The URL can be used to link to this page

Browse Search

Home My WebLink About20042655.tiff LAKOTA LAKES RANCH FINAL DRAINAGE REPORT Weld County, Colorado Prepared by: Weiland, Inc. 10395 W. Colfax Ave., Suite 350 Lakewood, CO 80215 March, 2004 2004-2655 PROFESSIONAL ENGINEER CERTIFICATION I hereby affirm that this report for the final drainage design of the Lakota Lakes Development was prepared under my direct supervision for the owners thereof and meets or exceeds the criteria set fo by Weld County. p00 REGj $ 1° William C. Klawitter, P.E. -:;t4 ~: :� State of Colorado No. 32726 ot elsi �\�� Table of Contents 1.0 INTRODUCTION 1 1.1 Site Location 1 1.2 Site Description 1 1.3 Proposed Development 2 1.4 Flood Hazard and Drainage Studies Relevant to the Site 2 2.0 HISTORIC CONDITIONS 3 _ 2.1 Historic Basins and Site Drainage 3 3.0 PROPOSED CONDTITIONS 6 3.1 On-Site Runoff 6 3.2 Off-Site Runoff 7 3.3 Detention 8 3.4 Erosion Control 8 4.0 SUMMARY 9 5.0 CONCLUSIONS 10 6.0 REFERENCES APPENDIX A— Figures - • Site Location APPENDIX B — Hydrologic Computations — • Hydrologic Zones & Design Parameters (Colorado) • Intensity Duration Frequency (IDF) Table • 1-Hour Rainfall Depth Design Chart • IDF Curves (Weld County) • Runoff Coefficients (Rural) • Runoff Coefficients (Urban) • Channel Velocity Chart • CUHP Output • Historic Runoff Computations • Developed Runoff Computations APPENDIX C — Hydraulic Computations • Culvert Nomograph • Open Channel Calculations (West Ditch, Max HW) • Open Channel Calculations (West Ditch, Full Flow Capacity) • Open Channel Calculations (Borrow Ditch, East) • Open Channel Calculations (Borrow Ditch, East 2) • Open Channel Calculations (Borrow Ditch, West) APPENDIX D — Photographs APPENDIX E — References 7.0 DRAWINGS Back Pocket of Report SHEET 1 — Watershed Basin Boundaries SHEET 2 — Centerline WCR 54 (profile) SHEET 3 — Drainage Ditch West (profile) SHEET 4 — Final Drainage and Grading Plan March, 2004 1.0 INTRODUCTION This final report has been prepared in order to fulfill the storm drainage requirements for the proposed Lakota Lakes Development as indicated by Weld County. Weld County Code indicates that the minor storm shall be considered to be the 5-year event and the major storm is considered to be the 100-year event. This report looks at the affects of all watershed basins upgradient of the proposed site. In the absence of supplied storm drainage criteria by Weld County, all drainage calculations have been performed using the procedures outlined in the Urban Storm Drainage Criteria Manual, Volume 1, June 2001. The Rational Method was used to quantify the design runoff for most of the delineated watershed basins. The largest upstream basin (OS-1, 352.2 acres) required the use of the Colorado Urban Hydrograph Procedure (CUHP) so as not to underestimate the design runoff for this watershed basin. 1.1 SITE LOCATION The proposed development is located in the northwest quarter of the northwest quarter and the southwest quarter of the northwest quarter of section 29, Township 5 North, Range 67 West of the 6th Prime Meridian. The site is roughly 3-miles east of Interstate 25; south and east of the intersection between Weld County Road (WCR) 54 and WCR15. 1.2 SITE DESCRIPTION The proposed development consists of approximately 83 acres lying adjacent the Big Thompson River. The land has been subdivided into 7 lots having a combined area of 22 acres and 4 outlots having a combined area of 61 acres. (See Vicinity Map, Appendix A.) The south outlots are currently occupied by Coulson Excavation, a gravel mining operation that is nearing the end of production. The Challenger Pits encompass approximately 28 acres south of the proposed development while the north side of the site is mostly fallow agricultural fields. The existing site topography slopes generally southwest toward the Big Thompson River. The average slope across the property is approximately 1 percent. The proposed development is bounded on the north by County Road 54, the Great Western Railroad line on the east, the Big Thompson River on the south, and a drainage ditch on the west. Lakota Lakes Final Drainage Page l of 10 March, 2004 The drainage ditch lies just inside the western edge of the property and conveys runoff from offsite through the property. The ditch is supplied via a 24"x42" oval CMP passing under WCR 54. The pipe has approximately 1-foot of cover over it that provides a maximum headwater depth of roughly 3 feet. 1.3 PROPOSED DEVELOPMENT The proposed development will consist of 7 individual housing units on each of the 7 lots in the subdivided area (lots 1 through 7). All proposed lots lie north of the Challenger gravel mining operation that will be reclaimed to become onsite ponds. The proposed lots vary in size between 2.6 acres and 4 acres and will all have frontage on the ponds within Outlot C (approx. 42 acres). The subdivision will be accessed via paved road (Lakota Lakes Road) to serve each of the 7 lots. Lakota Lakes Road is located within the bounds of Outlot A (approx. 2.3 acres). Outlot B (approx. 1.9 acres) lies in the northeast corner of the site. on the north side of the Hill and Brush Ditch. Outlot B provides for an undeveloped open space. Outlot D (approx. 