..• MN. VG* Ipf23/19 w $1142-A 01 009 I I I I I 2 (M) •(• *C• Cu.ytlt .4111 a 4•a S. 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COWACI 10 05>< .VOFCD •ROCIa. lu*MUY OR1 tl4tltl 3 TRICKLE CHANNEL NTS na.-4•a tN otol(IR(t C.Sc ISSi I7001 OR O➢•RO.m (OWl TYPICAL RIP RAP INSTALLATION N 7- a1DD*D TYPICAL SWALE SECTION A A Nlh DSrMCL y/R[t S[t (AAO•C rim .: l I 6 w I S g Os. MCN 10/23/19 `+r• b4•. 51142-A-01-010 S I I I I I 3 F I I I P1K( liala(xMMl COYNCItW 10 IOt ~MO n•OC?OI POWs rtO a tuv MMllts Ntn vNMS SR Fla 0111•1 144.1101s S346 0(Pin wWIL! SR Cana Pima PIK( ISWOYI Al COWNCIIO 10 W( W)OI l(0 MOCIOS 4. tlmOln vat% tic nal TYPICAL POND BERM SECTION NTS nee( ;NOES L SR PUP. .000(0 ,t00n WV ant DETENTION BERM EMERGENCY WEIR CONCRETE HEADWALL DETAIL NIS IMP n sal u6PDSIC. Pima 14 510 hi am Ur• nr. r.Ot OMCS`or PLM:( (WMllay(nl COWPPCII0 IO Wt( x001140 PPOC,O. _ •'•.*C( t Iona UGC PIO ,P(CIIC4tos J MOTs( P4t1 SIC PUN Pu(t • 10P7oa Sign MW VICIa'AISWs 5* twat (UN Mtn 'IMAMS". WtNI Ito It 16Ma 00 NMI1M0 101.106 qv ift •' 111M141It 0(Pnt 444 Io0(S TYPICAL POND BERM & OVERFLOW WEIR SECTION N.T S NWM (tints 57400 .t_Cl ta• 04('4 0.-6" POCu M -W _ Uinta GROWN, • —r 4 Y 15 NIP PIACI POdat G401CIIIU saint (awl 140s 06 APMO4D (WN4IWl) U41st rJ wn • t t 1'.4 C —a• MMt0 (OW 0x OOSUta�lt STN 01 <es it'litkIIk lee%t1... DETENTION BERM EMERGENCY WEIR DETAIL NIS 16' TOMOS 7 MCW w 1 i I 1 Lloyd Sisson Substation DETENTION POND DETAILS C i 1 I a IZt lit' 0 van" 14 00 1 J ;$V,n oOT o Y 10/xs/Io 11" SI142 A-01 Oil I) 4 • 11s.ttt lilt, SUPPORT WI T( 0014 • 060'. at MOW OPINa1aa KdKK Watt UNSEX WC KAN ate StaICIcK roe ••r -I)' ewe • a'NA SECTION NT/ -H- �1 IC N tacit 0 T)♦' 0060' Intl lull MCI slat (! IA) JoV KLOLD MCN/ 60351 TN • Saud •ON% CC. LOC 1100 . 5.451 • (Mt OMN MIA)ROMOtl RAs Arta) -a0 SECTI NIB 100 year Wi'L 174457 10 sr WSEL ISM 17 WDCV 52!47 Tnd . 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I / l L_I 1 J \` - ---�-` -----------------O�I 'o/?)J10 COUNTY ROAD 130 / 51142 A 01 013 / { I 1 , I 1 I, I STORMWATER MANAGEMENT PLAN (SWMP) For Colorado Construction Activities at. Lloyd Sisson Substation Prepared for: el; TRI-STATE G&T A Touchstone Energy® sit Cooperative r_ 1100 W. 116Th AVENUE WESTMINSTER, COLORADO 80234 Prepared by: - - - - - - -a - -- -- - a - - a -a ma�_- - _ DEL-MONT CONSULTANTS, INC. ENGINEER I N G ♦ SURVEYING 125 Colorado Ave. • Montrose, CO 81401 • (970) 249-2251 • (970) 249-2342 FAX www.del-mont.com • service©del-mont.com DMC # 19095 Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan Table of Contents: 1.0 INTRODUCTION 1 1.1 The National Pollutant Discharge Elimination System (NPDES) Process and Construction Stormwater Management Plan (SWMP) 1 1.2 Project Owner/Operator and Key Personnel 2 2.0 CONSTRUCTION ACTIVITY AND SITE DESCRIPTION 5 2.1 Project Location 5 2.2 Nature and Description of Construction Activities 5 2.3 Proposed Sequence of Activities 5 2.4 Estimation of the Total Area of Disturbance 5 2.5 Existing Soil Conditions 5 2.6 Existing Vegetation and Runoff Characteristics 6 2.7 Potential Pollutants 6 2.8 Allowable Sources of Non-Stormwater Discharges 8 2.9 Receiving Waters 8 2.10 Site Map 8 3.0 CONTROL MEASURES 9 3.1 Structural Measures for Erosion and Sediment Control 9 3.2 Non -Structural CMs for Erosion and Sediment Control 13 3.3 Phased CM Installation 17 3.4 Dedicated Concrete or Asphalt Batch Plants 17 3.5 Vehicle Tracking Control 17 3.6 Waste Management and Disposal (Including Concrete Washouts) 18 3.7 Product Specific Practices 18 3.8 Groundwater and Stormwater Dewatering 19 4.0 FINAL STABILIZATION AND LONG-TERM STORMWATER MANAGEMENT 20 4.1 Temporary Stabilization 20 4.2 Description of Final Stabilization Practices 20 4.3 Final Stabilization Methods 20 4.4 Final Stabilization Achievement 20 5.0 INSPECTION AND MAINTENANCE 22 5.1 Minimum Inspection Schedule 22 5.1.1 Post -storm inspections 22 5.1.2 Inspections at Completed Sites/Areas 22 5.1.3 Winter Conditions Inspections Exclusion 23 5.2 Inspection Requirements 23 5.2.1 Inspection Scope 23 5.2.2 Inspection Reports 23 5.3 Required Actions Following Site Inspections 24 5.4 CM Maintenance 24 5.5 Corrective Actions 25 Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan 5.6 SWMP Requirements 25 5.6.1 SWMP Availability 25 5.6.2 SWMP Retention 25 5.6.3 SWMP Amendment 26 5.6.4 Responsive SWMP Changes 26 5.7 RECORD KEEPING 27 6.0 SPILL PREVENTION AND RESPONSE 28 6.1 Introduction 28 6.2 Material Management Practices 28 6.2.1 Good Housekeeping 28 6.3 Product -Specific Practices 29 6.3.1 Flammable and Combustible Liquids and Hazardous Materials 29 6.3.2 Petroleum Products 29 6.4 Spill Control and Cleanup 30 6.5 Spill Reporting 30 6.6 SWMP Modification Procedures Related to Reportable Releases 31 APPENDIX A: Site Maps APPENDIX B: Soil Erosion and Sediment Control (CMs) Details APPENDIX C: Phased CM Implementation APPENDIX D: Inspection Forms APPENDIX E: Spill Report Form APPENDIX F: Permit Application and Permit APPENDIX G: Geotechnical Soils Report Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan 1.0 INTRODUCTION 1.1 The National Pollutant Discharge Elimination System (NPDES) Process and Construction Stormwater Management Plan (SWMP) This document establishes a plan to manage the quality of stormwater runoff from construction activities associated with the Lloyd Sisson Substation, Weld County, CO. This project will disturb at least 1 acre or is part of a larger common plan of development, which will disturb more than 1 acre. For construction projects that require the disturbance of more than 1 acre. the U.S. Environmental Protection Agency (USEPA) requires that the project owner or contractor apply for a stormwater permit under the NPDES program. For the purposes of the NPDES program. construction activities are defined as clearing, grubbing, excavating, grading, import and placement of road material. improvements to existing or new drainage. installation of permanent drainage structures. installing landscaping improvements, paving (asphalt or concrete). construction of permanent structures, or any similar activity that causes native / undisturbed areas to be disturbed. This NPDES permit program is administered in Colorado by the Colorado Department of Public Health and Environment (CDPHE). Water Quality Control Division (Division) under the Colorado Discharge Permit System (CDPS). CDPHE has a general permit for stormwater discharges from construction activities_ The Construction Stormwater Permit (COR400000) was renewed and issued on October 31, 2018. and effective on April 2. 2019. This document, including its attachments and appendices comprises the Stormwater Management Plan (SWMP) required by CDPHE's general permit for Stormwater Discharges from Construction Activities. This plan was written in accordance with the guidelines in the Division's Construction Guidance Document: COR400000 Stormwater Management Plan Guidance". Reference material was used from the Urban Drainage and Flood Control District's Urban Storm Drainage Criteria Manual (V. 3) (updated 11/2010). the EPA "Developing Your Stormwater Pollution Prevention Plan. A Guide for Construction Sites" (May 2007). and the Colorado Department of Transportation (C.D.O.T.) Drainage Design Manual. A permit application for Stormwater Discharges Associated with Construction Activity must be submitted to CDPHE at least 10 days prior to the start of construction, and the applicant must receive written notification that the Division granted permit coverage prior to conducting construction activities. The plan and permit will be available on -site while construction activities are taking place. The USEPA and the State of Colorado have substantial penalties for non-compliance with the permit. Any permit non-compliance constitutes a violation of the Clean Water Act and is grounds for enforcement action including: permit termination: revocation, reissuance. or modifications: or denial of permit renewal application. Individuals responsible for such violations are subject to criminal, civil and administrative penalties. Tri-State Generation & Transmission - Lloyd Sisson Substation Stormwater Management Plan The Construction Stormwater Permit only authorizes the discharges of the stormwater and those non-stormwater sources listed in Part 1.A.1. of the Construction Stormwater Permit. The permit does not cover discharges currently covered under an individual permit or a Division Low Risk Discharge Guidance developed in accordance with the Low Risk Discharge Policy (WQCD Policy 27). 1.2 Project Owner/Operator and Key Personnel Owner/Operator: Tri-State Generation and Transmission Association 1100 W. 116th Ave Westminster, CO 80234 Contact for Owner/Operator: Selina Koler Senior Transmission Siting & Environmental Planner Tri-State Generation and Transmission Association 1100 W. 116th Ave Westminster, CO 80234 (303) 229-3207 skoler@tristategt.org The owner is the party that has overall control of the activities and that has funded the implementation of the construction plans and specifications. This is the party with ownership of. a long term lease of. or easements on the property on which the construction activity is occurring. The operator is the party that has operational control over day-to-day activities at the project site which are necessary to ensure compliance with the permit. This party is authorized to direct individuals at a site to carry out activities required by the permit. Tri-State owns/leases the Lloyd Sisson Substation property and has operational control over the activities at the project site. SWMP Administrator/Qualified Stormwater Manager (QSM): Selina Koler Senior Transmission Siting & Environmental Planner Tri-State Generation and Transmission Association 1100 W. 116' Ave Westminster, CO 80234 (303) 229-3207 skoler@tristategt.org Qualified Stormwater Manager: An individual knowledgeable in the principles and practices of erosion and sediment control and pollution prevention. and with the skills to assess conditions at construction sites that could impact stormwater quality and to assess the effectiveness of stormwater controls implemented to meet Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan the requirements of this permit. Tri-State's Stormwater Administrator. Developer, and Inspector are all identified as Qualified Stormwater Managers (QSM). The SWMP Administrator is responsible for developing, implementing. maintaining, and revising the SWMP. This individual serves as the comprehensive point of contact for all aspects of this SWMP. SWMP Administrator/QSM Signature: Name: Title: Date: SWMP Developer/QSM: David Schieldt, P.E. Del -Mont Consultants. Inc. 125 Colorado Ave. Montrose, CO 81401 dschieldt@del-mont.com (970) 249-2251 The SWMP Developer is responsible for developing the SWMP in accordance with the requirements of the General Permit. Critically important in developing the SWMP is to identify all potential sources of pollution which may reasonably be expected to affect the quality of stormwater discharges associated with construction activity. to describe the practices to be used to reduce these pollutants. and to ensure that pollution prevention practices are based on good engineering practices (includes installation, implementation and maintenance requirements). The SWMP Developer is also available to adjust or update the plan as needed during construction, to make field visits and provide recommendations on appropriate Control Measures (CMs) for specific areas of concern or to determine if final stabilization has been achieved. and can help with administration of the plan or with Inactivation. Transfer, or Reassignment of the Permit. SWMP Developer/QSM Signature: SWMP Inspector/QSM Signature: Name: Title: Date: Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan The SWMP Inspector is responsible for conducting and documenting required site inspections in accordance with the Permit. The SWMP Inspector must notify the Construction Contractor and the SWMP Administrator immediately if any additional or different CMs are required on the site, if any CMs require maintenance, or if any CM has failed. During construction. the SWMP Inspector will assist the Construction Contractor with implementing and maintaining stormwater controls at the site and the SWMP Administrator with revising the SWMP as needed. Construction Contractor: Name: Company: Address: _ Email: Phone: The Construction Contractor is responsible for installing and maintaining CMs as defined in the SWMP and is responsible for notifying the SWMP Administrator immediately if any CMs fail, require maintenance. or if additional CMs are required. The Construction Contractor will work closely with both the SWMP Inspector and the SWMP Administrator throughout the duration of the project. Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan 2.0 CONSTRUCTION ACTIVITY AND SITE DESCRIPTION 2.1 Project Location The proposed substation yard is located on a 7.5 -acre parcel owned by TSGT. situated in the SE 1/4 of Section 11, Township 11 North, Range 63 West, 6th Principal Meridian in Weld County, Colorado. The substation site is accessed from County Road 130 approximately 430' west of County Road 71. 2.2 Nature and Description of Construction Activities The scope of this project is to build a new high voltage substation. The construction will include clearing/grubbing substation pad area. grading drainage swales and detention pond. and installation of high voltage electrical equipment. 2.3 Proposed Sequence of Activities Construction Task Planned Start Month/Year Install initial CMs June 2020 Construct Substation Summer -Fall 2020 Remove CMs no longer required Winter 2020 Reclaim and stabilize all disturbed areas Winter 2020 Remove all temporary CMs Winter 2020 Site stabilization Spring 2021 Close Construction Stormwater Permit Spring/Summer 2021 2.4 Estimation of the Total Area of Disturbance The total area of the site is 7.5 acres. The estimated area of the site to be disturbed by all construction -related activities is approximately 4 acres. 2.5 Existing Soil Conditions Consistent with other similar sites in the Weld County area, the Lloyd Sisson Substation site has the sandy soil with varying amounts of gravel, silt, and clay. A Geotechnical Soils Report (see Appendix G) confirms this typical soil and was used to develop and apply appropriate CMs. Engineering judgment and construction experience with local drainage patterns were relied on to develop appropriate CMs to prevent soil erosion and migration. Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan 2.6 Existing Vegetation and Runoff Characteristics The site naturally drains to the southeast. The natural vegetation consists of native grasses. weeds, and cultivated land. The site is estimated to have 20-50% ground cover prior to construction. The percent density was determined by examining a representative 10'x10' square and determining the plant density within the area. At final stabilization. ground cover should be greater than 70% of the pre -construction cover, 0.70 x 0.20-0.50. or approximately 15-35% vegetation coverage. 2.7 Potential Pollutants The following chart identifies the potential pollutants that need to be addressed per the CDPS General Permit and their applicability to this project. Potential Pollutant Source/Activity Potential Pollutant Potential with this Project? Description of Activities CMs Selected to Control Source All disturbed and stored soils Sediment X Construction of access road Controlled Parking Controlled Site Entrance Designated Staging Area Detention Basins Drainage Swales/Check Dams Dust Control Good Housekeeping Practices Inlet Protection Natural Vegetative Barrier Seeding Silt Fence Straw Bales Straw Wattles (fiber rolls) Surface Roughening Vehicle Tracking Control Vehicle Tracking of Sediments Sediment X Delivery of construction materials: installation of sub -base materials: clearing and grubbing: daily construction traffic: construction of new access roads. excavation and removal of excess materials Controlled Site Entrance Controlled Parking Designated Staging Area Dust Control Vehicle Tracking Control Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan Potential Pollutant Source/Activity Potential Pollutant Potential with this Project? Description of Activities CMs Selected to Control Source Management of Contaminated soils Fuel spill, runoff from contaminated area X On -Site vehicle maintenance & refueling Spill Prevention Plan Loading & Unloading Operations Sediment, runoff from area Xcontaminated Equipment/material drop off and pick up; portable sanitary delivery & routine cleaning Controlled Site Entrance Designated Staging Area Outdoor storage activities Sediment, Fuel spill, runoff from contaminated area X Construction material storage on -site for the duration of project Controlled Site Entrance Designated Staging Area Spill Prevention Plan Vehicle & equipment maintenance and refueling Fuel spill, runoff from contaminated area X Vehicles & equipment which will remain at the site until work is completed will be maintained and refueled on site: fuels will not be stored on site Controlled Parking Designated Vehicle Fueling and Maintenance Area Spill Prevention Plan Significant dust or particulate generating processes Dust X Construction of new pad area. grading pad, installation of structures Dust Control Routine Maintenance activities involving fertilizers, pesticides, detergents, etc. Nitrogen, phosphorous None Project does not require use of these materials. On site waste management practices Debris. trash X Construction debris: portable sanitary facilities: personal trash I Designated Staging Area Solid Waste Management Concrete truck & equipment washing Concrete waste, concrete wash water Equipment foundations Concrete Washout(s) Dedicated asphalt or concrete batch plants Waste products, runoff from contaminated areas None Project will not require use of dedicated asphalt or concrete batch plants. Non -industrial waste sources Bacteria, parasites, viruses X Portable sanitary I facilities; Personal trash and construction debris Designated Staging Area Solid Waste Management Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan Potential Pollutant Source/Activity Potential Pollutant Potential with this Project? Description of Activities CMs Selected to Control Source Other areas where spills could potentially occur Runoff from contaminated areas None No other potential sources of pollutant were identified. Irrigation Return Flows Erosion/sedime nt from construction activities None No irrigation return flows expected on this project 2.8 Allowable Sources of Non-Stormwater Discharges Irrigation return flows are not anticipated on this site. When construction activity involving concrete is required. a concrete washout will be installed in a designated area. No other allowable sources of discharge exist on the site. 2.9 Receiving Waters Receiving waters include any classified or unclassified surface water segment (including tributaries) in the State of Colorado into which stormwater associated with construction activities discharges. This includes all water courses, even if they are usually dry. such as borrow ditches, arroyos. and other unnamed waterways. Runoff from the project site flows southeast flowing overland through various drainages ultimately running to Little Crow Creek. Runoff from the substation will flow to the on -site detention pond to provide water quality treatment prior to discharge following historical drainage patterns. There are no stream crossings located within the construction site. There are no discharges to Outstanding Waters. 2.10Site Map The site map (see Appendix A) will show the following per the CDPS Permit: • Construction site boundaries • Flow arrows that depict stormwater flow directions on -site and runoff direction • Entrances and exits (if applicable) • All areas of ground disturbance including areas of cut and fill • Areas used for vehicle parking. storage of building materials, equipment, soil or waste • Locations of concrete washouts • Locations of all structural CMs (including existing CMs) • Locations of all non-structural CMs (including areas that will be subject to re -seeding) • Locations of springs. streams. wetlands, and other surface waters (including areas that require pre-existing vegetation be maintained within 50 feet of a receiving water) • Locations of all stream crossings located within the construction site boundary • Any other factors that are important to the site and/or the SWMP Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan 3.0 CONTROL MEASURES 3.1 Structural Measures for Erosion and Sediment Control Structural measures are those physical structures implemented at the site to minimize erosion and sediment transport. The CMs specified for use on the project are described below. Specific locations for CM implementation at the site are indicated on the site map in Appendix A. The installation details for these CMs are provided in Appendix B. This SWMP anticipates that not all of these CMs are going to be used and additional CMs may be added as site conditions change or climatic conditions warrant. If additional CMs are added. description and construction details will be added to Appendix B or to a revision of the Site Map prior to installation. Concrete Washout A concrete washout is used to capture waste water and waste products resulting from the cleaning of concrete equipment. The wash water is alkaline and can contaminate groundwater. increase the pH of receiving waters.. clog storm drains, and harm wildlife. Examples of concrete washouts include, but is not limited to, a bermed excavation, a mobile disposal unit, small excavations located near the point of concrete placement, water tight vessels (such as a rigid pre- fabricated impermeable plastic wading pool. stock tanks. small dumpsters, buckets. etc.). and geotextile bags. Control measures designed for concrete washout waste shall be implemented at the project site. and Tri-State will ensure that washing activities do not contribute pollutants to stormwater runoff or receiving waters. Discharges that may reach groundwater will flow through soil that has a buffering capacity prior to reaching groundwater. The concrete washout area shall not be located in an area where shallow groundwater may be present and would result in the soil buffering capacity not being adequate. Hardened concrete wastes on the ground will be picked up daily and disposed of properly Concrete pours will be scheduled so that no pours occur when a storm event is anticipated. No concrete pours will be conducted during storm events. A concrete washout will not be necessary if all washout operations are performed off -site (at the vendor mixing plant for example). Concrete washout will only be allowed in the designated area. For project phases with large amounts of concrete work. concrete washout will be conducted at a dedicated concrete washout pit installed and maintained on the site. For project phases with small amounts of concrete work, the driver will be directed to return to the mixing facility to washout the truck drum or a rigid pre- fabricated impermeable plastic wading pool can be used to contain the washout. If the concrete contractor is able to provide a prefabricated washout container. this will be used in place of constructing one onsite. A concrete washout will be installed or provided prior to any construction activities that include the handling of materials containing cement (e.g. concrete. masonry. etc.). Concrete washouts will Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan be installed per the attached detail ("Concrete Washout Area" CWA-1 through CWA-4 from Urban Drainage and Flood Control District Drainage Criteria Manual Volume 3). The concrete washout will be inspected daily during periods of concrete construction to make sure appropriate access control, tracking and containment is in place. Additionally, the project manager/superintendent will ensure that concrete washing is being conducted only at this designated area and that no damage is present at the washout. For lined washouts. the liner will be inspected for rips. tears. etc. Concrete operations will be suspended until any needed repairs are completed. Maintenance will include the removal of excess material. cleaning. and general structural integrity of the installation as needed. The concrete washout will be cleaned of excess water and solids on a regular basis to maintain its proper function. The washout will be cleaned out when at 75% of capacity (50% if rigid containment is used). The concrete waste will be properly disposed by a qualified contractor. If a water -tight vessel is used to contain concrete washout water. the following management practices will be followed: (1) The CM will be inspected for waterproof integrity prior to each use: (2) The CM will not be filled to more than 50% of capacity with either liquid or solid waste: (3) Immediately after concrete washing is complete. the CM will be covered with a waterproof barrier: (4) Upon termination of use of the washout site or when waste reaches 50% capacity. the accumulated waste will be removed from the site and properly disposed. If unlined pits are used to contain concrete washout. the following management practices will be followed. (1) The use of the washout site must be temporary (less than 1 year): (2) The washout site will not be located in an area where groundwater may be present. such as near natural drainages. springs, or wetlands. or down slope of construction activity where runoff could flow into the washout: (3) Upon termination of use of the washout site. accumulated solid waste. including concrete waste and any contaminated soils, will be removed from the site to prevent on -site disposal of solid waste. The washout will be removed when it is no longer needed. Drainage Swales/Check Dams Drainage swales and check dams may be constructed during the initial stages of new construction to ensure run-on and run-off are managed correctly. Check dams may also be constructed where existing drainage patterns cross onto the site and bring neighboring property run-on into the construction area. Check dams are generally constructed from rock. straw wattles. or straw bales. They are designed to slow water velocity allowing some sediment to settle. Check dams will be used in areas of concentrated flows along drainage swales. The check dam will be installed Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan across the entire width of the drainage swale in order to function properly. The center of the check dam should be lower than the sides. Drainage swales will be installed per the construction drawings and from Standard Plan No. M-208-1. Temporary Erosion Control.. from the Colorado Department of Transportation (CDOT) 2006 M -Standard (Miscellaneous Standard) Plans. rev 8- 2010. Check dams will be inspected for proper installation and sediment accumulation on the up - gradient side Accumulated sediment and debris will be removed when the sediment level reaches one-half the height of the CM or at any time that sediment or debris adversely impacts the functioning of the CM. The removed sediment shall be placed with the topsoil stockpile and debris shall be hauled from site and disposed of. Check dam materials will be cleaned and replaced as needed to maintain function and integrity. Inlet/culvert protection Inlet protection consists of a barrier placed in front. around. or immediately up -gradient from the inlet or culvert. The most common forms of inlet protection are straw wattles or straw bales. Inlet protection is designed to slow stormwater flow into the inlet or culvert, allowing sediment time to settle and accumulate on the up -gradient side to the structure, without constricting the inlet throat. As permanent stormwater system inlets are constructed in areas with potential disturbed area run-off or when existing inlets are potentially impacted by construction activity, inlet protection will be installed. Any structure with a potential to receive run-off from non -stabilized surfaces will be treated with an inlet protection CM. Inlet protection will remain in place until all up -gradient areas are stabilized See attached detail for further description and applications (excerpt from Standard Plan No. M-208-1, Temporary Erosion Control. from the Colorado Department of Transportation (CDOT) 2006 M -Standard (Miscellaneous Standard) Plans, rev 8- 2010. Inlet protection will be inspected for damage, structural integrity. and proper installation in relationship to the culvert, and accumulated sediment/debris. Maintenance includes repairing or replacing as needed, repositioning the inlet protection and/or removing accumulated sediment. Riprap Rip rap is a layer of rock used to reduce the velocity of stormwater and to trap sediment. It is a permanent CM that is used to line channels, ditches. drainage swales. and at culvert inlets/outlets. The depth of the rip rap should be a minimum of twice the maximum rock diameter. A geotextile fabric can be used to extend the effectiveness of rip rap. See construction drawings regarding specifications of riprap. Sediment Trap Sediment traps are small impoundments which allow sediment to settle out which are generally installed in a drainage way or other point of discharge from a disturbed area. They are formed by excavating an area or by placing an earthen embankment across a low area or drainage swale. Typically, a spillway or outlet is constructed to allow the slow release of stormwater runoff. Sediment traps are commonly used at the outlets of diversion structures. slope drains or any other runoff that discharges waters containing sediment. If detailed engineering drawings specifically are not designed for this project. see attached installation detail and notes ("Sediment Trap" ST -1 through ST -3 from Urban Drainage and Flood Control District Drainage Criteria Manual Volume Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan 3). Sediment Traps will be inspected for accumulated sediment. erosion and to ensure effective operation. Silt Fence Silt fence consists of geotextile fabric installed with at least six inches of the fabric entrenched into the soil attached to wooden stakes on the down -gradient side. Wire -backed fence may be used or additional stakes or lathe may be added on the down -gradient side for strengthening the fence around corners or in high wind conditions. Silt fence provides sediment control by reducing water velocity and ponding water to facilitate the deposition of sediment on the up -gradient side of the fence. Silt fence applications include, but are not limited to: project perimeter control. secondary containment. back of curb protection, containment for any disturbed or staging area, or around temporary material stockpiles (outer boundary). Silt fence is an optional CM to be used at the discretion of either the construction foreman and/or the SWMP Administrator. When silt fence is used, it will primarily be installed prior to clearing and grubbing operations in a new phase of construction where a sediment control measure is appropriate. Usually other CMs. such as natural vegetative barriers, straw wattles. and rock sediment traps. will be employed before use of silt fence. The primary application for silt fence will be in steeper sections of the project to protect the site from neighboring run-on or to direct project run-off toward a large sediment trap. Silt fence will be installed per the attached detail ("Silt Fence" SF -1 through Sf-4 from Urban Drainage and Flood Control District Drainage Criteria Manual Volume 3). Silt fence will be inspected regularly for sediment accumulation one-half the height of the fence. tears or holes in the fabric, broken stakes. and gaps in the fabric or areas where the fabric needs to be re -attached to the wooden stakes. Straw Bales A straw bale should be a minimum of 14" X 18" X 36- and have a minimum mass of 50 pounds. It should be composed of only vegetative matter, except for the binding. The straw bales should be bound by steel wire (minimum 14 -gauge), nylon or polypropylene. Applications include. but are not limited to. check dams in swales. inlet protection. outlet protection, perimeter control, disturbed areas with significant potential for off -site drainage, protection from neighboring site run-on, or during the construction of drainage swales and ditches. Straw bales may also be used as `final discharge check dams" for drainage swales and ditches to slow run-off and collect sediment. Straw bales will be keyed into the soil perpendicular to the run-off flow. Straw bales will be installed per the attached detail (Excerpt from Standard Plan No. M-208-1. Temporary Erosion Control. from the Colorado Department of Transportation (CDOT) 2006 M -Standard (Miscellaneous Standard) Plans. rev 8-2010). Straw Wattles (fiber rolls) A straw wattle consists of a net or geotextile fabric filled with straw, excelsior. wood mulch or other fillers. Straw wattles reduce water velocity allowing sediment to accumulate on the up -gradient side of the straw wattle. Applications include. but are not limited to. disturbed areas with significant potential for off -site drainage. protection from neighboring site run-on. during the construction of drainage swales and ditches. slope stabilization. check dams in swales. back of curb protection. or temporary secondary containment for stock piles and materials storage. Straw Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan wattles will be keyed into the soil in a trench a minimum of two inches deep perpendicular to the run-off flow, secured in the trench using stakes. and backfilled on the up -gradient side. When necessary they will be stacked two courses high with joints off -set or overlapped. Straw wattles will be installed per the attached detail (Excerpt from Standard Plan No. M-208-1, Temporary Erosion Control, from the Colorado Department of Transportation (CDOT) 2006 M -Standard (Miscellaneous Standard) Plans. rev 8-2010). Straw wattles should be inspected for proper installation, structural integrity and sediment accumulation. A straw wattle that has been flattened out of round may not need to be replaced if they remain sufficiently sound to function appropriately on the up -gradient side of the straw wattle. Topsoil Berm A topsoil berm is a ridge of compacted soil which is used to prevent run-off and sheet flow of stormwater. The minimum height of the berm is 18 inches with side slopes less than 2:1. Topsoil berms shall be used to intercept and divert drainage to a designated outlet point. Topsoil berms will be installed per the attached detail (Excerpt from Standard Plan No. M-208-1, Temporary Erosion Control, from the Colorado Department of Transportation (CDOT) 2006 M -Standard (Miscellaneous Standard) Plans. rev 8-2010). Vehicle Tracking Control Vehicle tracking control will consist of an area with a geotextile liner and gravel, metal grate, medium-sized (6" to 12") rough -cut rocks, or asphalt/concrete "rumble strip". Tracking control is designed to cause soil to vibrate off equipment and vehicles as they transition from disturbed soils to paved areas. The vehicle tracking control will remain in place until access to the areas used by the control are stabilized or no longer needed. All appropriate points of ingress and egress. where traffic transitions from a stabilized road surface (e.g. gravel or pavement) to disturbed soil. will have vehicle tracking control installed. Tracking control will be moved or eliminated as on -site conditions and activities change. Tracking control will be inspected for depth of gravel/rock.. presence of excess soil, proper usage and the overall general condition. Strict site access will be maintained throughout the project. Once the section is stabilized and surface drainage features are built. tracking pads will be removed in favor of controlled site access. See attached detail for further description and applications (Standard Plan No. M-208-1. Temporary Erosion Control. from the Colorado Department of Transportation (CDOT) 2006 M -Standard (Miscellaneous Standard) Plans, rev 8-2010. 3.2 Non -Structural CMs for Erosion and Sediment Control Non-structural practices are those practices which when implemented will minimize erosion and sediment transport. Practices implemented at this site include interim stabilization practices, permanent stabilization practices (see Section 4). site -specific scheduling for implementation of the practices. and site management practices and personnel training. The CMs specified for the project are described below. Specific locations for CM implementation at the site are indicated on the site map in Appendix A. The installation details for these CMs are provided in Appendix B. Additional CMs may be added as site conditions change and will be identified in the "New CMs Added to the Site" form (Appendix C) prior to installation. Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan Controlled Parking During construction activity. controlled parking areas will be established to allow workers to commute to/from the job site. Limited and designated parking areas will be established for all new phases of construction. This CM is an administrative measure to control access to/from the site. Controlled Site Entrance During construction activity or when construction activity is temporarily left in an intermediate state awaiting final treatment (concrete. finished gravel surface. etc.). controlled access will be established to direct traffic in/out and across/through the areas under construction. Limited access points will be established for all new phases of construction. This CM is an administrative measure to control access to/from the site and to ensure the general public is directed through the construction site via a safe and stabilized route. Designated Staging Area A designated staging area is a specific location on -site for stockpiling/staging materials or staging equipment for use on -site. A stabilized staging area allows for a central location for deliveries and storage of equipment when not in use. and to prevent disturbance of areas not scheduled for construction activities. Stabilized staging areas will be implemented as needed on site and will be located out of areas of active construction activity. If possible. the designated area will be located so it can be utilized during the entire construction period. Stabilized staging areas will be inspected for adequate vehicle tracking control and perimeter control. The staging area will be repaired or modified as needed. No hazardous material will be stored on site. This CM is an administrative measure to control access to/from the site. Designated Vehicle Fueling and Maintenance Area During all active construction phases. vehicle fueling and maintenance will only be conducted in a designated area. Any waste (oil, antifreeze. solvents. etc.) will be disposed according to manufacturer's instructions or Material Safety Data Sheets (MSDS). Vehicles and equipment will be inspected for leaks. Leaks will be repaired on site immediately or the vehicle/equipment will be removed from the site. Spill kits will be readily available. Any spills will be immediately cleaned up and properly dispose as described in Section 6.4. Spill Control and Cleanup. No fuel will be stored on -site. Dust Control Dust control reduces dust generated from disturbed surfaces and wind. To control dust that may be generated at the project site during construction. water will be applied from water trucks as needed. Care will be taken to apply water per industry standard in small volumes and at a low rate to prevent surface runoff. Correct application is just enough water to moisten the surface and calm dust, but not so much as to create standing water and mud. Erosion Control Blankets (ECBs) and Turf Reinforcement Mats ;TRMs) ECBs and TRMs are sheets of straw, excelsior, coconut. manmade fiber. or combination thereof. usually contained between layers of netting to provide structural integrity. ECBs and TRMs provide a ground cover that reduces erosive action. TRMs are able to handle higher levels of Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan concentrated flows and are used mainly in channel applications. ECBs and TRMs may be used in conjunction with other velocity reducing CMs. ECB and TRM applications include. but are not limited to. slope and swale protection. See attached detail for further description and applications (Standard Plan No. M-208-1. Temporary Erosion Control, from the Colorado Department of Transportation (CDOT) 2006 M -Standard (Miscellaneous Standard) Plans. rev 8-2010). ECB and TRMs will be inspected for erosion underneath and at the sides. sediment accumulation. rips. tears and other structural problems. Maintenance will include removing sediment (to be placed with topsoil stockpile), re -securing material to ground, and re -trenching at up -gradient portions and sides as needed. Good Housekeeping Practices Good housekeeping will be used to keep potential areas where pollutants exist clean and orderly. Any containers. drums, and bags will be stored away from direct traffic routes to reduce the risk of accidental spills. stacked according to manufacturer's instructions. and stored on pallets or similar items. Materials which require spill containment practices (described in Section 6) shall be stored in close proximity to an appropriately stocked spill response kit. Hazardous materials will not be stored on this site. The site will be managed to keep materials, equipment. and portable sanitary facilities (these will additionally be staked to prevent/inhibit tipping) only in designated areas and promptly directing the thorough clean-up of any debris resulting from these operations. Stockpiles will be protected from run-on and run-off with berms. natural vegetative barriers, or structural CMs (straw wattles. straw bales, silt fence. etc.). Mulching Mulching uses materials such as grass, wood chips or fibers, hay. straw or native mowed vegetation to stabilize exposed or recently seeded soil and to reduce stormwater velocity and improve infiltration. It is most effective when used in conjunction with vegetation. Mulching can additionally aid vegetation growth by preventing birds from eating the seeds. retaining moisture. etc. Natural mulches will be used whenever possible. For steep slopes and critical areas, mulch matting with anchoring or matting will be utilized. The SWMP administrator will determine the appropriateness of utilizing mulching throughout the project. See attached detail for further description and applications (Figure C4-2. Mulching. from the Urban Drainage and Flood Control District Drainage Criteria Manual (V.3)). Since subject to erosion, mulched areas will be inspected frequently for effectiveness. Natural Vegetative Barrier A natural vegetative barrier is a preexisting vegetated area that is retained during construction to reduce water velocity and prevent erosion. Natural vegetative barrier provides a barrier zone where sediment is trapped. which reduces sediment discharge off -site. and are encouraged for any perimeter or environmentally sensitive areas. Whenever possible. a natural vegetative barrier will be maintained between the construction area and stormwater drainage areas. For best efficiency. buffer strips should be a minimum of 20' in length along the direction of flow: shorter distances should be supplemented with additional CMs. Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan Perimeter control Perimeter control will control access during construction activity. Perimeter control will consist of various CMs. including, but not limited to controlled parking, controlled site entrances. vehicle tracking control, wire boundary fencing, etc. This CM is an administrative measure to control access to/from the site and to ensure the general public safety. Seeding Seeding involves the mechanical or hand application of specific seed mixes appropriate for the site location and soil type Seeding provides plant growth to stabilize the soil reducing the likelihood of erosion or sediment transport and provides permanent stabilization. Drilling is the preferred method of seeding. As soon as practical, after the completion of final grading. disturbed surfaces as well as all areas which will not be hard surfaced or graveled, shall be properly prepared and seeded per the recommended seed mix below. To maximize seed germination and to utilize natural precipitation. seeding will normally occur from March to May or September to October. The SWMP Administrator will determine the appropriateness of seeding throughout the project. Seeding may be accompanied by an additional CM. such as mulching or straw mats. to protect the seed and soil from erosion during the germination and growth process. Straw mats will be stapled to the slopes and overlapped. Stockpiled topsoil will be redistributed over areas to be seeded. At the discretion of the SWMP administrator. a soil conditioner (3CY per 1,000 SF) may be rototilled into the top 6" of the topsoil soil before fine grading. The topsoil shall be graded to a reasonably even and smooth surface. Seed shall be uniformly distributed over the area. Drilled seed shall be applied .25 to .5 inches deep in rows spaced no more than 7 inches apart. On slopes steeper than 3:1, seed shall be applied by a mechanical broadcaster or hand broadcast at double the rate required for drill seeding. All seed sown by mechanical broadcasters shall be raked or dragged into the soil to a depth of 1/2". Seed mix to be provided by Contractor to be approved by the owner. All seed must comply with Colorado weed seed guidelines. There should be no prohibited/noxious weed species seeds in the mix. Use certified Pure Live Seed (PLS). Deliver in original unopened containers with seed tags dealers warranty analysis attached. Seeded areas will be inspected every 14 days and after an erosion causing storm event to ensure that the soil stabilization method (e.g. surface roughening, erosion control blankets, etc.) was applied correctly and has not been compromised. The area will also be inspected for erosion and/or sediment deposition. If vegetation does not begin to grow in a seeded area after 4 to 6 weeks. the area will be reseeded. fertilized, and mulched. Maintenance items would include re- grading and seeding bare or areas of thin vegetative growth and/or adding additional CMs as appropriate. Seeded area will be inspected and monitored until the area obtains final stabilization. Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan Solid Waste Management To reduce the risk of pollution at the project site, construction wastes require proper management and disposal. This includes location of refuse piles, materials that may be displaced by stormwater. trash disposal and spill prevention. Waste collection will be scheduled to prevent containers from overflowing. Debris stockpiles will be continuously monitored and dispose of properly throughout the construction period. Additionally, waste will be monitored around the site perimeter. The onsite portable sanitary facilities will be staked to prevent tipping and will be monitored and cleaned weekly. Trays can be used to contain spills. Any spills of sewage chemicals will be cleaned up according to Section 6.4. Surface Roughening Surface roughening consists of grooves or tracks installed in the soil surface, perpendicular to the slope. This is a temporary soil stabilization technique that works well in areas that will remain inactive for a short time. It reduces water velocity and promotes infiltration, thus decreasing the potential for erosion to occur. As areas are cleared. surfaces will be left rough to inhibit run-off sheeting from disturbed areas. Where practical. surfaces will be left in a roughened state and slopes will be graded (or "tracked") parallel to the contour to further inhibit sheet flow drainage. Any disturbed areas with no construction activity planned for more than 14 days or longer will be surfaced roughened. See attached detail for further guidance and potential applications (`Surface Roughening" SR -1 through SR -4 from Urban Drainage and Flood Control District Drainage Criteria Manual Volume 3). In areas where it is impractical to apply surface roughening using tracked equipment the surface may be manually raked to create the desired texture. 3.3 Phased CM Installation Phased CMs will be used in conjunction with the installation of permanent structural CMs (rip - rapped outfalls. culvert installations. etc.). Temporary additional sediment control and/or erosion control CMs will be added to the upstream side of the permanent CM. As an example, if new culverts are installed, rip -rapped scour protection will generally be installed at the outlet end. A temporary (phased) sediment control CM (usually straw bales or straw wattles) will be installed on the inlet side to prevent the culvert and the outlet rip -rap from silting in before the upstream ditch/drainage can be stabilized (usually with natural vegetation). Phased CMs can be a combination of both Structural and Non -Structural CMs. Refer to Appendix C for phased CM Installation. 3.4 Dedicated Concrete or Asphalt Batch Plants No onsite concrete or asphalt production will be used for this project unless approved by the owner. All concrete and asphalt will be imported and placed the same day. 3.5 Vehicle Tracking Control Vehicle tracking controls are used to prevent sediment transport from the construction site to paved or permanently graveled roads. These controls are: Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan • Controlled Parking • Controlled Site Entrance • Designated Staging Area • Dust Control • Vehicle Tracking Control. including management of general public traffic 3.6 Waste Management and Disposal (Including Concrete Washouts) On -site waste disposal including personnel trash. construction debris. sanitary wastes, etc. is prohibited. The following practices shall be implemented as directed. Concrete Washout Designated concrete washout(s) will be installed on site during construction phases involving concrete. The location of these washout(s) will be added to the site map. No concrete waste will be discharged directly into the ground without a containment feature. The concrete waste and/or excess wash water will be properly disposed as needed. Additionally. signs will clearly indicate the concrete washout location. Concrete washout water will not be discharged to receiving waters, storm sewer systems or the ground. Portable Sanitary Facilities Portable sanitary facilities will be provided (if necessary) in a convenient, level location away from traffic areas at least three feet from curb flow lines and paved/driving surfaces, storm drains. or retention areas. A qualified contractor will maintain and clean the units, inspect for any deficiencies. and keep the units in good working order. Portable sanitary facilities will be adequately anchored to prevent tipping. The construction contractor will be responsible for ensuring that the units are properly used and maintained. Solid Waste Large amounts of solid waste are not anticipated to be generated during this project. The majority of solid waste will be collected. removed from site, and properly disposed on a daily basis. If dumpsters are needed, they will be installed in a convenient, level location away from traffic areas, storm drains, drainage areas, or retention areas. The dumpsters will be kept off of paved surfaces (to avoid damages to the asphalt) and a qualified contractor will empty the dumpsters. as needed. The site perimeter will be monitored to ensure that all site personnel utilize the proper waste disposal practices and facilities. Hazardous Wastes Fuel and hazardous materials will not be stored at the site. 3.7 Product Specific Practices Due to the chemical makeup of specific products. certain handling and storage procedures are required to promote the safety of personnel and prevent the possibility of pollution. Site personnel Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan will be instructed to follow all directions and warnings for products used on the site. All pertinent information can be found on the Material Safety Data Sheets (MSDS) for each product. The appropriate MSDS will be located with each product container or in a readily accessible central location. 3.8 Groundwater and Stormwater Dewatering Based on the shallow nature of construction, dewatering of groundwater or stormwater is not anticipated on this project. The Division's Low Risk Discharge Guidance for Discharges of Uncontaminated Groundwater to Land allows the discharge of construction dewatering to the ground, under specific conditions. when appropriate control measures are implemented. It does not allow discharge of construction dewatering of non-stormwater to be discharged to the surface waters or to storm sewer systems without separate permit coverage. Although the Construction Stormwater permit does not authorize the conditional discharge of construction dewatering to the ground. discharge of uncontaminated groundwater to land may be covered under the Low Risk Discharge Guidance when all the provisions in the guidance document are adhered to. In all cases when groundwater is encountered, a geotechnical and/or a professional engineer will be consulted before proceeding with the project. Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan 4.0 FINAL STABILIZATION AND LONG-TERM STORMWATER MANAGEMENT 4.1 Temporary Stabilization Temporary stabilization must be implemented for earth disturbing activities on any portion of the site where ground disturbing construction activity has permanently ceased, or temporarily ceased for more than 14 calendar days. Temporary stabilization methods may include. but are not limited to, tarps, soil tackifier, and hydroseed. The 14 -day schedule may be exceeded when either the function of the specific area of the site requires it to remain disturbed. or. physical characteristics of the terrain and climate prevent stabilization. The constraints necessitating the alternative schedule must be documented, an alternate stabilization schedule provided. and all locations where the alternative schedule is applicable on the site map need to be identified. 4.2 Description of Final Stabilization Practices Final stabilization for disturbed areas of the site will be to return to their original condition or to the improved design (native re -vegetated areas, access roads. gravel yards. drainage basins. etc.). For disturbed areas. temporary CMs will be maintained until the final surface cover is constructed or established. 4.3 Final Stabilization Methods Final stabilization includes those measures taken to control pollutants in stormwater after soil disturbing activities are complete. Practices implemented to achieve final stabilization include: • Preparation of the soil prior to seed application: • Seed mix appropriate for the area will be broadcasted per recommended instructions: • Maintaining appropriate erosion and sediment control CMs until final stabilization is achieved; and • Removal of temporary CMs once work is completed and final stabilization achieved. 4.4 Final Stabilization Achievement Final stabilization of road surface areas and graveled areas will be achieved when the final surface (improved gravel surface. landscaping, etc.) is accepted by the Owner. Final stabilization will be reached when all ground surface disturbing activities at the site have been completed, and for all areas of ground surface disturbing activities where a uniform vegetative cover has been established with an individual plant density of at least 70 percent of pre -disturbance levels. or equivalent permanent, physical erosion reduction methods have been employed. Coverage under the Stormwater Construction Permit may be terminated by the permittee when the entire site has attained final stabilization, all temporary erosion and sediment control measures have been removed. and all components of the SWMP are complete. Vegetative ground cover shall be greater than 70% of the pre -construction cover. 0.70 x 0.2-0.50. or approximately 15-35% Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan vegetation coverage depending on the location. for areas of disturbance that are not hard surfaced. graveled. or landscaped. When the site has attained final stabilization and all temporary erosion and sediment control measures have been removed, the permittee will submit an Inactivation Notice form. Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan 5.0 INSPECTION AND MAINTENANCE 5.1 Minimum Inspection Schedule A thorough inspection will be conducted within 7 calendar days of the commencement of construction activities. and in accordance with one of the following minimum frequencies: • At least one inspection every 7 calendar days • At least one inspection every 14 calendar days. PLUS post -storm even inspections conducted within 24 hours after the end of any precipitation or snowmelt event that causes surface erosion. Post -storm inspections may be used to fulfill the 14 -day routine inspection requirement. Inspections will be conducted on either the 7 day or 14 day schedule.. and may switch between these schedules as appropriate for the site. The inspection frequency will be noted on the inspection reports. There are no discharges to Outstanding Waters: therefore inspections will not be required at least once every 7 days. 5.1.1 Post -storm inspections Post -storm inspections will be conducted within 24 hours after the end of any precipitation or snowmelt event that causes surface erosion. If no construction activities will occur following a storm event, post -storm event inspections will be conducted prior to re -commencing construction activities, but no later than 72 hours following the storm event. The delayed inspection will be documented in the inspection record. 5.1.2 Inspections at Completed Sites/Areas For completed construction sites. an inspection of the site will be made at least once every month until final stabilization is reached. The following must be met in order for the site to be inspected on a monthly basis instead of every 14 days: • All construction activities that will result in surface ground disturbance are completed: • All activities required for final stabilization have been completed, with the exception of the application of seed that has not occurred due to seasonal conditions or the necessity for additional seed application to augment previous efforts; and • The SWMP has been amended to indicate those areas that will be inspected in accordance with the reduced schedule. The reduced frequency schedule also applies to the site or portions of the site where continuing construction activities can be conducted without disturbance of the ground surface. Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan 5.1.3 Winter Conditions Inspections Exclusion Inspections will not be conducted where construction activities are temporarily halted. snow cover exists over the entire site for an extended period. and melting conditions posing a risk of surface erosion do not exist. The following information will be documented in the inspection record for use of this exclusion: • Dates when snow cover occurred, • Date when construction activities ceased, and • Date melting conditions began. 5.2 Inspection Requirements Inspections should include a visual verification of whether all implemented control measures are in effective operational condition and are working as designed to minimize pollutant discharges. It should be determined if there are new potential sources of pollutants The adequacy of control measures should be assessed to identify areas requiring new or modified control measures. All areas of non-compliance should be identified and corrective actions implemented. 5.2.1 Inspection Scope The following items will be examined for evidence of, or the potential for, pollutants leaving the construction site boundaries. entering the stormwater drainage system. or discharging to state waters during the inspection and reported on the inspection reports: • Construction site perimeter: • All disturbed areas; • Designated haul routes: • Material and/or waste storage areas that are exposed to precipitation: • Discharge locations; • Locations where vehicles access the site: and • All CMs implemented will be evaluated to ensure that they are maintained and operating correctly 5.2.2 Inspection Reports The inspection report form is located in Appendix D. Inspection reports must identify any incidents of non-compliance with the terms and conditions of the general permit. The inspection records will be retained for three years from the expiration or inactivation of permit coverage. Tri-State Generation & Transmission - Lloyd Sisson Substation Stormwater Management Plan The inspection record will note evidence of, or the potential for. pollutants leaving the construction site boundaries. entering the stormwater drainage system. or discharging to state waters. The inspection report will include: • The inspection date: • Name(s) and title(s) of personnel making the inspection; • Weather conditions at the time of inspection: • Phase of construction at the time of inspection: • Estimated acreage of disturbance at the time of inspection; • Location(s) of discharges of sediment or other pollutants from the site: • Location(s) of CMs that need to be maintained: • Location(s) and identification of inadequate control measures • Location(s) and identification of additional control measures needed that were not in place at the time of inspection • Description of the minimum inspection frequency. and any deviations from the minimum inspection schedule: • Identification of control measures observed that require routine maintenance (any control measure that is still operating in accordance with its design and the requirements of the permit. but requires maintenance to prevent a breach of the control measure) • After adequate corrective action(s) have been taken. or where a report does not identify any incidents requiring corrective action, the report will contain a signed statement indicating "all corrective action and maintenance items identified during the inspection are complete, and the site is currently in compliance with the permit." 5.3 Required Actions Following Site Inspections CMs will be maintained or replaced in accordance with Sections 5.4 and 5.5 of this SWMP. The SWMP will be updated in accordance with Section 5.6.3. Where site inspections note the need for CM maintenance activities. CMs must be maintained such that the conditions in those sections are met. 5.4 CM Maintenance All erosion and sediment control practices and other protective measures identified in the SWMP will be maintained in effective operating condition in accordance with Section 3.0 and Appendix B. CMs that are not adequately maintained in accordance with good engineering. hydrologic and pollution control practices are considered to be no longer operating effectively and will be modified or replaced. CMs implemented at the site must be adequately designed and maintained to provide control for all potential pollutant sources associated with the construction activity to prevent pollution or degradation of State waters. Where site inspections note the need for CM maintenance activities. CMs will be maintained such as these conditions are met. Maintenance Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan items include. but are not limited to: removal of accumulated sediment. repair or replacement of worn or damaged sections. repositioning to correct placement: and reinstallation of CMs displaced. Accumulated sediment and debris will be removed from a CM when the sediment level reaches one-half the height of the CM (unless otherwise noted in the design drawings or CM detail) or at any time that sediment or debris adversely impacts the functioning of the CM. 5.5 Corrective Actions Adequate site assessment will be performed as part of the comprehensive inspection and maintenance procedures. to assess the adequacy of CMs at the site, and the necessity of changes to those CMs to ensure continued effective performance. When an inadequate control measure is identified, the following corrective action requirements apply: All necessary steps must be taken to minimize or prevent the discharge of pollutants. until a control measure is implemented and made operational and/or an inadequate control measure is replaced or corrected and returned to effective operating condition. • If it is infeasible to install or repair a control measure immediately after discovering the deficiency. the following information must be documented and kept on record: o Describe why it is infeasible to initiate the installation or repair immediately, and o Provide a schedule for installing or repairing the control measure and returning it to an effective operating condition as soon as possible. If applicable. any unauthorized release or discharge must be removed and properly disposed of. Contaminated surfaces must be cleaned up to minimize discharges of the material in subsequent storm events. 5.6 SWMP Requirements 5.6.1 SWMP Availability The SWMP will be implemented prior to commencement of construction activities. The SWMP will be kept accurate and up-to-date. and will reflect the actual on site ground conditions. Only changes in site conditions that require new or modified CMs need to be addressed in the SWMP. 5.6.2 SWMP Retention A copy of the SWMP must be retained on site unless another location. specified by the permittee. is approved by the Division. Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan 5.6.3 SWMP Amendment The SWMP will be amended: • When there is a change in design, construction. operation. or maintenance of the site. which would require the implementation of new or revised CMs: or • If the SWMP proves to be ineffective in achieving the general objectives of controlling pollutants in stormwater discharges associated with construction activity: or • When CMs are no longer necessary and are removed. SWMP changes will be made prior to changes in the site conditions. except as noted below under `Responsive SWMP Changes.' SWMP revisions may include. but are not limited to: potential pollutant source identification: selection of appropriate CMs for site conditions: CM maintenance procedures: and interim and final stabilization practices. The SWMP changes may include a schedule for further CM design and implementation. provided that. if any interim CMs are needed to comply with the permit. they are also included in the SWMP and implemented during the interim period. For SWMP revisions made prior to or following a change(s) onsite. including revisions to sections addressing site conditions and control measures, a notation must be included in the plan that identifies: the date of the site change: the control measure removed or modified: the location(s) of those control measures: and any changes to the control measure(s). 5.6.4 Responsive SWMP Changes The majority of SWMP revisions to address changing site conditions can be made immediately with simple field revisions to the SWMP. In the less common scenario where more complex development of materials to modify the SWMP are necessary.. SWMP revisions will be made in accordance with the following requirements: • The SWMP will be revised as soon as practicable, but in no case more than 72 hours after the change(s) in CM installation and/or implementation occur at the site, and • A notation must be included in the site map prior to the site change(s) that includes the date of the change(s) in the field, an identification of the CM(s) removed or added. and the location(s) of those CM(s). Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan 5.7 RECORD KEEPING Copies of the SWMP. amendments to or changes to the SWMP, inspection records and all other data must be retained by the owner (permittee) for three (3) years after the expiration or inactivation of the permit. Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan 6.0 SPILL PREVENTION AND RESPONSE 6.1 Introduction This section describes measures to prevent. control. and minimize impacts from a spill of chemical products (hazardous. toxic, or petroleum substances) during construction of this project. This plan identifies the handling. transportation. storage. and disposal procedures for these chemical products and outlines procedures to be followed in the event of a spill. 6.2 Material Management Practices Properly managing these materials on the site will greatly reduce the potential for stormwater pollution. Good housekeeping along with proper use and storage of these construction materials form the basis for proper management of chemical products. 6.2.1 Good Housekeeping The proper use of materials and equipment along with the use of general common sense greatly reduce the potential for contaminating stormwater runoff. The following is a list of good housekeeping practices to be used during the construction project: • Provide secondary containment (or equivalent protection) for any container containing 55 gallons or greater. • Fueling of construction equipment will not be performed within 150 feet of definitive stormwater drainages. • An effort will be made to store only enough product required to do the job. • Materials will be stored in a neat. orderly manner. in appropriate closed containers, in secondary containment and, if possible, under a roof or other enclosure. • Products will be kept in their original containers with the original manufacturer's label. • Substances will not be mixed with one another unless recommended by the manufacturer. • Whenever possible, all of the product will be used up before properly disposing of the container. • Manufacturer's recommendations for proper use of a product will be followed. • If surplus product must be disposed of, local and state recommended methods for proper disposal will be followed. Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan 6.3 Product -Specific Practices Due to the chemical makeup of specific products, certain handling and storage procedures are required to promote the safety of personnel and prevent the possibility of pollution. Care will be taken to follow all directions and warnings for products used on the site. All pertinent information can be found on the Material Safety Data Sheets (MSDS) for each product. The MSDSs will be located with each product container it represents or in a readily accessible central location. Several product -specific practices are listed in the following sections. 6.3.1 Flammable and Combustible Liquids and Hazardous Materials All products will be stored in tightly sealed containers that are clearly labeled. The containers will be stored in secondary containment, which will be of sufficient size to contain the entire contents of the primary container plus a sufficient quantity for precipitation (a total of approximately 110 percent of the volume of the primary container). The secondary containment will be an impermeable containment basin to prevent any spills or leaks from reaching the ground. The containment may be one of the following or other means that meets the definition of impermeable: 1) a temporary earthen berm lined with 20-m1 plastic. 2) a portable tank or basin, or 3) a galvanized steel trough. After each storm event, all secondary containment areas will be inspected. If there is no visible sheen on the collected water, it can be pumped or drained to the ground in a manner that does not cause scouring. If a sheen is present, it must be cleaned up using absorbent materials prior to discharging or disposing of the water. The absorbent material will be disposed of properly. 6.3.2 Petroleum Products In addition to the requirements above in Section 6.2.1, petroleum products are required to have some additional procedures for handling and storage to prevent the possibility of pollution. On -site vehicles will be monitored for leaks and receive regular maintenance to reduce the potential for leakage. Bulk fuel or lubricating oil dispensers will have a valve that must be manually held open to allow the flow of fuel. When not in use, the fuel dispensing nozzles and/or associated hoses will be kept inside the containment basin. During fueling operations, personnel will be present at all times to detect and contain spills. If any spills or leaks occur. the activity will be stopped immediately. and the containment and cleanup will begin immediately. In addition. the contractor will follow the procedure listed in Section 6.4. Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan 6.4 Spill Control and Cleanup In addition to the material management practices discussed in Section 6.2, the following spill control and cleanup practices will be followed to prevent stormwater pollution in the event of a spill: • Spills will be contained and cleaned up immediately after discovery. • Manufacturer's methods for spill cleanup of a material will be followed as described on the materials MSDS. • Materials and equipment needed for cleanup procedures ("spill kits") will be kept readily available on the site. either at an equipment storage area or on contractor's trucks. Equipment to be kept on the site may include but is not be limited to brooms. dust pans. shovels. granular absorbents. sand. sawdust. absorbent pads and socks, plastic and metal trash containers. gloves. and goggles. • Drums containing used clean up materials will be labeled with the contents and date. • Personnel on the site will be made aware of cleanup procedures and the location of spill cleanup equipment. In general. every vehicle with bulk fuel or petroleum lubrication supplies will be outfitted with a spill containment and clean-up kit. • The contractor will be responsible for all cleanup activities in accordance with applicable local, state, and federal regulations. 6.5 Spill Reporting If a spill occurs. the contractor is responsible for immediately (within 5 to 10 minutes) reporting the spill to the Owners Authorized Technical Representative/Project Manager the Tri-State Environmental Services at (303) 349-7711. Tri-State Environmental Services is responsible for calling all agencies in the event of a spill. If there is a spill of antifreeze, gasoline or oils from personal vehicles, it does not need to be reported to Tri-State's Environmental Services or the SWMP Administrator, but should be documented and kept with the master SWMP. All spills should be documented using the `Spill Report" form provided in Appendix E and a record kept with the master SWMP. Copies of the forms can be found in Appendix E. Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan 6.6 SWMP Modification Procedures Related to Reportable Releases If a reportable release occurs. a modification to the SWMP must be made within 14 days. The modification will include: a description of the release, the date of the release, an explanation of why the spill happened, a description of procedures to prevent future spills and/or releases from happening, and a description of response procedures should a spill or release occur again and within 14 days of the release. A written description of the release must be submitted to the permitting authority that includes: a description of the release, including the type of material and an estimated amount of spill, the date of the release; an explanation of why the spill happened: and a description of the steps taken to prevent and control future releases. The SWMP Administrator will submit spill reports to the appropriate agencies. Modifications to the SWMP will be made by the SWMP Administrator, or his designee. and will be documented on the "New CMs Added to the Site" form in Appendix C. Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan APPENDIX A: Site Maps Tri-State Generation & Transmission — Lloyd Sisson Substation I I II I I I i t ) D 1 I I I I I SYMQOL LEGEND 11 // I I I I ; s Isign —a —�1 ® owns, 00C.a h I 1 / I �:a�� Z© .. (Mamamaassail (Wl) I I I T® J'® I I I WWI Mw = 1 // gin CD WSW iltor Nl da Ca) / l ` 1 I I I a looms roll / /j // I 1 ep t fua n/aet — I I I ® WWM:1 a111Y1otork. CD *Mtnoga7O ( / Iv 0 >q a I I I IVi[•rc ow I I IVV itcocain M® rtOUt (Mn .0CAIOY SGM) ~ / I I I 'Mall IOUs 1 / I- I COUNTY ROAD 71 I I NN I N. I I •/ I', // \ / T�\ Y I I I I I I I I I I I I .. eel•+ n j LLOYD SISSON SUBSTATION 1I) W EROSION CONTROL PUN TM- STATE GENERATION & TRANSMISSION ASSOCIATION. INCORPORATED e =J 1 I I ' r �\ I / \ i I IP I I I ' I 1 I I 1 I I 1 I _ ka TRI-STATE Taiwan [mg,' tarre, 1 100 W. 116th Ave P,O. Box 33695 Denver. Colorado 80233 303-452-6111 ..,. tWs.....es—......_ `w.,...... PROJfC" Fd( wiCIARV — IP 'P CND / I / // ' / / I / I I I I I / l . —_I - - - _ i COUNTY ROAD 130 --1 / -- _ / -' } . . -. -. r-• . Stormwater Management Plan APPENDIX B: Soil erosion and Sediment Control Measures (CMs) Details Tri-State Generation & Transmission — Lloyd Sisson Substation Check Dams (CD) EC -12 Description Check dams are temporary grade control structures placed in drainage channels to limit the erosivity of stormwater by reducing flow velocity. Check dams are typically constructed from rock, gravel bags, sand bags, or sometimes, proprietary devices. Reinforced check dams are typically constructed from rock and wire gabion. Although the primary function of check dams is to reduce the velocity of concentrated flows, a secondary benefit is sediment trapping upstream of the structure. Appropriate Uses Photograph CD -1. Rock check dams in a roadside ditch. Photo courtesy of WWE. E. Use as a grade control for temporary drainage ditches or swales until final soil stabilization measures are established upstream and downstream. Check dams can be used on mild or moderately steep slopes. Check dams may be used under the following conditions: • As temporary grade control facilities along waterways until final stabilization is established. • Along permanent swales that need protection prior to installation of a non -erodible lining. • Along temporary channels, ditches or swales that need protection where construction of a non - erodible lining is not practicable. • Reinforced check dams should be used in areas subject to high flow velocities. Design and Installation Place check dams at regularly spaced intervals along the drainage swale or ditch. Check dams heights should allow for pools to develop upstream of each check dam, extending to the downstream toe of the check dam immediately upstream. When rock is used for the check dam, place rock mechanically or by hand. Do not dump rocks into the drainage channel. Where multiple check dams are used, the top of the lower dam should be at the same elevation as the toe of the upper dam. When reinforced check dams are used, install erosion control fabric under and around the check dam to prevent erosion on the upstream and downstream sides. Each section of the dam should be keyed in to reduce the potential for washout or undermining. A rock apron upstream and downstream of the dam may be necessary to further control erosion. Check Dams Functions Erosion Control Yes Sediment Control Moderate Site/Material Management No November 2010 Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual Volume 3 CD -1 EC -12 Check Dams (CD) Design details with notes are provided for the following types of check dams: • Rock Check Dams (CD -1) • Reinforced Check Dams (CD -2) Sediment control logs may also be used as check dams; however, silt fence is not appropriate for use as a check dam. Many jurisdictions also prohibit or discourage use of straw bales for this purpose. Maintenance and Removal Replace missing rocks causing voids in the check dam. If gravel bags or sandbags are used, replace or repair torn or displaced bags. Remove accumulated sediment, as needed to maintain BMP effectiveness, typically before the sediment depth upstream of the check dam is within '/2 of the crest height. Remove accumulated sediment prior to mulching, seeding, or chemical soil stabilization. Removed sediment can be incorporated into the earthwork with approval from the Project Engineer, or disposed of at an alternate location in accordance with the standard specifications. Check dams constructed in permanent swales should be removed when perennial grasses have become established, or immediately prior to installation of a non -erodible lining. All of the rock and accumulated sediment should be removed, and the area seeded and mulched, or otherwise stabilized. CD -2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Check Dams (CD) EC -12 COMPACTED BACKFILL, (•) CHANNEL GRADE UPSTREAM AND DOWNSTREAM 1' 6" FLOW a MIN. 1' MIN. LENGTH, TOP OF CHECK DAM CHECK DAM ELEVATION VIEW 2' 6' 050 = 12" RIPRAP, TYPE M OR TYPE L D50= 9" (SEE TABLE MO -7, MAJOR DRAINAGE, VOL. 1 FOR GRADATION) FLOW -- SECTION A 8 1 1' MIN. -re. •-. D50 = 12" RIPRAP, TYPE M OR TYPE L 050=9" (SEE TABLE MO -7, MAJOR DRAINAGE. VOL. 1 FOR GRADATION) SECTION B CHANNEL GRADE EXCAVATION TO NEAT LINE, AVOID OVER -EXCAVATION, (TYP.) r_ CHANNEL GRADE EXCAVATION TO NEAT - LINE. AVOID OVER -EXCAVATION (TYP. ) SPACING BETWEEN CHECK DAMS SUCH THAT A AND B ARE EQUAL ELEVATION CHANNEL GRADE PROFILE CD- 1. CHECK DAM November 2010 Urban Drainage and Flood Control District CD -3 Urban Storm Drainage Criteria Manual Volume 3 EC -12 Check Dams (CD) CHECK DAM INSTALLATION NOTES 1. SEE PLAN VIEW FOR: -LOCATION OF CHECK DAMS. -CHECK DAM TYPE (CHECK DAM OR REINFORCED CHECK DAM). -LENGTH (L), CREST LENGTH (CL), AND DEPTH (D). 2. CHECK DAMS INDICATED ON INITIAL SWMP SHALL BE INSTALLED AFTER CONSTRUCTION FENCE. BUT PRIOR TO ANY UPSTREAM LAND DISTURBING ACTIVITIES. 3. RIPRAP UTIUZED FOR CHECK DAMS SHOULD BE OF APPROPRIATE SIZE FOR THE APPUCATION. TYPICAL TYPES OF RIPRAP USED FOR CHECK DAMS ARE TYPE M (D50 12") OR TYPE L (D50 9"). 4. RIPRAP PAD SHALL BE TRENCHED INTO THE GROUND A MINIMUM OF 1'. 5. THE ENDS OF THE CHECK DAM SHALL BE A MINIMUM OF 1' 6" HIGHER THAN THE CENTER OF THE CHECK DAM. CHECK DAM MAINTENANCE NOTES 1. INSPECT BMPs EACH WORKDAY, AND MAINTAIN THEM IN EFFECTIVE OPERATING CONDITION. MAINTENANCE OF BMPs SHOULD BE PROACTIVE, NOT REACTIVE. INSPECT BMPs AS SOON AS POSSIBLE (AND ALWAYS WITHIN 24 HOURS) FOLLOWING A STORM THAT CAUSES SURFACE EROSION. AND PERFORM NECESSARY MAINTENANCE. 2. FREQUENT OBSERVATIONS AND MAINTENANCE ARE NECESSARY TO MAINTAIN BMPs IN EFFECTIVE OPERATING CONDITION. INSPECTIONS AND CORRECTIVE MEASURES SHOULD BE DOCUMENTED THOROUGHLY. 3. WHERE BMPs HAVE FAILED. REPAIR OR REPLACEMENT SHOULD BE INITIATED UPON DISCOVERY OF THE FAILURE. 4. SEDIMENT ACCUMULATED UPSTREAM OF THE CHECK DAMS SHALL BE REMOVED WHEN THE SEDIMENT DEPTH IS WITHIN $ OF THE HEIGHT OF THE CREST. 5. CHECK DAMS ARE TO REMAIN IN PLACE UNTIL THE UPSTREAM DISTURBED AREA IS STABIUZED AND APPROVED BY THE LOCAL JURISDICTION. 6 WHEN CHECK DAMS ARE REMOVED, EXCAVATIONS SHALL BE FILLED WITH SUITABLE COMPACTED BACKFILL. DISTURBED AREA SHALL BE SEEDED AND MULCHED AND COVERED WITH GEOTEXTILE OR OTHERWISE STABIUZED IN A MANNER APPROVED BY THE LOCAL JURISDICTION. (DETAILS ADAPTED FROM DOUGLAS COUNTY. COLORADO. NOT AVAILABLE IN AUTOCAD) NOTE: MANY JURISDICTIONS HAVE BMP DETAILS THAT VARY FROM UDFCD STANDARD DETAILS. CONSULT WITH LOCAL JURISDICTIONS AS TO WHICH DETAIL SHOULD BE USED WHEN DIFFERENCES ARE NOTED. CD -4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Check Dams (CD) EC -12 Ac --..._,5k ALTERNATIVE TO STEPS ON BANKS ABOVE CREST: DEFORM GABIONS AS NECESSARY TO ALIGN TOP OF GABIONS WITH GROUND SURFACE: AVOID GAPS BETWEEN GABIONS MAX. STEP HEIGHT 1'6" 1 COMPACTED BACKFILL LENGTH, L CREST LENGTH. CL TYPJ HOG RINGS (TYP) 0 (1'6" MIN) MIN. BURY DEPTH 1 '6" ROCK FILLED GABION SECURED TO ADJACENT GABION REINFORCED CHECK DAM ELEVATION VIEW FLOW COMPACTED BACKFILL 3 D50=6" RIPRAP ENCLOSED IN GABION 1,6., r 6" MIN. k- CHANNEL GRADE GEOTEXTILE BLANKET SECTION A REINFORCED CHECK DAM INSTALLATION NOTES 1. SEE PLAN VIEW FOR: - LOCATIONS OF CHECK DAMS. -CHECK DAM TYPE (CHECK DAM OR REINFORCED CHECK DAM). - LENGTH (L). CREST LENGTH (CO. AND DEPTH (D). 2. CHECK DAMS INDICATED ON THE SWMP SHALL BE INSTALLED PRIOR TO AN UPSTREAM LAND -DISTURBING ACTIVITIES. 3. REINFORCED CHECK DAMS, GABIONS SHALL HAVE GALVANIZED TWISTED WIRE NETTING WITH A MAXIMUM OPENING DIMENSION OF 4)6" AND A MINIMUM WIRE THICKNESS OF 0.10". WIRE "HOG RINGS" AT 4" SPACING OR OTHER APPROVED MEANS SHALL BE USED AT ALL GABION SEAMS AND TO SECURE THE GABION TO THE ADJACENT SECTION. 4. THE CHECK DAM SHALL BE TRENCHED INTO THE GROUND A MINIMUM OF 1' 6". 5. GEOTEXTILE BLANKET SHALL BE PLACED IN THE REINFORCED CHECK DAM TRENCH EXTENDING A MINIMUM OF 1' 6" ON BOTH THE UPSTREAM AND DOWNSTREAM SIDES OF THE REINFORCED CHECK DAM. CD -2. REINFORCED CHECK DAM November 2010 Urban Drainage and Flood Control District CD -5 Urban Storm Drainage Criteria Manual Volume 3 EC -12 Check Dams (CD) REINFORCED CHECK DAM MAINTENANCE NOTES 1. INSPECT BMPs EACH WORKDAY, AND MAINTAIN THEM IN EFFECTIVE OPERATING CONDITION. MAINTENANCE OF BMPs SHOULD BE PROACTIVE, NOT REACTIVE. INSPECT BMPs AS SOON AS POSSIBLE (AND ALWAYS WITHIN 24 HOURS) FOLLOWING A STORM THAT CAUSES SURFACE EROSION, AND PERFORM NECESSARY MAINTENANCE. 2. FREQUENT OBSERVATIONS AND MAINTENANCE ARE NECESSARY TO MAINTAIN BMPs IN EFFECTIVE OPERATING CONDITION. INSPECTIONS AND CORRECTIVE MEASURES SHOULD BE DOCUMENTED THOROUGHLY. 3. WHERE BMPs HAVE FAILED, REPAIR OR REPLACEMENT SHOULD BE INITIATED UPON DISCOVERY OF THE FAILURE. 4. SEDIMENT ACCUMULATED UPSTREAM OF REINFORCED CHECK DAMS SHALL BE REMOVED AS NEEDED TO MAINTAIN THE EFFECTIVENESS OF BMP, TYPICALLY WHEN THE UPSTREAM SEDIMENT DEPTH IS WITHIN )i THE HEIGHT OF THE CREST. 5. REPAIR OR REPLACE REINFORCED CHECK DAMS WHEN THERE ARE SIGNS OF DAMAGE SUCH AS HOLES IN THE GABION OR UNDERCUTTING. 6. REINFORCED CHECK DAMS ARE TO REMAIN IN PLACE UNTIL THE UPSTREAM DISTURBED AREA IS STABIUZED AND APPROVED BY THE LOCAL JURISDICTION. 