17 acres) is located adjacent to the Big Thompson River on the south side of the site and provides open space to pasture livestock. 1.4 FLOOD HAZARD AND DRAINAGE STUDIES RELEVANT TO THE SITE The Federal Emergency Management Agency (FEMA) Flood Insurance Rate Map (FIRM) pertaining to this study is located in panel 615, Community panel 080266 0615 C, dated September 28, 1982. The most recent Flood Insurance Study (FIS) dated September 22, 1999 shows 500, 100, 50, and 10-year base flood elevations (BFE) for the Big Thompson within the vicinity of the development. An updated floodplain study titled "Floodplain Analysis Modeling Report for Proposed Lakota Lake Development" by Weiland, Inc. dated March 19, 2003 has been approved by Weld County as the corrected effective BFE's _ for this development. The updated floodplain study indicates that the 100- year floodplain encroaches on the southern fringe of Lots 5 through 7. The floodplain boundary appears to be located so close to the southern lot _ lines, that it will easily be avoided when locating the building pads for the affected lots. A 100-year floodplain boundary will be included on the final plat as well as notes to raise the finish floor elevation (FFE) a minimum of 1 foot above existing ground to establish a positive local drainage of storm water away from building pads. Lakota Lakes Final Drainage Page 2 of 10 March, 2004 2.0 HISTORIC CONDITIONS 2.1 HISTORIC BASINS AND SITE DRAINAGE The site's proximity to the Big Thompson River flood plain is the single most important factor in determining the storm runoff characteristics for the proposed site. Localized runoff has historically sheet flowed across the site, southwest to the river. Offsite runoff has been historically controlled for irrigation and livestock watering purposes. A visual investigation of the upstream conditions (Appendix A) provided supporting information for the computational analysis that supplements this report. All historic calculations were made using methods described in the Colorado Urban Storm Drainage Criteria Manual. Supporting calculations are provided in Appendix B. A total of four offsite watershed basins potentially affect the runoff conveyed through an existing ditch on the west side of the proposed development. All four watersheds currently have storm runoff that is highly controlled by structures that either limit flow or divert flow for irrigation and livestock watering. The engineering analysis assumed however, that none of these controlling structures affect the peak runoff from these basins. This assumption creates a very conservative approach for quantifying the runoff that affects the site. Basin OS-1 is approximately 352 acres of uncultivated agricultural field. The 1.4 mile long by 0.5 mile wide basin is bisected by a natural drainage swale that is dry for most of the year except during storms or when conveying irrigation water. The Loveland and Greeley Canal and the Farmers Ditch cross the basin near its center. Two natural depressions in the basin will pond water for livestock. The natural drainage swale conveys water under the tracks of the Union Pacific Railroad via twin trestles. The design point for the basin is approximately 600-feet downstream of this trestle. A 24-inch diameter culvert passes flow from basin OS-1 under the tracks of the Great Western Railroad to basin OS-4. _ Basin OS-2 is approximately 12.6 acres of natural grass. It lies between the Great Western and Union Pacific rail lines and is centered between WCR 54 and WCR 15. The basin conveys runoff to the southwest where it is intercepted by the rail ballast for the Great Western tracks and is directed southeast along the tracks. This ditch conveyance flows southeast until it passes under the railroad tracks via 2, 18-inch diameter CMP's that exit into basin OS-4. Basin OS-3 is approximately 8.2 acres of farm buildings, feed lot, natural grasses and lawn, as well as paved roadway. The basin conveys runoff to a single 18-inch CMP that passes accumulated ditch drainage from both o Lakota Lakes Final Drainage Page 3 of 10 March, 2004 the northeast side of the Great Western railroad tracks and the north side of WCR 54. The 18-inch CMP conveys the runoff to basin OS-4. Basin OS-4 is the recipient of all upstream runoff prior to crossing WCR 54 at the existing 42" x 24" CMP east of the intersection of WCR 15 and WCR 54. There is no visual evidence of any erosive affects at the design points for Basins OS-1, 2, or 3 as runoff enters Basin OS-4 via CMP. (See photographs.) The runoff conveyed to Basin OS-4 is captured by an irrigation control structure that allows for several options. The captured runoff can be released slowly to the farm field (OS-4), routed to the field west of WCR 15, routed south in an existing 30-inch pipe that daylights in a ditch approximately 600-feet north of the WCR 15 and WCR 54 intersection, or any combination of the above. The storm runoff remaining after the controlling affects of the upstream irrigation structures, is intercepted by the Hill and Brush Ditch or allowed to pass to the 42" x 24" CMP crossing WCR 54. The offsite basins produce a combined storm runoff rate of 19.6 cfs for the 5-year event and 363.6 cfs for the 100-year event. The Hydrologic Computation Forms provided in Appendix B, use