7. WHEN REINFORCED CHECK DAMS ARE REMOVED, ALL DISTURBED AREAS SHALL BE COVERED WITH TOPSOIL, SEEDED AND MULCHED, AND COVERED WITH A GEOTEXTILE BLANKET, OR OTHERWISE STABIUZED AS APPROVED BY LOCAL JURISDICTION. (DETAIL ADAPTED FROM DOUGLAS COUNTY, COLORADO AND CITY OF AURORA, COLORADO, NOT AVAILABLE IN AUTOCAD) NOTE: MANY JURISDICTIONS HAVE BMP DETAILS THAT VARY FROM UDFCD STANDARD DETAILS. CONSULT WITH LOCAL JURISDICTIONS AS TO WHICH DETAIL SHOULD BE USED WHEN DIFFERENCES ARE NOTED. CD -6 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Concrete Washout Area (CWA) MM -1 Description Concrete waste management involves designating and properly managing a specific area of the construction site as a concrete washout area. A concrete washout area can be created using one of several approaches designed to receive wash water from washing of tools and concrete mixer chutes, liquid concrete waste from dump trucks, mobile batch mixers, or pump trucks. Three basic approaches are available: excavation of a pit in the ground, use of an above ground storage area, or use of prefabricated haul - away concrete washout containers. Surface discharges of concrete washout water from construction sites are prohibited. Appropriate Uses I IIII r1 IIIIPIIry 11, i IIIIIhI11111[I IIIIN/I111111/ 7UU[llltllilli Ill IIl11I' u,P IS.111l :v.re,o„ ; itllm,:.IIAI Photograph CWA-1. Example of concrete washout area. Note gravel tracking pad for access and sign. Concrete washout areas must be designated on all sites that will generate concrete wash water or liquid concrete waste from onsite concrete mixing or concrete delivery. Because pH is a pollutant of concern for washout activities, when unlined pits are used for concrete washout, the soil must have adequate buffering capacity to result in protection of state groundwater standards; otherwise, a liner/containment must be used. The following management practices are recommended to prevent an impact from unlined pits to groundwater: • The use of the washout site should be temporary (less than 1 year), and • The washout site should be not be located in an area where shallow groundwater may be present, such as near natural drainages, springs, or wetlands. Design and Installation Concrete washout activities must be conducted in a manner that does not contribute pollutants to surface waters or stormwater runoff. Concrete washout areas may be lined or unlined excavated pits in the ground, commercially manufactured prefabricated washout containers, or aboveground holding areas constructed of berms, sandbags or straw bales with a plastic liner. Although unlined washout areas may be used, lined pits may be required to protect groundwater under certain conditions. Do not locate an unlined washout area within 400 feet of any natural drainage pathway or waterbody or within 1,000 feet of any wells or drinking water sources. Even for lined concrete washouts, it is advisable to locate the facility away from waterbodies and drainage paths. If site constraints make these Concrete Washout Area Functions Erosion Control No Sediment Control No Site/Material Management Yes November 2010 Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual Volume 3 CWA-1 MM -1 Concrete Washout Area (CWA) setbacks infeasible or if highly permeable soils exist in the area, then the pit must be installed with an impermeable liner (16 mil minimum thickness) or surface storage alternatives using prefabricated concrete washout devices or a lined aboveground storage area should be used. Design details with notes are provided in Detail CWA-1 for pits and CWA-2 for aboveground storage areas. Pre -fabricated concrete washout container information can be obtained from vendors. Maintenance and Removal A key consideration for concrete washout areas is to ensure that adequate signage is in place identifying the location of the washout area. Part of inspecting and maintaining washout areas is ensuring that adequate signage is provided and in good repair and that the washout area is being used, as opposed to washout in non -designated areas of the site. Remove concrete waste in the washout area, as needed to maintain BMP function (typically when filled to about two-thirds of its capacity). Collect concrete waste and deliver offsite to a designated disposal location. Upon termination of use of the washout site, accumulated solid waste, including concrete waste and any contaminated soils, must be removed from the site to prevent on -site disposal of solid waste. If the wash water is allowed to evaporate and the concrete hardens, it may be recycled. Photograph CWA-2. Prefabricated concrete washout. Photo courtesy of CDOT. Photograph CWA-3. Earthen concrete washout. Photo courtesy of CDOT. CWA-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Concrete Washout Area (CWA) MM -1 1 CONCRETE WASHOUT AREA PLAN 12"TYP.� >4 UNDISTURBED OR 1 ≥3 COMPACTED SOIL CONCRETE WASHOUT KSIGN 25 MIN. COMPACTED BERM AROUND THE PERIMETER 3' MIN. 8 X 8 MIN. SECTION A VEHICLE TRACKING CONTROL (SEE VTC DETAIL) OR OTHER STABLE SURFACE 2% SLOPE • VEHICLE TRACKING CONTROL (SEE VTC - DETAIL ) CWA-1. CONCRETE WASHOUT AREA CWA INSTALLATION NOTES 1. SEE PLAN VIEW FOR: -CWA INSTALLATION LOCATION. 2. DO NOT LOCATE AN UNLINED CWA WITHIN 400' OF ANY NATURAL DRAINAGE PATHWAY OR WATERBODY. DO NOT LOCATE WITHIN 1,000' OF ANY WELLS OR DRINKING WATER SOURCES. IF SITE CONSTRAINTS MAKE THIS INFEASIBLE, OR IF HIGHLY PERMEABLE SOILS EXIST ON SITE, THE CWA MUST BE INSTALLED WITH AN IMPERMEABLE LINER (16 MIL MIN. THICKNESS) OR SURFACE STORAGE ALTERNATIVES USING PREFABRICATED CONCRETE WASHOUT DEVICES OR A LINED ABOVE GROUND STORAGE ARE SHOULD BE USED. 3. THE CWA SHALL BE INSTALLED PRIOR TO CONCRETE PLACEMENT ON SITE. 4. CWA SHALL INCLUDE A FLAT SUBSURFACE PIT THAT IS AT LEAST 8' BY 8' SLOPES LEADING OUT OF THE SUBSURFACE PIT SHALL BE 3:1 OR FLATTER THE PIT SHALL BE AT LEAST 3' DEEP. 5. BERM SURROUNDING SIDES AND BACK OF THE CWA SHALL HAVE MINIMUM HEIGHT OF 1'. 6. VEHICLE TRACKING PAD SHALL BE SLOPED 2% TOWARDS THE CWA. 7. SIGNS SHALL BE PLACED AT THE CONSTRUCTION ENTRANCE, AT THE CWA, AND ELSEWHERE AS NECESSARY TO CLEARLY INDICATE THE LOCATION OF THE CWA TO OPERATORS OF CONCRETE TRUCKS AND PUMP RIGS. 8. USE EXCAVATED MATERIAL FOR PERIMETER BERM CONSTRUCTION. November 2010 Urban Drainage and Flood Control District CWA-3 Urban Storm Drainage Criteria Manual Volume 3 MM -1 Concrete Washout Area (CWA) CWA MAINTENANCE NOTES 1. INSPECT BMPs EACH WORKDAY, AND MAINTAIN THEM IN EFFECTIVE OPERATING CONDITION. MAINTENANCE OF BMPs SHOULD BE PROACTIVE, NOT REACTIVE. INSPECT BMPs AS SOON AS POSSIBLE (AND ALWAYS WITHIN 24 HOURS) FOLLOWING A STORM THAT CAUSES SURFACE EROSION, AND PERFORM NECESSARY MAINTENANCE. 2. FREQUENT OBSERVATIONS AND MAINTENANCE ARE NECESSARY TO MAINTAIN BMPs IN EFFECTIVE OPERATING CONDITION. INSPECTIONS AND CORRECTIVE MEASURES SHOULD BE DOCUMENTED THOROUGHLY. 3. WHERE BMPs HAVE FAILED, REPAIR OR REPLACEMENT SHOULD BE INITIATED UPON DISCOVERY OF THE FAILURE. 4. THE CWA SHALL BE REPAIRED, CLEANED, OR ENLARGED AS NECESSARY TO MAINTAIN CAPACITY FOR CONCRETE WASTE. CONCRETE MATERIALS, ACCUMULATED IN PIT, SHALL BE REMOVED ONCE THE MATERIALS HAVE REACHED A DEPTH OF 2'. 5. CONCRETE WASHOUT WATER, WASTED PIECES OF CONCRETE AND ALL OTHER DEBRIS IN THE SUBSURFACE PIT SHALL BE TRANSPORTED FROM THE JOB SITE IN A WATER -TIGHT CONTAINER AND DISPOSED OF PROPERLY. 6. THE CWA SHALL REMAIN IN PLACE UNTIL ALL CONCRETE FOR THE PROJECT IS PLACED. 7 WHEN THE CWA IS REMOVED, COVER THE DISTURBED AREA WITH TOP SOIL, SEED AND MULCH OR OTHERWISE STABILIZED IN A MANNER APPROVED BY THE LOCAL JURISDICTION. (DETAIL ADAPTED FROM DOUGLAS COUNTY, COLORADO AND THE CITY OF PARKER, COLORADO, NOT AVAILABLE IN AUTOCAD). NOTE: MANY JURISDICTIONS HAVE BMP DETAILS THAT VARY FROM UDFCD STANDARD DETAILS. CONSULT WITH LOCAL JURISDICTIONS AS TO WHICH DETAIL SHOULD BE USED WHEN DIFFERENCES ARE NOTED. CWA-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 CONCRETE WASHOUT "KIDDIE" POOL N.T.S LIQUID CONCRETE WASHOUT WASTE a 8" DRIED CONCRETE WASHOUT WASTE NOTES: .; • . • 48" "KIDDIE POOL" (TYPICAL) 1. Use only rigid, prefabricated impermeable plastic wading pool. 2. Inspect Containment for waterproof integrity prior to each use. 3. Do not fill Containment more than 50% of capacity with either liquid or solid concrete waste. 4. Immediately after each use, cover the Containment with a waterproof barrier to prevent collection of rain water or snow. 5. Properly dispose of dried concrete waste at a landfill when the project is complete or when waste reaches a 50% capacity. DEL-MONT CONSULTANTS, INC. ENGINEERING • SURVEYING • PLANNING t2• Cam••• A.• • tea 07 •uN • WO) IM7L. • IN•I71••7W - SCA__ N/A N S. SNS E NAME CONCRETE WASHOUT -KIDDIE POOL BMP DETAIL CONCRETE WASHOUT - "KIDDIE" POOL `M JOB NC N/A ]ATE SSLJED 5-13-2011 1of1 Inlet Protection (IP) SC -6 Description Inlet protection consists of permeable barriers installed around an inlet to filter runoff and remove sediment prior to entering a storm drain inlet. Inlet protection can be constructed from rock socks, sediment control logs, silt fence, block and rock socks, or other materials approved by the local jurisdiction. Area inlets can also be protected by over -excavating around the inlet to form a sediment trap. Appropriate Uses Install protection at storm sewer inlets that are operable during construction. Consider the potential for tracked -out sediment or temporary stockpile areas to contribute sediment to inlets when determining which inlets must be protected. This may include inlets in the general proximity of the construction area, not limited to downgradient inlets. Inlet protection is not a stand-alone BMP and should be used in conjunction with other upgradient BMPs. Photograph IP-1. Inlet protection for a curb opening inlet. 4 • Design and Installation To function effectively, inlet protection measures must be installed to ensure that flows do not bypass the inlet protection and enter the storm drain without treatment. However, designs must also enable the inlet to function without completely blocking flows into the inlet in a manner that causes localized flooding. When selecting the type of inlet protection, consider factors such as type of inlet (e.g., curb or area, sump or on -grade conditions), traffic, anticipated flows, ability to secure the BMP properly, safety and other site -specific conditions. For example, block and rock socks will be better suited to a curb and gutter along a roadway, as opposed to silt fence or sediment control logs, which cannot be properly secured in a curb and gutter setting, but are effective area inlet protection measures. Several inlet protection designs are provided in the Design Details. Additionally, a variety of proprietary products are available for inlet protection that may be approved for use by local governments. If proprietary products are used, design details and installation procedures from the manufacturer must be followed. Regardless of the type of inlet protection selected, inlet protection is most effective when combined with other BMPs such as curb socks and check dams. Inlet protection is often the last barrier before runoff enters the storm sewer or receiving water. Design details with notes are provided for these forms of inlet protection: IP-1. Block and Rock Sock Inlet Protection for Sump or On -grade Inlets IP-2. Curb (Rock) Socks Upstream of Inlet Protection, On -grade Inlets Inlet Protection (various forms) Functions Erosion Control No Sediment Control Yes Site/Material Management No August 2013 Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual Volume 3 IP-1 SC -6 Inlet Protection (IP) IP-3. Rock Sock Inlet Protection for Sump/Area Inlet IP-4. Silt Fence Inlet Protection for Sump/Area Inlet IP-5. Over -excavation Inlet Protection IP-6. Straw Bale Inlet Protection for Sump/Area Inlet CIP-l. Culvert Inlet Protection Propriety inlet protection devices should be installed in accordance with manufacturer specifications. More information is provided below on selecting inlet protection for sump and on -grade locations. Inlets Located in a Sump When applying inlet protection in sump conditions, it is important that the inlet continue to function during larger runoff events. For curb inlets, the maximum height of the protective barrier should be lower than the top of the curb opening to allow overflow into the inlet during larger storms without excessive localized flooding. If the inlet protection height is greater than the curb elevation, particularly if the filter becomes clogged with sediment, runoff will not enter the inlet and may bypass it, possibly causing localized flooding, public safety issues, and downstream erosion and damage from bypassed flows. Area inlets located in a sump setting can be protected through the use of silt fence, concrete block and rock socks (on paved surfaces), sediment control logs/straw wattles embedded in the adjacent soil and stacked around the area inlet (on pervious surfaces), over -excavation around the inlet, and proprietary products providing equivalent functions. Inlets Located on a Slope For curb and gutter inlets on paved sloping streets, block and rock sock inlet protection is recommended in conjunction with curb socks in the gutter leading to the inlet. For inlets located along unpaved roads, also see the Check Dam Fact Sheet. Maintenance and Removal Inspect inlet protection frequently. Inspection and maintenance guidance includes: • Inspect for tears that can result in sediment directly entering the inlet, as well as result in the contents of the BMP (e.g., gravel) washing into the inlet. • Check for improper installation resulting in untreated flows bypassing the BMP and directly entering the inlet or bypassing to an unprotected downstream inlet. For example, silt fence that has not been properly trenched around the inlet can result in flows under the silt fence and directly into the inlet. • Look for displaced BMPs that are no longer protecting the inlet. Displacement may occur following larger storm events that wash away or reposition the inlet protection. Traffic or equipment may also crush or displace the BMP. ■ Monitor sediment accumulation upgradient of the inlet protection. IP-2 Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual Volume 3 August 2013 Inlet Protection (IP) SC -6 • Remove sediment accumulation from the area upstream of the inlet protection, as needed to maintain BMP effectiveness, typically when it reaches no more than half the storage capacity of the inlet protection. For silt fence, remove sediment when it accumulates to a depth of no more than 6 inches. Remove sediment accumulation from the area upstream of the inlet protection as needed to maintain the functionality of the BMP. • Propriety inlet protection devices should be inspected and maintained in accordance with manufacturer specifications. If proprietary inlet insert devices are used, sediment should be removed in a timely manner to prevent devices from breaking and spilling sediment into the storm drain. Inlet protection must be removed and properly disposed of when the drainage area for the inlet has reached final stabilization. August 2013 Urban Drainage and Flood Control District IP-3 Urban Storm Drainage Criteria Manual Volume 3 SC -6 Inlet Protection (IP) le %,r. -a- I SEE ROCK SOCK DESIGN DETAIL FOR JOINTING 16" CINDER BLOCKS { 2"x4" WOOD - SECTION A - STUD IP-1. BLOCK AND ROCK SOCK SUMP OR ON GRADE INLET PROTECTION 16" CINDER BLOCKS FLOW ROCK SOCKS 2"x4" WOOD STUD CURB INLET BLOCK AND CURB SACK INLET PROTECTLON INSTALLATION NOTES 1. SEE ROCK SOCK DESIGN DETAIL FOR INSTALLATION REQUIREMENTS. 2. CONCRETE "CINDER" BLOCKS SHALL BE LAID ON THEIR SIDES AROUND THE INLET IN A SINGLE ROW, ABUTTING ONE ANOTHER WITH THE OPEN END FACING AWAY FROM THE CURB. 3. GRAVEL BAGS SHALL BE PLACED AROUND CONCRETE BLOCKS, CLOSELY ABUTTING ONE ANOTHER AND JOINTED TOGETHER IN ACCORDANCE WITH ROCK SOCK DESIGN DETAIL. r r CURB SOCK FLOW -- MINIMUM OF TWO CURB SOCKS APPROX 30 DEG. BLOCK AND ROCK SOCK INLET PROTECTION (SEE DETAIL IP-1) IP-2. CURB ROCK SOCKS UPSTREAM OF INLET PROTECTION CURB ROCK SOCK INLET PROTECTION INSTALLATION NOTES 1. SEE ROCK SOCK DESIGN DETAIL INSTALLATION REQUIREMENTS. 2. PLACEMENT OF THE SOCK SHALL BE APPROXIMATELY 30 DEGREES FROM PERPENDICULAR IN THE OPPOSITE DIRECTION OF FLOW. 3. SOCKS ARE TO BE FLUSH WITH THE CURB AND SPACED A MINIMUM OF 5 FEET APART. 4. AT LEAST TWO CURB SOCKS IN SERIES ARE REQUIRED UPSTREAM OF ON -GRADE INLETS. 1P-4 Urban Drainage and Flood Control District August 2013 Urban Storm Drainage Criteria Manual Volume 3 Inlet Protection (IP) SC -6 Vrit Cit C ROCK SOCK INLET GRATE SEE ROCK SOCK DETAIL FOR JOINTING IP-3. ROCK SOCK SUMP/AREA INLET PROTECTION ROCK SOCK SUMP/AREA INLET PROTECTION INSTALLATION NOTES 1. SEE ROCK SOCK DESIGN DETAIL FOR INSTALLATION REQUIREMENTS. 2. STRAW WATTLES/SEDIMENT CONTROL LOGS MAY BE USED IN PLACE OF ROCK SOCKS FOR INLETS IN PERVIOUS AREAS. INSTALL PER SEDIMENT CONTROL LOG DETAIL. u. U) SF -1 m LSFJ SILT FENCE (SEE SILT FENCE DESIGN DETAIL ) IP-4. SILT FENCE FOR SUMP INLET PROTECTION SILT FENCE INLET PROTECTION INSTALLATION NOTES 1. SEE SILT FENCE DESIGN DETAIL FOR INSTALLATION REQUIREMENTS. 2. POSTS SHALL BE PLACED AT EACH CORNER OF THE INLET AND AROUND THE EDGES AT A MAXIMUM SPACING OF 3 FEET. 3. STRAW WATTLES/SEDIMENT CONTROL LOGS MAY BE USED IN PLACE OF SILT FENCE FOR INLETS IN PERVIOUS AREAS. INSTALL PER SEDIMENT CONTROL LOG DETAIL. August 2013 Urban Drainage and Flood Control District IP-5 Urban Storm Drainage Criteria Manual Volume 3 SC -6 Inlet Protection (IP) SHEET FLOW SILT FENCE I J I },,'' c I I C ROCK FILTER OR ROCK SOCK (USE IF FLOW IS CONCENTRATED) AREA INLET ECB L CONCENTRATED FLOW IP-5. OVEREXCAVATION INLET PROTECTION OVEREXCAVATION INLET PROTECTION INSTALLATION NOTES 1. THIS FORM OF INLET PROTECTION IS PRIMARILY APPLICABLE FOR SITES THAT HAVE NOT YET REACHED FINAL GRADE AND SHOULD BE USED ONLY FOR INLETS WITH A RELATIVELY SMALL CONTRIBUTING DRAINAGE AREA. 2. WHEN USING FOR CONCENTRATED FLOWS, SHAPE BASIN IN 2:1 RATIO WITH LENGTH ORIENTED TOWARDS DIRECTION OF FLOW. 3. SEDIMENT MUST BE PERIODICALLY REMOVED FROM THE OVEREXCAVATED AREA. STRAW BALE (SEE STRAW BALE DESIGN DETAIL) • • INI MO • • 1 • • • 0 INLET GRATE IP-6. STRAW BALE FOR SUMP INLET PROTECTION STRAW BALE BARRIER INLET PROTECTION INSTALLATION NOTES 1. SEE STRAW BALE DESIGN DETAIL FOR INSTALLATION REQUIREMENTS. 2. BALES SHALL BE PLACED IN A SINGLE ROW AROUND THE INLET WITH ENDS OF BALES TIGHTLY ABUTTING ONE ANOTHER. [P-6 Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual Volume 3 August 2013 Inlet Protection (IP) SC -6 FLOW -- CULVERT END SECTION ROCK SOCK BACKFILL UPSTREAM ROCK L OF WATTLE CULVERT INLET PROTECTION SECTION A PLAN 10" MIN. f SOCK i_ KEY IN ROCK SOCK O" ON BEDROCK, PAVEMENT OR RIPRAP KEY IN ROCK SOCK 2" ON EARTH SECTION B CIP-1. CULVERT INLET PROTECTION CULVERT INLET PROTECTION INSTALLATION NOTES 1. SEE PLAN VIEW FOR -LOCATION OF CULVERT INLET PROTECTION. 2. SEE ROCK SOCK DESIGN DETAIL FOR ROCK GRADATION REQUIREMENTS AND JOINTING DETAIL. CULVERT INLET PROTECTION MAINTENANCE NOTES 1. INSPECT BMPs EACH WORKDAY, AND MAINTAIN THEM IN EFFECTIVE OPERATING CONDITION. MAINTENANCE OF BMPs SHOULD BE PROACTIVE, NOT REACTIVE. INSPECT BMPs AS SOON AS POSSIBLE (AND ALWAYS WITHIN 24 HOURS) FOLLOWING A STORM THAT CAUSES SURFACE EROSION, AND PERFORM NECESSARY MAINTENANCE. 2. FREQUENT OBSERVATIONS AND MAINTENANCE ARE NECESSARY TO MAINTAIN BMPs IN EFFECTIVE OPERATING CONDITION. INSPECTIONS AND CORRECTIVE MEASURES SHOULD BE DOCUMENTED THOROUGHLY. 3. WHERE BMPs HAVE FAILED, REPAIR OR REPLACEMENT SHOULD BE INITIATED UPON DISCOVERY OF THE FAILURE. 4. SEDIMENT ACCUMULATED UPSTREAM OF THE CULVERT SHALL BE REMOVED WHEN THE SEDIMENT DEPTH IS Y2 THE HEIGHT OF THE ROCK SOCK. 5. CULVERT INLET PROTECTION SHALL REMAIN IN PLACE UNTIL THE UPSTREAM DISTURBED AREA IS PERMANENTLY STABILIZED AND APPROVED BY THE LOCAL JURISDICTION. (DETAILS ADAPTED FROM AURORA, COLORADO, NOT AVAILABLE IN AUTOCAD) NOTE: MANY JURISDICTIONS HAVE BMP DETAILS THAT VARY FROM UDFCD STANDARD DETAILS. CONSULT WITH LOCAL JURISDICTIONS AS TO WHICH DETAIL SHOULD BE USED WHEN DIFFERENCES ARE NOTED. August 2013 Urban Drainage and Flood Control District IP-7 Urban Storm Drainage Criteria Manual Volume 3 SC -6 Inlet Protection (IP) GENERAL INLET PROTECTION INSTALLATION NOTES 1. SEE PLAN VIEW FOR: -LOCATION OF INLET PROTECTION. -TYPE OF INLET PROTECTION (IP.1, IP.2, IP.3, IP.4, IP.5, IP.6) 2. INLET PROTECTION SHALL BE INSTALLED PROMPTLY AFTER INLET CONSTRUCTION OR PAVING IS COMPLETE (TYPICALLY WITHIN 48 HOURS). IF A RAINFALL/RUNOFF EVENT IS FORECAST, INSTALL INLET PROTECTION PRIOR TO ONSET OF EVENT. 3. MANY JURISDICTIONS HAVE BMP DETAILS THAT VARY FROM UDFCO STANDARD DETAILS. CONSULT WITH LOCAL JURISDICTIONS AS TO WHICH DETAIL SHOULD BE USED WHEN DIFFERENCES ARE NOTED. INLET PROTECTION MAINTENANCE NOTES 1. INSPECT BMPs EACH WORKDAY, AND MAINTAIN THEM IN EFFECTIVE OPERATING CONDITION. MAINTENANCE OF BMPs SHOULD BE PROACTIVE, NOT REACTIVE. INSPECT BMPs AS SOON AS POSSIBLE (AND ALWAYS WITHIN 24 HOURS) FOLLOWING A STORM THAT CAUSES SURFACE EROSION, AND PERFORM NECESSARY MAINTENANCE. 2. FREQUENT OBSERVATIONS AND MAINTENANCE ARE NECESSARY TO MAINTAIN BMPs IN EFFECTIVE OPERATING CONDITION. INSPECTIONS AND CORRECTIVE MEASURES SHOULD BE DOCUMENTED THOROUGHLY. 3. WHERE BMPs HAVE FAILED, REPAIR OR REPLACEMENT SHOULD BE INITIATED UPON DISCOVERY OF THE FAILURE. 4. SEDIMENT ACCUMULATED UPSTREAM OF INLET PROTECTION SHALL BE REMOVED AS NECESSARY TO MAINTAIN BMP EFFECTIVENESS, TYPICALLY WHEN STORAGE VOLUME REACHES 50% OF CAPACITY, A DEPTH OF 6" WHEN SILT FENCE IS USED, OR Y4 OF THE HEIGHT FOR STRAW BALES. 5. INLET PROTECTION IS TO REMAIN IN PLACE UNTIL THE UPSTREAM DISTURBED AREA IS PERMANENTLY STABILIZED, UNLESS THE LOCAL JURISDICTION APPROVES EARLIER REMOVAL OF INLET PROTECTION IN STREETS. 6. WHEN INLET PROTECTION AT AREA INLETS IS REMOVED, THE DISTURBED AREA SHALL BE COVERED WITH TOP SOIL, SEEDED AND MULCHED, OR OTHERWISE STABILIZED IN A MANNER APPROVED BY THE LOCAL JURISDICTION. (DETAIL ADAPTED FROM TOWN OF PARKER, COLORADO AND CITY OF AURORA, COLORADO, NOT AVAILABLE IN AUTOCAD) NOTE: MANY JURISDICTIONS HAVE BMP DETAILS THAT VARY FROM UDFCD STANDARD DETAILS. CONSULT WITH LOCAL JURISDICTIONS AS TO WHICH DETAIL SHOULD BE USED WHEN DIFFERENCES ARE NOTED. NOTE: THE DETAILS INCLUDED WITH THIS FACT SHEET SHOW COMMONLY USED, CONVENTIONAL METHODS OF INLET PROTECTION IN THE DENVER METROPOLITAN AREA. THERE ARE MANY PROPRIETARY INLET PROTECTION METHODS ON THE MARKET. UDFCD NEITHER ENDORSES NOR DISCOURAGES USE OF PROPRIETARY INLET PROTECTION; HOWEVER, IN THE EVENT PROPRIETARY METHODS ARE USED, THE APPROPRIATE DETAIL FROM THE MANUFACTURER MUST BE INCLUDED IN THE SWMP AND THE BMP MUST BE INSTALLED AND MAINTAINED AS SHOWN IN THE MANUFACTURER'S DETAILS. NOTE: SOME MUNICIPALITIES DISCOURAGE OR PROHIBIT THE USE OF STRAW BALES FOR INLET PROTECTION. CHECK WITH LOCAL JURISDICTION TO DETERMINE IF STRAW BALE INLET PROTECTION IS ACCEPTABLE. IP-8 Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual Volume 3 August 2013 Straw Bale Barrier (SBB) SC -3 Description A straw bale barrier is a linear wall of straw bales designed to intercept sheet flow and trap sediment before runoff exits a disturbed area. Appropriate Uses Appropriate uses of properly installed straw bale barriers may include: • As a perimeter control for a site or soil stockpile. • As a sediment control at the toe of an erodible slope. -5 - . Photograph SBB-1. Straw bale barrier used for perimeter control. Photo courtesy of Tom Gore. • Along the edge of a stream or drainage pathway to reduce sediment laden runoff from entering the waterway. • As part of an inlet protection design in sump conditions (See Inlet Protection BMP). Do not use straw bale barriers in areas of concentrated flow or in areas where ponding is not desirable Straw bales tend to degrade quickly, so they should generally not be used in areas where longer term disturbance is expected. Due to a history of inappropriate placement, poor installation, and short effective lifespan, the use of straw bales is discouraged or prohibited by some communities. Design and Installation The maximum recommended tributary drainage area per 100 lineal feet of straw bale barrier is 0.25 acres with a disturbed slope length of up to 150 feet and a tributary slope gradient no steeper than 3:1; longer and steeper slopes require additional measures. Design details with notes are provided in Detail SBB-1. To be effective, bales must be installed in accordance with the design details with proper trenching, staking, and binding. Jute and cotton string must not be used to bind the straw bale. The bales should be certified weed -free prior to use. Maintenance and Removal Check bales for rotting and replace as necessary. Straw bales degrade, and rotting bales require replacement on a regular basis (as often as every three months) depending on environmental conditions. Check for undercutting, bypassed flows, and displacement. Repair by properly re -installing the straw bale barrier and repairing washouts around the bales. Remove sediment accumulated behind the bale when it reaches one -quarter of the bale height. Remove and properly dispose of the straw bale once the upstream area has been stabilized. Areas of disturbance beneath the bale should be seeded and mulched when the bale is removed. Straw Bale Barrier Functions Erosion Control No Sediment Control Moderate Site/Material Management No November 2010 Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual Volume 3 SBB-1 SC -3 Straw Bale Barrier (SBB) BALE LENGTH STRAW BALE TRENCH FOR STRAW BALE 18" TYP BALE WIDTH 18" TYP 6 " MIN 2"X2"X24" STAKE FLOW BACKFILL AND COMPACT EXCAVATED TRENCH SOIL BINDING WIRE OR TWINE L 4" MIN BALE WIDTH _ 18" TYP 2"X2"X24" STAKE BACKFILL AND COMPACT EXCAVATED TRENCH SOIL L4"MIN SECTION A SBB-1 . STRAW BALE FLOW SBB-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Straw Bale Barrier (SBB) SC -3 STRAW BALE INSTALLATION NOTES 1. SEE PLAN VIEW FOR: -LOCATION(S) OF STRAW BALES. 2 STRAW BALES SHALL CONSIST OF CERTIFIED WEED FREE STRAW OR HAY. LOCAL JURISDICTIONS MAY REQUIRE PROOF THAT BALES ARE WEED FREE. 3. STRAW BALES SHALL CONSIST OF APPROXIMATELY 5 CUBIC FEET OF STRAW OR HAY AND WEIGH NOT LESS THAN 35 POUNDS. 4. WHEN STRAW BALES ARE USED IN SERIES AS A BARRIER, THE END OF EACH BALE SHALL BE TIGHTLY ABUTTING ONE ANOTHER. 5. STRAW BALE DIMENSIONS SHALL BE APPROXIMATELY 36"X 18"X 18". 6. A UNIFORM ANCHOR TRENCH SHALL BE EXCAVATED TO A DEPTH OF 4". STRAW BALES SHALL BE PLACED SO THAT BINDING TWINE IS ENCOMPASSING THE VERTICAL SIDES OF THE BALE(S). ALL EXCAVATED SOIL SHALL BE PLACED ON THE UPHILL SIDE OF THE STRAW BALE(S) AND COMPACTED. 7. TWO (2) WOODEN STAKES SHALL BE USED TO HOLD EACH BALE IN PLACE. WOODEN STAKES SHALL BE 2"X2"X24". WOODEN STAKES SHALL BE DRIVEN 6" INTO THE GROUND. STRAW BALE MAINTENANCE NOTES 1. INSPECT BMPs EACH WORKDAY. AND MAINTAIN THEM IN EFFECTIVE OPERATING CONDITION. MAINTENANCE OF BMPs SHOULD BE PROACTIVE, NOT REACTIVE. INSPECT BMPs AS SOON AS POSSIBLE (AND ALWAYS WITHIN 24 HOURS) FOLLOWING A STORM THAT CAUSES SURFACE EROSION, AND PERFORM NECESSARY MAINTENANCE. 2. FREQUENT OBSERVATIONS AND MAINTENANCE ARE NECESSARY TO MAINTAIN BMPs IN EFFECTIVE OPERATING CONDITION. INSPECTIONS AND CORRECTIVE MEASURES SHOULD BE DOCUMENTED THOROUGHLY. 3. WHERE BMPs HAVE FAILED, REPAIR OR REPLACEMENT SHOULD BE INITIATED UPON DISCOVERY OF THE FAILURE. 4. STRAW BALES SHALL BE REPLACED IF THEY BECOME HEAVILY SOILED, ROTTEN, OR DAMAGED BEYOND REPAIR. 5 SEDIMENT ACCUMULATED UPSTREAM OF STRAW BALE BARRIER SHALL BE REMOVED AS NEEDED TO MAINTAIN FUNCTIONALITY OF THE BMP, TYPICALLY WHEN DEPTH OF ACCUMULATED SEDIMENTS IS APPROXIMATELY Y4 OF THE HEIGHT OF THE STRAW BALE BARRIER. 6. STRAW BALES ARE TO REMAIN IN PLACE UNTIL THE UPSTREAM DISTURBED AREA IS STABILIZED AND APPROVED BY THE LOCAL JURISDICTION. 7. WHEN STRAW BALES ARE REMOVED, ALL DISTURBED AREAS SHALL BE COVERED WITH TOPSOIL, SEEDED AND MULCHED OR OTHERWISE STABILIZED AS APPROVED BY LOCAL JURISDICTION. (DETAILS ADAPTED FROM TOWN OF PARKER, COLORADO. NOT AVAILABLE IN AUTOCAD) NOTE: MANY JURISDICTIONS HAVE BMP DETAILS THAT VARY FROM UDFCD STANDARD DETAILS. CONSULT WITH LOCAL JURISDICTIONS AS TO WHICH DETAIL SHOULD BE USED WHEN DIFFERENCES ARE NOTED. November 2010 Urban Drainage and Flood Control District SBB-3 Urban Storm Drainage Criteria Manual Volume 3 Sediment Control Log (SCL) SC -2 Description A sediment control log is a linear roll made of natural materials such as straw, coconut fiber, or other fibrous material trenched into the ground and held with a wooden stake. Sediment control logs are also often referred to as "straw wattles." They are used as a sediment barrier to intercept sheet flow runoff from disturbed areas. Appropriate Uses Sediment control logs can be used in the following applications to trap sediment: • As perimeter control for stockpiles and the site. ■ As part of inlet protection designs. • As check dams in small drainage ditches. (Sediment control logs are not intended for use in channels with high flow velocities.) os- Photographs SCI. -1 and SCL-2. Sediment control logs used as 1) a perimeter control around a soil stockpile: and, 2) as a "J -hook" ■ On disturbed slopes to shorten flow perimeter control at the corner of a construction site. lengths (as an erosion control). • As part of multi -layered perimeter control along a receiving water such as a stream, pond or wetland. Sediment control logs work well in combination with other layers of erosion and sediment controls. Design and Installation Sediment control logs should be installed along the contour to avoid concentrating flows. The maximum allowable tributary drainage area per 100 lineal feet of sediment control log, installed along the contour, is approximately 0.25 acres with a disturbed slope length of up to 150 feet and a tributary slope gradient no steeper than 3:1. Longer and steeper slopes require additional measures. This recommendation only applies to sediment control logs installed along the contour. When installed for other uses, such as perimeter control, it should be installed in a way that will not produce concentrated flows. For example, a "J -hook" installation may be appropriate to force runoff to pond and evaporate or infiltrate in multiple areas rather than concentrate and cause erosive conditions parallel to the BMP. Sediment Control Log Functions Erosion Control Moderate Sediment Control Yes Site/Material Management No November 2010 Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual Volume 3 SCL-1 SC -2 Sediment Control Log (SCL) Although sediment control logs initially allow runoff to flow through the BMP, they can quickly become a barrier and should be installed is if they are impermeable. Design details and notes for sediment control logs are provided in Detail SCL-l. Sediment logs must be properly trenched and staked into the ground to prevent undercutting, bypassing and displacement. When installed on slopes, sediment control logs should be installed along the contours (i.e., perpendicular to flow). Improper installation can lead to poor performance. Be sure that sediment control logs are properly trenched, anchored and tightly jointed. Maintenance and Removal Be aware that sediment control logs will eventually degrade. Remove accumulated sediment before the depth is one-half the height of the sediment log and repair damage to the sediment log, typically by replacing the damaged section. Once the upstream area is stabilized, remove and properly dispose of the logs. Areas disturbed beneath the logs may need to be seeded and mulched. Sediment control logs that are biodegradable may occasionally be left in place (e.g., when logs are used in conjunction with erosion control blankets as permanent slope breaks). However, removal of sediment control logs after final stabilization is typically recommended when used in perimeter control, inlet protection and check dam applications. SCL-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Sediment Control Log (SCL) SC -2 SCIL DIAM. FLOW OF SCL (TYP. COMPACTED EXCAVATED TRENCH SOIL 9" DIAMETER (MIN) SEDIMENT CONTROL LOG SECTION A SEDIMENT CONTROL LOG 1}12" x 1)2" x 18" (MIN) WOODEN STAKE 9" DIAMETER (MIN) SEDIMENT CONTROL LOG /NOTE: LARGER DIAMETER SEDIMENT {�z CONTROL LOGS MAY NEED TO BE EMBEDDED DEEPER. CENTER STAKE IN CONTROL LOG 9" DIAMETER (MIN) SEDIMENT CONTROL LOG %'S DIAM. SCL (TYP.) 1312 x 13i" x 18" (MIN) WOODEN STAKE SEDIMENT CONTROL LOG JOINTS SCL-1. SEDIMENT CONTROL LOG November 2010 Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual Volume 3 SCL-3 SC -2 Sediment Control Log (SCL) COMPACTED EXCAVATED TRENCH SOIL FLOW ---� 3' 6' MIN. CEN-ER STAKE IN CONTROL LOG _ 9" DIAMETER (MIN) SEDIMENT CONTROL LOG PLACE LOG AGAINST BACK OF CURB 1 $DIAM. SCL (TYP.) SCL-2. SEDIMENT CONTROL LOG AT BACK OF CURB 3" 1 6" M N. CEN I _R STAKE P IN CONTROL LOG 9" DIAMETER (MIN) SEDIMENT CONTROL LOG } DIAM. SCL (TYP.) FLOW TREE LAWN (TYPICAL) L PLACE CONTROL LOG >•22; St@E'�IALK AGAINST SIDEWALK N • CURE SCL-3. SEDIMENT CONTROL LOG AT SIDEWALK WITH TREE LAWN STAKING AT 4' MAX. ON CENTER (TYP. 1 VERTICAL SPACING VARIES DEPENDING _ION SLOPE CONTINJOUS SCL AT PER METER O= CONS -RUCTION SITE SCL-4. SEDIMENT CONTROL LOGS TO CONTROL SLOPE LENGTH SCL-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Sediment Control Log (SCL) SC -2 SF0IMENT CONTROL LOG INSTALLATION NOTES 1. SEE PLAN VIEW FOR LOCATION AND LENGTH OF SEDIMENT CONTROL LOGS. 2. SEDIMENT CONTROL LOGS THAT ACT AS A PERIMETER CONTROL SHALL BE INSTALLED PRIOR TO ANY UPGRADIENT LAND -DISTURBING ACTIVITIES. 3 SEDIMENT CONTROL LOGS SHALL CONSIST OF STRAW, COMPOST, EXCELSIOR OR COCONUT FIBER, AND SHALL BE FREE OF ANY NOXIOUS WEED SEEDS OR DEFECTS INCLUDING RIPS, HOLES AND OBVIOUS WEAR. 4. SEDIMENT CONTROL LOGS MAY BE USED AS SMALL CHECK DAMS IN DITCHES AND SWALES. HOWEVER, THEY SHOULD NOT BE USED IN PERENNIAL STREAMS OR HIGH VELOCITY DRAINAGE WAYS. 5. IT IS RECOMMENDED THAT SEDIMENT CONTROL LOGS BE TRENCHED INTO THE GROUND TO A DEPTH OF APPROXIMATELY } OF THE DIAMETER OF THE LOG. IF TRENCHING TO THIS DEPTH IS NOT FEASIBLE AND/OR DESIRABLE (SHORT TERM INSTALLATION WITH DESIRE NOT TO DAMAGE LANDSCAPE) A LESSER TRENCHING DEPTH MAY BE ACCEPTABLE WITH MORE ROBUST STAKING 6. THE UPHILL SIDE OF THE SEDIMENT CONTROL LOG SHALL BE BACKFILLED WITH SOIL THAT IS FREE OF ROCKS AND DEBRIS. THE SOIL SHALL BE TIGHTLY COMPACTED INTO THE SHAPE OF A RIGHT TRIANGLE USING A SHOVEL OR WEIGHTED LAWN ROLLER. 7. FOLLOW MANUFACTURERS' GUIDANCE FOR STAKING. IF MANUFACTURERS' INSTRUCTIONS 00 NOT SPECIFY SPACING, STAKES SHALL BE PLACED ON 4' CENTERS AND EMBEDDED A MINIMUM OF 6" INTO THE GROUND. 3" OF THE STAKE SHALL PROTRUDE FROM THE TOP OF THE LOG. STAKES THAT ARE BROKEN PRIOR TO INSTALLATION SHALL BE REPLACED. SEDIMENT CONTROL LOG MAINTENANCE NOTES 1. INSPECT BMPs EACH WORKDAY, AND MAINTAIN THEM IN EFFECTIVE OPERATING CONDITION. MAINTENANCE OF BMPs SHOULD BE PROACTIVE, NOT REACTIVE. INSPECT BMPs AS SOON AS POSSIBLE (AND ALWAYS WITHIN 24 HOURS) FOLLOWING A STORM THAT CAUSES SURFACE EROSION. AND PERFORM NECESSARY MAINTENANCE. 2. FREQUENT OBSERVATIONS AND MAINTENANCE ARE NECESSARY TO MAINTAIN BMPs IN EFFECTIVE OPERATING CONDITION. INSPECTIONS AND CORRECTIVE MEASURES SHOULD BE DOCUMENTED THOROUGHLY. 3. WHERE BMPs HAVE FAILED, REPAIR OR REPLACEMENT SHOULD BE INITIATED UPON DISCOVERY OF THE FAILURE. 4. SEDIMENT ACCUMULATED UPSTREAM OF SEDIMENT CONTROL LOG SHALL BE REMOVED AS NEEDED TO MAINTAIN FUNCTIONALITY OF THE BMP, TYPICALLY WHEN DEPTH OF ACCUMULATED SEDIMENTS IS APPROXIMATELY )6 OF THE HEIGHT OF THE SEDIMENT CONTROL LOG. 5. SEDIMENT CONTROL LOG SHALL BE REMOVED AT THE END OF CONSTRUCTION. IF DISTURBED AREAS EXIST AFTER REMOVAL, THEY SHALL BE COVERED WITH TOP SOIL, SEEDED AND MULCHED OR OTHERWISE STABIUZED IN A MANNER APPROVED BY THE LOCAL JURISDICTION. (DETAILS ADAPTED FROM TOWN OF PARKER. COLORADO. JEFFERSON COUNTY. COLORADO. DOUGLAS COUNTY, COLORADO, AND CITY OF AURORA, COLORADO. NOT AVAILABLE IN AUTOCAD) NOTE: MANY JURISDICTIONS HAVE BMP DETAILS THAT VARY FROM UDFCD STANDARD DETAILS. CONSULT WITH LOCAL JURISDICTIONS AS TO WHICH DETAIL SHOULD BE USED WHEN DIFFERENCES ARE NOTED. November 2010 Urban Drainage and Flood Control District SCL-5 Urban Storm Drainage Criteria Manual Volume 3 Sediment Trap (ST) SC -8 Description Sediment traps are formed by excavating an area or by placing an earthen embankment across a low area or drainage swale. Sediment traps are designed to capture drainage from disturbed areas less than one acre and allow settling of sediment. Appropriate Uses Sediment traps can be used in combination with other layers of erosion and sediment controls to trap sediment from small drainage areas (less than one acre) or areas with localized high sediment loading. For example, sediment traps are often provided in conjunction with vehicle tracking controls and wheel wash facilities. Design and Installation Photograph ST -1. Sediment traps arc used to collect sediment -laden runoff from disturbed area. Photo courtesy of EPA Menu of BMPs. A sediment trap consists of a small excavated basin with an earthen berm and a riprap outlet. The berm of the sediment trap may be constructed from the excavated material and must be compacted to 95 percent of the maximum density in accordance with ASTM D698. An overflow outlet must be provided at an elevation at least 6 inches below the top of the berm. See Detail ST -1 for additional design and installation information. Maintenance and Removal Inspect the sediment trap embankments for stability and seepage. Remove accumulated sediment as needed to maintain the effectiveness of the sediment trap, typically when the sediment depth is approximately one-half the height of the outflow embankment. Inspect the outlet for debris and damage. Repair damage to the outlet, and remove all obstructions. A sediment trap should not be removed until the upstream area is sufficiently stabilized. Upon removal of the trap, the disturbed area should be covered with topsoil and stabilized. Sediment Trap Functions Erosion Control No Sediment Control Yes Site/Material Management No November 2010 Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual Volume 3 ST -1 SC -8 Sediment Trap (ST) FLOW - - RIPRAP, TYPE M (050=12") TYP.SMALLER ROCK SIZE MAY BE ALLOWABLE FOR SMALLER TRAPS IF APPROVED BY LOCAL JURISDICTION TOP OF EARTHEN BERM 2:1 MAX. TRANSITION EXISTING CHANNEL INTO SEDIMENT TRAP 2:1 MAX. 2 1 MAX. L SEDIMENT TRAP PLAN 6" (CENTER OF RIPRAP 6" LOWER THAN ENDS 6" MINIMUM FREEBOARD 1 FLOW ff _ I '6" MIN. 1'8" MIN. 12' MIN. 30" f SECTION A CHANNEL GRADE 2' 6' RIPRAP, TYPE M (D50=12") TYP. SMALLER ROCK SIZE MAY BE ALLOWABLE FOR SMALLER TRAPS IF APPROVED BY LOCAL JURISDICTION SECTION B ST -1. SEDIMENT TRAP FLOW --- ST -2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Sediment Trap (ST) SC -8 SEDIMENT TRAP INSTALLATION NOTES 1. SEE PLAN VIEW FOR: -LOCATION, LENGTH AND WIDTH OF SEDIMENT TRAP 2. ONLY USE FOR DRAINAGE AREAS LESS THAN 1 ACRE. 3. SEDIMENT TRAPS SHALL BE INSTALLED PRIOR TO ANY UPGRADIENT LAND -DISTURBING ACTIVITIES. 4. SEDIMENT TRAP BERM SHALL BE CONSTRUCTED FROM MATERIAL FROM EXCAVATION. THE BERM SHALL BE COMPACTED TO 95% OF THE MAXIMUM DENSITY IN ACCORDANCE WITH ASTM D698. 5. SEDIMENT TRAP OUTLET TO BE CONSTRUCTED OF RIPRAP, TYPE M (050=12") TYP.SMALLER ROCK SIZE MAY BE ALLOWABLE FOR SMALLER TRAPS IF APPROVED BY LOCAL JURISDICTION. 6 THE TOP OF THE EARTHEN BERM SHALL BE A MINIMUM OF 6" HIGHER THAN THE TOP OF THE RIPRAP OUTLET STRUCTURE. 7. THE ENDS OF THE RIPRAP OUTLET STRUCTURE SHALL BE A MINIMUM OF 6" HIGHER THAN THE CENTER OF THE OUTLET STRUCTURE. SEDIMENT TRAP MAINTENANCE NOTES 1. INSPECT BMPs EACH WORKDAY, AND MAINTAIN THEM IN EFFECTIVE OPERATING CONDITION. MAINTENANCE OF BMPs SHOULD BE PROACTIVE, NOT REACTIVE. INSPECT BMPs AS SOON AS POSSIBLE (AND ALWAYS WITHIN 24 HOURS) FOLLOWING A STORM THAT CAUSES SURFACE EROSION, AND PERFORM NECESSARY MAINTENANCE. 2. FREQUENT OBSERVATIONS AND MAINTENANCE ARE NECESSARY TO MAINTAIN BMPs IN EFFECTIVE OPERATING CONDITION INSPECTIONS AND CORRECTIVE MEASURES SHOULD BE DOCUMENTED THOROUGHLY. 3 WHERE BMPs HAVE FAILED, REPAIR OR REPLACEMENT SHOULD BE INITIATED UPON DISCOVERY OF THE FAILURE. 4. REMOVE SEDIMENT ACCUMULATED IN TRAP AS NEEDED TO MAINTAIN THE FUNCTIONALITY OF THE BMP, TYPICALLY WHEN THE SEDIMENT DEPTH REACHES Jf THE HEIGHT OF THE RIPRAP OUTLET. 5. SEDIMENT TRAPS SHALL REMAIN IN PLACE UNTIL THE UPSTREAM DISTURBED AREA IS STABILIZED AND APPROVED BY THE LOCAL JURISDICTION. 6. WHEN SEDIMENT TRAPS ARE REMOVED, THE DISTURBED AREA SHALL BE COVERED WITH TOPSOIL, SEEDED AND MULCHED OR OTHERWISE STABILIZED IN A MANNER APPROVED BY THE LOCAL JURISDICTION. (DETAILS ADAPTED FROM DOUGLAS COUNTY, COLORADO, NOT AVAILABLE IN AUTOCAD) NOTE: MANY JURISDICTIONS HAVE BMP DETAILS THAT VARY FROM UDFCD STANDARD DETAILS. CONSULT WITH LOCAL JURISDICTIONS AS TO WHICH DETAIL SHOULD BE USED WHEN DIFFERENCES ARE NOTED. November 2010 Urban Drainage and Flood Control District ST -3 Urban Storm Drainage Criteria Manual Volume 3 Silt Fence (SF) SC -1 Description A silt fence is a woven geotextile fabric attached to wooden posts and trenched into the ground. It is designed as a sediment barrier to intercept sheet flow runoff from disturbed areas. Appropriate Uses A silt fence can be used where runoff is conveyed from a disturbed area as sheet flow. Silt fence is not designed to receive concentrated flow or to be used as a filter fabric. Typical uses include: • Down slope of a disturbed area to accept sheet flow. • Along the perimeter of a receiving water such as a stream, pond or wetland. ■ At the perimeter of a construction site. Design and Installation Photograph SF -1. Silt fence creates a sediment barrier, forcing sheet flow runofito evaporate or infiltrate. Silt fence should be installed along the contour of slopes so that it intercepts sheet flow. The maximum recommended tributary drainage area per 100 lineal feet of silt fence, installed along the contour, is approximately 0.25 acres with a disturbed slope length of up to 150 feet and a tributary slope gradient no steeper than 3:1. Longer and steeper slopes require additional measures. This recommendation only applies to silt fence installed along the contour. Silt fence installed for other uses, such as perimeter control, should be installed in a way that will not produce concentrated flows. For example, a "J -hook" installation may be appropriate to force runoff to pond and evaporate or infiltrate in multiple areas rather than concentrate and cause erosive conditions parallel to the silt fence. See Detail SF -1 for proper silt fence installation, which involves proper trenching, staking, securing the fabric to the stakes, and backfilling the silt fence. Properly installed silt fence should not be easily pulled out by hand and there should be no gaps between the ground and the fabric. Silt fence must meet the minimum allowable strength requirements, depth of installation requirement, and other specifications in the design details. Improper installation of silt fence is a common reason for silt fence failure; however, when properly installed and used for the appropriate purposes, it can be highly effective. Silt Fence Functions Erosion Control No Sediment Control Yes Site/Material Management No November 2010 Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual Volume 3 SF -1 SC -1 Silt Fence (SF) Maintenance and Removal Inspection of silt fence includes observing the material for tears or holes and checking for slumping fence and undercut areas bypassing flows. Repair of silt fence typically involves replacing the damaged section with a new section. Sediment accumulated behind silt fence should be removed, as needed to maintain BMP effectiveness, typically before it reaches a depth of 6 inches. Silt fence may be removed when the upstream area has reached final stabilization. Photograph SF -2. When silt fence is not installed along the contour, a "J -hook" installation may be appropriate to ensure that the BMP does not create concentrated flow parallel to the silt fence. Photo courtesy of Tom Gore. SF -2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Silt Fence (SF) SC -1 SF - SF - SF SILT FENCE GEOTEXTILE COMPACTED BACKFILL F.O EXISTING GROUND 6" MIN AT LEAST 10" OF SILT FENCE "TAIL" SHALL BE BURIED JOIN FIRST ROTATE SECOND POSTS SHALL BE JO NED AS SHOWN, THEN ROTATED 180 DEC. IN DIRECTION SHOWN AND DRIVEN INTO THE GROUND I ;�X 1 h„ (RECOMMENDED) WOODEN / FENCE POST WITH 10' MAX SPACING MIN V 18" MIN 36"- 48" TYP. SILT FENCE POSTS SHALL OVERLAP AT JOINTS SO THAT NO GAPS EXIST IN SILT FENC THICKNESS OF GEOTEXTILE HAS BEEN EXACGERATED, TYP SECTION A SF -1. SILT FENCE November 2010 Urban Drainage and Flood Control District SF -3 Urban Storm Drainage Criteria Manual Volume 3 SC -1 Silt Fence (SF) SILT FENCE INSTALLATION NOTES 1. SILT FENCE MUST BE PLACED AWAY FROM THE TOE OF THE SLOPE TO ALLOW FOR WATER PONDING. SILT FENCE AT THE TOE OF A SLOPE SHOULD BE INSTALLED IN A FLAT LOCATION AT LEAST SEVERAL FEET (2-5 FT) FROM THE TOE OF THE SLOPE TO ALLOW ROOM FOR PONDING AND DEPOSITION. 2. A UNIFORM 6" X 4" ANCHOR TRENCH SHALL BE EXCAVATED USING TRENCHER OR SILT FENCE INSTALLATION DEVICE. NO ROAD GRADERS, BACKHOES, OR SIMILAR EQUIPMENT SHALL BE USED. 3. COMPACT ANCHOR TRENCH BY HAND WITH A "JUMPING JACK" OR BY WHEEL ROLLING. COMPACTION SHALL BE SUCH THAT SILT FENCE RESISTS BEING PULLED OUT OF ANCHOR TRENCH BY HAND. 4. SILT FENCE SHALL BE PULLED TIGHT AS IT IS ANCHORED TO THE STAKES. THERE SHOULD BE NO NOTICEABLE SAG BETWEEN STAKES AFTER IT HAS BEEN ANCHORED TO THE STAKES. 5. SILT FENCE FABRIC SHALL BE ANCHORED TO THE STAKES USING 1" HEAVY DUTY STAPLES OR NAILS WITH 1" HEADS. STAPLES AND NAILS SHOULD BE PLACED 3" ALONG THE FABRIC DOWN THE STAKE. 6. AT THE END OF A RUN OF SILT FENCE ALONG A CONTOUR, THE SILT FENCE SHOULD BE TURNED PERPENDICULAR TO THE CONTOUR TO CREATE A "J -HOOK." THE "J -HOOK" EXTENDING PERPENDICULAR TO THE CONTOUR SHOULD BE OF SUFFICIENT LENGTH TO KEEP RUNOFF FROM FLOWING AROUND THE END OF THE SILT FENCE (TYPICALLY 10' - 20'). 7. SILT FENCE SHALL BE INSTALLED PRIOR TO ANY LAND DISTURBING ACTMTIES. SILT FENCE MAINTENANCE NOTES 1. INSPECT BMPs EACH WORKDAY, AND MAINTAIN THEM IN EFFECTIVE OPERATING CONDITION. MAINTENANCE OF BMPs SHOULD BE PROACTIVE, NOT REACTIVE. INSPECT BMPs AS SOON AS POSSIBLE (AND ALWAYS WITHIN 24 HOURS) FOLLOWING A STORM THAT CAUSES SURFACE EROSION, AND PERFORM NECESSARY MAINTENANCE. 2. FREQUENT OBSERVATIONS AND MAINTENANCE ARE NECESSARY TO MAINTAIN BMPs IN EFFECTIVE OPERATING CONDITION. INSPECTIONS AND CORRECTIVE MEASURES SHOULD BE DOCUMENTED THOROUGHLY. 3. WHERE BMPs HAVE FAILED, REPAIR OR REPLACEMENT SHOULD BE INITIATED UPON DISCOVERY OF THE FAILURE. 4. SEDIMENT ACCUMULATED UPSTREAM OF THE SILT FENCE SHALL BE REMOVED AS NEEDED TO MAINTAIN THE FUNCTIONALITY OF THE BMP, TYPICALLY WHEN DEPTH OF ACCUMULATED SEDIMENTS IS APPROXIMATELY 6". 5. REPAIR OR REPLACE SILT FENCE WHEN THERE ARE SIGNS OF WEAR, SUCH AS SAGGING, TEARING, OR COLLAPSE. 6. SILT FENCE IS TO REMAIN IN PLACE UNTIL THE UPSTREAM DISTURBED AREA IS STABILIZED ANO APPROVED BY THE LOCAL JURISDICTION, OR IS REPLACED BY AN EQUIVALENT PERIMETER SEDIMENT CONTROL BMP. 7. WHEN SILT FENCE IS REMOVED, ALL DISTURBED AREAS SHALL BE COVERED WITH TOPSOIL, SEEDED AND MULCHED OR OTHERWISE STABILIZED AS APPROVED BY LOCAL JURISDICTION. (OETNL ADAPTED FROM TOWN OF PARKER. COLORADO AND CITY OF AURORA, NOT AVAILABLE IN AUTOCAD) NOTE: MANY JURISDICTIONS HAVE BMP DETAILS THAT VARY FROM UDFCD STANDARD DETAILS. CONSULT WITH LOCAL JURISDICTIONS AS TO WHICH DETAIL SHOULD BE USED WHEN DIFFERENCES ARE NOTED. SF -4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Surface Roughening (SR) EC -1 Description Surface roughening is an erosion control practice that involves tracking, scarifying, imprinting, or tilling a disturbed area to provide temporary stabilization of disturbed areas. Surface roughening creates variations in the soil surface that help to minimize wind and water erosion. Depending on the technique used, surface roughening may also help establish conditions favorable to establishment of vegetation. Appropriate Uses Surface roughening can be used to provide temporary stabilization of disturbed areas, such as when revegetation cannot be immediately established due to seasonal planting limitations. Surface roughening is not a stand-alone BMP, and should be used in conjunction with other erosion and sediment controls. Photograph SR -1. Surface roughening via imprinting for temporary stabilization. Surface roughening is often implemented in conjunction with grading and is typically performed using heavy construction equipment to track the surface. Be aware that tracking with heavy equipment will also compact soils, which is not desirable in areas that will be revegetated. Scarifying, tilling, or ripping are better surface roughening techniques in locations where revegetation is planned. Roughening is not effective in very sandy soils and cannot be effectively performed in rocky soil. Design and Installation Typical design details for surfacing roughening on steep and mild slopes are provided in Details SR -1 and SR -2, respectively. Surface roughening should be performed either after final grading or to temporarily stabilize an area during active construction that may be inactive for a short time period. Surface roughening should create depressions 2 to 6 inches deep and approximately 6 inches apart. The surface of exposed soil can be roughened by a number of techniques and equipment. Horizontal grooves (running parallel to the contours of the land) can be made using tracks from equipment treads, stair -step grading, ripping, or tilling. Fill slopes can be constructed with a roughened surface. Cut slopes that have been smooth graded can be roughened as a subsequent operation. Roughening should follow along the contours of the slope. The tracks left by truck mounted equipment working perpendicular to the contour can leave acceptable horizontal depressions; however, the equipment will also compact the soil. Surface Roughening Functions Erosion Control Yes Sediment Control No Site/Material Management No November 2010 Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual Volume 3 SR -1 EC -1 Surface Roughening (SR) Maintenance and Removal Care should be taken not to drive vehicles or equipment over areas that have been surface roughened. Tire tracks will smooth the roughened surface and may cause runoff to collect into rills and gullies. Because surface roughening is only a temporary control, additional treatments may be necessary to maintain the soil surface in a roughened condition. Areas should be inspected for signs of erosion. Surface roughening is a temporary measure, and will not provide long-term erosion control. SR -2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Surface Roughening (SR) EC -1 2" TO 4" DEEP TRACKING OR IMPRINTING FURROWS 2" TO 4" DEEP WITH 6" MAXIMUM SPACING PARALLEL TO CONTOURS SR -1. SURFACE ROUGHENING FOR STEEP SLOPES (3:1 OR STEEPER) SR -2. SURFACE ROUGHENING ROUGHENED ROWS SHALL BE 4" TO 6" DEEP WITH 6" MAXIMUM SPACING PARALLEL TO CONTOURS FOR LOW SLOPES (LESS THAN 3:1) rTh SR K__Y November 2010 Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual Volume 3 SR -3 EC -1 Surface Roughening (SR) SURFACE ROUGHENING INSTALLATION NOTES 1. SEE PLAN VIEW FOR: -LOCATION(S) OF SURFACE ROUGHENING. 2. SURFACE ROUGHENING SHALL BE PROVIDED PROMPTLY AFTER COMPLETION OF FINISHED GRADING (FOR AREAS NOT RECEIVING TOPSOIL) OR PRIOR TO TOPSOIL PLACEMENT OR ANY FORECASTED RAIN EVENT. 3. AREAS WHERE BUILDING FOUNDATIONS, PAVEMENT, OR SOD WILL BE PLACED WITHOUT DELAY IN THE CONSTRUCTION SEQUENCE, SURFACE ROUGHENING IS NOT REQUIRED. 4. DISTURBED SURFACES SHALL BE ROUGHENED USING RIPPING OR TILLING EQUIPMENT ON THE CONTOUR OR TRACKING UP AND DOWN A SLOPE USING EQUIPMENT TREADS. 5. A FARMING DISK SHALL NOT BE USED FOR SURFACE ROUGHENING. SURFACE ROUGHENING MAINTENANCE NOTES 1. INSPECT BMPs EACH WORKDAY, AND MAINTAIN THEM IN EFFECTIVE OPERATING CONDITION. MAINTENANCE OF BMPs SHOULD BE PROACTIVE, NOT REACTIVE. INSPECT BMPs AS SOON AS POSSIBLE (AND ALWAYS WITHIN 24 HOURS) FOLLOWING A STORM THAT CAUSES SURFACE EROSION, AND PERFORM NECESSARY MAINTENANCE. 2. FREQUENT OBSERVATIONS AND MAINTENANCE ARE NECESSARY TO MAINTAIN BMPs IN EFFECTIVE OPERATING CONDITION. INSPECTIONS AND CORRECTIVE MEASURES SHOULD BE DOCUMENTED THOROUGHLY. 3. WHERE BMPs HAVE FAILED, REPAIR OR REPLACE UPON DISCOVERY OF THE FAILURE. 4. VEHICLES AND EQUIPMENT SHALL NOT BE DRIVEN OVER AREAS THAT HAVE BEEN SURFACE ROUGHENED. 5. IN NON -TURF GRASS FINISHED AREAS, SEEDING AND MULCHING SHALL TAKE PLACE DIRECTLY OVER SURFACE ROUGHENED AREAS WITHOUT FIRST SMOOTHING OUT THE SURFACE. 6. IN AREAS NOT SEEDED AND MULCHED AFTER SURFACE ROUGHENING, SURFACES SHALL BE RE -ROUGHENED AS NECESSARY TO MAINTAIN GROOVE DEPTH AND SMOOTH OVER RILL EROSION. (DETAILS ADAPTED FROM TOWN OF PARKER. COLORADO. NOT AVAILABLE IN AUTOCAD) NOTE; MANY JURISDICTIONS HAVE BMP DETAILS THAT VARY FROM UDFCD STANDARD DETAILS. CONSULT WITH LOCAL JURISDICTIONS AS TO WHICH DETAIL SHOULD BE USED WHEN DIFFERENCES ARE NOTED SR -4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Vehicle Tracking Control (VTC) SM-4 Description Vehicle tracking controls provide stabilized construction site access where vehicles exit the site onto paved public roads. An effective vehicle tracking control helps remove sediment (mud or dirt) from vehicles, reducing tracking onto the paved surface. Appropriate Uses Implement a stabilized construction entrance or vehicle tracking control where frequent heavy vehicle traffic exits the construction site onto a paved roadway. An effective vehicle tracking control is particularly important during the following conditions: Photograph VTC-1. A vehicle tracking control pad constructed with properly sized rock reduces off -site sediment tracking. • Wet weather periods when mud is easily tracked off site. • During dry weather periods where dust is a concern. • When poorly drained, clayey soils are present on site. Although wheel washes are not required in designs of vehicle tracking controls, they may be needed at particularly muddy sites. Design and Installation Construct the vehicle tracking control on a level surface. Where feasible, grade the tracking control towards the construction site to reduce off -site runoff. Place signage, as needed, to direct construction vehicles to the designated exit through the vehicle tracking control. There are several different types of stabilized construction entrances including: VTC-1. Aggregate Vehicle Tracking Control. This is a coarse -aggregate surfaced pad underlain by a geotextile. This is the most common vehicle tracking control, and when properly maintained can be effective at removing sediment from vehicle tires. VTC-2. Vehicle Tracking Control with Construction Mat or Turf Reinforcement Mat. This type of control may be appropriate for site access at very small construction sites with low traffic volume over vegetated areas. Although this application does not typically remove sediment from vehicles, it helps protect existing vegetation and provides a stabilized entrance. Vehicle Tracking Control Functions Erosion Control Moderate Sediment Control Yes Site/Material Management Yes November 2010 Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual Volume 3 VTC-1 SM-4 Vehicle Tracking Control (VTC) VTC-3. Stabilized Construction Entrance/Exit with Wheel Wash. This is an aggregate pad, similar to VTC-1, but includes equipment for tire washing. The wheel wash equipment may be as simple as hand-held power washing equipment to more advance proprietary systems. When a wheel wash is provided, it is important to direct wash water to a sediment trap prior to discharge from the site. Vehicle tracking controls are sometimes installed in combination with a sediment trap to treat runoff. Maintenance and Removal Inspect the area for degradation and replace aggregate or material used for a stabilized entrance/exit as needed. If the area becomes clogged and ponds water, remove and dispose of excess sediment or replace material with a fresh layer of aggregate as necessary. With aggregate vehicle tracking controls, ensure rock and debris from this area do not enter the public right-of-way. Remove sediment that is tracked onto the public right of way daily or more frequently as needed. Excess sediment in the roadway indicates that the stabilized construction entrance needs maintenance. Ensure that drainage ditches at the entrance/exit area remain clear. Photograph VTC-2. A vehicle tracking control pad with wheel wash facility. Photo courtesy of Tom Gore. A stabilized entrance should be removed only when there is no longer the potential for vehicle tracking to occur. This is typically after the site has been stabilized. When wheel wash equipment is used, be sure that the wash water is discharged to a sediment trap prior to discharge. Also inspect channels conveying the water from the wash area to the sediment trap and stabilize areas that may be eroding. When a construction entrance/exit is removed, excess sediment from the aggregate should be removed and disposed of appropriately. The entrance should be promptly stabilized with a permanent surface following removal, typically by paving. VTC-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Vehicle Tracking Control (VTC) SM-4 .ir.4+.SLra! akititea • SIDEWALK OR OTHER PAVED SURFACE PUBLIC ROADWAY INSTALL ROCK FLUSH WITH OR BELOW TOP OF PAVEMENT COMPACTED SUBGRADE 50 FOOT (MIN.) 20 FOOT (WIDTH CAN BE LESS IF CONST. VEHICLES ARE PHYSICALLY CONFINED ON BOTH SIDES) (MIN ) UNLESS OTHERWISE SPECIFIED BY LOCAL JURISDICTION, USE COOT SECT. #703, AASHTO #3 COARSE AGGREGATE OR 6" MINUS ROCK NON -WOVEN GEOTEXTILE FABRIC BETWEEN SOIL AND ROCK UNLESS OTHERWISE SPECIFIED BY LOCAL JURISDICTION, USE COOT SECT. #703, AASHTO #3 COARSE AGGREGATE OR 6" MINUS ROCK r 9„ (MIN.) SECTION A f NON -WOVEN GEOTEXTILE FABRIC VTC-1. AGGREGATE VEHICLE TRACKING CONTROL November 2010 Urban Drainage and Flood Control District VTC-3 Urban Storm Drainage Criteria Manual Volume 3 SM-4 Vehicle Tracking Control (VTC) PUBLIC ROADWAY NOTE: WASH WATER MAY NOT CONTAIN CHEMICALS OR SOAPS WITHOUT OBTAINING A SEPARATE PERMIT I. KKAtThis REINFORCED CONCRETE RA (MAY SUBSTITUTE STEEL CATTLE GUARD FOR CONCRETE RACK) DITCH TO CARRY WASH WATER TO SEDIMENT TRAP OR BASIN 6'7" MIN. stain4 I DRAIN SPACE SECTION A VTC-2. AGGREGATE VEHICLE TRACKING CONTROL WITH WASH RACK VTC-4 Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual Volume 3 November 2010 Vehicle Tracking Control (VTC) SM-4 EXISTING PAVED ROADWAY EXISTING PAVED ROADWAY Is. 1'o MAX. C F tF DISTURBED AREA, CONSTRUCTION SITE, STABIUZED STORAGE AREA OR STAGING AREA F. 18" MIN_ SPIKES OR STAKES TRM END OVERLAP WITH SPIKES OR STAKES CONSTRUCTION MATS, WOVEN OR TURF REINFORCEMENT STRAP MAT (TRM) CONNECTORS RESTRICT CONST. VEHICLE ACCESS TO SIDES OF MAT • CONSTRUCTION MAT END OVERLAP INTERLOCK WITH STRAP CONNECTORS 20' OR AS REQUIRED TO ACCOMMODATE ANTICIPATED TRAFFIC (WIDTH CAN BE LESS IF CONST. VEHICLES ARE PHYSICALLY CONFINED ON BOTH SIDES) VTC-3. VEHICLE TRACKING CONTROL W/ CONSTRUCTION MAT OR TURF REINFORCEMENT MAT (TRM) November 2010 Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual Volume 3 VTC-5 SM-4 Vehicle Tracking Control (VTC) STABIUZED CONSTRUCTION ENTRANCE/EXIT INSTALLATION NOTES 1. SEE PLAN VIEW FOR -LOCATION OF CONSTRUCTION ENTRANCE(S)/EXIT(S). -TYPE OF CONSTRUCTION ENTRANCE(S)/EXITS(S) (WITH/WITHOUT WHEEL WASH, CONSTRUCTION MAT OR TRM). 2. CONSTRUCTION MAT OR TRM STABILIZED CONSTRUCTION ENTRANCES ARE ONLY TO BE USED ON SHORT DURATION PROJECTS (TYPICALLY RANGING FROM A WEEK TO A MONTH) WHERE THERE WILL BE LIMITED VEHICULAR ACCESS. 3. A STABILIZED CONSTRUCTION ENTRANCE/EXIT SHALL BE LOCATED AT ALL ACCESS POINTS WHERE VEHICLES ACCESS THE CONSTRUCTION SITE FROM PAVED RIGHT-OF-WAYS. 4. STABILIZED CONSTRUCTION ENTRANCE/EXIT SHALL BE INSTALLED PRIOR TO ANY LAND DISTURBING ACTIVITIES. 5. A NON -WOVEN GEOTEXTILE FABRIC SHALL BE PLACED UNDER THE STABIUZED CONSTRUCTION ENTRANCE/EXIT PRIOR TO THE PLACEMENT OF ROCK. 6. UNLESS OTHERWISE SPECIFIED BY LOCAL JURISDICTION, ROCK SHALL CONSIST OF DOT SECT. #7O3, AASHTO ff 3 COARSE AGGREGATE OR 6" (MINUS) ROCK. STABIUZED CONSTRUCTION ENTRANCE/EXIT MAINTENANCE NOTES 1. INSPECT BMPs EACH WORKDAY, AND MAINTAIN THEM IN EFFECTIVE OPERATING CONDITION. MAINTENANCE OF BMPs SHOULD BE PROACTIVE, NOT REACTIVE. INSPECT BMPs AS SOON AS POSSIBLE (AND ALWAYS WITHIN 24 HOURS) FOLLOWING A STORM THAT CAUSES SURFACE EROSION, AND PERFORM NECESSARY MAINTENANCE. 2. FREQUENT OBSERVATIONS AND MAINTENANCE ARE NECESSARY TO MAINTAIN BMPs IN EFFECTIVE OPERATING CONDITION. INSPECTIONS AND CORRECTIVE MEASURES SHOULD BE DOCUMENTED THOROUGHLY. 3. WHERE BMPs HAVE FAILED, REPAIR OR REPLACEMENT SHOULD BE INITIATED UPON DISCOVERY OF THE FAILURE. 4. ROCK SHALL BE REAPPLIED OR REGRADED AS NECESSARY TO THE STABIUZED ENTRANCE/EXIT TO MAINTAIN A CONSISTENT DEPTH. 5. SEDIMENT TRACKED ONTO PAVED ROADS IS TO BE REMOVED THROUGHOUT THE DAY AND AT THE END OF THE DAY BY SHOVELING OR SWEEPING. SEDIMENT MAY NOT BE WASHED DOWN STORM SEWER DRAINS. NOTE: MANY JURISDICTIONS HAVE BMP DETAILS THAT VARY FROM UDFCD STANDARD DETAILS. CONSULT WITH LOCAL JURISDICTIONS AS TO WHICH DETAIL SHOULD BE USED WHEN DIFFERENCES ARE NOTED. (DETAILS ADAPTED FROM CITY OF BROOMFIELD. COLORADO. NOT AVAILABLE IN AUTOCAD) VTC-6 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Rolled Erosion Control Products (RECP) EC -6 Description Rolled Erosion Control Products (RECPs) include a variety of temporary or permanently installed manufactured products designed to control erosion and enhance vegetation establishment and survivability, particularly on slopes and in channels. For applications where natural vegetation alone will provide sufficient permanent erosion protection, temporary products such as netting, open weave textiles and a variety of erosion control blankets (ECBs) made of biodegradable natural materials (e.g., straw, coconut fiber) can be used. erosion and providing favorable conditions for revegetation. For applications where natural vegetation alone will not be sustainable under expected flow conditions, permanent rolled erosion control products such as turf reinforcement mats (TRMs) can be used. In particular, turf reinforcement mats are designed for discharges that exert velocities and sheer stresses that exceed the typical limits of mature natural vegetation. Appropriate Uses Photograph RECP-1. Erosion control blanket protecting the slope from RECPs can be used to control erosion in conjunction with revegetation efforts, providing seedbed protection from wind and water erosion. These products are often used on disturbed areas on steep slopes, in areas with highly erosive soils, or as part of drainageway stabilization. In order to select the appropriate RECP for site conditions, it is important to have a general understanding of the general types of these products, their expected longevity, and general characteristics. The Erosion Control Technology Council (ECTC 2005) characterizes rolled erosion control products according to these categories: ■ Mulch control netting: A planar woven natural fiber or extruded geosynthetic mesh used as a temporary degradable rolled erosion control product to anchor loose fiber mulches. • Open weave textile: A temporary degradable rolled erosion control product composed of processed natural or polymer yarns woven into a matrix, used to provide erosion control and facilitate vegetation establishment. • Erosion control blanket (ECB): A temporary degradable rolled erosion control product composed of processed natural or polymer fibers which are mechanically, structurally or chemically bound together to form a continuous matrix to provide erosion control and facilitate vegetation establishment. ECBs can be further differentiated into rapidly degrading single -net and double -net types or slowly degrading types. Rolled Erosion Control Products Functions Erosion Control Yes Sediment Control No Site/Material Management No November 2010 Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual Volume 3 RECP-1 EC -6 Rolled Erosion Control Products (RECP) • Turf Reinforcement Mat (TRM): A rolled erosion control product composed of non -degradable synthetic fibers, filaments, nets, wire mesh, and/or other elements, processed into a permanent, three- dimensional matrix of sufficient thickness. TRMs, which may be supplemented with degradable components, are designed to impart immediate erosion protection, enhance vegetation establishment and provide long-term functionality by permanently reinforcing vegetation during and after maturation. Note: TRMs are typically used in hydraulic applications, such as high flow ditches and channels, steep slopes, stream banks, and shorelines, where erosive forces may exceed the limits of natural, unreinforced vegetation or in areas where limited vegetation establishment is anticipated. Tables RECP-1 and RECP-2 provide guidelines for selecting rolled erosion control products appropriate to site conditions and desired longevity. Table RECP-1 is for conditions where natural vegetation alone will provide permanent erosion control, whereas Table RECP-2 is for conditions where vegetation alone will not be adequately stable to provide long-term erosion protection due to flow or other conditions. RECP-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Rolled Erosion Control Products (RECP) EC -6 Table RECP-1. ECTC Standard Specification for Temporary Rolled Erosion Control Products (Adapted from Erosion Control Technology Council 2005) Product Description Slope Applications* Channel Applications X Minimum Tensile Strength' Expected Longevity Maximum Gradient C Factor 1'5 Max. Shear Stressh"a 'a, Mulch Control Nets 5:1 (H:V) ≤0.10 @ 5:1 0.25 lbs/ft2 (12 Pa) 5 lbs/ft (0.073 kN/m) Up to 12 months Netless Rolled Erosion Control Blankets 4:1 (H:V) <0.10 @ — 4:1 0.5 lbs/ft2 (24 Pa) 5 lbs/ft (0.073 kN/m) Single -net Erosion Control Blankets & Open Weave Textiles 3:1 (H:V) <0.15 @ _ 3:1 1.5 lbs/ft2 (72 Pa) 50 lbs/ft (0.73 kN/m) Double -net Erosion Control Blankets 2:l (H:V) <0.20 @ — 2:1 1.75 lbs/ft2 (84 Pa) 75 lbs/ft (1.09 kN/m) Mulch Control Nets 5:1 (H:V) <0.10 @ — 5:1 0.25 lbs/ft2 (12 Pa) 25 lbs/ft (0.36 kN/m) 24 months Erosion Control Blankets & Open Weave Textiles (slowly degrading) 1.5:1 (H:V) 50.25 @ 1.5:1 2.00 lbs/ft2 (96 Pa) 100 lbs/ft (1.45 kN/m) 24 months Erosion Control Blankets & Open Weave Textiles 1:1 (H:V) <0.25 @ — 1:1 2.25 lbs/ft2 (108 Pa) 125 lbs/ft (1.82 kN/m) 36 months * C Factor and shear stress for mulch control nettings must be obtained with netting used in conjunction with pre -applied mulch material. (See Section 5.3 of Chapter 7 Construction BMPs for more information on the C Factor.) ' Minimum Average Roll Values, Machine direction using ECTC Mod. ASTM D 5035. 2 C Factor calculated as ratio of soil loss from RECP protected slope (tested at specified or greater gradient, H:V) to ratio of soil loss from unprotected (control) plot in large-scale testing. 3 Required minimum shear stress RECP (unvegetated) can sustain without physical damage or excess erosion (> 12.7 mm (0.5 in) soil loss) during a 30 -minute flow event in large-scale testing. `' The permissible shear stress levels established for each performance category are based on historical experience with products characterized by Manning's roughness coefficients in the range of 0.01 - 0.05. 5 Acceptable large-scale test methods may include ASTM D 6459, or other independent testing deemed acceptable by the engineer. 6 Per the engineer's discretion. Recommended acceptable large-scale testing protocol may include ASTM D 6460, or other independent testing deemed acceptable by the engineer. November 2010 Urban Drainage and Flood Control District RECP-3 Urban Storm Drainage Criteria Manual Volume 3 EC -6 Rolled Erosion Control Products (RECP) Table RECP-2. ECTC Standard Specification for Permanent' Rolled Erosion Control Products (Adapted from: Erosion Control Technology Council 2005) Product Type Slope Applications Channel Applications TRMs with a minimum thickness of 0.25 inches (6.35 mm) per ASTM D 6525 and UV stability of 80% per ASTM D 4355 (500 hours Maximum Gradient Maximum Shear Stress." Minimum Tensile Strength23 0.5:1 (H:V) z 6.0 lbs/ft2 Pa) 125 lbs/ft (1.82 kN/m) 051 HV kN/m) 80 lbs/ft2 384 P 150 lbs/ft (2.19 0.5:1 (H:V) 10.0 lbs/ft2 (480 Pa) 175 lbs/ft (2.55 kN/m) ' For TRMs containing degradable components, all property values must be obtained on the non- degradable portion of the matting alone. 2 Minimum Average Roll Values, machine direction only for tensile strength determination using ASTM D 6818 (Supersedes Mod. ASTM D 5035 for RECPs) 3 Field conditions with high loading and/or high survivability requirements may warrant the use of a TRM with a tensile strength of 44 kN/m (3,000 lb/ft) or greater. ' Required minimum shear stress TRM (fully vegetated) can sustain without physical damage or excess erosion (> 12.7 mm (0.5 in.) soil loss) during a 30 -minute flow event in large scale testing. 5 Acceptable large-scale testing protocols may include ASTM D 6460, or other independent testing deemed acceptable by the engineer. Design and Installation RECPs should be installed according to manufacturer's specifications and guidelines. Regardless of the type of product used, it is important to ensure no gaps or voids exist under the material and that all corners of the material are secured using stakes and trenching. Continuous contact between the product and the soil is necessary to avoid failure. Never use metal stakes to secure temporary erosion control products. Often wooden stakes are used to anchor RECPs; however, wood stakes may present installation and maintenance challenges and generally take a long time to biodegrade. Some local jurisdictions have had favorable experiences using biodegradable stakes. This BMP Fact Sheet provides design details for several commonly used ECB applications, including: ECB-1 Pipe Outlet to Drainageway ECB-2 Small Ditch or Drainageway ECB-3 Outside of Drainageway RECP-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Rolled Erosion Control Products (RECP) EC -6 Staking patterns are also provided in the design details according to these factors: • ECB type • Slope or channel type For other types of RECPs including TRMs, these design details are intended to serve as general guidelines for design and installation; however, engineers should adhere to manufacturer's installation recommendations. Maintenance and Removal Inspection of erosion control blankets and other RECPs includes: ■ Check for general signs of erosion, including voids beneath the mat. If voids are apparent, fill the void with suitable soil and replace the erosion control blanket, following the appropriate staking pattern. • Check for damaged or loose stakes and secure loose portions of the blanket. Erosion control blankets and other RECPs that are biodegradable typically do not need to be removed after construction. If they must be removed, then an alternate soil stabilization method should be installed promptly following removal. Turf reinforcement mats, although generally resistant to biodegradation, are typically left in place as a dense vegetated cover grows in through the mat matrix. The turf reinforcement mat provides long-term stability and helps the established vegetation resist erosive forces. November 2010 Urban Drainage and Flood Control District RECP-5 Urban Storm Drainage Criteria Manual Volume 3 EC -6 Rolled Erosion Control Products (RECP) UNDISTURBED SOIL PERIMETER ANCHOR TRENCH, TYP. JOINT ANCHOR TRENCH, TYP. TOP OF CHANNEL BANK A i r X TYPE OF EC8 AS INDICATED IN PLAN VIEW. INSTALL IN KLL DISTURBED AREAS OF STREAMS AND DRAINAGE CHANNELS TO DEPT 0 ABOVE CHANNEL INVERT. ECB SHALL GENERALLY BE ORIENTED PARALLEL TO FLOW DIRECTION (I.E. LONG DIMENSIONS OF BLANKET PARALLEL TO FLOWLINES) STAKING PATTERN SHALL MATCH ECB AND/OR CHANNEL TYPE. ECB-1. PIPE OUTLET TO DRAINAGEWAY JOINT ANCHOR TRENCH, TYP. 6" TOPSOIL TYPE OF ECB, INDICATED IN PLAN VIEW ECB SHALL EXTEND TO THE TOP OF THE CHANNEL PERIMETER ANCHOR TRENCH, TYP. COMPACTED SUBGRADE STAKING PATTERN PER MANUFACTURER SPEC. OR PATTERN BASED ON ECB AND/OR CHANNEL TYPE (SEE STAKING PATTERN DETAIL) ECB-2. SMALL DITCH OR DRAINAGEWAY ANCHOR DETAILS GEOTEXTILE FABRIC OR MAT, TYP. {-- 3" MIN, TYP. 'MIN, TYP. COMPACTED BACKFILL, I PERIMETER SINGLE STAKE, TYP. ANCHOR TRENCH TYP. EDGE JOINT ANCHOR TWO EDGES OF TWO ADJACENT ROLLS TRENCH LOOP FROM INTERMEDIATE MIDDLE ROLL ANCHOR OF TRENCH I-- 6" FLOW -----I OVERLAPPING JOINT I Fe- 3" MIN. 12" MIN. WOOD STAKE DETAIL RECP-6 Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual Volume 3 November 2010 Rolled Erosion Control Products (RECP) EC -6 DIVERSION DITCH TYPICALLY AT TOP OF SLOPE PERIMETER ANCHOR TRENCH OR JOINT, TYP. 6 STAGGER OVERLAPS OVERLAPPING JOINT STAKING PATTERN PER MANUFACTURER SPEC. OR PATTERN BASED ON ECB AND/OR SLOPE TYPE (SEE STAKING PATTERN DETAIL) ERIMETER ANCHOR TREN C H ECB-3. OUTSIDE OF DRAINAGEWAY ROLL IWIDTH W, TYP.I STRAW x2 w 6' STRAW -COCONUT COCONUT OR STAKING PATTERNS BY ECB TYPE 4:1 -3:1 SLOPES 6' 4 3:1 -2:1 SLOPES w �r 20" 4' 2' 2' EXCELSIOR 2:1 AND STEEPER SLOPES O 0 O ►- 10 000 I- O 0 0 W L 2' Y.w w LOW FLOW CHANNEL HIGH FLOW CHANNEL STAKING PATTERNS BY SLOPE OR CHANNEL TYPE November 2010 Urban Drainage and Flood Control District RECP-7 Urban Storm Drainage Criteria Manual Volume 3 EC -6 Rolled Erosion Control Products (RECP) EROSION CONTROL BLANKET INSTALLATION NOTES 1. SEE PLAN VIEW FOR: -LOCATION OF ECB. -TYPE OF ECB (STRAW. STRAW -COCONUT. COCONUT, OR EXCELSIOR). -AREA, A, IN SQUARE YARDS OF EACH TYPE OF ECB. 2. 100% NATURAL AND BIODEGRADABLE MATERIALS ARE PREFERRED FOR RECPs, ALTHOUGH SOME JURISDICTIONS MAY ALLOW OTHER MATERIALS IN SOME APPLICATIONS. 3. IN AREAS WHERE ECBs ARE SHOWN ON THE PLANS, THE PERMITTEE SHALL PLACE TOPSOIL AND PERFORM FINAL GRADING, SURFACE PREPARATION, AND SEEDING AND MULCHING. SUBGRADE SHALL BE SMOOTH AND MOIST PRIOR TO ECB INSTALLATION AND THE ECB SHALL BE IN FULL CONTACT WITH SUBGRADE. NO GAPS OR VOIDS SHALL EXIST UNDER THE BLANKET. 4. PERIMETER ANCHOR TRENCH SHALL BE USED ALONG THE OUTSIDE PERIMETER OF ALL BLANKET AREAS. 5. JOINT ANCHOR TRENCH SHALL BE USED TO JOIN ROLLS OF ECBs TOGETHER (LONGITUDINALLY AND TRANSVERSELY) FOR ALL ECBs EXCEPT STRAW WHICH MAY USE AN OVERLAPPING JOINT. 6. INTERMEDIATE ANCHOR TRENCH SHALL BE USED AT SPACING OF ONE-HALF ROLL LENGTH FOR COCONUT AND EXCELSIOR ECBs. 7. OVERLAPPING JOINT DETAIL SHALL BE USED TO JOIN ROLLS OF ECBs TOGETHER FOR ECBs ON SLOPES. 8. MATERIAL SPECIFICATIONS OF ECBs SHALL CONFORM TO TABLE ECB-1. 9. ANY AREAS OF SEEDING AND MULCHING DISTURBED IN THE PROCESS OF INSTALLING ECBS SHALL BE RESEEDED AND MULCHED. 10. DETAILS ON DESIGN PLANS FOR MAJOR DRAINAGEWAY STABILIZATION WILL GOVERN IF DIFFERENT FROM THOSE SHOWN HERE. TABLE ECB-1. ECB MATERIAL SPECIFICATIONS TYPE COCONUT CONTENT STRAW CONTENT EXCELSIOR CONTENT RECOMMENDED NETTING** STRAW - 100% - DOUBLE/ NATURAL STRAW- COCONUT 30% MIN 70% MAX _ DOUBLE/ NATURAL COCONUT 100% - - DOUBLE/ NATURAL EXCELSIOR - - 100% DOUBLE/ NATURAL s MAY ONLY BE USED OUTSIDE OF STREAMS AND DRAINAGE CMANN °ALTERNATE NETT NG MAY BE ACCEPTABLE IN SOME JURISDICTIONS RECP-8 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Rolled Erosion Control Products (RECP) EC -6 EROSION CONTROL BLANKET MAINTENANCE NOTES 1. INSPECT BMPs EACH WORKDAY, AND MAINTAIN THEM IN EFFECTIVE OPERATING CONDITION. MAINTENANCE OF BMPs SHOULD BE PROACTIVE, NOT REACTIVE. INSPECT BMPs AS SOON AS POSSIBLE (AND ALWAYS WITHIN 24 HOURS) FOLLOWING A STORM THAT CAUSES SURFACE EROSION, AND PERFORM NECESSARY MAINTENANCE. 2. FREQUENT OBSERVATIONS AND MAINTENANCE ARE NECESSARY TO MAINTAIN BMPs IN EFFECTIVE OPERATING CONDITION. INSPECTIONS AND CORRECTIVE MEASURES SHOULD BE DOCUMENTED THOROUGHLY. 3 WHERE BMPs HAVE FAILED, REPAIR OR REPLACEMENT SHOULD BE INITIATED UPON DISCOVERY OF THE FAILURE. 4. ECBs SHALL BE LEFT IN PLACE TO EVENTUALLY BIODEGRADE, UNLESS REQUESTED TO BE REMOVED BY THE LOCAL JURISDICTION. 5. ANY ECB PULLED OUT, TORN, OR OTHERWISE DAMAGED SHALL BE REPAIRED OR REINSTALLED. ANY SUBGRADE AREAS BELOW THE GEOTEXTILE THAT HAVE ERODED TO CREATED A VOID UNDER THE BLANKET, OR THAT REMAIN DEVOID OF GRASS SHALL BE REPAIRED, RESEEDED AND MULCHED AND THE ECB REINSTALLED. NOTE: MANY JURISDICTIONS HAVE BMP DETAILS THAT VARY FROM UDFCD STANDARD DETAILS. CONSULT WITH LOCAL JURISDICTIONS AS TO WHICH DETAIL SHOULD BE USED WHEN DIFFERENCES ARE NOTED. (DETAILS ADAPTED FROM DOUGLAS COUNTY, COLORADO AND TOWN OF PARKER COLORADO, NOT AVAILABLE IN AUTOCAD) November 2010 Urban Drainage and Flood Control District RECP-9 Urban Storm Drainage Criteria Manual Volume 3 MU r MULCHING M� Definition Application of plant residues or other suitable materials to the soil surface. Purposes 1. To prevent erosion by protecting the soil surface from raindrop impact and reducing the velocity of overland flow. 2. To foster the growth of vegetation by increasing available moisture and providing insulation against extreme heat and cold. From: Environmental Protection Agency, 1976 Figure C4 -2 ---Mulching From Urban Drainage and Flood Control District Drainage Criteria Manual V.3 Stormwater Management Plan APPENDIX C: Phased CM Implementation Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan CMs — Phasing, Implementation and Maintenance Phase CM Description/Function Installation/Implementation I _ Inspection/Maintenance l Install initial CMs Perimeter control Perimeter control serves as erosion and sediment control and, when appropriate, access control during construction activity. At down gradient locations on the perimeter, controls will be installed where overland sheet flow has the potential to leave the site. In up -gradient areas perimeter control may be added to define project boundaries, limit on -site flows or protect off -site features. Perimeter control may consist of any number of CMs, including, but not limited to diversion ditch & dike, earthen berms, straw wattles, silt fence, construction fencing, controlled parking, controlled site entrance, vehicle tracking control, etc. See the plan for approximateissues locations and type proposed for installation. Perimeter control will remain in place until areas up -gradient of controls are stabilized. - CM specific discussions for inspection maintenance Install initial CMs Vehicle tracking control Vehicle tracking control will consist of an area with a geotextile liner and gravel, metal grate, medium-sized (6" to 12") rough -cut rocks, or asphalt/concrete "rumble strip". Tracking control is designed to cause soil to vibrate off equipment and vehicles as they transition from disturbed soils to paved areas. All appropriate points of ingress and egress, from where traffic transitions from a stabilized road surface (e.g. gravel or pavement) to disturbed soil. will have a vehicle tracking control installed. Tracking control may be moved or eliminated as on -site conditions and activities change.gravel/rock. Tracking control should be inspected for depth of gravel/rock, presence of excess soil, proper usage and the overall general condition. The most common maintenance items include the removal of accumulated soil and addition of Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan CMs — Phasing, Implementation and Maintenance Phase _ CM Description/Function Installation/Implementation J Inspection/Maintenance Install initial CMs Designated Staging Area A stabilized staging area is a specific location on -site to stockpile/stage materials and equipment for use on- site. A stabilized staging area allows a central location for deliveries and storage of equipment when not in use, and to reduce disturbance of areas of the site not scheduled for disturbance through construction activities. Stabilized staging areas generally consist of a cleared area of the site with vehicle tracking control and perimeter controls Stabilized staging areas will be implemented as needed on site and will be located out of areas of active construction activity. If possible, the designated area will be located so it can be utilized during the entire construction period. Stabilized staging areas should be inspected for adequate vehicle tracking control and perimeter control. Stabilized staging areas should function as designed or repaired or modified as needed. Sediment traps are small impoundments which allow sediment to settle out which are generally installed in a drainage way or other point of discharge from a disturbed area. They are formed by excavating an area or by placing an earthen Sediment traps will be installed prior Sediment Trap will be inspected for Initial stages of Sediment embankment across a low area or to earth disturbing activities in areas accumulated sediment, erosion and construction Trap drainage swale. Typically, a spillway or outlet is constructed to allow the slow release of stormwater runoff. where it's determined to be needed. to ensure effective operation Sediment traps are commonly used at the outlets of diversion structures. slope drains or any other runoff that discharges waters containing sediment. Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan CMs — Phasing, Implementation and Maintenance Phase CM Description/Function Installation/Im lementation ) - Ins ection/Maintenance Initial stages of construction Diversion Ditch Diversion ditches are excavated channels, generally 6"-18" in depth which provide channelization of stormwater runoff for the purpose of directing sediment -laden flows to treatment facilities or interception of potential run-on flows to convey it around the disturbed area. All diversion ditches shall be of the 'unlined' type unless specifically noted on the Ian. Diversion ditches will be installed prior to earth disturbing activities in areas indicated on the site map. Diversion ditches will be inspected for effectiveness and repaired or modified as necessary. Clearing, Grubbing & Pad Grading Natural Vegetative Barrier A natural vegetative barrier is a preexisting vegetated, landscaped or sod/seed area that is retained to reduce water flow and prevent over disturbed soil. Additionally, natural vegetative barriers provide a barrier zone where overland sheet flow velocity is dissipated and sediment trapped, reducing sediment dischar a off -site. Natural vegetative barriers are encouraged for any perimeter or environmentally sensitive areas_erosion Whenever possible, a natural vegetative barrier will be maintained between the construction area and stormwater drainage areas Inspections include observation for sediment accumulation or erosion to the area Should damage occur to a vegetative buffer strip a new or additional CM should be considered Construction of temporary material storage areas, improvement or construction of drainage features if needed Straw Bales A straw bale should be a minimum of 14" X 18" X 36" with a minimum mass of 50 pounds. It should be composed of only vegetative matter, except for the binding. The straw bales should be bound by steel wire (minimum 14- gauge), nylon or polypropylene. Applications include check dams in swales, inlet protection. outlet protection, perimeter control, disturbed areas with significant potential for off -site drainage, protection from neighboring site run- on, or during the construction of The basic installation for a straw bale is to prepare a trench approximately four inches deep, secure the bale in the trench using stakes. and backfilled Straw bales will be inspected for proper installation, structural integrity and sediment accumulation. Straw bales degrade and need to be replaced on a regular basis. Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan CMs — Phasing, Implementation and Maintenance Phase CM Description/Function Installation/Implementation [ _ Inspection/Maintenance Installation of new culvert if needed Inlet protection Inlet protection consists of a barrier material place in front, around, or immediate) u radient from the y p -g inlet. The most common forms of inlet protection are wire or fabric socks filled with rock or straw wattles Inlet protection is designed to slow stormwater flow into the inlet, allowing sediment time to settle and accumulate on the up -gradient side of the structure, without constricting the inlet throat. Inlet protection will be installed prior to earth disturbing activity. As permanent stormwater system inlets are constructed in areas with potential disturbed area run-off or when existing inlets are potentially impacted by construction activity, inlet protection will be installed. If conditions warrant, protection will be provided to prevent sediment from entering the inlet from above or behind the opening. Any structure with a potential to receive run-off from non -stabilized surfaces will be treated with an inlet protection CM. Inlet protection will remain in place until all up -gradient areas are stabilized. Inlet protection will be inspected for damage, structural integrity and need for sediment removal. Maintenance includes repairing or replacing as needed, repositioning the inlet protection and/or removing accumulated sediment. Foundation construction Concrete Wash Out A concrete wash -out is designed to capture waste water and waste products resulting from the cleaning of concrete equipment. A concrete wash -out may not be necessary if all wash -out operations are performed off -site. A concrete wash -out will be installed or provided prior to any construction activities that include the handling of materials containing cement (e.g. concrete, masonry, etc.). Examples of permanent installations include a bermed excavation, a mobile disposal unit, small excavations located near the point of concrete placement, water tight vessels such as rigid pre -fabricated impermeable plastic pools, stock tanks, small dumpsters, buckets, etc. and geotextile bags. A concrete wash -out should be inspected to make sure appropriate access control, tracking and containment is in place. Maintenance would include the removal of excess material, and general structural integrity of the installation. Concrete wash -outs should be cleaned of excess water and solids when the capacity of the wash -out reaches no more than 50% (5" for rigid "kiddie" pools). Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan CMs — Phasing, Implementation and Maintenance I Phase I CM I Description/Function Installation/Implementation I Ins ection/Maintenance Throughout construction period Dust Control Dust control reduces dust generated from disturbed surfaces and wind. Water will be applied from water trucks as needed. Correct application is just enough water to moisten the surface and calm dust. but not so much as to create standing water and mud. Disturbed areas should be inspected for obvious signs of wind erosion and dust. This CM is implemented as needed. As appropriate during all phases of construction which cause soil disturbances on sloped surfaces. Surface Roughening Surface roughening consists of grooves or tracks installed in the soil surface, perpendicular to the slope This is a temporary soil stabilization technique that works well in areas that will remain inactive for a short time. Surface roughening works by reducing water velocity and promoting infiltration, thus decreasing the potential for erosion to occur Any disturbed areas with no construction activity planned for longer than 14 days may be surfaced roughened. Surface roughening may be applied by creating a continuous furrow perpendicular to the slope. This can be done with the teeth on a loader bucket, ripping, disking or plowing equipment. Surface roughening can also be created by running tracked equipment up and down the slope. Inspection of surface roughened areas would include proper implementation, structural integrity and areas of erosion or sediment accumulation. Maintenance for surface roughening would include re - applying the technique or installation of new or additional CMs. All Phases where appropriate to the water volume and velocity Straw Wattles (fiber rolls) Straw wattles consist of a net or geotextile fabric filled with straw, excelsior, wood mulch or other man made fillers. They reduce water velocity allowing sediment to accumulate on the up -gradient side of the wattle. Applications include, but are not limited to, slope stabilization, check dams in swales, back of curb protection and temporary secondary containment for stock iles and materials stora e. The basic installation for a net wrapped wattle is to prepare a trench approximately three inches deep, secure the wattle in the trench using a stake or landscape pin, and backfill approximately 1/3 of the wattle on the up -gradient side_ Wattles should be installed based on manufacturer's directions. Typical wattle installation details are provided. Straw wattles should be inspected for proper installation, structural integrity and sediment accumulation Note: A wattle that has been flattened out of round may not need to be replaced if they remain sufficient to function appropriately on the up gradient side of the wattle. Tri-State Generation & Transmission - Lloyd Sisson Substation Stormwater Management Plan CMs — Phasing, Implementation and Maintenance Phase CM Description/Function Installation/Implementation I Inspection/Maintenance Rock check dams will be used in Check dams should be inspected All Phases areas of concentrated flows along the for proper installation, structural where swales to slow water velocity to allow The check dam will be installed integrity and accumulated appropriate to the water Check Dams sediment to settle and to prevent erosion Additionally, this may be used in areas where existing across the entire width of the swale. with the center of the check dam sediment. Maintenance would include volume and drainage patterns cross onto the site lower than the sides. repairing or replacing damaged velocity and bring neighboring property run-on rock berms and removing _ into the construction area. accumulated sediment. Seeding involves the mechanical or As soon as practicable, after the Seed areas should be inspected to 1 hand application of a specific seed mixes appropriate for the site completing of construction activities, soil should be properly prepared and ensure that the straw mat was applied correctly and has not been After location and soil type. Seeding can seeded. The choice of seed mix will compromised. The area should completion of Erosion be used as a permanent or dictate application rates and also be inspected for erosion and construction Control Mats temporary CM. methods. Seeding should always be sediment deposition. activities & Seeding Seeding provides plant growth to stabilize the soil reducing the accompanied by an additional CM, such as mulching or straw mat to protect the seed and soil from Maintenance items would include re -grading and seeding bare or areas of thin vegetative growth likelihood of erosion or sediment erosion during the germination and and/or adding additional CMs as transport. _ _ growth process. a appropriate. Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan New CMs Added to the Site Use the following space to provide information regarding new CMs added to site. Phase CM Description/Function Installation/Implementation [ Inspection/Maintenance Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan APPENDIX D: Inspection Forms Tri-State Generation & Transmission — Lloyd Sisson Substation a Summit SERVICES GROUP StormWater Inspection Report Facility Name Permittee Date of Inspection Weather Conditions Permit Certification ft Current Acres Disturbed Phase of Construction Inspector Title Inspector Name Location of SWMP Is the above inspector a qualified stormwater manager? (permittee is responsible for ensuring that the inspector is a qualified stormwater manager) GENERAL NOTES INSPECTION FREQUENCY I Check the box that describes the minimum inspection frequency utilized when conducting each inspection At least one inspection every 7 calendar days At least one inspection every 14 calendar days PLUS post -storm event inspections •This is a post -storm event inspection within 24 hours after storm. Event Date: Reduced inspection frequency - Include site conditions that warrant reduced inspection frequency • Post -storm inspections at temporarily idle sites (prior to construction/within 72 hours after storm) • Inspections at completed sites/area (at least once every 30 days) • Winter conditions exclusion Have there been any deviations from the minimum inspection schedule? If yes, describe: Summit ES GROUP StormWater Inspection Report INSPECTION REQUIREMENTS RESULT COMMENT Are control measures in effective operational condition and working as designed in the specifications? Are there any new potential sources of pollutants? If answer is yes, list new pollutants in comments. Does the site require any new or modified control measures to minimize pollutant discharges? Are there any areas that require temporary or permanent stabilization? (e.g. slopes, inactive disturbed areas, stockpiles, etc.). Are there any Bulk storage (55 gal. or greater) of petroleum products and other liquid chemicals on site that require secondary containment? Are there any areas of non-compliance with the permit requirements? If answer is yes, implement corrective actions in section below. AREAS TO INSPECT Is there evidence of, or the potential for, pollutants leaving the construction site boundaries, entering the stormwater drainage system or discharging to state waters at the following locations? If "YES" describe discharge or potential for discharge below. Then document related maintenance, inadequate control measures and corrective actions on the approriate subseqent forms. Location Result Description Construction site perimeter All disturbed areas Designated haul routes Material and waste storage areas exposed to precipitation Locations where stormwater has the potential to discharge offsite Locations where vehicles exit the site Other: a Summit SERVICES GRC ' StormWater Inspection Report CONTROL MEASURES REQUIRING ROUTINE MAINTENANCE Definition: Any control measure that is still operating in accordance with its design and the requirements of the permit, but requires maintenance to prevent a breach of the control measure. These items are not subject to the corrective action requirements as specified in Part I.B.1.c of the permit. Are there control measures requiring maintenance? If YES, Document below Location Control Measure Maintenance Required Date Observed Date Completed Et Initials IN Summit aSERVICES GROUP StormWater Inspection Report CONTROL MEASURES REQUIRING ROUTINE MAINTENANCE Location Control Measure Maintenance Required Date Observed Date Completed Et Initials eats Summit StormWater Inspection Report INADEQUATE CONTROL MEASURES REQUIRING CORRECTIVE ACTION Definition: Any control measure that is not designed or implemented in accordance with the requirements of the permit and/or any control measure that is not implemented to operate in accordance with its design. This includes control measures that have not been implemented for pollutant sources. If it is infeasible to install or repair the control measure immediately after discovering the deficiency the reason must be documented and a schedule included to return the control measure to effective operating condition as possible. Are there control measures requiring corrective action? If YES, Document below. Are there additional control measures needed that were not in place at the time of inspection? If YES, Document below. Location Description of Inadequate Control Measure Description of Corrective Action Was deficiency corrected when discovered? YES/NO. If "NO" provide reason and schedule to correct. Date Observed Date Completed Et Initials SERVICE( GAOL� ID Summit StormWater Inspection Report INADEQUATE CONTROL MEASURES REQUIRING CORRECTIVE ACTION I Location Description of Inadequate Control Measure Description of Corrective Action Was deficiency corrected when discovered? YES/NO. If "NO" provide reason and schedule to correct. Date Observed Date Completed Et Initials Summit aSERVICES GROUP StormWater Inspection Report Has there been an incident of noncompliance requiring 24 -hour notification? If YES, Document Below: (INSPECTION CERTIFICATION i I certify this inspection is, to the best of my knowledge and belief, true, accurate and complete. I am aware that there are significant penalties for submitting false information. Qualified Stormwater Manager/Inspector (Name, Title, Company Et Signature) Date: COMPLIANCE CERTIFICATON I verify that, to the best of my knowledge and belief, all corrective action and maintenance items identified during the inspection are complete, and the site is currently in compliance with the permit. Qualified Stormwater Manager/Designee (Name, Title, Company Et Signature) Date: Stormwater Management Plan APPENDIX E: Spill Reports Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan ;TRI-STATE GENERATION AND TRANSMISSION ASSOCIATION, INC. Construction Stormwater Pollution Prevention Spill Report Form Spill Reported By: Phone Number: Details Date Reported: Time: Date of Spill: Time: Name of the Facility: Lloyd Sisson Substation, Weld County, CO Describe Spill Location and Events Leading to Spill: Material Spilled: Source of Spill: AMOUNT OF THE SPILL (GALLONS OR POUNDS): Containment and Cleanup Containment or Cleanup Action: Date and Time Cleanup Completed or Terminated: Description of Materials Contaminated: Label on the Drum of Cleanup Materials: Signed: Contractor Superintendent or Environmental Inspector Tri-State Generation & Transmission — Lloyd Sisson Substation Stormwater Management Plan APPENDIX F: Permit Application and Permit Tri-State Generation & Transmission — Lloyd Sisson Substation STATE OF COLORADO COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT Water Quality Control Division CDPS GENERAL PERMIT STORMWATER DISCHARGES ASSOCIATED WITH CONSTRUCTION ACTIVITY AUTHORIZATION TO DISCHARGE UNDER THE COLORADO DISCHARGE PERMIT SYSTEM (CDPS) In compliance with the provisions of the Colorado Water Quality Control Act, (25-8-101 et seq., CRS, 1973 as amended) and the Federal Water Pollution Control Act, as amended (33 U.S.C. 1251 et seq.; the "Act"), this permit authorizes the discharge of stormwater associated with construction activities (and specific allowable non-stormwater discharges in accordance with Part I.A.1. of the permit) certified under this permit, from those locations specified throughout the State of Colorado to specified waters of the State. Such discharges shall be in accordance with the conditions of this permit. This permit specifically authorizes the facility listed on the certification to discharge in accordance with permit requirements and conditions set forth in Parts I and II hereof. All discharges authorized herein shall be consistent with the terms and conditions of this permit. This permit becomes effective on April 1, 2019, and shall expire at midnight March 31, 2024. Issued and signed this 1st day of November 2018. COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT Ellen Howard Kutzer, Permits Section Manager Water Quality Control Division Permit History Originally signed and issued October 31, 2018; effective April 1, 2019. Table of Contents Part I 1 A. COVERAGE UNDER THIS PERMIT 1 1. Authorized Discharges 1 2. Limitations on Coverage 1 3. Permit Certification and Submittal Procedures 2 B. EFFLUENT LIMITATIONS 6 1. Requirements for Control Measures Used to Meet Effluent Limitations 6 2. Discharges to an Impaired Waterbody 9 3. General Requirements 10 C. STORMWATER MANAGEMENT PLAN (SWMP) REQUIREMENTS 11 1. SWMP General Requirements 11 2. SWMP Content 11 3. SWMP Review and Revisions 13 4. SWMP Availability 14 D. SITE INSPECTIONS 14 1. Person Responsible for Conducting Inspections 14 2. Inspection Frequency 14 3. Inspection Frequency for Discharges to Outstanding Waters 15 4. Reduced Inspection Frequency 15 5. Inspection Scope 16 E. DEFINITIONS 17 F. MONITORING 20 G. Oil and Gas Construction 21 Part II: Standard Permit Conditions 22 A. DUTY TO COMPLY 22 B. DUTY TO REAPPLY 22 C. NEED TO HALT OR REDUCE ACTIVITY NOT A DEFENSE 22 D. DUTY TO MITIGATE 22 E. PROPER OPERATION AND MAINTENANCE 22 F. PERMIT ACTIONS 22 G. PROPERTY RIGHTS 22 H. DUTY TO PROVIDE INFORMATION 23 I. INSPECTION AND ENTRY 23 J. MONITORING AND RECORDS 23 K. SIGNATORY REQUIREMENTS 24 PART I Permit No.: COR400000 1. Authorization to Sign • 24 2. Electronic Signatures 25 3. Change in Authorization to Sign 25 L. REPORTING REQUIREMENTS 25 1. Planned Changes 25 2. Anticipated Non -Compliance 25 3. Transfer of Ownership or Control 25 4. Monitoring reports 26 5. Compliance Schedules 26 6. Twenty-four hour reporting 26 7. Other non-compliance 27 8. Other information 27 M. BYPASS 27 1. Bypass not exceeding limitations 27 2. Notice of bypass 27 3. Prohibition of Bypass 27 N. UPSET 28 1. Effect of an upset 28 2. Conditions necessary for demonstration of an Upset 28 3. Burden of Proof 28 0. RETENTION OF RECORDS 28 1. Post -Expiration or Termination Retention 28 2. On -site Retention 29 P. REOPENER CLAUSE 29 1. Procedures for modification or revocation 29 2. Water quality protection 29 Q. SEVERABILITY 29 R. NOTIFICATION REQUIREMENTS 29 1. Notification to Parties 29 S. RESPONSIBILITIES 30 1. Reduction, Loss, or Failure of Treatment Facility 30 T. Oil and Hazardous Substance Liability 30 U. Emergency Powers 30 V. Confidentiality 30 W. Fees 30 PART I Permit No.: COR400000 X. Duration of Permit 30 Y. Section 307 Toxics 30 PART I Permit No.: COR400000 Part Note: At the first mention of terminology that has a specific connotation for the purposes of this permit, the terminology is electronically linked to the definitions section of the permit in Part I.E. A. COVERAGE UNDER THIS PERMIT 1. Authorized Discharges This general permit authorizes permittee(s) to discharge the following to state waters: stormwater associated with construction activity and specified non-stormwater associated with construction activity. The following types of stormwater and non-stormwater discharges are authorized under this permit: a. Allowable Stormwater Discharges i. Stormwater discharges associated with construction activity. ii. Stormwater discharges associated with producing earthen materials, such as soils, sand, and gravel dedicated to providing material to a single contiguous site, or within 'l4 mile of a construction site (i.e. borrow or fill areas) iii. Stormwater discharges associated with dedicated asphalt, concrete batch plants and masonry mixing stations (Coverage under this permit is not required if alternative coverage has been obtained.) b. Allowable Non-Stormwater Discharges The following non-stormwater discharges are allowable under this permit if the discharges are identified in the stormwater management plan in accordance with Part I.C. and if they have appropriate control measures in accordance with Part I.B.1. i. Discharges from uncontaminated springs that do not originate from an area of land disturbance. ii. Discharges to the ground of concrete washout water associated with the washing of concrete tools and concrete mixer chutes. Discharges of concrete washout water must not leave the site as surface runoff or reach receiving waters as defined by this permit. iii. Discharges of landscape irrigation return flow. c. Emergency Fire Fighting Discharges resulting from emergency firefighting activities are authorized by this permit. 2. Limitations on Coverage Discharges not authorized by this permit include, but are not limited to, the discharges and activities listed below. Permittees may seek individual or alternate general permit coverage for the discharges, as appropriate and available. a. Discharges of Non-Stormwater Page 1 of 33 PART I Permit No.: COR400000 Discharges of non-stormwater, except the authorized non-stormwater discharges listed in Part I.A.1.b., are not eligible for coverage under this permit. b. Discharges Currently Covered by another Individual or General Permit c. Discharges Currently Covered by a Water Quality Control Division (division) Low Risk Guidance Document 3. Permit Certification and Submittal Procedures a. Duty to apply The following activities shall apply for coverage under this permit: i. Construction sites that will disturb one acre or more; or ii. Construction sites that are part of a common plan of development or sale; or iii. Stormwater discharges that are designated by the division as needing a stormwater permit because the discharge: (a) Contributes to a violation of a water quality standard; or (b) is a significant contributor of pollutants to state waters. b. Application Requirements To obtain authorization to discharge under this permit, applicants applying for coverage following the effective date of the renewal permit shall meet the following requirements: i. Owners and operators submitting an application for permit coverage will be co- permittees subject to the same benefits, duties, and obligations under this permit. ii. Signature requirements: Both the owner and operator (permittee) of the construction site, as defined in Part I.E., must agree to the terms and conditions of the permit and submit a completed application that includes the signature of both the owner and the operator. In cases where the duties of the owner and operator are managed by the owner, both application signatures may be completed by the owner. Both the owner and operator are responsible for ensuring compliance with all terms and conditions of the permit, including implementation of the stormwater management plan. iii. Applicants must use the paper form provided by the division or the electronic form provided on the division's web -based application platform when applying for coverage under this permit. iv. The applicant(s) must develop a stormwater management plan (SWMP) in accordance with the requirements of Part I.C. The applicant(s) must also certify that the SWMP is complete, or will be complete, prior to commencement of any construction activity. Page 2 of 33 PART Permit No.: COR400000 v. The applicant(s) must submit a complete, accurate, and signed permit application electronically, by mail or hand delivery to the division at least 10 days prior to the commencement of construction activity except that construction activities that are in response to a public emergency related site shall apply for coverage no later than 14 days after the commencement of construction activities. The provisions of this part in no way remove a violation of the Colorado Water Quality Control Act if a point source discharge occurs prior to the issuance of a CDPS permit. vi. The application must be signed in accordance with the requirements of Part IA. Applications submitted by mail or hand delivered should be directed to: Colorado Department of Public Health and Environment Water Quality Control Division Permits Section, WQCD-PS-B2 4300 Cherry Creek Drive South Denver, CO 80246 vii. The applicant(s) must receive written notification that the division granted permit coverage prior to conducting construction activities except for construction activities that are in response to a public emergency related site c. Division Review of Permit Application Within 10 days of receipt of the application, and following review of the application, the division may: i. Issue a certification of coverage; ii. request additional information necessary to evaluate the discharge; iii. delay the authorization to discharge pending further review; iv. notify the applicant that additional terms and conditions are necessary; or v. deny the authorization to discharge under this general permit. d. Alternative Permit Coverage Division Required Alternate Permit Coverage: The Division may require an applicant or permittee to apply for an individual permit or an alternative general permit if it determines the discharge does not fall under the scope of this general permit. In this case, the Division will notify the applicant or permittee that an individual permit application is required. ii. Permittee Request for alternate permit coverage: A permittee authorized to discharge stormwater under this permit may request to be excluded from coverage under this general permit by applying for an individual permit. In this case, the permittee must submit an individual application, with reasons supporting the request, to the Division at least 180 days prior to any discharge. When an individual permit is issued, the permittee's authorization to discharge under this permit is terminated on the effective date of the individual permit. e. Submittal Signature Requirements Page 3 of 33 PART Permit No.: COR400000 Documents required for submittal to the division in accordance with this permit, including applications for permit coverage and other documents as requested by the division, must include signatures by both the owner and the operator, except for instances where the duties of the owner and operator are managed by the owner. Signatures on all documents submitted to the division as required by this permit must meet the Standard Signatory Requirements in Part ILK. of this permit in accordance with 40 C.F.R. 122.41(k). i. Signature Certification Any person(s) signing documents required for submittal to the Division must make the following certification: "I certify under penalty of law that this document and all attachments were prepared under my direction or supervision in accordance with a system designed to assure that qualified personnel properly gather and evaluate the information submitted. Based on my inquiry of the person or persons who manage the system, or those persons directly responsible for gathering the information, the information submitted is, to the best of my knowledge and belief, true, accurate, and complete. I am aware that there are significant penalties for submitting false information, including the possibility of fine and imprisonment for knowing violations." f. Compliance Document Signature Requirements Documents which are required for compliance with the permit, but for which submittal to the division is not required unless specifically requested by the division, must be signed by the individual(s) designated as the Qualified Stormwater Manager, as defined in Part I.E. i. Any person(s) signing inspection documents required for compliance with the permit must make the following statement: "I verify that, to the best of my knowledge and belief, all corrective action and maintenance items identified during the inspection are complete, and the site is currently in compliance with the permit." g• Field Wide Permit Coverage for Oil and Gas Construction At the discretion of the division, a single permit certification may be issued to a single oil and gas permittee to cover construction activity related discharges from an oil and gas field at multiple locations that are not necessarily contiguous. h. Permit Coverage without Application Qualifying Local Program: When a small construction site is within the jurisdiction of a qualifying local program, the owner and operator of the construction activity are authorized to discharge stormwater associated with small construction activity under this general permit without the submittal of an application to the division. Sites covered by a qualifying local program are exempt from the following sections of this general permit: Page 4 of 33 PART I Permit No.: COR400000 Part I.A.3.a.; Part I.A.3.b.; Part I.A.3.c.; Part I.A.3.d.; Part I.A.3.g.; Part I.A.3.i.; Part I.A.3.j.; Part I.A.3.k. Sites covered by a qualifying local program are subject to the following requirements: i. Local Agency Authority: This permit does not pre-empt or supersede the authority of local agencies to prohibit, restrict, or control discharges of stormwater to storm drain systems or other water courses within their jurisdiction. ii. Permit Coverage Termination: When a site under a Qualifying Local Program is finally stabilized, coverage under this permit is automatically terminated. iii. Compliance with Qualifying Local Program: Qualifying Local Program requirements that are equivalent to the requirements of this permit are incorporated by reference. Permittees authorized to discharge under this permit, must comply with the equivalent requirements of the Qualifying Local Program that has jurisdiction over the site as a condition of this permit. iv. Compliance with Remaining Permit Conditions. Requirements of this permit that are in addition to or more stringent than the requirements of the Qualifying Local Program apply in addition to the requirements of the Qualifying Local Program. v. Written Authorization of Coverage: The division or local municipality may require any permittee within the jurisdiction of a Qualifying Local Program covered under this permit to apply for, and obtain written authorization of coverage under this permit. The permittee must be notified in writing that an application for written authorization of coverage is required. Permittee Initiated Permit Actions Permittee initiated permit actions, including but not limited to modifications, contact changes, transfers, reassignments, and terminations, shall be conducted following division guidance and using appropriate division -provided forms. Sale of Residence to Homeowner Residential construction sites only: The permittee may remove residential lots from permit coverage once the lot meets the following criteria: i. the residential lot has been sold to the homeowner(s) for private residential use; ii. a certificate of occupancy, or equivalent, is maintained on -site and is available during division inspections; iii. the lot is less than one acre of disturbance; iv. all construction activity conducted on the lot by the permittee is complete; v. the permittee is not responsible for final stabilization of the lot; and vi. the SWMP was modified to indicate the lot is no longer part of the construction activity. If the residential lot meets the criteria listed above then activities occurring on the lot are no longer considered to be construction activities with a duty to apply and maintain permit coverage. Therefore, the permittee is not required to meet the final stabilization requirements and may terminate permit coverage for the lot. Page 5 of 33 PART Permit No.: COR400000 k. Permit Expiration and Continuation of Permit Coverage Authorization to discharge under this general permit shall expire at midnight on March 31, 2024. While Regulation 61.4 requires a permittee to submit an application for continuing permit coverage 180 days before the permit expires, the division is requiring that permittees desiring continued coverage under this general permit must reapply at least 90 days in advance of this permit expiration. The Division will determine if the permittee may continue to discharge stormwater under the terms of the general permit. An individual permit may be required for any facility not reauthorized to discharge under the reissued general permit. If this permit is not reissued or replaced prior to the expiration date, it will be administratively continued and remain in force and effect. For permittees that have applied for continued permit coverage, discharges authorized under this permit prior to the expiration date will automatically remain covered by this permit until the earliest of: An authorization to discharge under a reissued permit, or a replacement of this permit, following the timely and appropriate submittal of a complete application requesting authorization to discharge under the new permit and compliance with the requirements of the new permit; or ii. The issuance and effect of a termination issued by the Division; or iii. The issuance or denial of an individual permit for the facility's discharges; or iv. A formal permit decision by the Division not to reissue this general permit, at which time the Division will identify a reasonable time period for covered dischargers to seek coverage under an alternative general permit or an individual permit. Coverage under this permit will cease when coverage under another permit is granted/authorized; or v. The Division has informed the permittee that discharges previously authorized under this permit are no longer covered under this permit. B. EFFLUENT LIMITATIONS 1. Requirements for Control Measures Used to Meet Effluent Limitations The permittee must implement control measures to minimize the discharge of pollutants from all potential pollutant sources at the site. Control measures must be installed prior to commencement of activities that may contribute pollutants to stormwater discharges. Control measures must be selected, designed, installed and maintained in accordance with good engineering, hydrologic and pollution control practices. Control measures implemented at the site must be designed to prevent pollution or degradation of state waters. a. Stormwater Pollution Prevention The permittee must implement structural and/or nonstructural control measures that effectively minimize erosion, sediment transport, and the release of other pollutants related to construction activity. i. Control Measures for Erosion and Sediment Control Page 6 of 33 PART Permit No.: COR400000 Control measures for erosion and sediment control may include, but are not limited to, wattles/sediment control logs, silt fences, earthen dikes, drainage swales, sediment traps, subsurface drains, pipe slope drains, inlet protection, outlet protection, gabions, sediment basins, temporary vegetation, permanent vegetation, mulching, geotextiles, sod stabilization, slope roughening, maintaining existing vegetation, protection of trees, and preservation of mature vegetation. Specific non-structural control measures must meet the requirements listed below. Specific control measures must meet the requirements listed below. (a) Vehicle tracking controls shall either be implemented to minimize vehicle tracking of sediment from disturbed areas, or the areas where vehicle tracking occurs shall meet subsection Part I.B.1.a.i(b); (b) Stormwater runoff from all disturbed areas and soil storage areas for which permanent or temporary stabilization is not implemented, must flow to at least one control measure to minimize sediment in the discharge. This may be accomplished through filtering, settling, or straining. The control measure must be selected, designed, installed and adequately sized in accordance with good engineering, hydrologic and pollution control practices. The control measure(s) must contain or filter flows in order to prevent the bypass of flows without treatment and must be appropriate for stormwater runoff from disturbed areas and for the expected flow rate, duration, and flow conditions (i.e., sheet or concentrated flow); (c) Outlets that withdraw water from or near the surface shall be installed when discharging from basins and impoundments, unless infeasible. (d) Maintain pre-existing vegetation or equivalent control measures for areas within 50 horizontal feet of receiving waters as defined by this permit, unless infeasible. (e) Soil compaction must be minimized for areas where infiltration control measures will occur or where final stabilization will be achieved through vegetative cover. (f) Unless infeasible, topsoil shall be preserved for those areas of a site that will utilize vegetative final stabilization. (g) Minimize the amount of soil exposed during construction activity, including the disturbance of steep slopes. ii. Practices for Other Common Pollutants (a) Bulk storage, 55 gallons or greater, for petroleum products and other liquid chemicals must have secondary containment, or equivalent protection, in order to contain spills and to prevent spilled material from entering state waters. (b) Control measures designed for concrete washout waste must be implemented. This includes washout waste discharged to the ground as authorized under this permit and washout waste from concrete trucks and masonry operations contained on site. The permittee must ensure the washing activities do not contribute pollutants to stormwater runoff, or receiving waters in accordance Part I.A.1.b.ii. Discharges that may reach groundwater must flow through soil Page 7 of 33 PART I Permit No.: COR400000 that has buffering capacity prior to reaching groundwater, as necessary to meet the effluent limits in this permit, including Part I.B.3.a. The concrete washout location shall be not be located in an area where shallow groundwater may be present and would result in buffering capacity not being adequate, such as near natural drainages, springs, or wetlands. This permit authorizes discharges to the ground of concrete washout waste. iii. Stabilization Requirements The following requirements must be implemented for each site. (a) Temporary stabilization must be implemented for earth disturbing activities on any portion of the site where ground disturbing construction activity has permanently ceased, or temporarily ceased for more than 14 calendar days. Temporary stabilization methods may include, but are not limited to, tarps, soil tackifier, and hydroseed. The permittee may exceed the 14 -day schedule when either the function of the specific area of the site requires it to remain disturbed, or, physical characteristics of the terrain and climate prevent stabilization. The SWMP must document the constraints necessitating the alternative schedule, provide the alternate stabilization schedule, and identify all locations where the alternative schedule is applicable on the site map. (b) Final stabilization must be implemented for all construction sites. Final stabilization is reached when all ground surface disturbing activities at the construction site are complete; and, for all areas of ground surface disturbing activities, either a uniform vegetative cover with an individual plant density of at least 70 percent of pre -disturbance levels is established, or equivalent permanent alternative stabilization methods are implemented. The division may approve alternative final stabilization criteria for specific operations. (c) Final stabilization must be designed and installed as a permanent feature. Final stabilization measures for obtaining a vegetative cover or alternative stabilization methods include, but are not limited to, the following as appropriate: (1) Seed mix selection and application methods; (2) Soil preparation and amendments; (3) Soil stabilization methods (e.g., crimped straw, hydro mulch or rolled erosion control products); (4) Appropriate sediment control measures as needed until final stabilization is achieved; (5) Permanent pavement, hardscape, xeriscape, stabilized driving surfaces; (6) Other alternative stabilization practices as applicable; Page 8 of 33 PART Permit No.: COR400000 (d) The permittee(s) must ensure all temporary control measures are removed from the construction site once final stabilization is achieved, except when the control measure specifications allow the control measure to be left in place (i.e., bio-degradable control measures). b. Maintenance The permittee must ensure that all control measures remain in effective operating condition and are protected from activities that would reduce their effectiveness. Control measures must be maintained in accordance with good engineering, hydrologic and pollution control practices. Observations leading to the required maintenance of control measures can be made during a site inspection, or during general observations of site conditions. The necessary repairs or modifications to a control measure requiring routine maintenance, as defined in Part I.E., must be conducted to maintain an effective operating condition. This section is not subject to the requirements in Part I.B.1.c. B.1. c. below. Corrective Actions The permittee must assess the adequacy of control measures at the site, and the need for changes to those control measures, to ensure continued effective performance. When an inadequate control measure, as defined in Part I.E., is identified (i.e., new or replacement control measures become necessary), the following corrective action requirements apply. The permittee is in noncompliance with the permit until the inadequate control measure is replaced or corrected and returned to effective operating condition in compliance with Part I.B.1. and the general requirements in Part I.B.3. If the inadequate control measure results in noncompliance that meets the conditions of Part II.L., the permittee must also meet the requirements of that section. The permittee must take all necessary steps to minimize or prevent the discharge of pollutants, until a control measure is implemented and made operational and/or an inadequate control measure is replaced or corrected and returned to effective operating condition. If it is infeasible to install or repair of control measure immediately after discovering the deficiency, the following must be documented and kept on record in accordance with the recordkeeping requirements in Part II. (a) Describe why it is infeasible to initiate the installation or repair immediately; and (b) Provide a schedule for installing or repairing the control measure and returning it to an effective operating condition as soon as possible. ii. If applicable, the permittee must remove and properly dispose of any unauthorized release or discharge (e.g., discharge of non-stormwater, spill, or leak not authorized by this permit.) The permittee must also clean up any contaminated surfaces to minimize discharges of the material in subsequent storm events. 2. Discharges to an Impaired Waterbody a. Total Maximum Daily Load (TMDL) If the permittee's discharge flows to or could reasonably be expected to flow to any water body for which a TMDL has been approved, and stormwater discharges Page 9 of 33 PART I Permit No.: COR400000 associated with construction activity were assigned a pollutant -specific Wasteload Allocation (WLA) under the TMDL, the division may: i. ensure the WLA is implemented properly through alternative local requirements, such as by a municipal stormwater permit; or ii. notify the permittee of the WLA and amend the permittee's certification to add specific effluent limits and other requirements, as appropriate. The permittee may be required to do the following: (a) under the permittee's SWMP, implement specific control measures based on requirements of the WLA, and evaluate whether the requirements are met through implementation of existing stormwater control measures or if additional control measures are necessary. Document the calculations or other evidence demonstrating that the requirements are expected to be met; and (b) if the evaluation shows that additional or modified control measures are necessary, describe the type and schedule for the control measure additions or modifications. iii. Discharge monitoring may also be required. The permittee may maintain coverage under the general permit provided they comply with the applicable requirements outlined above. The division reserves the right to require individual or alternate general permit coverage. 3. General Requirements a. Discharges authorized by this permit shall not cause, have the reasonable potential to cause, or measurably contribute to an exceedance of any applicable water quality standard, including narrative standards for water quality. b. The division may require sampling and testing, on a case -by -case basis, in the event that there is reason to suspect that the SWMP is not adequately minimizing pollutants in stormwater or in order to measure the effectiveness of the control measures in removing pollutants in the effluent. Such monitoring may include Whole Effluent Toxicity testing. c. The permittee must comply with the lawful requirements of federal agencies, municipalities, counties, drainage districts and other local agencies including applicable requirements in Municipal Stormwater Management Programs developed to comply with CDPS permits. The permittee must comply with local stormwater management requirements, policies and guidelines including those for erosion and sediment control. d. All construction site wastes must be properly managed to prevent potential pollution of state waters. This permit does not authorize on -site waste disposal. This permit does not relieve the permittee of the reporting requirements in 40 CFR 110, 40 CFR 117 or 40 CFR 302. Any discharge of hazardous material must be handled in accordance with the division's Noncompliance Notification Requirements (see Part ILL. of the permit). Page 10 of 33 PART I Permit No.: COR400000 C. STORMWATER MANAGEMENT PLAN (SWMP) REQUIREMENTS 1. SWMP General Requirements a. A SWMP shall be developed for each construction site covered by this permit. The SWMP must be prepared in accordance with good engineering, hydrologic and pollution control practices. i. For public emergency related sites a SWMP shall be created no later than 14 days after the commencement of construction activities. b. The permittee must implement the provisions of the SWMP as written and updated, from commencement of construction activity until final stabilization is complete. The division may review the SWMP. c. A copy of the SWMP must be retained onsite or be onsite when construction activities are occurring at the site unless the permittee specifies another location and obtains approval from the division. 2. SWMP Content a. The SWMP, at a minimum, must include the following elements. Qualified Stormwater Manager. The SWMP must list individual(s) by title and name who are designated as the site's qualified stormwater manager(s) responsible for implementing the SWMP in its entirety. This role may be filled by more than one individual. ii. Spill Prevention and Response Plan. The SWMP must have a spill prevention and response plan. The plan may incorporate by reference any part of a Spill Prevention Control and Countermeasure (SPCC) plan under section 311 of the Clean Water Act (CWA) or a Spill Prevention Plan required by a separate CDPS permit. The relevant sections of any referenced plans must be available as part of the SWMP consistent with Part I.C.4. iii. Materials Handling. The SWMP must describe and locate all control measures implemented at the site to minimize impacts from handling significant materials that could contribute pollutants to runoff. These handling procedures can include control measures for pollutants and activities such as, exposed storage of building materials, paints and solvents, landscape materials, fertilizers or chemicals, sanitary waste material, trash and equipment maintenance or fueling procedures. iv. Potential Sources of Pollution. The SWMP must list all potential sources of pollution which may reasonably be expected to affect the quality of stormwater discharges associated with construction activity from the site. This shall include, but is not limited to, the following pollutant sources: (a) disturbed and stored soils; (b) vehicle tracking of sediments; (c) management of contaminated soils; (d) loading and unloading operations; Page 11 of 33 PART I Permit No.: COR400000 (e) outdoor storage activities (erodible building materials, fertilizers, chemicals, etc.); (f) vehicle and equipment maintenance and fueling; (g) significant dust or particulate generating processes (e.g., saw cutting material, including dust); (h) routine maintenance activities involving fertilizers, pesticides, herbicides, detergents, fuels, solvents, oils, etc.; (i) on -site waste management practices (waste piles, liquid wastes, dumpsters); (j) concrete truck/equipment washing, including washing of the concrete truck chute and associated fixtures and equipment; (k) dedicated asphalt, concrete batch plants and masonry mixing stations; (l) non -industrial waste sources such as worker trash and portable toilets. v. Implementation of Control Measures. The SWMP must include design specifications that contain information on the implementation of the control measure in accordance with good engineering hydrologic and pollution control practices; including as applicable drawings, dimensions, installation information, materials, implementation processes, control measure -specific inspection expectations, and maintenance requirements. The SWMP must include a documented use agreement between the permittee and the owner or operator of any control measures located outside of the permitted area, that are utilized by the permittee's construction site for compliance with this permit, but not under the direct control of the permittee. The permittee is responsible for ensuring that all control measures located outside of their permitted area, that are being utilized by the permittee's construction site, are properly maintained and in compliance with all terms and conditions of the permit. The SWMP must include all information required of and relevant to any such control measures located outside the permitted area, including location, installation specifications, design specifications and maintenance requirements. vi. Site Description. The SWMP must include a site description which includes, at a minimum, the following: (a) the nature of the construction activity at the site; (b) the proposed schedule for the sequence for major construction activities and the planned implementation of control measures for each phase. (e.g.: clearing, grading, utilities, vertical, etc.); (c) estimates of the total acreage of the site, and the acreage expected to be disturbed by clearing, excavation, grading, or any other construction activities; (d) a summary of any existing data used in the development of the construction site plans or SWMP that describe the soil or existing potential for soil erosion; Page 12 of 33 PART I Permit No.: COR400000 (e) a description of the percent of existing vegetative ground cover relative to the entire site and the method for determining the percentage; (f) a description of any allowable non-stormwater discharges at the site, including those being discharged under a division low risk discharge guidance policy; (g) a description of areas receiving discharge from the site. Including a description of the immediate source receiving the discharge. If the stormwater discharge is to a municipal separate storm sewer system, the name of the entity owning that system, the location of the storm sewer discharge, and the ultimate receiving water(s); and (h) a description of all stream crossings located within the construction site boundary. vii. Site Map. The SWMP must include a site map which includes, at a minimum, the following: (a) construction site boundaries; (b) flow arrows that depict stormwater flow directions on -site and runoff direction; (c) all areas of ground disturbance including areas of borrow and fill; (d) areas used for storage of soil; (e) locations of all waste accumulation areas, including areas for liquid, concrete, masonry, and asphalt; (f) locations of dedicated asphalt, concrete batch plants and masonry mixing stations; (g) locations of all structural control measures; (h) locations of all non-structural control measures; (i) locations of springs, streams, wetlands and other state waters, including areas that require pre-existing vegetation be maintained within 50 feet of a receiving water, where determined feasible in accordance with Part I.B.1.a.i.(d).; and (j) locations of all stream crossings located within the construction site boundary. viii. Final Stabilization and Long Term Stormwater Management. The SWMP must describe the practices used to achieve final stabilization of all disturbed areas at the site and any planned practices to control pollutants in stormwater discharges that will occur after construction operations are completed. Including but not limited to, detention/retention ponds, rain gardens, stormwater vaults, etc. ix. Inspection Reports. The SWMP must include documented inspection reports in accordance with Part ID. 3. SWMP Review and Revisions Page 13 of 33 PART I Permit No.: COR400000 Permittees must keep a record of SWMP changes made that includes the date and identification of the changes. The SWMP must be amended when the following occurs: a. a change in design, construction, operation, or maintenance of the site requiring implementation of new or revised control measures; b. the SWMP proves ineffective in controlling pollutants in stormwater runoff in compliance with the permit conditions; c. control measures identified in the SWMP are no longer necessary and are removed; and d. corrective actions are taken onsite that result in a change to the SWMP. For SWMP revisions made prior to or following a change(s) onsite, including revisions to sections addressing site conditions and control measures, a notation must be included in the SWMP that identifies the date of the site change, the control measure removed, or modified, the location(s) of those control measures, and any changes to the control measure(s). The permittee must ensure the site changes are reflected in the SWMP. The permittee is noncompliant with the permit until the SWMP revisions have been made. 4. SWMP Availability A copy of the SWMP must be provided upon request to the division, EPA, and any local agency with authority for approving sediment and erosion plans, grading plans or stormwater management plans within the time frame specified in the request. If the SWMP is required to be submitted to any of these entities, the submission must include a signed certification in accordance with Part I.A.3.e., certifying that the SWMP is complete and compliant with all terms and conditions of the permit. All SWMPs required under this permit are considered reports that must be available to the public under Section 308(b) of the CWA and Section 61.5(4) of the CDPS regulations. The permittee must make plans available to members of the public upon request. However, the permittee may claim any portion of a SWMP as confidential in accordance with 40 CFR Part 2. D. SITE INSPECTIONS Site inspections must be conducted in accordance with the following requirements. The required inspection schedules are a minimum frequency and do not affect the permittee's responsibility to implement control measures in effective operating condition as prescribed in the SWMP. Proper maintenance of control measures may require more frequent inspections. Site inspections shall start within 7 calendar days of the commencement of construction activities on site. 1. Person Responsible for Conducting Inspections The person(s) inspecting the site may be on the permittee's staff or a third party hired to conduct stormwater inspections under the direction of the permittee(s). The permittee is responsible for ensuring that the inspector is a qualified stormwater manager. 2. Inspection Frequency Page 14 of 33 PART I Permit No.: COR400000 Permittees must conduct site inspections in accordance with one of the following minimum frequencies, unless the site meets the requirements of Part ID.3 a. At least one inspection every 7 calendar days. Or b. At least one inspection every 14 calendar days, if post -storm event inspections are conducted within 24 hours after the end of any precipitation or snowmelt event that causes surface erosion. Post -storm inspections may be used to fulfill the 14 -day routine inspection requirement. c. When site conditions make the schedule required in this section impractical, the permittee may petition the Division to grant an alternate inspection schedule. The alternative inspection schedule may not be implemented prior to written approval by the division and incorporation into the SWMP. 3. Inspection Frequency for Discharges to Outstanding Waters Permittees must conduct site inspections at least once every 7 calendar days for sites that discharge to a water body designated as an Outstanding Water by the Water Quality Control Commission. 4. Reduced Inspection Frequency The permittee may perform site inspections at the following reduced frequencies when one of the following conditions exists: a. Post -Storm Inspections at Temporarily Idle Sites For permittees choosing to combine 14 -day inspections and post -storm -event - inspections, if no construction activities will occur following a storm event, post -storm event inspections must be conducted prior to re -commencing construction activities, but no later than 72 hours following the storm event. The delay of any post -storm event inspection must be documented in the inspection record. Routine inspections must still be conducted at least every 14 calendar days. b. Inspections at Completed Sites/Areas When the site, or portions of a site are awaiting establishment of a vegetative ground cover and final stabilization, the permittee must conduct a thorough inspection of the stormwater management system at least once every 30 days. Post -storm event inspections are not required under this schedule. This reduced inspection schedule is allowed if all of the following criteria are met: i. all construction activities resulting in ground disturbance are complete; ii. all activities required for final stabilization, in accordance with the SWMP, have been completed, with the exception of the application of seed that has not occurred due to seasonal conditions or the necessity for additional seed application to augment previous efforts; and iii. the SWMP has been amended to locate those areas to be inspected in accordance with the reduced schedule allowed for in this paragraph. c. Winter Conditions Inspections Exclusion Page 15 of 33 PART Permit No.: COR400000 Inspections are not required for sites that meet all of the following conditions: construction activities are temporarily halted, snow cover exists over the entire site for an extended period, and melting conditions posing a risk of surface erosion do not exist. This inspection exception is applicable only during the period where melting conditions do not exist, and applies to the routine 7 -day, 14 -day and monthly inspections, as well as the post -storm -event inspections. When this inspection exclusion is implemented, the following information must be documented in accordance with the requirements in Part II: i. dates when snow cover existed; ii. date when construction activities ceased; and iii. date melting conditions began. 5. Inspection Scope a. Areas to be Inspected When conducting a site inspection the following areas, if applicable, must be inspected for evidence of, or the potential for, pollutants leaving the construction site boundaries, entering the stormwater drainage system, or discharging to state waters: i. construction site perimeter; ii. all disturbed areas; iii. designated haul routes; iv. material and waste storage areas exposed to precipitation; v. locations where stormwater has the potential to discharge offsite; and vi. locations where vehicles exit the site. b. Inspection Requirements i. Visually verify whether all implemented control measures are in effective operational condition and are working as designed in their specifications to minimize pollutant discharges. ii. Determine if there are new potential sources of pollutants. iii. Assess the adequacy of control measures at the site to identify areas requiring new or modified control measures to minimize pollutant discharges. iv. Identify all areas of non compliance with the permit requirements and, if necessary, implement corrective action in accordance with Part IB.1.c. c. Inspection Reports The permittee must keep a record of all inspections conducted for each permitted site. Inspection reports must identify any incidents of noncompliance with the terms and conditions of this permit. Inspection records must be retained in accordance with Part 11.0. and signed in accordance with Part I.A.3.f. At a minimum, the inspection report must include: i. the inspection date; Page 16 of 33 PART I Permit No.: COR400000 ii. name(s) and title(s) of personnel conducting the inspection; iii. weather conditions at the time of inspection; iv. phase of construction at the time of inspection; v. estimated acreage of disturbance at the time of inspection vi. location(s) of discharges of sediment or other pollutants from the site; vii. location(s) of control measures needing maintenance; viii. location(s) and identification of inadequate control measures; ix. location(s) and identification of additional control measures are needed that were not in place at the time of inspection; x. description of the minimum inspection frequency (either in accordance with Part I.D.2., I.D.3. or I.D.4.) utilized when conducting each inspection. xi. deviations from the minimum inspection schedule as required in Part I.D.2.; xii. after adequate corrective action(s) and maintenance have been taken, or where a report does not identify any incidents requiring corrective action or maintenance, the report shall contain a statement as required in Part I.A.3.f. E. DEFINITIONS For the purposes of this permit: (1) Bypass - the intentional diversion of waste streams from any portion of a treatment facility in accordance with 40 CFR 122.41(m)(1)(i) and Regulation 61.2(12). (2) Common Plan of Development or Sale - A contiguous area where multiple separate and distinct construction activities may be taking place at different times on different schedules, but remain related. The Division has determined that "contiguous" means construction activities located in close proximity to each other (within 1 mile). Construction activities are considered to be "related" if they share the same development plan, builder or contractor, equipment, storage areas, etc. "Common plan of development or sale" includes construction activities that are associated with the construction of field wide oil and gas permits for facilities that are related. (3) Construction Activity - Ground surface disturbing and associated activities (land disturbance), which include, but are not limited to, clearing, grading, excavation, demolition, installation of new or improved haul roads and access roads, staging areas, stockpiling of fill materials, and borrow areas. Construction does not include routine maintenance to maintain the original line and grade, hydraulic capacity, or original purpose of the facility. Activities to conduct repairs that are not part of routine maintenance or for replacement are construction activities and are not routine maintenance. Repaving activities where underlying and/or surrounding soil is exposed as part of the repaving operation are considered construction activities. Construction activity is from initial ground breaking to final stabilization regardless of ownership of the construction activities. (4) Control Measure - Any best management practice or other method used to prevent or reduce the discharge of pollutants to state waters. Control measures include, but are not limited to, best management practices. Control measures can include other methods such as the installation, operation, and maintenance of structural controls and treatment devices. Page 17 of 33 PART I Permit No.: COR400000 (5) Control Measure Requiring Routine Maintenance - Any control measure that is still operating in accordance with its design and the requirements of this permit, but requires maintenance to prevent a breach of the control measure. See also inadequate control measure. (6) Dedicated Asphalt, Concrete Batch Plants and Masonry Mixing Stations - are batch plants or mixing stations located on, or within 'A mile of, a construction site and that provide materials only to that specific construction site. (7) Final Stabilization - The condition reached when all ground surface disturbing activities at the site have been completed, and for all areas of ground surface disturbing activities where a uniform vegetative cover has been established with an individual plant density of at least 70 percent of pre - disturbance levels, or equivalent permanent, physical erosion reduction methods have been employed. (8) Good Engineering, Hydrologic and Pollution Control Practices: are methods, procedures, and practices that: a. Are based on basic scientific fact(s). b. Reflect best industry practices and standards. c. Are appropriate for the conditions and pollutant sources. d. Provide appropriate solutions to meet the associated permit requirements, including practice based effluent limits. (9) Inadequate Control Measure - Any control measure that is not designed or implemented in accordance with the requirements of the permit and/or any control measure that is not implemented to operate in accordance with its design. See also Control Measure Requiring Routine Maintenance. (10) Infeasible - Not technologically possible, or not economically practicable and achievable in light of best industry practices. (11) Minimize - reduce or eliminate to the extent achievable using control measures that are technologically available and economically practicable and achievable in light of best industry practice. (12) Municipality - A city, town, county, district, association, or other public body created by, or under, State law and having jurisdiction over disposal of sewage, industrial wastes, or other wastes, or a designated and approved management agency under section 208 of CWA (1987). (13) Municipal Separate Storm Sewer System (MS4) - A conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels, or storm drains): a) owned or operated by a State, city, town, county, district, association, or other public body (created by or pursuant to State law) having jurisdiction over disposal of sewage, industrial wastes, stormwater, or other wastes, including special districts under State law such as a sewer district, flood control district or drainage district, or similar entity, or a designated and approved management agency under section 208 of the CWA that discharges to state waters; i. designed or used for collecting or conveying stormwater; ii. are not a combined sewer; and iii. are not part of a Publicly Owned Treatment Works (POTW). See 5 CCR 1002-61.2(62). (14) Municipal Stormwater Management Program - A stormwater program operated by a municipality, typically to meet the requirements of the municipalities MS4 discharge certification. Page 18 of 33 PART I Permit No.: COR400000 (15) Operator - The party that has operational control over day-to-day activities at a project site which are necessary to ensure compliance with the permit. This party is authorized to direct individuals at a site to carry out activities required by the permit.(e.g. the general contractor) (16) Owner - The party that has overall control of the activities and that has funded the implementation of the construction plans and specifications. This is the party with ownership of, a long term lease of, or easements on the property on which the construction activity is occurring (e.g., the developer). (17) Permittee(s) - The owner and operator named in the discharge certification issued under this permit for the construction site specified in the certification. (18) Point Source - Any discernible, confined, and discrete conveyance, including, but not limited to, any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation, or vessel or other floating craft, from which pollutants are or may be discharged. Point source does not include irrigation return flow. See 5 CCR 102-61.2(75). (19) Pollutant - Dredged spoil, dirt, slurry, solid waste, incinerator residue, sewage, sewage sludge, garbage, trash, chemical waste, biological nutrient, biological material, radioactive material, heat, wrecked or discarded equipment, rock, sand, or any industrial, municipal or agricultural waste. See 5 CCR 1002-61.2(76). (20) Presentation of credentials - a government issued form of identification, if in person; or (ii) providing name, position and purpose of inspection if request to enter is made via telephone, email or other form of electronic communication. A Permittee's non -response to a request to enter upon presentation of credentials constitutes a denial to such request, and may result in violation of the Permit. (21) Process Water - Any water which, during manufacturing or processing, comes into contact with or results from the production of any raw material, intermediate product, finished product, by product or waste product. (22) Public Emergency Related Site - a project initiated in response to an unanticipated emergency (e.g., mud slides, earthquake, extreme flooding conditions, disruption in essential public services), for which the related work requires immediate authorization to avoid imminent endangerment to human health or the environment, or to reestablish essential public services. (23) Qualified Stormwater Manager - An individual knowledgeable in the principles and practices of erosion and sediment control and pollution prevention, and with the skills to assess conditions at construction sites that could impact stormwater quality and to assess the effectiveness of stormwater controls implemented to meet the requirements of this permit. (24) Qualifying Local Program - A municipal program for stormwater discharges associated with small construction activity that was formally approved by the division as a qualifying local program. (25) Receiving Water - Any classified or unclassified surface water segment (including tributaries) in the State of Colorado into which stormwater associated with construction activities discharges. This definition includes all water courses, even if they are usually dry, such as borrow ditches, arroyos, and other unnamed waterways. (26) Severe Property Damage - substantial physical damage to property, damage to the treatment facilities which causes them to become inoperable, or substantial and permanent loss of natural resources which can reasonably be expected to occur in the absence of a bypass. Severe property damage does not mean economic loss caused by delays in production. See 40 CFR 122.41(m)(1)(ii). Page 19 of 33 PART I Permit No.: COR400000 (27) Significant Materials - Include, but not limited to, raw materials; fuels; materials such as solvents, detergents, and plastic pellets; finished materials such as metallic products; raw materials used in food processing or production; hazardous substances designated under section 101(14) of CERCLA; any chemical the permittee is required to report under section 313 of Title III of the Superfund Amendments and Reauthorization Act (SARA); fertilizers; pesticides; and waste products such as ashes, slag and sludge that have the potential to be released with stormwater discharges. (28) Small Construction Activity - The discharge of stormwater from construction activities that result in land disturbance of equal to, or greater than, one acre and less than five acres. Small construction activity also includes the disturbance of less than one acre of total land area that is part of a larger common plan of development or sale, if the larger common plan ultimately disturbs equal to, or greater than, one acre and less than five acres. (29) Spill - An unintentional release of solid or liquid material which may pollute state waters. (3o) State Waters - means any and all surface and subsurface waters which are contained in or flow in or through this state, but does not include waters in sewage systems, waters in treatment works of disposal systems, waters in potable water distribution systems, and all water withdrawn for use until use and treatment have been completed. (31) Steep Slopes: where a local government, or industry technical manual (e.g., stormwater BMP manual) has defined what is to be considered a "steep slope", this permit's definition automatically adopts that definition. Where no such definition exists, steep slopes are automatically defined as those that are 3:1 or greater. (32) Stormwater - Precipitation runoff, snow melt runoff, and surface runoff and drainage. See 5 CCR 1002-61.2(103). (33) Total Maximum Daily Loads (TMDLs) -The sum of the individual wasteload allocations (WLA) for point sources and load allocations (LA) for nonpoint sources and natural background. For the purposes of this permit, a TMDL is a calculation of the maximum amount of a pollutant that a waterbody can receive and still meet water quality standards, and an allocation of that amount to the pollutant's sources. A TMDL includes WLAs, LAs, and must include a margin of safety (MOS), and account for seasonal variations. See section 303(d) of the CWA and 40 C.F.R. 130.2 and 130.7. (34) Upset - an exceptional incident in which there is unintentional and temporary noncompliance with permit effluent limitations because of factors beyond the reasonable control of the permittee. An upset does not include noncompliance to the extent caused by operational error, improperly designed treatment facilities, inadequate treatment facilities, lack of preventative maintenance, or careless or improper operation in accordance with 40 CFR 122.41(n) and Regulation 61.2(114). F. MONITORING The division may require sampling and testing, on a case -by -case basis. If the division requires sampling and testing, the division will send a notification to the permittee. Reporting procedures for any monitoring data collected will be included in the notification. If monitoring is required, the following applies: 1. the thirty (30) day average must be determined by the arithmetic mean of all samples collected during a thirty (30) consecutive -day period; and 2 a grab sample, for monitoring requirements, is a single "dip and take" sample. Page 20 of 33 PART I Permit No.: COR400000 G. Oil and Gas Construction Stormwater discharges associated with construction activities directly related to oil and gas exploration, production, processing, and treatment operations or transmission facilities are regulated under the Colorado Discharge Permit System Regulations (5 CCR 1002-61), and require coverage under this permit in accordance with that regulation. However, references in this permit to specific authority under the CWA do not apply to stormwater discharges associated with these oil and gas related construction activities, to the extent that the references are limited by the federal Energy Policy Act of 2005. Page 21 of 33 PART II Permit No.: COR400000 Part II: Standard Permit Conditions A. DUTY TO COMPLY The permittee must comply with all conditions of this permit. Any permit noncompliance constitutes a violation of the Water Quality Control Act and is grounds for: a. enforcement action; b. permit termination, revocation and reissuance, or modification; or c. denial of a permit renewal application. B. DUTY TO REAPPLY If the permittee wishes to continue an activity regulated by this permit after the expiration date of this permit, the permittee must apply for and obtain authorization as required by Part I.A.3. k. of the permit. C. NEED TO HALT OR REDUCE ACTIVITY NOT A DEFENSE It shall not be a defense for a permittee in an enforcement action that it would have been necessary to halt or reduce the permitted activity in order to maintain compliance with the conditions of this permit. D. DUTY TO MITIGATE A permittee must take all reasonable steps to minimize or prevent any discharge in violation of this permit which has a reasonable likelihood of adversely affecting human health or the environment. E. PROPER OPERATION AND MAINTENANCE A permittee must at all times properly operate and maintain all facilities and systems of treatment and control (and related appurtenances) that are installed or used by the permittee to achieve compliance with the conditions of this permit. Proper operation and maintenance also includes adequate laboratory controls and appropriate quality assurance procedures. This provision requires the operation of backup or auxiliary facilities or similar systems which are installed by the permittee only when the operation is necessary to achieve compliance with the conditions of this permit. This requirement can be met by meeting the requirements for Part I.B., I.C., and I.D. above. See also 40 C.F.R. § 122.41(e). F. PERMIT ACTIONS This permit may be modified, revoked and reissued, or terminated for cause. The permittee request for a permit modification, revocation and reissuance, or termination, or a notification of planned changes or anticipated noncompliance does not stay any permit condition. Any request for modification, revocation, reissuance, or termination under this permit must comply with all terms and conditions of Regulation 61.8(8). G. PROPERTY RIGHTS In accordance with 40 CFR 122.41(g) and 5 CCR 1002-61, 61.8(9): 1. The issuance of a permit does not convey any property or water rights in either real or personal property, or stream flows or any exclusive privilege. Page 22 of 33 PART II Permit No.: COR400000 2. The issuance of a permit does not authorize any injury to person or property or any invasion of personal rights, nor does it authorize the infringement of federal, state, or local laws or regulations. 3. Except for any toxic effluent standard or prohibition imposed under Section 307 of the Federal act or any standard for sewage sludge use or disposal under Section 405(d) of the Federal act, compliance with a permit during its term constitutes compliance, for purposes of enforcement, with Sections 301, 302, 306, 318, 403, and 405(a) and (b) of the Federal act. However, a permit may be modified, revoked and reissued, or terminated during its term for cause as set forth in Section 61.8(8) of the Colorado Discharge Permit System Regulations. H. DUTY TO PROVIDE INFORMATION The permittee shall furnish to the division, within a reasonable time, any information which the division may request to determine whether cause exists for modifying, revoking and reissuing, or terminating this permit, or to determine compliance with this permit. The permittee shall also furnish to the division, upon request, copies of records required to be kept by this permit in accordance with 40 CFR 122.41(h) and/or Regulation 61.8(3)(q). I. INSPECTION AND ENTRY The permittee shall allow the division and the authorized representative, upon the presentation of credentials as required by law, to allow for inspections to be conducted in accordance with 40 CFR 122.41(i), Regulation 61.8(3), and Regulation 61.8(4): 1. to enter upon the permittee's premises where a regulated facility or activity is located or in which any records are required to be kept under the terms and conditions of this permit, 2. at reasonable times to have access to and copy any records required to be kept under the terms and conditions of this permit; 3. at reasonable times, inspect any monitoring equipment or monitoring method required in the permit; and 4. to enter upon the permittee's premises in a reasonable manner and at a reasonable time to inspect or investigate, any actual, suspected, or potential source of water pollution, or any violation of the Colorado Water Quality Control Act. The investigation may include: sampling of any discharges, stormwater or process water, taking of photographs, interviewing site staff on alleged violations and other matters related to the permit, and assessing any and all facilities or areas within the site that may affect discharges, the permit, or an alleged violation. The permittee shall provide access to the division or other authorized representatives upon presentation of proper credentials. A permittee's non -response to a request to enter upon presentation of credentials constitutes a denial of such request, and may result in a violation of the permit. J. MONITORING AND RECORDS 1. Samples and measurements taken for the purpose of monitoring must be representative of the volume and nature of the monitored activity. Page 23 of 33 PART II Permit No.: COR400000 2. The permittee must retain records of all monitoring information, including all calibration and maintenance records and all original strip chart recordings for continuous monitoring instrumentation, copies of all reports required by this permit, and records of all data used to complete the application for this permit, for a period of at least three years from the date the permit expires or the date the permittee's authorization is terminated. This period may be extended by request of the division at any time. 3. Records of monitoring information must include: a. The date, exact place, and time of sampling or measurements; b. The individual(s) who performed the sampling or measurements; c. The date(s) analyses were performed d. The individual(s) who performed the analyses; e. The analytical techniques or methods used; and f. The results of such analyses. 4. Monitoring must be conducted according to test procedures approved under 40 CFR Part 136, unless other test procedures have been specified in the permit. K. SIGNATORY REQUIREMENTS 1. Authorization to Sign: All documents required to be submitted to the division by the permit must be signed in accordance with the following criteria: a. For a corporation: By a responsible corporate officer. For the purpose of this subsection, a responsible corporate officer means: a president, secretary, treasurer, or vice president of the corporation in charge of a principal business function, or any other person who performs similar policy- or decision -making functions for the corporation, or ii. the manager of one or more manufacturing, production, or operating facilities, provided, the manager is authorized to make management decisions which govern the operation of the regulated facility including having the explicit or implicit duty of making major capital investment recommendations, and initiating and directing other comprehensive measures to assure long term environmental compliance with environmental laws and regulations; the manager can ensure that the necessary systems are established or actions taken to gather complete and accurate information for permit application requirements; and where authority to sign documents has been assigned or delegated to the manager in accordance with corporate procedures. b. For a partnership or sole proprietorship: By a general partner or the proprietor, respectively; or c. For a municipality, state, federal, or other public agency: By either a principal executive officer or ranking elected official. For purposes of this subsection, a principal executive officer of a federal agency includes i. (i) the chief executive officer of the agency, or Page 24 of 33 PART II Permit No.: COR400000 ii. (ii) a senior executive officer having responsibility for the overall operations of a principal geographic unit of the agency. (e.g., Regional Administrator of EPA) 2. Electronic Signatures For persons signing applications for coverage under this permit electronically, in addition to meeting other applicable requirements stated above, such signatures must meet the same signature, authentication, and identity -proofing standards set forth at 40 CFR 5 3.2000(b) for electronic reports (including robust second -factor authentication). Compliance with this requirement can be achieved by submitting the application using the Colorado Environmental Online Service (CEOS) system. 3. Change in Authorization to Sign If an authorization is no longer accurate because a different individual or position has responsibility for the overall operation of the facility, a new authorization must be submitted to the division, prior to the re -authorization, or together with any reports, information, or applications to be signed by an authorized representative. L. REPORTING REQUIREMENTS 1. Planned Changes The permittee shall give advance notice to the division, in writing, of any planned physical alterations or additions to the permitted facility in accordance with 40 CFR 122.41(1) and Regulation 61.8(5)(a). Notice is required only when: a. The alteration or addition to a permitted facility may meet one of the criteria for determining whether a facility is a new source in 40 CFR 122.29(b); or b. The alteration or addition could significantly change the nature or increase the quantity of pollutants discharged. This notification applies to pollutants which are subject neither to effluent limitations in the permit, nor to notification requirements under 40 CFR 122.41(a)(1). 2. Anticipated Non -Compliance The permittee shall give advance notice to the division, in writing, of any planned changes in the permitted facility or activity that may result in noncompliance with permit requirements. The timing of notification requirements differs based on the type of non-compliance as described in subparagraphs 5, 6, 7, and 8 below. 3. Transfer of Ownership or Control The permittee shall notify the division, in writing, ten (10) calendar days in advance of a proposed transfer of the permit. This permit is not transferable to any person except after notice is given to the division. Page 25 of 33 PART II Permit No.: COR400000 a. Where a facility wants to change the name of the permittee, the original permittee (the first owner or operators) must submit a Notice of Termination. b. The new owner or operator must submit an application. See also signature requirements in Part II.K, above. c. A permit may be automatically transferred to a new permittee if: i. The current permittee notifies the Division in writing 30 calendar days in advance of the proposed transfer date; and ii. The notice includes a written agreement between the existing and new permittee(s) containing a specific date for transfer of permit responsibility, coverage and liability between them; and iii. The division does not notify the existing permittee and the proposed new permittee of its intent to modify, or revoke and reissue the permit. iv. Fee requirements of the Colorado Discharge Permit System Regulations, Section 61.15, have been met. 4. Monitoring reports Monitoring results must be reported at the intervals specified in this permit per the requirements of 40 CFR 122.41(l)(4). 5. Compliance Schedules Reports of compliance or noncompliance with, or any progress reports on, interim and final requirements contained in any compliance schedule in the permit, shall be submitted on the date listed in the compliance schedule section. The fourteen (14) calendar day provision in Regulation 61.8(4)(n)(i) has been incorporated into the due date. 6. Twenty-four hour reporting In addition to the reports required elsewhere in this permit, the permittee shall report the following circumstances orally within twenty-four (24) hours from the time the permittee becomes aware of the circumstances, and shall mail to the division a written report containing the information requested within five (5) working days after becoming aware of the following circumstances: a. Circumstances leading to any noncompliance which may endanger health or the environment regardless of the cause of the incident; b. Circumstances leading to any unanticipated bypass which exceeds any effluent limitations in the permit; c. Circumstances leading to any upset which causes an exceedance of any effluent limitation in the permit; Page 26 of 33 PART II Permit No.: COR400000 d. Daily maximum violations for any of the pollutants limited by Part I of this permit. This includes any toxic pollutant or hazardous substance or any pollutant specifically identified as the method to control any toxic pollutant or hazardous substance. e. The division may waive the written report required under subparagraph 6 of this section if the oral report has been received within 24 hours. 7. Other non-compliance A permittee must report all instances of noncompliance at the time monitoring reports are due. If no monitoring reports are required, these reports are due at least annually in accordance with Regulation 61.8(4)(p). The annual report must contain all instances of non-compliance required under either subparagraph 5 or subparagraph 6 of this subsection. 8. Other information Where a permittee becomes aware that it failed to submit any relevant facts in a permit application, or submitted incorrect information in a permit application, or in any report to the Permitting Authority, it has a duty to promptly submit such facts or information. M. BYPASS 1. Bypass not exceeding limitations The permittees may allow any bypass to occur which does not cause effluent limitations to be exceeded, but only if it also is for essential maintenance to assure efficient operation. These bypasses are not subject to the provisions of Part II.M.2 of this permit. See 40 CFR 122.41(m)(2). 2. Notice of bypass Anticipated bypass. If the permittee knows in advance of the need for a bypass, the permittee must submit prior notice, if possible at least ten days before the date of the bypass. ee 40 CFR §122.41(m)(3)(i) and/or Regulation 61.9(5)(c). b. Unanticipated bypass. The permittee must submit notice of an unanticipated bypass in accordance with Part II.L.6. See 40 CFR §122.41(m)(3)(ii) . 3. Prohibition of Bypass Bypasses are prohibited and the division may take enforcement action against the permittee for bypass, unless: i. the bypass is unavoidable to prevent loss of life, personal injury, or severe property damage; Page 27 of 33 PART II Permit No.: COR400000 ii. There were no feasible alternatives to the bypass, such as the use of auxiliary treatment facilities, retention of untreated wastes, or maintenance during normal periods of equipment downtime. This condition is not satisfied if adequate backup equipment should have been installed in the exercise of reasonable engineering judgment to prevent a bypass which occurred during normal periods of equipment downtime or preventive maintenance; and iii. proper notices were submitted to the division. N. UPSET 1. Effect of an upset An upset constitutes an affirmative defense to an action brought for noncompliance with permit effluent limitations if the requirements of Part II.N.2. of this permit are met. No determination made during administrative review of claims that noncompliance was caused by upset, and before an action for noncompliance, is final administrative action subject to judicial review in accordance with Regulation 61.8(3)(j). 2. Conditions necessary for demonstration of an Upset A permittee who wishes to establish the affirmative defense of upset shall demonstrate through properly signed contemporaneous operating logs, or other relevant evidence that a. an upset occurred and the permittee can identify the specific cause(s) of the upset; b. the permitted facility was at the time being properly operated and maintained; and c. the permittee submitted proper notice of the upset as required in Part II.L.6.(24- hour notice); and d. the permittee complied with any remedial measure necessary to minimize or prevent any discharge or sludge use or disposal in violation of this permit which has a reasonable likelihood of adversely affecting human health or the environment. In addition to the demonstration required above, a permittee who wishes to establish the affirmative defense of upset for a violation of effluent limitations based upon water quality standards shall also demonstrate through monitoring, modeling or other methods that the relevant standards were achieved in the receiving water. 3. Burden of Proof In any enforcement proceeding, the permittee seeking to establish the occurrence of an upset has the burden of proof. O. RETENTION OF RECORDS 1. Post -Expiration or Termination Retention Copies of documentation required by this permit, including records of all data used to complete the application for permit coverage to be covered by this permit, must be Page 28 of 33 PART II Permit No.: COR400000 retained for at least three years from the date that permit coverage expires or is terminated. This period may be extended by request of EPA at any time. 2. On -site Retention The permittee must retain an electronic version or hardcopy of the SWMP at the construction site from the date of the initiation of construction activities to the date of expiration or inactivation of permit coverage; unless another location, specified by the permittee, is approved by the division. P. REOPENER CLAUSE 1. Procedures for modification or revocation Permit modification or revocation of this permit or coverage under this permit will be conducted according to Regulation 61.8(8). 2. Water quality protection If there is evidence indicating that the stormwater discharges authorized by this permit cause, have the reasonable potential to cause or contribute to an excursion above any applicable water quality standard, the permittee may be required to obtain an individual permit, or the permit may be modified to include different limitations and/or requirements. Q. SEVERABILITY The provisions of this permit are severable. If any provisions or the application of any provision of this permit to any circumstances, is held invalid, the application of such provision to other circumstances and the application of the remainder of this permit shall not be affected. R. NOTIFICATION REQUIREMENTS 1. Notification to Parties All notification requirements, excluding information submitted using the CEOS portal, shall be directed as follows: a. Oral Notifications, during normal business hours shall be to: Clean Water Compliance Section Water Quality Control Division Telephone: (303) 692-3500 b. Written notification shall be to: Clean Water Compliance Section Water Quality Control Division Colorado Department of Public Health and Environment WQCD-WQP-B2 4300 Cherry Creek Drive South Denver, CO 80246-1530 Page 29 of 33 PART II Permit No.: COR400000 S. RESPONSIBILITIES 1. Reduction, Loss, or Failure of Treatment Facility The permittee has the duty to halt or reduce any activity if necessary to maintain compliance with the effluent limitations of the permit. It shall not be a defense for a permittee in an enforcement action that it would be necessary to halt or reduce the permitted activity in order to maintain compliance with the conditions of this permit. T. Oil and Hazardous Substance Liability Nothing in this permit shall be construed to preclude the institution of any legal action or relieve the permittee from any responsibilities, liabilities, or penalties to which the permittee is or may be subject to under Section 311 (Oil and Hazardous Substance Liability) of the CWA. U. Emergency Powers Nothing in this permit shall be construed to prevent or limit application of any emergency power of the division. V. Confidentiality Any information relating to any secret process, method of manufacture or production, or sales or marketing data which has been declared confidential by the permittee, and which may be acquired, ascertained, or discovered, whether in any sampling investigation, emergency investigation, or otherwise, shall not be publicly disclosed by any member, officer, or employee of the Water Quality Control Commission or the division, but shall be kept confidential. Any person seeking to invoke the protection of of this section shall bear the burden of proving its applicability. This section shall never be interpreted as preventing full disclosure of effluent data. W. Fees The permittee is required to submit payment of an annual fee as set forth in the 2016 amendments to the Water Quality Control Act. Section 25-8-502 (1.1) (b), and the Colorado Discharge Permit System Regulations 5 CCR 1002-61, Section 61.15 as amended. Failure to submit the required fee when due and payable is a violation of the permit and will result in enforcement action pursuant to Section 25-8-601 et. seq., C.R.S.1973 as amended. X. Duration of Permit The duration of a permit shall be for a fixed term and shall not exceed five (5) years. If the permittee desires to continue to discharge, a permit renewal application shall be submitted at least ninety (90) calendar days before this permit expires. Filing of a timely and complete application shall cause the expired permit to continue in force to the effective date of the new permit. The permit's duration may be extended only through administrative extensions and not through interim modifications. If the permittee anticipates there will be no discharge after the expiration date of this permit, the division should be promptly notified so that it can terminate the permit in accordance with Part I.A.3.i. Y. Section 307 Toxics If a toxic effluent standard or prohibition, including any applicable schedule of compliance specified, is established by regulation pursuant to Section 307 of the Federal Act for a toxic pollutant which is present in the permittee's discharge and such standard or prohibition is more stringent than any limitation upon such pollutant in the discharge permit, the division Page 30 of 33 PART II Permit No.: COR400000 shall institute proceedings to modify or revoke and reissue the permit to conform to the toxic effluent standard or prohibition Page 31 of 33 Stormwater Management Plan APPENDIX G: Geotechnical Soils Report Tri-State Generation & Transmission — Lloyd Sisson Substation 1 KLEINFELDER Bright People. Right Solutions. GEOTECHNICAL ENGINEERING REPORT LLOYD SISSON SUBSTATION NORTHWEST OF COUNTY ROAD 30 AND COUNTY ROAD 71 WELD COUNTY, COLORADO KLEINFELDER PROJECT #: 20201380.001A SEPTEMBER 13, 2019 Copyright 2019 Kleinfelder All Rights Reserved ONLY THE CLIENT OR ITS DESIk3NATED REPRESENTATIVES MAY USE THIS DOCUMENT AND ONLY FOR THE SPECIFIC PROJECT FOR WHICH THIS REPORT WAS PREPARED. 201201380.001A/DEN19R101024 2019 Kleinfelder Page i of iii September 13, 2019 www.kleinfelder.com KL EINFEL DER ...a.. prop. *y., tokeba o A Report Prepared for: Tri-State Generation and Transmission Association, Inc. 1100 West 116th Avenue Westminster. CO 80234 GEOTECHNICAL ENGINEERING REPORT LLOYD SISSON SUBSTATION NORTHWEST OF COUNTY ROAD 30 AND COUNTY ROAD 71 WELD COUNTY, COLORADO KLEINFELDER PROJECT #: 20201380.001A Prepared by: Cindy A. Wright. PG* Staff Professional II *Registered in CA Reviewed by: Thomas J. Nevin, PE Principal Geotechnical Engineer KLEINFELDER 1801 California Street, Suite 1100 Denver. Colorado 80202 303.237.6601 FAX: 303.237.6602 September 13. 2019 Kleinfelder Project No. 20201380.001A 201201380.001A/DEN19R101024 Page ii of iii September 13. 2019 2019 Kleinfelder www.kleuifelder.com ( KLE/NFELOER Nagar Prep* Olen st.nt TABLE OF CONTENTS Section Page 1 INTRODUCTION 1 1.1 PURPOSE AND OBJECTIVE 1 1.2 SCOPE OF SERVICES 1 1.3 PROJECT LOCATION AND DESCRIPTION 2 2 FIELD EXPLORATIONS AND LABORATORY TESTING 3 2.1 GENERAL 3 2.2 SUBSURFACE EXPLORATION 3 2.3 LABORATORY TESTING 4 3 SITE CONDITIONS 5 3.1 SITE DESCRIPTION 5 3.2 GEOLOGY 5 3.3 SUBSURFACE CONDITIONS 5 3.4 GROUNDWATER 7 4 CONCLUSIONS AND RECOMMENDATIONS 8 4.1 GENERAL 8 4.2 CONSTRUCTION CONSIDERATIONS 8 4.2.1 Site Preparation and Grading 8 4.2.2 Excavations 9 4.2.3 Structural Fill 9 4.2.4 Compaction Recommendations 10 4.2.5 Substation Yard Surface Preparation 10 4.2.6 Construction in Wet or Cold Weather 11 4.2.7 Construction Testing and Observation 11 4.2.8 Subsurface and Surface Drainage 11 4.3 SHALLOW FOUNDATIONS 11 4.4 DRILLED PIER FOUNDATIONS 13 4.4.1 Axial Capacity 13 4.4.2 Lateral Capacity 14 4.5 GEOLOGIC HAZARDS 16 4.5.1 Seismicity 16 4.5.2 Liquefaction Hazards 17 4.5.3 Corrosivity 17 5 LIMITATIONS 18 FIGURES Figure 1 Exploration Location Plan and Vicinity Map APPENDICES A Boring Logs B Laboratory Test Results C Electrical Resistivity Testing D Important Information About Your Geotechnical Engineering Report 201201380.001A/DEN19R101024 Page iii of iii September 13, 2019 © 2019 Kleinfelder www.kleinfelder.com KLEINFELDER gegAr #004 •qnf soAnwu 1 INTRODUCTION 1.1 PURPOSE AND OBJECTIVE The purpose of this geotechnical engineering report is to summarize geological and geotechnical engineering data obtained from Kleinfelder's recent field exploration for the proposed Lloyd Sisson Substation Project located northwest of the intersection of County Road 130 and County Road 71 in Weld County, Colorado. and to provide geotechnical engineering recommendations for foundation design of the proposed substation. This report includes information obtained from exploratory borings as well as results of laboratory testing of the soil and rock and is based on the request for proposal provided by Tri-State titled Lloyd Sisson Substation Geologic Investigations and Soil Resistivity Testing and Soil Boring Layout. The information within this report will be used by Tri-State Generation and Transmission Association. Inc. (Tri-State) to facilitate the design and construction of the proposed Lloyd Sisson Substation. The geotechnical data provided are subject to the provisions in the Limitations section. In addition, an article prepared by Geoprofessional Business Association (GBA), Important Information about This Geotechnical Engineering Report. has been included in Appendix C. We recommend that all individuals who read the report understand the report limitations along with the included GBA document. 1.2 SCOPE OF SERVICES The scope of service performed for this project included the following: • Coordination and project initialization • Site characterization, including preparation. coordination, and execution of a subsurface exploration program • Electrical resistivity testing • Laboratory testing • Engineering analysis • Report preparation 201201380.001 A/DEN 19R 101024 © 2019 Kleinfelder Page 1 of 19 September 13, 2019 vww .kleintelder.conr KL E/NFEL DER Groh, h o• $.qnr %oAl en. 1.3 PROJECT LOCATION AND DESCRIPTION The project is located northwest of the intersection of County Road 130 and County Road 71 in Weld County. Colorado (Figure 1). We understand the substation equipment is tentatively designed to be founded on soil -supported slabs. spread footings and drilled piers. Kleinfelder has assumed that small cuts or fills, less than about three feet. may be required for grading. 201201380.001 A/DEN 19R101024 O 2019 Kleinfelder Page 2 of 19 September 13. 2019 www.kleinfelder.com ALE/NA-ELDER I .t' h.00l. 0401 %okmons 2 FIELD EXPLORATIONS AND LABORATORY TESTING 2.1 GENERAL The geotechnical field exploration was performed on August 29. 2019 and September 12. 2019. This section provides a summary of the subsurface explorations completed as part of this project. 2.2 SUBSURFACE EXPLORATION On August 29, 2019. a total of five borings (B-1 through B-5) were drilled and one test pit (TP-1) was excavated to explore the subsurface conditions at the proposed substation. The Exploration Location Plan and Vicinity Map. Figure 1. shows the approximate boring and test pit locations. The borings were terminated at a depth of approximately 30 to 31 feet beneath the ground surface (bgs). The test pit was excavated to a depth of approximately 6.5 feet bgs. The borings and the test pit were advanced with an all -terrain CME-750 drill rig equipped with solid -stem. continuous -flight auger and a hollow -stem auger. Samples were obtained using the Modified California (2.5 -inch O.D.). and Standard Penetration Test (2 -inch O.D.) samplers. The samplers were driven 12 inches or 18 inches into relatively undisturbed material using a 30 -inch drop of a 140 -pound hammer (ASTM D1586). The samples were packaged and sealed in the field to reduce moisture loss and disturbance. During the exploration, a Kleinfelder geotechnical professional observed drilling and logged the borings and test pit by visually identifying and classifying soils in general accordance with ASTM D2488 and the Unified Soil Classification System (USCS). Upon completion of laboratory testing. soil classifications were further evaluated in general accordance with ASTM D2487 and are presented in the boring logs in Appendix A. The lines defining boundaries between soil types on the logs are based on drill rig observation and interpolation between samples and are therefore approximate. Transitions between soil types may be abrupt or gradual. Electrical resistivity (ER) testing was completed September 12, 2019. Electrical resistivity (ER) testing included two perpendicular electrical resistivity lines (North -South and East-West) that were performed in the proposed substation footprint. The electrical resistivity testing was 201201380.001A/DEN19R101024 Page 3 of 19 September 13. 2019 © 2019 Kleinfelder www.kleinfelaer.com KL ElNFEL DER - .•,.,C, • •w t._ conducted by Kleinfelder personnel utilizing an AGI Super Sting R1 and the Wenner 4 -pin array method. The tests were performed using array arrangements with probe spacings ranging from 2 to 500 feet. The results of the electrical resistivity tests are presented in Appendix C. 2.3 LABORATORY TESTING Laboratory tests were performed on selected soils and bedrock obtained during the investigation to evaluate their physical and engineering properties. The tests were performed in general accordance with the current ASTM standards. Results of the laboratory tests are included in Appendix B. Selected laboratory results are also summarized in the boring logs (Appendix A). 201201380.001A/DEN19R101024 Page 4 of 19 September 13. 2019 © 2019 Kleinfelder www.kleinfelder.com �\ KL E/NFEL DER kg". P'gp. Mger SoIuton, 3 SITE CONDITIONS 3.1 SITE DESCRIPTION The substation project site is located northwest of the intersection of County Road 130 and County Road 71 in Weld County, Colorado. The proposed substation site is relatively flat, undeveloped agricultural land. At the time of our investigation the surface was covered in low grasses and weeds. The closest structure is a pump jack, tank battery, and associated work pad located southeast of the intersection of County Road 130 and County Road 71 or approximately 700 feet from the project site. The project site is a total of approximately 6.7 acres and the substation is planned to be within a fenced area 350 feet by 300 feet. 3.2 GEOLOGY The geology of the site was evaluated by reviewing published geologic maps, including: Preliminary Geologic Map of the Greely 1°x2° Quadrangle, Colorado and Wyoming, U.S. Geological Survey. Braddock. W.A. and Cole, J.C.. 1978. Local geology at the substation was mapped as the White River Formation of the Oligocene Epoch. The White River Formation is characterized as a light colored. massive, argillaceous and calcareous siltstone interbedded sandstone. conglomerate, and volcanic ash beds. 3.3 SUBSURFACE CONDITIONS The subsurface conditions encountered in the borings were observed to generally consist of sand with varying amounts of gravel. silt. and clay interbedded with lean clay with varying amounts of sand over claystone and siltstone bedrock. Topsoil containing organics was encountered to a depth of up to approximately eight inches. Native soil deposits were encountered from below the topsoil layer to depths ranging from approximately 9 to 14 feet below ground surface (bgs). The soils were comprised of sand with 201201380.001 A/DEN 19R 101024 Page 5 of 19 September 13, 2019 © 2019 Kleinfelder vww.kleinfelder.com KLE/NFELOER OFOOM � Part %Anon, varying amounts of clay, silt. and gravel. Borings B-1, B-2, BA and B-5 each had a stratum of lean clay soils present with medium plasticity and varying amounts of sand. The sand soils were generally very loose to loose near the surface and increased in relative density to very dense with depth. The clay soils ranged from soft to hard in consistency. The claystone and sandstone bedrock ranged from moderately weathered to slightly weathered and extremely weak to very weak in strength. Five soil and rock samples were selected for shrink/swell testing. In this test the samples are wetted and then surcharge loaded, and then their percentage of shrinkage or swelling is measured. All five samples experienced moderate shrinking or compression under the load. The following table presents the results of this testing. TABLE 1 SHRINK/SWELL TESTING RESULTS Boring and Depth Material Type Surcharge Load Compression B-1. 10 feet Siltstone 1.000 psf' 1.1'% B-2. 25 feet Claystone 500 psf 2.4% B-3; 15 feet Claystone 1.000 psf 0.1% B-4, 2.5 feet Sandy dean 500 psf 0.4% B-5, 2.5 feet SanC a�ean Clay 500 psf 1.5% 1 Pounds per Square foot (psf) Compressible or Collapse -prone soils can rapidly decrease in volume when wetted. In the high plains of Colorado, development activities typically raise subsurface moisture content by interrupting the natural flow of moisture from the earth to the relatively dry atmosphere. Foundations constructed on expansive or collapse -prone soils can heave or settle in response to the increases in moisture. Typical substation design includes isolated concrete foundations (that are relatively impermeable to air and moisture migration) with a more permeable gravel surface between and surrounding the foundations. Thus. foundations with larger footprints will likely be 201201380.001 A/DEN 19R 101024 © 2019 Kleinfelder Page 6 of 19 September 13, 2019 www.kleinfelder.com KL E/NFEL DER ay+.t w..[ • '.r* S.:Wea more susceptible to movement. To help reduce the risk of movement. Kleinfelder recommends over -excavation and recompaction of soils below all shallow foundations, as recommended in Section 4 of this report. 3.4 GROUNDWATER Groundwater was not encountered in the borings or test pit during drilling operations to the extents of exploration depths ranging from approximately 6.5 to 31 feet bgs. Soil moisture levels and groundwater levels commonly vary over time depending upon seasonal precipitation. irrigation practices. land use and runoff conditions. The soil moisture and groundwater data in this report pertain only to the locations and time when the borings were drilled. which was during fall. Groundwater may be shallower during spring when runoff is present. 201201380.001A/DEN19R101024 © 2019 Kleinfelder Page 7 of 19 September 13, 2019 www.kleinteloer.com KL E/NFEL OER 6q44 Prop* 0.A/NI folvticson 4 CONCLUSIONS AND RECOMMENDATIONS 4.1 GENERAL Based on the subsurface conditions encountered in the borings and our experience with similar projects, it is Kleinfelder's opinion that development of the site as planned is geotechnically feasible, provided the recommendations in this report are incorporated in the design and construction of the project. Due to the presence of near -surface very loose to loose sand and soft clay soils. over -excavation and replacement of these materials will be required to a depth of approximately four feet below the existing ground surface below movement sensitive structures. If movement on the order of one to two inches or more is considered acceptable then complete removal of these very loose to loose sand and soft clay soils will not be required. It is likely that these soils will be unstable under construction traffic and some removal on the order of one to two feet of these materials will likely be required to provide a stable construction platform. Our geotechnical design and construction recommendations for site preparation, foundations. and other related construction topics are provided in the following sections. 4.2 CONSTRUCTION CONSIDERATIONS 4.2.1 Site Preparation and Grading All site preparation and earthwork operations should be performed in accordance with applicable codes, safety regulations and other local, state. or federal guidelines. Prior to site grading or development. the construction area should be stripped of vegetation and deleterious or organic material. Stripping operations should be observed by the geotechnical engineer. and should include removing materials that. in the judgment of the geotechnical engineer, are not suitable for the anticipated loading conditions. 201201380.001A/DEN19R101024 Page 8 of 19 September 13, 2019 © 2019 Kleinfelder www.kleinfelder.com KL E/NFEL DER ...ps, Soho an 4.2.2 Excavations We anticipate that most excavations can be performed with conventional heavy-duty earthmoving equipment. Groundwater was not observed in the borings at the time of drilling and we do not anticipate that temporary dewatering measures will be required for shallow excavations. All excavations must comply with the applicable local. state, and federal safety regulations. and particularly with the excavation standards of the Occupational Safety and Health Administration (OSHA). Construction site safety, including excavation safety, is the sole responsibility of the Contractor as part of its overall responsibility for the means. methods. and sequencing of construction operations. The actual determination of soil type and required sloping must be made in the field by the contractor's OSHA "competent person". 4.2.3 Structural Fill Structural fill is defined as any fill which will support structural elements. Structural fill will be required for backfill of utilities and for site grading fill. All structural fill must be free of sod. rubbish. topsoil. frozen soil. cobbles, and other deleterious materials. Structural fill materials should consist of a non - expansive. mainly granular material as specified below. On -site soils may be suitable for reuse as structural fill. if they meet the criteria present in Table 2. Import materials can also be used. if desired. TABLE 2 STRUCTURAL FILL CRITERIA GRADATION REQUIREMENTS Standard Sieve Size Percent Passing 3 inch 100 3/4 inch 80 - 100 No. 200 10 - 35 PLASTICITY REQUIREMENTS (ATTERBERG LIMITS) Liquid Limit 30 or less Plasticity Index 12 or less 201201380.001 A/DEN 19R 101024 © 2019 Kleinfelder Page 9 of 19 September 13, 2019 wviw.kleinfelder.com ice\ I KL EINFEL DER pgwr Roc. • .tr %r,:a n, A sample of any imported fill material should be submitted to the geotechnical engineer for approval and testing at least one week prior to stockpiling at the site. Structural fill should be placed according to the recommendations in Section 4.2.4. 4.2.4 Compaction Recommendations All fill should be moistened. placed in loose lifts of eight inches or less thickness, and compacted to the specifications presented in Table 3. TABLE 3 COMPACTION SPECIFICATIONS Fill Location Material Type Compaction Moisture Content (%) Site Grading Fill/ Structural Fill Sand. Silty Sand. Clayey Sand. and Structural Fill minimum maximum density (ASTM Method 95% of dry D1557) -2 to +2 of optimum Clay minimum 95% of maximum dry density (ASTM Method D698) 0 to +3 of optimum 4.2.5 Substation Yard Surface Preparation After initial site grading has been completed. the substation yard surface preparation should consist of scarifying the upper eight inches of the subgrade materials, moisture conditioning and compacting the subgrade to the criteria of section 4.2.4. Any areas that appear disturbed or soft should be over -excavated a depth of about two feet and be replaced with well -compacted structural fill. As mentioned previously, near -surface very loose to loose sand and soft clay soils are present at the site. It is likely that these soils will be unstable under construction traffic and some removal on the order of one to two feet of these materials will likely be required to provide a stable construction platform. 201201380 001A/DEN 19R101024 Page 10 of 19 September 13, 2019 2019 Kleinfelder www.klernfelder.com I KLE/NFELDER • gM Pine Oar S44fpm 4.2.6 Construction in Wet or Cold Weather During construction. grade the site such that surface water can drain readily away from the improvement areas. Promptly pump out or otherwise remove any water that may accumulate in excavations or on subgrade surfaces and allow these areas to dry before resuming construction. The use of berms, ditches, and similar means may be used to prevent stormwater from entering the work area and to convey any water off site efficiently. If construction occurs during cold weather, fill and concrete elements should not be constructed on frozen soil. Frozen subgrade soils should be completely removed. or thawed. scarified and re - compacted. The amount of time passing between subgrade preparation and placing fill or concrete should be minimized during freezing conditions to prevent the prepared soils from freezing. Blankets. soil cover or heating as required may be utilized to prevent the subgrade from freezing. 4.2.7 Construction Testing and Observation Fill construction should be observed and tested by Kleinfelder to support our professional opinion as to whether the earthwork does or does not substantially conform to the recommendations in this report. The opinions and conclusions of a geotechnical report are based on the interpretation of a limited amount of information obtained from the field exploration. It is therefore not uncommon to find that actual site conditions differ somewhat from those indicated in the report. Kleinfelder should remain involved throughout the project to evaluate such differing conditions as they appear, and to modify or add to the geotechnical recommendations as necessary. 4.2.8 Subsurface and Surface Drainage Positive drainage away from the structures is essential to the performance of foundations and should be provided during the life of the structures. Surface drainage should be created such that water is diverted off the site and away from equipment foundations. 4.3 SHALLOW FOUNDATIONS The proposed substation equipment may be supported upon isolated spread or strip footing and mat foundations constructed on properly prepared native soils. or structural fill extending to 201201380.001 A/DEN 19R 101024 © 2019 Kleinfelder Page 11 of 19 September 13, 2019 vwwv.kleinfelder.com I KL EINFEL OER properly prepared native soils. At the surface in most of the borings there was a very loose to loose or soft layer of soil extending down approximately four feet. For movement sensitive structures. this loose or soft layer of soil must be removed or recompacted according to the recommendations below. If movement on the order of one to two inches or more is considered acceptable then complete removal of these very loose to loose sand and soft clay soils will not be required. It is likely that these soils will be unstable under construction traffic and some removal on the order of one to two feet of these materials will likely be required to provide a stable construction platform. The shallow foundations should be designed and constructed in accordance with the following criteria. • Foundation excavations must be cleaned of all topsoil. non -engineered fill. soft or disturbed soils. construction debris. frozen soil. moisture sensitive soils. or ponded water. All loose or disturbed soils should be completely removed or recompacted to the requirements of structural fill. Cobbles or boulders must be removed from the upper eight inches of the bearing level soils or fill. • Prior to placement of foundation steel. the upper eight inches of the bearing level soils should be scarified, moisture conditioned. and compacted to the specifications of Section 4.2.4. • Foundations prepared in accordance with this report may be designed for an allowable bearing pressure of 2.000 psf. • Foundations may be designed to resist lateral movement with a nominal coefficient of sliding friction of 0.45. and a passive earth pressure calculated as an equivalent fluid density of 400 pcf. The structural engineer should select and apply appropriate factors of safety for lateral resistance parameters. • Footing size should be determined by a structural engineer. As a minimum. we recommend isolated columns be supported on square pads at least 18 inches wide. Continuous strip footings should be at least 16 inches in width. • An allowable modulus of subgrade reaction, Kv1, of 100 pounds per square inch per inch deflection (pci) may be used for design of mat foundations. Kv, refers to a 1 -foot square plate and should be adjusted for actual foundation dimensions using the following equation (B is foundation width in feet): (B� 1 1- = Kvl 2R 201201380.001 A/DEN 19R 101024 © 2019 Kleinfelder Page 12 of 19 September 13, 2019 www.klemfelder.com KLE/NFEL DER fr rr Pop* light SM,aum • Exterior foundations should be protected from frost action. Frost depth at this location is 36 inches. We recommend the footings be protected with at least 36 inches of soil cover. or that which is required by local building codes. whichever is greater. • For slab -on -grade foundations where settlement or heave is not considered critical. these foundations can bear at a depth of at least 12 inches below the surrounding ground surface. 4.4 DRILLED PIER FOUNDATIONS We understand that some structures at the substation may be supported on drilled pier foundations. Tri-State uses the software packages MFAD and LPILE for design. The design parameters provided in the subsequent sections for axial capacity and lateral capacity are for the substation location. 4.4.1 Axial Capacity Table 4 provides ultimate end -bearing and side resistance values for drilled piers within the substation. The design parameters for axial capacity for each transmission line boring (Boring B- 1 to B-6) are provided in the Appendix A. A safety factor value of 3 should be applied to these values when evaluating allowable capacity. TABLE 4 DRILLED PIER CAPACITY SUMMARY FOR THE SUBSTATION MATERIAL LAYER DEPTH (FT) ULTIMATE BEARING CAPACITY (KSF) END 1 ULTIMATE SIDE RESISTANCE COMPRESSION (KSF) UPLIFT (KSF) Clay 0 to 4 Neglect Sand 4 to 8 11.0 0.6 0.4 Sand 8 to 10 32.0 1.5 1.1 Stiff Clay w/o Free Water 10 to 14 32.0 2.6 1.8 Bedrock 14 (2) to 31 55.0 4.5 3.2 201201380.001 A/DEN 19R101024 © 2019 Kleinfelder Page 13 of 19 September 13, 2019 www.kleinfelder.com KL E/NFEL DER Notes: (1) Kips per square foot (KSF). (2) Bedrock depth in the exploratory borings varied from 9 to 14 feet. Additional considerations for axial capacity include: • • • • • • • • • frigrit rtao. •qni So.Vnon. Piers should be designed by a qualified structural engineer. Piers should be reinforced their full length. We recommend concrete be designed and placed at a slump between five and seven inches. Pier holes should be cleaned of all loose material and have less than three inches of water in the bottom of the hole at time of concrete placement. If excessive ground water seepage occurs. casing or tremie placement of concrete may be required for proper pier installation. The soil profile in the borings included up to 14 feet of sand soils with gravel present. Caving of pier holes may occur and is more likely for larger diameter holes. Casing should be present on -site if stabilization of holes is required. Concrete placement should occur immediately after pier hole drilling. cleaning, installation of reinforcement and observation. Concrete should be placed in one continuous placement without any cold joints. If casing is used. a positive head of concrete must be maintained above the end of the casing as the casing is withdrawn. A minimum pier diameter of 18 inches is recommended to allow for pier cleaning and observation. Pier caps that overhang the drilled pier should be embedded below frost depth to prevent uplift. The installation of the drilled piers should be observed by a Kleinfelder representative to observe the construction techniques and confirm the subsurface conditions are as anticipated from our exploratory boring. For foundations constructed in accordance to the recommendations presented herein, total foundation settlement should be less than one inch. 4.4.2 Lateral Capacity We understand the computer programs MFAD and LPILE will be used for design of the drilled pier foundations. The unit weight and soil strength data were developed from the results of the 201201380.001A/DEN19R101024 Page 14 of 19 September 13. 2019 © 2019 Kleinfelder ‘Armv.kleuitelder.com KLE/NFEL DER laboratory testing. field exploration. and our experience with similar soils in the area. The modulus of deformation values presented are based on laboratory and field test data and correlated design values published in the 1982 EPRI Design Manual. entitled. "Laterally Loaded Drilled Pier Research. Volume 1: Design Methodology." The following tables present the ultimate soil properties for use with MFAD and LPILE, for design of piers within the substation. TABLE 5 MFAD PARAMETERS FOR DESIGN OF FOUNDATIONS FOR THE SUBSTATION LAYER TYPE LAYER DEPTH (FT) TOTAL UNIT WEIGHT (PCF) DEFORMATION MODULUS (KSI) FRICTION ANGLE (DEGREE) UNDRAINED COHESION (KSF) ULTIMATE ROCK/CONCRE TE STRENGTH (KSF) Clay 0 to 4 Neglect Sand 4 to 8 107 0.63 34 n/a n/a Sand 8 to 10 122 3.07 38 n/a n/a Clay 10 to 14 135 4.00 24 5.900 n/a Weak Rock 14 to 31 135 562 30 8.00 10 201201380.001A/DEN19R101024 Page 15 of 19 September 13, 2019 © 2019 Kleinfelder wvw.kleinfelder.com KLE/NFELOER &ire hoc. .4n, s.wwn. TABLE 6 LPILE PARAMETERS FOR DESIGN OF FOUNDATIONS FOR THE SUBSTATION SOIL MODEL LAYER DEPTH (FT) TOTAL UNIT WEIGHT (PCF) SOIL MODULUS K (PCI) (DEGREES) FRICTION ANGLE STRAIN FACTOR, Eso UNDRAINED COHESION (PSF) Stiff Clay w/o Free Water 0 to 4 Neglect Sand 4 to 8 107 130 34 n/a n/a Sand 8 to 10 122 280 38 n/a n/a Stiff Clay w/o Free Water 10 to 14 135 n/a n/a 0.004 5.900 Weak Rock 14 to 31 135 n/a n/a n/a 8.000 4.5 GEOLOGIC HAZARDS 4.5.1 Seismicity Subsurface materials encountered at the substation site and the transmission line to the maximum depth explored of 31 feet, as well as our interpretation of underlying conditions to a depth of 100 feet based on experience and published geology. correspond with 2015 International Building Code (IBC) Site Class D designation. Acceleration coefficients for Site Class D are presented in Table 7. TABLE 7 SEISMIC DESIGN TABLE 7. SEISMIC DESIGN SITE CLASS SEISMIC DESIGN PARAMETERS Ss Si Fa Fv D 0.128 0.049 1.6 2.4 ss S. Fa F,, = The mapped spectral accelerations for short periods (U.S. Geological Survey Web Page, 2016) The mapped spectral accelerations for 1 -second period (U.S. Geological Survey Web Page. 2016) Site coefficient from Table 1613.3.3(1), 2012 IBC Site coefficient from Table 1613.3.3(2), 2012 IBC 201201380.001A/DEN19R101024 Page 16 of 19 CO 2019 Kleinfelder September 13. 2019 4wwv.kleinfelder.com KLE/NFELOER Prop* Say Soli/torn 4.5.2 Liquefaction Hazards Earthquake -induced soil liquefaction can be described as a significant loss of soil strength and stiffness caused by an increase in pore water pressure resulting from cyclic loading during shaking. Liquefaction risk is greater in loose to medium -dense, sandy and gravelly soils below the groundwater table. The low magnitude of seismic ground motions indicates the site does not exhibit characteristics consistent with liquefaction risk. It is our opinion that the liquefaction hazard is negligible. 4.5.3 Corrosivity The degradation of concrete or cement grout can be caused by constituents in the soil or groundwater that react with cement. The concentration of water-soluble sulfates in the soils is a good indicator of the potential for chemical attack of concrete or cement grout. Laboratory test results indicate water-soluble sulfate concentrations ranging from 0.001 to 0.011 percent. Based on the sulfate exposure guidance of the American Concrete Institute (ACI) the samples present a Class SO (negligible) sulfate exposure to concrete. ACI has no special cement requirements in Class SO exposure. If there is minimal cost difference between Type I and Type II, use of Type II Portland cement is recommended for additional sulfate resistance of construction concrete. 201201380.001A/DEN19R101024 Page 17 of 19 September 13, 2019 © 2019 Kleinfelder w\m,v.kleinfelder.com KL E/NEEL DER &vett hope ROW Scru .om 5 LIMITATIONS This work was performed in a manner consistent with that level of care and skill ordinarily exercised by members of Kleinfelder's' profession practicing in the same locality, under similar conditions and at the date the services are provided. Our conclusions, opinions. and recommendations are based on a limited number of observations and data. The scope of services was limited to exploratory borings, laboratory testing. analysis, and preparation of this report. It is likely that subsurface conditions could vary at other locations. It should be recognized that definition and evaluation of subsurface conditions is difficult. Judgments leading to conclusions and recommendations are generally made with incomplete knowledge of the subsurface conditions present due to the limitations of data from field studies. Kleinfelder makes no other representation, guarantee. or warranty. express or implied, regarding the services. communication (oral or written). report. opinion, or instrument of service provided. Kleinfelder offers various levels of investigative and engineering services to suit the varying needs of different clients. Although risk can never be eliminated, more detailed and extensive studies yield more information, which may help understand and manage the level of risk. Since detailed study and analysis involves greater expense, our clients participate in determining levels of service, which provide information for their purposes at acceptable levels of risk. The client and key members of the design team should discuss the issues covered in this report with Kleinfelder, so that the issues are understood and applied in a manner consistent with the owner's budget, tolerance of risk and expectations for future performance and maintenance. Recommendations contained in this report are based on our field observations and subsurface explorations. limited laboratory tests, and our present knowledge of the proposed construction. It is possible that soil, rock, or groundwater conditions could vary between or beyond the points explored. If soil. rock, or groundwater conditions are encountered during construction that differ from those described herein. the client is responsible for ensuring that Kleinfelder is notified immediately so that we may reevaluate the recommendations of this report. If the scope of the proposed construction changes from that described in this report, the conclusions and recommendations contained in this report are not considered valid unless the changes are reviewed, and the conclusions of this report are modified or approved in writing by Kleinfelder. 201201380.001 A/DEN 19R 101024 © 2019 Kleinfelder Page 18 of 19 September 13. 2019 www.kleinfelder.corri �/-'\ KL E/NFEL DER •i. t Mai) Roast SONLwK As the geotechnical engineering firm that performed the geotechnical evaluation for this project, Kleinfelder should be retained to confirm that the recommendations of this report are properly incorporated in the design of this project, and properly implemented during construction. This may avoid misinterpretation of the information by other parties and will allow us to review and modify our recommendations if variations in the soil conditions are encountered. Kleinfelder cannot be responsible for interpretation by others of this report. The scope of services for this subsurface exploration and geotechnical report did not include environmental assessments or evaluations regarding the presence or absence of wetlands or hazardous substances in the soil. surface water. or groundwater at this site. This report may be used only by the client and the registered design professional in responsible charge and only for the purposes stated for this specific engagement within a reasonable time from its issuance. but in no event later than two years from the date of the report. 201201380.001 A/DEN 19R 101024 © 2019 Kleinfelder Page 19 of 19 September 13. 2019 wvnv.kleinfelcer.coni ( KLE/NFELOER FIGURE 201201380.001A/DEN19R101024 September 13, 2019 © 2019 Kleinfelder www.kleinfelder.com Pt r7TTFfl ,71n in to 1r. 1? AM PATH "\ayrn'sstnrpO 1\Workingt_ctients\_Automated_Exploration Plans LEGEND • SOIL BORING TEST PIT ELECTRICAL RESISTIVITY TESTING - APPROX LINE LAYOUT NOTE: BASE MAPPING AND VICINITY MAP CREATED FROM LAYERS COMPILED BY ESRI PRODUCTS AND 2019 MICROSOFT CORPORATION COORDINATE SYSTEM NAD 1983 2011 STATEPLANE COLORADO NORTH FIPS 0501 Proposed Lloyd Sisson Substation: 350'x300' The information induded on this graphic representation has been compiled from a vanety of sources and is subject to change without notice Kleinfelder makes no representations or warranties express or implied. as to accuracy. completeness timeliness. or nghts to the use of such information This document is not intended for use as a land survey product nor is it designed or intended as a construction design document The use or misuse of the information contained on this graphic representation is at the sole nsk of the party using or misusing the information 0 7- SITE 200 VICINITY MAP 400 1 " = 200 SCALE IN FEET NOT TO SCALE L E KL E/NFEL DER Bright People. Right Solutions. PROJECT NO 20201380 001A DRAWN BY: CHECKED BY DATE CWnght T Nevin 09-08-2019 EXPLORATION LOCATION PLAN AND VICINITY MAP Tri-State Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 Weld County, Colorado FIGURE 1 KL E/NFEL DER „., ;..r h-.. • • qnr 104.,1 o.., APPENDIX A BORING LOG SHEETS 201201380.001A/DEN19R101024 September 13, 2019 © 2019 Kleinfelder www.kleinfelder.com SAMPLE/SAMPLER TYPE GRAPHICS UNIFIED SOIL CLASSIFICATION SYSTEM (ASTM D 2487) MODIFIED CALIFORNIA SAMPLER (2 or 2-1/2 in. (50.8 or 63.5 mm.) outer diameter) If of material is larger than the #200 sieve) GRAVELS (More than half of coarse fraction is larger than the #4 sieve) CLEAN GRAVEL Cu≥4 and 1-C�`3 • •' �• GW WELL -GRADED GRAVELS, GRAVEL -SAND MIXTURES WITH LITTLE OR NO FINES STANDARD PENETRATION SPLIT SPOON SAMPLER WITH el (2 in. (50.8 mm.) outer diameter and 1-3/8 in. (34.9 mm.) inner diameter) <5% FINES Cu<4 and/ ° ° Q° GP POORLY GRADED GRAVELS, GRAVEL -SAND MIXTURES WITH GROUND WATER GRAPHICS or 1>Cc>3 )O 0 LITTLE OR NO FINES a WATER LEVEL (level where first observed) I WATER LEVEL (level after exploration completion) Cu≥4 and • • I • GW-GM WELL -GRADED GRAVELS GRAVEL -SAND MIXTURES, WITH LITTLE FINES Q WATER LEVEL (additional levels after exploration) A4 OBSERVED SEEPAGE GRAVELS TO W12% 1sCcs3 • • 1� GW-GC WELL -GRADED GRAVELS, GRAVEL -SAND MIXTURES WITH LITTLE CLAY FINES NOTES 5%I FINES ° ° GP -GM POORLY GRADED GRAVELS, GRAVEL -SAND MIXTURES WITH • The report and graphics key are an integral part of these logs. All data Cu <4 and/'� LITTLE FINES and interpretations in this log are subject to the explanations and limitations stated in the report. • Lines separating strata on the logs represent approximate boundaries or 1>Cc>3 0 ° �p GP -GC POORLY GRADED GRAVELS, GRAVEL -SAND MIXTURES WITH LITTLE CLAY FINES only. Actual transitions may be gradual or differ from those shown. • No warranty is provided as to the continuity of soil or rock conditions between individual sample locations. ° 7 o Z GM SILTY GRAVELS, GRAVEL -SILT -SAND MIXTURES • Logs represent general soil or rock conditions observed at the point of exploration on the date indicated. • In Unified Soil Classification System designations GRAVELS WITH > 12% FINES Ollb GC CLAYEY GRAVELS, GRAVEL -SAND -CLAY MIXTURES general, presented on the logs were based on visual classification in the field and were modified where appropriate based on gradation and index property testing. • Fine grained sods that plot within the hatched area on the Plasticity I GC -GM CLAYEY GRAVELS: GRAVEL -SAND -CLAY -SILT MIXTURES Chart, and coarse grained soils with between 5% and 12% passing the No. 200 sieve require dual USCS symbols, ie., GW-GM, GP -GM, GW-GC, GP -GC, GC -GM, SW-SM, SP-SM, SW -SC, SP -SC, SC-SM. COARSE GRAINED SOILS (More than hi SANDS (Half or more of coarse fraction is smaller than the #4 sieve) CLEAN SANDS WITH Cu≥6 and 11Cc3 •••••• • • •;•;•; •..°. ' • SW • WELL -GRADED SANDS, SAND -GRAVEL MIXTURES WITH LITTLE OR NO FINES • if sampler is not able to be driven at least 6 inches then 50/X indicates number of blows required to drive the identified sampler X inches with a 140 pound hammer falling 30 inches. <5% FINES Cu <6 and/ or 1>Cc>3 • Sp POORLY GRADED SANDS, SAND -GRAVEL MIXTURES WITH LITTLE OR NO FINES ABBREVIATIONS s • WOH - Weight of Hammer WOR - Weight of Rod Cu≥6 and •;• ••• ' ' I.• ' SW-SM WELL -GRADED SANDS, SAND -GRAVEL MIXTURES WITH LITTLE FINES SANDS WITH 5%TO 1sC�3 ••• •' • . •LITTLE SW -SC WELL -GRADED SANDS, SAND -GRAVEL MIXTURES WITH CLAY FINES 12% FINES Cu <6 and/ :. SP-SM POORLY GRADED SANDS, SAND -GRAVEL MIXTURES WITH LITTLE FINES or 1>Cc>3 SP -SC POORLY GRADED SANDS, SAND -GRAVEL MIXTURES WITH LITTLE CLAY FINES SM SILTY SANDS, SAND -GRAVEL -SILT MIXTURES SANDS WITH > 12% FINES ,% � SC CLAYEY SANDS, SAND -GRAVEL -CLAY MIXTURES j SC-SM CLAYEY SANDS, SAND -SILT -CLAY MIXTURES FINE GRAINED SOILS (Half or more of material is smaller than the #200 sieve) ML INORGANIC SILTS AND VERY FINE SANDS, SILTY OR CLAYEY FINE SANDS, SILTS WITH SLIGHT PLASTICITY SILTS AND CLAYS �� CL INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY, GRAVELLY CLAYS, SANDY CLAYS, SILTY CLAYS, LEAN CLAYS (Liquid Limit less than 50) l! CL -ML INORGANIC CLAYS -SILTS OF LOW PLASTICITY, GRAVELLY CLAYS, SANDY CLAYS, SILTY CLAYS, LEAN CLAYS - OL ORGANIC SILTS & ORGANIC SILTY CLAYS OF LOW PLASTICITY MH INORGANIC SILTS, MICACEOUS OR DIATOMACEOUS FINE SAND OR SILT SILTS AND CLAYS (Liquid Limit 50 Pi CH INORGANIC CLAYS OF HIGH PLASTICITY, FAT CLAYS or greater) ' ti A A. 0.PROJECT OH ORGANIC CLAYS & ORGANIC SILTS OF MEDIUM -TO HIGH PLASTICITY NO.: 20201380.001A DRAWN BY: MAP CHECKED BY: CAW / TJN DATE: 9/10/2019 GRAPHICS KEY FIGURE A-1 KL E/NFEL DER Tri-State: Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 Weld County, Colorado Bright People. Right Solutions. �� GRAIN SIZE DESCRIPTION SIEVE SIZE GRAIN SIZE APPROXIMATE SIZE Boulders >12 in. (304.8 mm.) >12 in. (304.8 mm.) Larger than basketball -sized Cobbles 3 - 12 in. (76.2 - 304.8 mm.) 3 - 12 in. (76.2 - 304.8 mm.) Fist -sized to basketball -sized Gravel coarse 3/4 -3 in. (19 - 76.2 mm.) 3/4 -3 in. (19 - 76.2 mm.) Thumb -sized to fist -sized fine #4 - 3/4 in. (#4 - 19 mm.) 0.19 - 0.75 in. (4.8 - 19 mm.) Pea -sized to thumb -sized coarse #10 - #4 0.079 - 019 in. (2 - 4.9 mm.) Rock salt -sized to pea -sized O Sand medium #40 - #10 0.017 - 0.079 in. (0.43 - 2 mm.) Sugar to rock -sized salt -sized k fine #200 - #40 0.0029 - 0.017 in. (0.07 - 0.43 mm.) Flour -sized to sugar -sized • Fines Passing #200 <0.0029 in. (<0.07 mm.) Flour -sized and smaller SECONDARY CONSTITUENT MOISTURE CONTENT CEMENTATION AMOUNT DESCRIPTION FIELD TEST DESCRIPTION FIELD TEST Term of Use Secondary Constituent is Fine Grained Secondary Constituent is Coarse Grained Dry Absence of moisture, dusty. dry to the touch Weakly Crumbles or breaks with handling or slight finger pressure Damp but no Crumbles or breaks Trace <5% o <15% Moist visible water Moderately with considerable finger pressure With 45 to <15% e15 to <30% Visible free water, Will not crumble or Modifier z 15% a 30% Wet usually soil is below water table Strongly break with finger pressure CONSISTENCY - FINE-GRAINED SOIL REACTION WITH UNCONFINED HYDROCHLORIC ACID SPT-N6, Pocket Pen CONSISTENCY (# blows / ft) (tsf) COMPRESSIVE STRENGTH (Q)(psf) VISUAL / MANUAL CRITERIA DESCRIPTION FIELD TEST Very Soft <2 PP < 0.25 <5p0 Thumb will penetrate more than 1 inch (25 mm). Extrudes between fingers when squeezed. None No visible reaction Thumb will soil about 1 inch (25 mm). Soft 2 - 4 0.25 5 PP <0.5 500 - 1000 penetrate Remolded by light finger pressure. Some reaction, Medium Stiff 4 - 8 0.5; PP <1 1000 - 2000 Thumb will penetrate soil about 1/4 inch (6 mm). Remolded by strong finger Weak with bubbles forming slowly pressure. Violent Stiff 8 - 15 1 5 PP <2 2000 - 4000 Can be impnnted with considerable pressure from thumb. Strong reaction, with bubbles forming Thumb will not indent soil but readily indented with immediately Very Stiff 15 - 30 2 , PP <4 4000 - 8000 thumbnail. Hard >30 4s PP >8000 Thumbnail will not indent soil. FROM TERZAGHI AND PECK 1948 LAMBE AND WHITMAN 1969 FHWA, 2002; AND ASTM D2488 APPARENT / RELATIVE DENSITY - COARSE -GRAINED SOIL PLASTICITY APPARENT SPT Ns, MODIFIED CA SAMPLER CALIFORNIA SAMPLER RELATIVE DENSITY DESCRIPTION LL FIELD TEST DENSITY (# blows/ft) (# blows/ft) (# blows/ft) (%) Non -plastic NP A 1/8 in. (3 mm.) thread cannot be rolled at any water content. Very Loose <4 <4 <5 0 - 15 Low (L) < 30 The thread can barely be rolled and the lump or thread cannot be formed when drier than the limit. plastic Loose 4 - 10 5 - 12 5 - 15 15 - 35 The thread is easy to roll and not much time is required to Medium Dense 10 - 30 12 - 35 15 - 40 35 - 65 Medium (M) 30 - 50 reach the plastic limit. The thread cannot be rerolled after reaching the plastic limit. The lump or thread crumbles when dner than the plastic limit. Dense 30 - 50 35 - 60 40 - 70 65 - 85 It takes considerable time rolling and kneading to reach the Very Dense >50 >60 >70 85 - 100 High (H) > plastic limit. The thread can be rerolled several times after reaching the plastic limit. The lump or thread can be formed without crurnblinq when drier than the plastic limit. FROM TERZAGHI AND PECK. 1948 STRUCTURE ANGULARITY DESCRIPTION CRITERIA DESCRIPTION CRITERIA Stratified Alternating layers of varying material or color with layers at least 1/4 -in. thick. note thickness. Angular Particles have sharp edges and relatively plane sides with unpolished surfaces. Alternating layers the layer Laminated of varying matenal or color with less than 1/4 -in. thick, note thickness. Subangular Particles are similar to angular description but have rounded Fissured Breaks along definite planes of fracture with edges. little resistance to fractunnq. Particles have nearly sides but have well-rounded Slickensided Fracture planes appear polished or glossy. sometimes striated.edges. Subrounded plane corners and Blocky Cohesive soil that can be broken down into small angular lumps which resist further breakdown.I Rounded Particles have smoothly curved sides and no edges. Lensed Inclusion of small pockets of different soils, such as small lenses of sand scattered through a mass of day. note thickness. PROJECT NO.. 20201380.001A DRAWN BY MAP CHECKED BY CAW / TJN DATE 9/10/2019 SOIL DESCRIPTION KEY FIGURE /� _� /-1 �-- froTh ( KL E/NFEL DER Tri-State Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 Weld County Colorado Bright People. Right Solutions. INFILLING TYPE RELATIVE HARDNESS / STRENGTH DESCRIPTIONS NAME ABBR NAME ABBR GRADE UCS (Mpa) FIELD TEST Albite a Muscovite Mus R0 Extremely Weak 0.25 - 1.0 Indented by thumbnail Apatite AP None No R1 Very Weak 1.0 - 5.0 Crumbles under firm blows of geological hammer, can be peeled by a pocket knife. Biotite Bi Pyrite Py R2 Weak 5.0 25 Can be peeled by a pocket knife with difficulty, shallow indentations made by firm blow with point of geological hammer. Clay CI Quartz Qz R3 Medium Strong 25 - 50 Cannot be scraped or peeled with a pocket knife, specimen can be fractured with a single firm blow of a geological hammer. Calcite Ca Sand Sd R4 Strong 50 - 100 Specimen requires more than one blow of geological hammer to fracture it. Chlorite Ch Sencite Ser R5 Very Strong 100 - 250 Specimen requires many blows of geological hammer to fracture it. Epidote Ep Silt Si R6 Extremely Strong > 250 Specimen can only be chipped with a geological hammer. Iron Oxide Fe Talc Ta ROCK QUALITY DESIGNATION (RQDI JOINT ROUGHNESS COEFFICIENT (JRC) Manganese Mn Unknown Uk DESCRIPTION RQD (%) 0-2 DENSITY/SPACING OF DISCONTINUITIES Very Poor 0 - 25 DESCRIPTION SPACING CRITERIA Poor 25 - 50 2-4 Unfractured >6 ft. (>1.83 meters) Fair 50 - 75 4 - 6 Slightly Fractured 2 - 6 ft. (0.061 - 1.83 meters) Good 75 - 90 -- 6 - 8 Moderately Fractured 8 in - 2 ft. (203.20 - 609.60 mm) Excellent 90 - 100 -_------„...- 8 - 10 Highly Fractured 2 - 8 in (50.80 - 203.30 mm) APERTURE Intensely Fractured <2 in (<50.80 mm) DESCRIPTION CRITERIA [in (mm)1 10 - 12 ADDITIONAL TEXTURAL ADJECTIVES Tight <0.04 (<1) 12- 14 —� DESCRIPTION RECOGNITION Open 0.04 - 0.20 (1 - 5) 14 - 16 Pinhole to 0.03 ft. (3/8 in.) (>1 to Wide >0.20 Pit (Pitted) (>5) 10 mm.) openings 16 - 18 Small openings (usually lined with crystals) ranging in diameter from BEDDING CHARACTERISTICS Vu Vu 9 ( 99Y) 18 - 20 0.03 ft. (3/8 in.) to 0.33 ft. (4 in.) (10 to 100 mm.) DESCRIPTION Thickness [in (mm)) An opening larger than 0.33 ft. (4 in.) (100 mm.), size descriptions Very Thick Bedded >36 (>915) 0 5 cm 10 cm Cavity are required, and adjectives such g I as small, large, etc.. may be used Thick Bedded 12 - 36 (305 - 915) From Barton and Choubey, 1977 If numerous enough that only thin 9 Moderately Bedded 4 - 12 (102 - 305) ROD Rock -quality designation (RQD) Rough measure of the degree of jointing or fracture in a Honeycombed walls separate individual pits or bugs. this term further describes Thin Bedded 1 - 4 (25 - 102) rock mass, measured as a percentage of the drill core in lengths of 10 cm. or more. the preceding nomenclature to indicate cell-like form. Very Thin Bedded 0.4 - 1 (10 - 25) Small openings in volcanic rocks Laminated 0.1 - 0.4 (2.5 - 10) Vesicle (Vesicular) of vanable shape and size formed by entrapped gas bubbles during Thinly Laminated <0.1 (<2.5) solidification. Bedding Planes Planes dividing the individual layers. ADDITIONAL TEXTURAL ADJECTIVES beds. or stratigraphy of rocks. Joint Fracture in rock. generally more or DESCRIPTION CRITERIA less vertical or traverse to bedding. Seam Applies to bedding plane with Unweathered No evidence of chemical / mechanical alternation, rings with hammer blow. unspecified degree of weather. Slight discoloration on surface; CORE SAMPLER TYPE GRAPHICS Slightly Weathered slight alteration along discontinuities: <10% rock volume altered. CORE SAMPLER = = ti F EX CORE BARREL (0 846 in. (21.5 mm.) core diameter) Moderately Weathered Discoloring evident; surface pitted and alteration penetration well below surface: Weathering "halos" I I AQ CORE BARREL (1.067 in. (27.1 mm.) core diameter) HO CORE SAMPLE (2.500 in. (63.5 mm.) core diameter) evident, 10-50% rock altered. I AX CORE BARREL NO CORE SAMPLE Entire mass discolored. Alteration (1.185 in. (30.1 mm.) core diameter) (1.874 in. (47.6 mm.) core diameter) Highly Weathered pervading most rock, some slight weathering pockets. some minerals may be leached out. BQ CORE BARREL (1.433 in. (36.4 mm.) core diameter) NO RECOVERY CORE SAMPLE r Decomposed Rock reduced to soil with relic rock texture/structure; Generally CONTINUOUS CORE SAMPLE (2.000 in. (50.8 mm.) core diameter) NX CORE SAMPLE (2.154 in. (54.7 mm.) core diameter) molded and crumbled by hand. '— PROJECT NO. 20201380. 001A DRAWN BY MAP CHECKED BY' CAW / TJN DATE 9/10/2019 ROCK DESCRIPTION KEY FIGURE A_3 KL E/NFEL DER Tri-State Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 Weld County. Colorado Bright People. Right Solutions. Date Begin - End: 8/29/2019 Drilling Company: Vine Laboratories BORING LOG B-1 Logged By: B. Monterde Drill Crew: Nick & Paul Hor.-Vert. Datum: Not Available Drilling Equipment: CME-750 Hammer Type - Drop: 140 lb. Auto - 30 in. Plunge: -90 degrees Drilling Method: Solid Stem Auger Weather: P. Cloudy Exploration Diameter: 4 in. O.D. .- L a o FIELD EXPLORATION LABORATORY RESULTS o lc a Latitude: 40.93071' Longitude: -104.39239° Surface Condition: Grass a a. 0 o e' c °. o f o a Zice > Z o 11 _ � U `_'oi �. c N �a v E D o c CO o o c Cl) axi v, m o U Z II m i-- c) O m N Lt. 0 Lithologic Description N u7 o c app d 2 o- ? CO >. DV) @ O > O Z o m a. COft1 CL N a a. Z -13 4) < a 5_ TOPSOIL -8" Silty SAND (SM): fine-grained sand, light brown, moist, very loose BC=1 2 12" Poorly Graded SAND with Gravel (SP): fine to coarse -grained sand, angular to sub -angular gravel, brown, loose to dense BC=2 9 12" 3.6 107.7 _ pale red and moist, BC=10 15" 19.9 Sulfates= 0.006% 10 Lean CLAY with Sand and Gravel (CL) medium plasticity, gray, moist, hard 15 20 - -x 15 - _ -x _ 20 X X x x SILTSTONE: tan, slightly weathered. very weak, weakly cemented, homogeneous 1BC=17 22 12" 17.1 92.7 Expansion/Compression= Compression= 1.1% 1 ksf- x x x x x x x x x x x x x x x x x x x under when wetted. - x x x x x x BC=15 50/5' 22.5 65 32 6 x x x x x x x x x x x x x x x x x - 25— 30 J CLAYSTONE: tan, slightly weathered extremely 26.0 92.7 1BC20 37 weak Some cobbles observed in cuttings - brown below 25 feet BC=21 28.8 88.6 Unc. Comp. Str.= 50/6' 8350 Q- psf Strain Failure: 4.5% at _ BC=14 29.6 87.4 21 - - The boring was terminated at approximately 31 ft. GROUNDWATER LEVEL INFORMATION below ground surface. The boring was backfilled Groundwater was not observed during drilling or after with auger cuttings on August 29. 2019. completion. GENERAL NOTES: (------PROJECTNO.: 20201380.001A DRAWN BY: MAP CHECKED BY: CAW / TJN DATE: 9/10/2019 BORING LOG B-1 BORING PAGE B_ 1 1 of 1 KL EINF-EL DER Tri-State: Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 County, Colorado Bright People. Right Solutions. .'"---\\,%..............,----Weld Date Begin - End: 8/29/2019 Drilling Company: Vine Laboratories BORING LOG B-2 Logged By: B. Monterde Drill Crew: Nick & Paul Hor.-Vert. Datum: Not Available Drilling Equipment: CME-750 Hammer Type - Drop: 140 lb. Auto - 30 in. Plunge: -90 degrees Drilling Method: Solid Stem Auger Weather: Windy, 69° F Exploration Diameter: 4 in. O.D. Depth (feet) Graphical Log FIELD EXPLORATION LABORATORY RESULTS Latitude 40.93073' Longitude: -104.39186° Surface Condition: Grass Sample Type Blow C°unts(BC)= uncorr, Blows/6 in. Recovery (NR=No Recovery) USCS Symbol Water Content (°/o) Dry Unit Wt. (pcf) Passing #4 (%) Passing #200 (%) Liquid Limit Plasticity Index (NP=NonPlastic) n- 11 w (— c u) o m Lithologic Description < re _7 TOPSOIL: -8" Sandy Lean CLAY (CL): brown, dry, soft, organics BC=2 3 12" Sulfates= 0.001% _✓ 10 -� 15— - - - _ 20— _ -x _ -x 25— Silty, Clayey SAND (SC-SM): fine-grained sand, angular gravel, low plasticity, light brown, loose - BC=3 4 12" SC-SM 5.0 100.9 34 23 6 - - fine to coarse -grained sand, pale red, medium dense below 7.5 feet BC=12 20 12" Chattenng while drilling at 8 feet ■ y Lean CLAY with Sand (CL): medium plasticity, light gray, moist, hard BC=15 25 27 18" _ 4 �a x x x x x x SILTSTONE: light gray_ moderately weathered, extremely weak 21.4 -- t x x x x BC=20 21.0 86.3 _ Unc. Comp. Str.= q,, 9595 psf - x x x x x x x x x x x x x x x x x x x x Strain at Failure: 4.5% _ - _ x x x x x x — _ x x x x x x x x x x x x x x x x x x - - - x x 30.6 89.3 -' Expansion/Compression= CLAYSTONE. brown, moderately weathered weak Compression= 2.4% under 0.5 - ksf when wetted. I 30 - - - - calcareous and cobbles at bottom BC=50/5" of sample GROUNDWATER LEVEL INFORMATION: The boring was terminated at approx mately 30.4 ft. Groundwater was not observed during drilling or after below ground surface. The boring was backfilled completion. with auger cuttings on August 29. 2019. GENERAL NOTES: PROJECT NO.: 20201380.001A DRAWN BY: MAP CHECKED BY CAW / TJN DATE: 9/10/2019 BORING LOG B-2 BORING RAGE B-2 1 of 1 KL EINFEL DER Tn-State: Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 Weld County, Colorado Bright People. Right Solutions. \i„.....----.........2 Date Begin - End: 8/29/2019 Drilling Company: Vine Laboratories BORING LOG B-3 Logged By: B. Monterde Drill Crew: Nick & Paul Hor.-Vert. Datum: Not Available Drilling Equipment: CME-750 Hammer Type - Drop: 140 lb. Auto - 30 in. Plunge: -90 degrees Drilling Method: Solid Stem Auger Weather: Not Available Exploration Diameter: 4 in. O.D. a- t (I) o FIELD EXPLORATION LABORATORY RESULTS O1 � .� Latitude. 40.93047' Longitude. -104.39213° Surface Condition. Grass & Weeds a F— a ^ s m�' O mp Ut z 0w > aoo a >2 u �� C 17;a a�� Q v C D Qf CO v o N co - E_ J • • axi ti im d a z -- n y tri F - 6 o Y =m c`a a Lithologic Description cEo cn o f op aii ., o: ? N >, D CO m o > U 0 m a_ ca o- a ' m a a ? v m Q cc 5_ 10— 07, TOPSOIL: -8" Clayey SAND (SC) fine-grained sand. brown, dry, loose. calcareous BC=2 2 Poorly Graded SAND with Gravel and Silt (SP-SM): fine to coarse -grained sand, sub -angular and Chattenng while dnlling at 3.5 _ feet sub -rounded gravel, light brown. dry. dense LBC..14 15 21 21 0.8 Sulfates= 0.001% Chattering while drilling from 6.5., Gravelly SAND with Clay (SPSC) fine to coarse -grained sand, angular to sub -angular gravel, light brown and dense BC=20 22 19 to 8 feet pink. moist, Chattering while drilling from 9.5_ BC -15 11.7 to 11 feet CLAYSTONE. gray, moderately weathered 32 39 extremely weak - Chattering while drilling at 11.5 _ feet. had to re-dnll hole due to collapse Water added to hole 15 BC=24 24.4 92.2 Expansion/Compression= 22 Compression= 0.1% under 1 ksf- when wetted. 20 - - brown below 20 feet BC=24 25 25 - - calcareous below 25 feet BC=37 23.6 87.6 Unc. Comp. Str.= 50/3" q�. 2770 psf Strain at Failure: 9.7% 30 - - — BC=19 50C The boring was terminated at approximately 30.8 ft. GROUNDWATER LEVEL INFORMATION below ground surface. The boring was backfulled Groundwater was not observed during drilling or after with auger cuttings on August 29. 2019. completion. GENERAL NOTES PROJECT NO.: 20201380.001A DRAWN BY. MAP CHECKED BY CAW / TJN DATE 9/10/2019 BORING LOG B-3 BORING PAGE: B_3 1 of 1 KL E/NFEL DER Tri-State: Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 Weld County, Colorado Bright People. Right Solutions. `t Date Begin - End: 8/29/2019 Drilling Company: Vine Laboratories BORING LOG B-4 Logged By: B. Monterde Drill Crew: Nick & Paul Hor.-Vert. Datum: Not Available Drilling Equipment: CME-750 Hammer Type - Drop: 140 lb. Auto - 30 in. Plunge: -90 degrees Drilling Method: Solid Stem Auger Weather: Sunny Exploration Diameter: 4 in. O.D. Depth (feet) Graphical Log FIELD EXPLORATION LABORATORY RESULTS Latitude 40.93023° Longitude: -104.39240° Surface Condition: Grass Sample Type Blowcounts(Bc)- Uncorr Blows/6 in Recovery (NR=No Recovery) UE Water Content (%) Dry Unit Wt. (pcf) Passing #4 (%) Passing #200 (%) Liquid Limit Plasticity Index (NP=NonPlast'c) CO 7 h w a) I — To c u g m is E Lithologic Description = cn Q ct 5—:. _ y- Sandy Lean CLAY (CL) medium plasticity. light brown, soft - Ali 1BCri 2 CL 14.9 83.3 62 33 14 Expansion/Compression= _ Compression= 0.4% under 0.5 Poorly Graded SAND with Gravel and Silt (SP -8M): fine to coarse -grained sand, red, dry, very dense ksf when wetted. _ pale BC=22 34 47 Chattenng while dnlling at 2.5 — feet Sulfates= 0_002% - Chattenng while drilling at 6 feet BC=30 32 46 _ 10— - _ _x _ 15— _ - x x x x x x SILTSTONE: grayish brown, slightly weathered, very weak — x x x x BC=t9 35 11.2 119.1 - x x x x x x x x x x x x x x x x x x x _ - _ — x x x x x x BC=19 27 _ x x x x x x x x x x x x x x - 20-1 25 30— _ - CLAYSTONE: brown, slightly weathered, extremely weak. weakly cemented — BC=20 29.1 85.0 Unc. Comp. Str.= 55 q,; 10048 psi - Strain at Failure 6.9% - — BC=18 Water in sampler 55 — BC=31 28.0 88.7 No water in sampler \ 50/2" The boring was terminated at approximately 30.7 ft. GROUNDWATER LEVEL INFORMATION: below ground surface. The bonng was backfilled Groundwater was not observed during drilling or after with auger cuttings on August 29. 2019. completion. GENERAL NOTES: r--..". PROJECT NO.. 20201380.001A DRAWN BY MAP CHECKED BY CAW / TJN DATE: 9/10/2019 BORING LOG B-4 BORING PAGE g_/� T 1 of 1 KL E/NFEL DER Tri-State: Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 Weld County, Colorado Bright People. Right Solutions. iiii\��- Date Begin - End: 8/29/2019 Drilling Company: Vine Laboratories BORING LOG B-5 Logged By: B. Monterde Drill Crew: Nick & Paul Hor.-Vert. Datum: Not Available Drilling Equipment: CME-750 Hammer Type - Drop: 140 lb. Auto - 30 in. Plunge: -90 degrees Drilling Method: Solid Stem Auger Weather: Windy Exploration Diameter: 4 in. O.D. Depth (feet) Graphical Log FIELD EXPLORATION LABORATORY RESULTS Latitude: 40.93023' Longitude: -104.3918T Surface Condition Grass Sample Type Blow Counts(BC) Uncoil' Blows/6 in Recovery (NR=No Recovery) (1) 2 0 E Water Content (%) Dry Unit Wt (pcf) Passing #4 (%) Passing #200 (%) Liquid Limit Plasticity Index (NP=NonPlastic) lil i-- m cn 2 ft - �E Lithologic Descnpt.on D co ID o Q x 5 ~ - 10 _:./ jSandy Lean CLAY (CL): light brown dry medium stiff $BC=5 5 8" 9.9 94.1 Expansion/Compression= i Compression= 1.5% 0.5 Poorly Graded SAND with Gravel and Silt (SP-SM): fine to coarse -grained sand. sub -angular tan, under ksf when wetted. gravel very dense BC=23 26 26 18" 0.8 Chattering while drilling at 3 feet - Chattering while dnlling at 6 feet Silty SAND with Gravel (SM): fine to coarse -grained sand tan, dry, very dense .:. BC=26 26 BC=22 38 ^ 13.7 100.0 Sulfates= 0.011% 15—_ 20— 25 1 30-' - - CLAYSTONE. tan. slightly weathered, extremely weak — BC=22 39 BC=25 25.8 89.4 Unc. Comp. Str.= 46 q, 5589 psf Strain at Failure 6.4% BC=21 - brown below 25 feet 5016.. - BC=22 5015" The bonng was terminated at approximately 30 9 ft. GROUNDWATER LEVEL INFORMATION. below ground surface. The boring was backfilled Groundwater was not observed during drilling or after with auger cuttings on August 29. 2019 completion GENERAL NOTES PROJECT NO. 20201380.001A DRAWN BY MAP CHECKED BY CAW / TJN DATE 9/10/2019 BORING LOG B-5 BORING B_5 PAGE 1 of 1 KL E/NFEL DER Tn-State: Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 Weld County, Colorado Bright People. Right Solutions. �� Date Begin - Logged By: Hor.-Vert. Datum: Plunge: Weather: End: 8/29/2019 Drilling Company: Crew: Equipment: Method: Diameter: Vine Laboratories Hammer BORING LOG TP-1 B. Monterde Drill Nick & Paul Type - Drop: 140 lb. Auto - 30 in. Not Available Drilling CME-750 -90 degrees Drilling Solid Stem Auger Not Available Exploration 4 in. O.D. Depth (feet) Graphical Log FIELD EXPLORATION LABORATORY RESULTS Latitude 40.93046' Longitude- -10439168° Surface Condition Grass Sample Type Blow Counts(BC)= Uncorr. Blows/6 in Recovery (NR=No Recovery) USCS Symbol Water Content (%) Dry Unit Wt. (pcf) Passing #4 (c)/0) Passing #200 (°/o) Liquid Limit Plasticity Index (NP=NonPlastic) in `) a, F- To O Y O fa E Q X Lithologic Description 1 2—//. 3— 4 5 ‘i 1 • TOPSOIL -8 SC 7.7 6.8 1.2 93.5 36 23 9 Test results from bulk sample 0.67 to 6.5 feet J — — — — _ /./ • • • • `" Clayey SAND (SC): fine to medium -grained sand low plastiaty brown, dry, loose trace roots BC=4 5 6-. Poorly Graded SAND with Gravel and Silt (SP-SM): fine to medium -grained sand. sub -angular to sub -rounded gravel. light brown and pink, dry. loose to medium dense BC=7 5 5 7_ _ 8- 9- 10- 11- 12- 13- 14 - The bonng was terminated at approzmately 6.5 ft. below ground surface. The boring was backfilled with excavated material on August 29 2019. GROUNDWATER LEVEL INFORMATION or after Groundwater was not observed completion GENERAL NOTES during drilling P.---- KL PROJECT NO. 20201380.001A DRAWN BY MAP CHECKED BY CAW / TJN DATE, 9/10/2019 BORING LOG TP-1 BORING T PAGE P-1 1of1 E/NFEL DER Tri-State Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 Weld County Colorado Bright People. Right Solutions. KL E/NFEL DER :,. 1.. An.. • . ' Li,. t au APPENDIX B LABORATORY TEST RESULTS 201201380.001A/DEN19R101024 September 13. 2019 © 2019 Kleinfelder wvwv.kleinfelder.com gINT FILE KIf_grnt_master_2020 PROJECT NUMBER 202013th.: :•. I F: Exploration ID Depth (ft) Sample Description Water Content (%) Dry Unit Wt. (pcf) Sieve Analysis (%) Atterberg Limits C) C 0 U, cC 0_ Passing #200 E J t J a - J Plastic Limit x v t C 2' v cn 4-' Cv a Additional Tests B-1 B-1 B-1 B-1 B-1 B-1 B-1 B-2 B-2 8-2 B-2 B-2 B-3 B-3 B-3 8-3 B-4 B-4 B-4 B-4 Refer to the Geotech plates performed above. NP = NonPlastic 5.0 7.5 10.0 15.0 20.0 25.0 30.0 2.5 5.0 11.5 15.0 25.0 5.0 10.0 15.0 25.0 2.5 5.0 10.0 20.0 hnical Evaluation for the method u POORLY GRADED SAND WITH GRAVEL (SP) LEAN CLAY WITH SAND (CL) SILTSTONE SILTSTONE CLAYSTONE CLAYSTONE CLAYSTONE SILTY, CLAYEY SAND (SC-SM) LEAN CLAY WITH SAND (CL) SILTSTONE SILTSTONE POORLY GRADED SAND WITH GRAVEL AND SILT (SP-SM) CLAYSTONE CLAYSTONE CLAYSTONE SANDY LEAN CLAY (CL) SILTSTONE CLAYSTONE Report or the sed for the testing 3.6 19.9 17.1 22.5 26.0 28.8 29.6 5.0 21.4 21.0 30.6 0.8 11.7 24.4 23.6 14.9 11.2 29.1 107.7 92.7 92.7 88.6 87.4 100.9 86.3 89.3 92.2 87.6 83.3 119.1 85.0 65 32 26 6 34 23 17 6 62 33 19 14 Sulfates= 0.006% Expansion/Compression= Compression= 1.1% under 1 ksf when wetted. Unconfined Compressive Strength= q,,: 8350 psf Strain at Failure: 4.5% Sulfates= 0.001% Unconfined Compressive Strength= q,,: 9595 psf Strain at Failure: 4.5% Expansion/Compression= Compression= 2.4% under 0.5 ksf when wetted. Sulfates= 0.001% Expansion/Compression= Compression= 0.1% under 1 ksf when wetted. Unconfined Compressive Strength= q,,: 2770 psf Strain at Failure: 9.7% Expansion/Compression= Compression= 0.4% under 0.5 ksf when wetted. Sulfates= 0.002% Unconfined Compressive Strength= q0: 10048 psf Strain at Failure: 6.9% KL E//VFELOER Bright People. Right Solutions. PROJECT NO.: 20201380.001A DRAWN BY: MAP CHECKED BY: CAW / TJN DATE: 9/10/2019 LABORATORY TEST RESULT SUMMARY Tri-State: Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 Weld County, Colorado TABLE B-1 gINT FILE klf_gint_neester_2020 PROJECT NUMBER 20201360 001A OFFILL r ILP. uL G:Lr. Exploration ID Depth (ft.) B-4 B-5 B-5 B-5 B-5 TP-1 TP-1 TP-1 30.0 2.5 5.0 10.0 20.0 0.67 - 6.5 1.0 5.0 Sample Description CLAYSTONE SANDY LEAN CLAY (CL) POORLY GRADED SAND WITH GRAVEL AND SILT (SP-SM) SILTY SAND WITH GRAVEL (SM) CLAYSTONE CLAYEY SAND (SC) CLAYEY SAND (SC) POORLY GRADED SAND WITH GRAVEL AND SILT (SP-SM) Water Content (%)4 Dry Unit Wt. (pcf) 28.0 9.9 0.8 13.7 25.8 7.7 6.8 1.2 88.7 94.1 100.0 89.4 93.5 Sieve Analysis (%) M a, C N IV a a C N 0 a Passing #200 Atterberg Limits Plastic Limit 36 23 14 a) a) c U y N a. 9 Additional Tests Expansion/Compression= Compression= 1.5% under 0.5 ksf when wetted. Sulfates= 0.011% Unconfined Compressive Strength= q,,: 5589 psf Strain at Failure: 6.4% Refer to the Geotechnical Evaluation Report or the supplemental plates for the method used for the testing performed above. NP = Non Plastic KL E/NFEL OER Bright People. Right Solutions. PROJECT NO.: 20201380.001A DRAWN BY MAP CHECKED BY: CAW / TJN DATE: 9/10/2019 LABORATORY TEST RESULT SUMMARY Tri-State Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 Weld County, Colorado TABLE B-2 60 / / For classification of fine-grained soils 0•,-- etand fine-grained fraction of coarse grained 0J// .7. - soils. / - PLASTICITY INDEX (PI) N W a U1 a a -1 O O co O a / / / / / 1 / / C'T 6 G / / / / / / / / / / & / / o / / / / / / G\' A MH or OH / X as. I I ML or OL Chart Reference: ASTM D2487 0 10 16 20 30 40 50 60 70 80 90 100 110 LIQUID LIMIT (LL) Exploration ID Depth (ft) Sample Description Passing #200 a PL PI • B-1 15 SILTSTONE 65 32 26 6 ►i B-2 5 SILTY, CLAYEY SAND (SC-SM) 34 23 17 6 A B-4 2.5 SANDY LEAN CLAY (CL) 62 33 19 14 X TP-1 0.67 - 6.5 CLAYEY SAND (SC) 36 23 14 9 Testing performed in general accordance with ASTM D4318 NP = Nonplastic NM = Not Measured PROJECT NO. 20201380.001A DRAWN BY MAP CHECKED BY CAW / TJN DATE. 9/10/2019 FIGURE B-3 ATTERBERG LIMITS KLEINFELDER DER Tri-State: Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 Weld County, Colorado Bright People. Right Solutions. �� EXPANSION/COMPRESSION (°/o) I I I I 1 J J J J J 1 Co1 1 1 1 1 1 1 a co N O c0 O 41 Q) C,Tp A W N -4 O -4 N W a Uh CO -I CO W O Compression= 1.1% under 1 ksf when wetted. /-- 0.1 1 10 STRESS (ksf) Exploration ID Depth (ft.) Sample Description Initial Water Content (%) Initial Dry Unit Wt. (pcfl Final Water Content (T) Final Dry Unit Wt. (Ixfl 3-' C SILTSTONE 17.1 927 27.6 92.7 PROJECT NO.. 20201380.001A DRAWN BY MAP CHECKED BY: CAW / TJN DATE: 9/10/2019 DENVER SWELL OF COHESIVE SOILS FIGURE B_4 KL E/NFEL DER Tri-State: Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 Weld County, Colorado Bright People. Right Solutions. EXPANSION/COMPRESSION (%) I I I I I 1 I 1 1 1 1 1 1 1 J O .A W N) a CD CO -1 C) CT A W N -. a N) W a CT Q) -4 CO CD O Compression= 2.4% under 0.5 ksf when wetted. 1 10 STRESS (ksf) Exploration ID Depth (ft.) Sample Description Initial Water Content (°I°) Initial Dry Unit Wt (txf) Final Water Content (%) Final Dry Unit Wt (pcf) B-2 25 SILTSTONE 8.9 90.1 2' G 90 1 KL \s3/4%.,,,._,r,._. DER Solutions. PROJECT NO. 20201380.001A DRAWN BY: MAP CHECKED BY: CAW / TJN DATE: 9/10/2019 DENVER SWELL OF COHESIVE SOILS FIGURE B_5 E/NFEL Tri-State: Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 Weld County, Colorado Bright People. Right � EXPANSION/COMPRESSION (%) I I I I I I 1 1 1 1 1 1 I 1 o cD W v a CT A W N o co A to O) -1 CO CD O Compression= 0.1% under 1 ksf when wetted. • ter—. 0.1 1 10 STRESS (ksf) Exploration ID Depth (ft.) Sample Description Initial Water Content (%) Initial Dry Unit Wt. (pOf) Final Water Content (%) Final Dry Unit Wt. (pcf) B-3 15 CLAYSTONE 24 4 92 2 28 5 92.2 PROJECT NO 20201380.001A DRAWN BY MAP CHECKED BY CAW / TJN DATE 9/10/2019 DENVER SWELL OF COHESIVE SOILS FIGURE U B-6 V KL E/NFEL DER Tri-State Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 Weld County, Colorado Bright People. Right Solutions. \-............i........._ EXPANSION/COMPRESSION (%) i i i u a W N j o CO Co -,l O) 61 - W N -+ O N co a cn Q) V Co in O Compression= 0.4% under 0.5 ksf when wetted. 0.1 1 10 STRESS (ksf) Exploration ID Depth (ft) Sample Description Initial Water Content (%) Initial Dry Unit Wt. (pcf) Final Water Content (%) Final Dry Unit Wt. (pcf) B-4 2.5 SANDY LEAN CLAY (CL) 14.9 83 3 34.3 83.3 realgal.—"N PROJECT NO. 20201380.001A DRAWN BY MAP CHECKED BY: CAW I TAN DATE: 9/10/2019 DENVER SWELL OF COHESIVE SOILS FIGURE Bv _7 KLEINFELDER DER Tri-State: Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 Weld County, Colorado Bright People. Right Solutions. � EXPANSION/COMPRESSION (°/a) I I I I I -a J J I Co1 1 I I I I I a W N -a a CO 0�! Cn Ui A W N -+ O - N co a Cu a) -J co CO O a Compression= 1.5% under 0.5 ksf when wetted. 0.1 1 10 STRESS (ksf) Exploration ID Depth (ft) Sample Description Initial Water Content (%) Initial Dry Unit Wt. (PO Final Water Content i (%) Final Dry Unit Wt. (pcf) B-5 2.5 SANDY LEAN CLAY (CL) 9.9 94.1 23.6 94.1 PROJECT NO.: 20201380.001A DRAWN BY MAP CHECKED BY CAW / TAN DATE 9/10/2019 DENVER SWELL OF COHESIVE SOILS FIGURE B_8 KL E/NFEL DER Tri-State: Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 County, Colorado Bright People. Right Solutions. \-----c-,...„„,--Weld 11 000 10.000 9 000 C U, a.8,000 U) rn w � 7.000 0 Lu > L7) 6,000 co w a a 2 5.000 O U 0 W 2 4,000 LL 2 O 3,000 Z D 2,000 1.000 0 2 4 6 8 10 AXIAL STRAIN (°/0) Exploration ID Depth (fL) Sample Description B-1 25 CLAYSTONE Time to Failure (min) Average Rate of Strain to Failure (%lmin) Shear Strength (�� Unconfined Compressive Strength (psfl a Strain at Failure (°/0) 4 "; • - -__� 4 5 Specimen Condition Type Initial Sample Dia. le (mm) Initial Height (mm) Initial HeDiamght eter Ratio Initial Water Content (%) Initial Unit �yyt, (�� Sate ruratiotti itial (%) Initial Void Ratio ic Gravity (Assumed) Passing #200 LL PL PI 1 Intact 48.5 102.4 28.8 88.6 NM NM 2.65 NM NM NM NM Testing performed in general accordance with ASTM D2166. NP = Nonplastic NM = Not Measured PROJECT No 20201380.001A DRAWN BY CHECKED BY: CAW DATE: UNCONFINED STRENGTH COMPRESSIVE FIGURE B-9 KL E/NFEL People. DER MAP / TAN 9/10/2019 Tri-State: Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 Weld County, Colorado Bright Right Solutions. 11.000 10.000 9.000 C to a 8,000 U) ,^ , V/ w I- 7,000 U) w\ V7 6.000 U) ww cc a 2 5.000 O U 0 w z 4.000 CZ Z O Z 3.000 2,000 1,000 2 4 6 8 10 AXIAL STRAIN (%) Exploration ID Depth (ft.) Sample Description ._ 15 SILTSTONE Time to Failure (min) Average Rate of Strain to Failure rt./min)Strength Shear Strength (psi) Unconfined Compressive (psf) Strain at Failure (%) 38 .-._b _... 4.5 Specimen No. Sample Condition Type Initial Sample Dia (mm) Initial Height (mm) Initial Height to Diameter Ratio Initial Water Content (%) Initial Dry Unit Wt ( f) Initial 'Saturation (%) Initial Void Ratio Specific Gravity (Assumed) Passing #200 LL PL PI 1 Intact 48 5 93.5 ' 9 ' 21,0 86 3 NM NV 2 65 NM NM NM NM Testing performed in general accordance with ASTM D2166. NP = Nonplastic NM = Not Measured KL PROJECT No. 20201380.001A DRAWN BY CHECKED BY: CAW DATE: UNCONFINED STRENGTH COMPRESSIVE FIGURE B-10 EINFEL People. DER MAP / TJN 9/10/2019 Tri-State: Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 County, Colorado Bright \04......Weld Right Solutions. 11 000 10,000 9,000 c En a 8.000 cn as F- 7.000 w in 6.000 rn w rr a 2 5..000 o a w z 4,000 LI Z O z 3,000 2.000 1,000 0 -- 2 4 6 8 10 AXIAL STRAIN (%) Exploration ID Depth (ft.) Sample Description - CLAYSTONE Time to Failure min (min) Average Rate of Strain to Failure (%/min) Shear Strength (�� Unconfined Compressive Strength (psf) o Strain at Failure (%) as Specimen No. Sample Condition Type Initial Sample Dia. (mm) Initial Height (mm) Initial Height to Diameter Ratio Initial Water Content r/o) Initial Dry Unit Wt_ (pcf) Initial Saturation Initial Void Ratio Specific Gravity (Assumed) Passing #200 a PL PI 1 Intact 48.5 101.9 2.1.1 23.6 87.6 NM NM -.c NM NM NM NM Testing performed in general accordance with ASTM D2166. NP = Nonplastic NM = Not Measured PROJECT NO.: A DRAWN BY CHECKED BY: CAW DATE UNCONFINED COMPRESSIVE STRENGTH FIGURE B-11 KL \- •20201380.001 E/NFEL People. DER MAP / TJN 9/10/2019 In -State: Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 Weld County, Colorado Bright Right Solutions. 1 1.000 10.000 9.000 C. CA a 8 w w F- 7.000 w > in 6.000 w tY a_ 2 5.000 O U 0 in Z 4.000 i Z O z 3.000 D 2.000 1 000 000 \\II 2 4 6 8 10 AXIAL STRAIN (%) Exploration ID Depth (ft.) Sample Description B-4 20 CLAYSTONE Time to Failure (min) Average Rate of Strain Failure (%/min) Shear Strength (psf) Unconfined Compressive Strength (psf) Strain at Failure (%)to 5.8 1.7 _,,. 10048 6.9 Specimen No. Sample Condition Type Initial Sample Dia. (mm) Initial Height (mm) Initial Height to Diameter Ratio Initial Water Content (%) Initial Dry Unit Wt. (�}) Initial Saturation (%) Initial Void Ratio Specific Gravity (Assumed) Passing #200 LL PL PI 48.8 101.6 2.1 1 29.1 85.0 NM NM 2.65 NM NM NM NM Testing performed in general accordance with ASTM D2166. NP = Nonplastic NM = Not Measured PROJECT NO. 20201380.001A DRAWN BY CHECKED BY CAW DATE 9/10/2019 UNCONFINED STRENGTH COMPRESSIVE FIGURE B-I 2 KL E/NF"EL People. DER MAP ! TJN Tri-State Tri-State Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 Weld County Colorado Bright Right Solutions. 11 10 9.000 17) a 8.000 Cl) 0 w I- 7.000 w Cl) 6,000 co Lu p a. 2 5,000 O U 0 w z 4,000 il z O o 3.000 z J 2,000 1,000 000 000 2 4 6 8 10 AXIAL STRAIN (%) Exploration ID Depth (ft.) Sample Description B-5 20 CLAYSTONE Time to Failure (min) Average Rate of Strain to Failure (%/min) Shear Strength (psf) Unconfined Compressive Strength (psf) o Strain at Failure (% 5.0 1 7 2794 5589 6 4 Specimen No. Sample Condition Type Initial Sample Dia. (mm) Initial Height (mm) Initial Height to Diameter Ratio Initial Water Content (%) Initial Dry Unit Wt. (pct Initial Saturation (%) Initial Void Ratio Specific Gravity (Assumed) Passing #200 LL PL PI 1 Intact 48.8 103.9 2 1 1 25 8 89 4 NM NM 2 65 NM NM NM NM Testing performed in general accordance with ASTM D2166. NP = Nonplastic NM = Not Measured -- KL PROJECT No 20201380.001A DRAWN BY MAP CHECKED BY CAW / TJN DATE 9/10/2019 UNCONFINED COMPRESSIVE STRENGTH FIGURE B-1 3 E/NFEL People. DER Tn-State: Lloyd Sisson Substation Northwest Corner of CR 130 and CR 71 Weld County Colorado Bright \�� Right Solutions. KL E/NFEL DER s..;•i f..xv awl swot«* APPENDIX C ELECTRICAL RESISTIVITY TESTING 201201380.001A/DEN19R101024 September 13, 2019 © 2019 Kleinfelder www.kleinfelder.com ra tKL E/IVFEL OER Bright People Solutions. 1801 California Street, Suite 1100 Denver. CO 80202 Tel_ (303) 237-6601 Fax (303) 237-6602 Project Number Project Name Client 220201380 Lloyd Sisson Substation Tn-State Date and Time Location Test Engineer(s) 9/12/2019 RES 1 DH & TJN Type of Test Weather Surface Conditions 4 -Point Test (Wenner) Sunny, Windy, 60° Grass and Silty Sand Equipment Make Model _ Checked by AGI Super Sting R1 CAW Probe Spacing "A" ;`e�.1 Probe depth "B" (inches) Apparent Resistance (f1) Apparent Resistivity p (D -m) Notes: North - South 2 4 & 2 11.72 44.89 3 4 & 2 9.885 56.79 5 4 & 2 8.441 80.83 7 4 & 2 6.873 92.14 10 4 & 2 6.593 126.26 20 4 & 2 4.189 160.45 30 12 & 6 2.603 149.55 40 12 & 6 1.526 116.90 50 12 & 6 0.751 71.91 70 12 & 6 0.2179 29.21 100 12 & 6 0.08179 15.66 200 12 & 6 0.02637 10.10 300 12 & 6 0.01824 10.48 500 12 & 6 0.01209 11.58 East - West 2 4 & 2 15.8 60.52 3 4 & 2 12.95 74.40 5 4 & 2 11.95 114.43 7 4 & 2 10.59 141.97 10 4 & 2 9.533 182.57 20 4 & 2 5.524 211.58 30 12 & 6 3.027 173.91 40 12 & 6 1.659 127.09 50 12 & 6 0.8975 85.94 70 12 & 6 0.2996 40.16 100 12 & 6 0.1122 21.49 200 12 & 6 0.02754 10.55 300 12 & 6 0.01866 10.72 500 12 & 6 0.01251 11.98 Notes: KL E/NFEL DER APPENDIX D IMPORTANT INFORMATION ABOUT YOUR GEOTECHNICAL ENGINEERING REPORT 201201380.001A/DEN19R101024 September 13. 2019 © 2019 Kleinfelder www.kleinfelder.com Important Intormation about This r _ Geotechnical-Engineering Report Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes. While you cannot eliminate all such risks, you can manage them. The following information is provided to help. The Geoprofessional Business Association (GBA) has prepared this advisory to help you — assumedly a client representative — interpret and apply this geotechnical-engineering report as effectively as possible. In that way, clients can benefit from a lowered exposure to the subsurface problems that, for decades, have been a principal cause of construction delays, cost overruns, claims, and disputes. If you have questions or want more information about any of the issues discussed below, contact your GBA-member geotechnical engineer. Active involvement in the Geoprofessional Business Association exposes geotechnical engineers to a wide array of risk -confrontation techniques that can be of genuine benefit for everyone involved with a construction project. Geotechnical-Engineering Services Are Performed for Specific Purposes, Persons, and Projects Geotechnical engineers structure their services to meet the specific needs of their clients. A geotechnical-engineering study conducted for a given civil engineer will not likely meet the needs of a civil - works constructor or even a different civil engineer. Because each geotechnical-engineering study is unique, each geotechnical- engineering report is unique, prepared solely for the client. Those who rely on a geotechnical-engineering report prepared for a different client can be seriously misled. No one except authorized client representatives should rely on this geotechnical-engineering report without first conferring with the geotechnical engineer who prepared it. And no one - not even you - should apply this report for any purpose or project except the one originally contemplated. Read this Report in Full Costly problems have occurred because those relying on a geotechnical- engineering report did not read it in its entirety. Do not rely on an executive summary. Do not read selected elements only. Read this report in full. You Need to Inform Your Geotechnical Engineer about Change Your geotechnical engineer considered unique, project -specific factors when designing the study behind this report and developing the confirmation -dependent recommendations the report conveys. A few typical factors include: • the client's goals, objectives, budget, schedule, and risk -management preferences; • the general nature of the structure involved, its size, configuration, and performance criteria; • the structure's location and orientation on the site; and • other planned or existing site improvements, such as retaining walls, access roads, parking lots, and underground utilities. Typical changes that could erode the reliability of this report include those that affect: • the site's size or shape; • the function of the proposed structure, as when it's changed from a parking garage to an office building, or from a light -industrial plant to a refrigerated warehouse; • the elevation, configuration, location, orientation, or weight of the proposed structure; • the composition of the design team; or • project ownership. As a general rule, always inform your geotechnical engineer of project changes - even minor ones - and request an assessment of their impact. The geotechnical engineer who prepared this report cannot accept responsibility or liability for problems that arise because the geotechnical engineer was not informed about developments the engineer otherwise would have considered. This Report May Not Be Reliable Do not rely on this report if your geotechnical engineer prepared it: • for a different client; • for a different project; • for a different site (that may or may not include all or a portion of the original site); or • before important events occurred at the site or adjacent to it; e.g., man-made events like construction or environmental remediation, or natural events like floods, droughts, earthquakes, or groundwater fluctuations. Note, too, that it could be unwise to rely on a geotechnical-engineering report whose reliability may have been affected by the passage of time, because of factors like changed subsurface conditions; new or modified codes, standards, or regulations; or new techniques or tools. If your geotechnical engineer has not indicated an `apply -by" date on the report, ask what it should be, and, in general, f you are the least bit uncertain about the continued reliability of this report, contact your geotechnical engineer before applying it. A minor amount of additional testing or analysis - if any is required at all - could prevent major problems. Most of the "Findings" Related in This Report Are Professional Opinions Before construction begins, geotechnical engineers explore a site's subsurface through various sampling and testing procedures. Geotechnical engineers can observe actual subsurface conditions only at those specific locations where sampling and testing were performed. The data derived from that sampling and testing were reviewed by your geotechnical engineer, who then applied professional judgment to form opinions about subsurface conditions throughout the site. Actual sitewide-subsurface conditions may differ - maybe significantly - from those indicated in this report. Confront that risk by retaining your geotechnical engineer to serve on the design team from project start to project finish, so the individual can provide informed guidance quickly, whenever needed. This Report's Recommendations Are Confirmation -Dependent The recommendations included in this report - including any options or alternatives - are confirmation -dependent. In other words, they are not final, because the geotechnical engineer who developed them relied heavily on judgment and opinion to do so. Your geotechnical engineer can finalize the recommendations only after observing actual subsurface conditions revealed during construction. If through observation your geotechnical engineer confirms that the conditions assumed to exist actually do exist, the recommendations can be relied upon, assuming no other changes have occurred. The geotechnical engineer who prepared this report cannot assume responsibility or liability for confirmation - dependent recommendations if you fail to retain that engineer to perform construction observation. This Report Could Be Misinterpreted Other design professionals' misinterpretation of geotechnical- engineering reports has resulted in costly problems. Confront that risk by having your geotechnical engineer serve as a full-time member of the design team, to: • confer with other design -team members, • help develop specifications, • review pertinent elements of other design professionals' plans and specifications, and • be on hand quickly whenever geotechnical-engineering guidance is needed. You should also confront the risk of constructors misinterpreting this report. Do so by retaining your geotechnical engineer to participate in prebid and preconstruction conferences and to perform construction observation. Give Constructors a Complete Report and Guidance Some owners and design professionals mistakenly believe they can shift unanticipated -subsurface -conditions liability to constructors by limiting the information they provide for bid preparation. To help prevent the costly, contentious problems this practice has caused, include the complete geotechnical-engineering report, along with any attachments or appendices, with your contract documents, but be certain to note conspicuously that you've included the material for informational purposes only. To avoid misunderstanding, you may also want to note that "informational purposes" means constructors have no right to rely on the interpretations, opinions, conclusions, or recommendations in the report, but they may rely on the factual data relative to the specific times, locations, and depths/elevations referenced. Be certain that constructors know they may learn about specific project requirements, including options selected from the report, only from the design drawings and specifications. Remind constructors that they may perform their own studies if they warn to, and be sure to allow enough time to permit them to do so. Only then might you be in a position to give constructors the information available to you, while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions. Conducting prebid and preconstruction conferences can also be valuable in this respect. Read Responsibility Provisions Closely Some client representatives, design professionals, and constructors do not realize that geotechnical engineering is far less exact than other engineering disciplines. That lack of understanding has nurtured unrealistic expectations that have resulted in disappointments, delays, cost overruns, claims, and disputes. To confront that risk, geotechnical engineers commonly include explanatory provisions in their reports. Sometimes labeled "limitations;' many of these provisions indicate where geotechnical engineers' responsibilities begin and end, to help others recognize their own responsibilities and risks. Read these provisions closely. Ask questions. Your geotechnical engineer should respond fully and frankly. Geoenvironmental Concerns Are Not Covered The personnel, equipment, and techniques used to perform an environmental study - e.g., a "phase -one" or "phase -two" environmental site assessment — differ significantly from those used to perform a geotechnical-engineering study. For that reason, a geotechnical- engineering report does not usually relate any environmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Unanticipated subsurface environmental problems have led to project failures. If you have not yet obtained your own environmental information, ask your geotechnical consultant for risk -management guidance. As a general rule, do not rely on an environmental report prepared for a different client, site, or project, or that is more than six months old. Obtain Professional Assistance to Deal with Moisture Infiltration and Mold While your geotechnical engineer may have addressed groundwater, water infiltration, or similar issues in this report, none of the engineer's services were designed, conducted, or intended to prevent uncontrolled migration of moisture - including water vapor - from the soil through building slabs and walls and into the building interior, where it can cause mold growth and material -performance deficiencies. Accordingly, proper implementation of the geotechnical engineer's recommendations will not of itself be sufficient to prevent moisture infiltration. Confront the risk of moisture infiltration by including building -envelope or mold specialists on the design team. Geotechnical engineers are not building - envelope or mold specialists. GEOPROFESSIONAL GarBUSINESS t ASSOCIATION Telephone: 301/565-2733 e-mail: info@geoprofessional.org www.geoprofessional.org Copyright 2016 by Geoprofessional Business Association (GBA). Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, is strictly prohibited, except with GBA's specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of GBA, and only for purposes of scholarly research or book review. Only members of GBA may use this document or its wording as a complement to or as an element of a report of any kind. Any other firm, individual, or other entity that so uses this document without being a GBA member could be committing negligent I Hello