the Rational Method to calculate the peak runoff for each basin. Since Basin OS-1 is greater than 160 acres, the Colorado Urban Hydrograph Procedure (CUHP) was -- utilized in order not to underestimate the runoff contribution larger basins. The CUHP approach indicates a peak 5-year discharge of 17.0 cfs and a peak 100-year discharge of 313 cfs for Basin OS-1. These values were used instead of the values found via the Rational Method so that the runoff was not underestimated for this large basin. The maximum flow capacity of the existing 42" x 24" CMP conveying runoff to the drainage ditch west of the site was analyzed. Maximum headwater on this structure just prior to overtopping is conservatively estimated as 3-feet of depth. This provides a HW/D ratio of 1.5. Using the Hydraulic Engineering Circular No. 5 and a conservative pipe size of 42" x 27" as well as a conservative pipe material (concrete, n = 0.010- 0.013 versus CMP, n = 0.022-0.027), the maximum conveyance through this structure is roughly 50 cfs. The nomograph used for this analysis is provided in Appendix C. Storm runoff exceeding 50 cfs will inundate the north side of the WCR 54 and WCR 15 intersection, overtopping WCR 15, and flowing west in the roadside ditch to the Big Thompson River. The longitudinal slope of WCR 54, shown on Sheet 2 in the back pocket of this report, directs storm water west, away from the site and away from the drainage ditch on the west side of the site. Lakota Lakes Final Drainage Page 4 of 10 March, 2004 The drainage ditch on the west side of the site is conservatively sized as an irregularly shaped channel. The bottom (low flow) portion of the channel is approximately 2-feet wide by 2-feet deep. Sideslopes extend from the top of the low flow portion of the channel up approximately 3-feet to a top width between berms of roughly 10-feet. Assuming a Manning "n" value for thick grass and weeds, a longitudinal channel slop of 1% and the input Q from the upstream CMP, the Manning equation indicates a flow depth of 3.6-feet. This flow is well within the banks of the ditch. The full- flowing capacity of the ditch was found to be 134 cfs. Lakota Lakes Final Drainage Page 5 of 10 March, 2004 3.0 PROPOSED CONDITIONS 3.1 ON-SITE RUNOFF All proposed development calculations were made using methods described in the Colorado Urban Storm Drainage Criteria Manual. — Supporting hydrologic calculations are provided in Appendix B. The proposed grading and drainage plans are provided with Sheets 4 and 5 in the back pockets of this report. Onsite basin S-1 will remain in its historic state as an open grassy field. Storm runoff overland flows southwest until it encounters the ditch spoils from the Hill and Brush Irrigation Ditch. The runoff then channel flows southeast, paralleling the Hill and Brush Ditch where it will exit the site at the railroad trestle of the Great Western RR. This basin produces 0.2 cfs during a 5-year storm event and 3.0 cfs during a 100-year storm. The proposed Lakota Lakes Road (Basins S-2 and S3) will include a • borrow ditch on either side of a 2% crowned surface to capture flows from the roadway. The storm runoff from the northeast side of the road sheet flows off the road to the northeast into a 2-feet deep v-ditch (borrow ditch) that conveys the water southeast. (See Sheet 4 of the Grading and Drainage Plan). This runoff combines with the off site runoff from basin OS-5 at the south end of the cul de sac. The borrow ditch will transition from a 2-feet deep v-ditch to a 2.5-feet deep v-ditch at the end of the cul de sac and will convey collected runoff along the east property boundary of the site into a wetland area south of Lot 7. The storm flow from the southwest side of the road will sheet flow into the _ 2-feet deep borrow ditch on the southwest side of the road and is conveyed southeast to a point near the south end of the cul de sac where it veers south along the west property line of Lot 7. This borrow ditch terminates in the onsite pond. Onsite runoff from Basin S-4 will sheet flow through the developed area to the southwest into the reclaimed onsite pond. The proposed lots of the site are all sloping naturally at a 1% grade to the Big Thompson River. The lots will however, be graded locally to have a 2% slope away from all building foundations. All structures located on the propose lots will have a finished floor elevation (FFE) 1-foot above the existing ground surface elevation in order to promote positive drainage away from the foundations of proposed homes. Additionally, no structure is allowed to be constructed a basement. Lakota Lakes Final Drainage Page 6 of 10 March, 2004 3.2 OFFSITE RUNOFF The offsite runoff from Basins OS-1, 2, 3, and 4, (393 acres) north of the proposed site will only affect the site insofar as a storm water conveyance of approximately 50 cfs passing the 42"x24" CMP under WCR 54. This 50-cfs flow rate is the maximum rate of conveyance that this pipe is capable of passing, given the existing physical conditions of the CMP (i.e. headwater, slope, length, and end treatments). (See Chart 3, Appendix C). A higher runoff rate will not pass this structure and the storm water surface elevation will rise upstream of the structure until overtopping of WCR 15 occurs. Flows exceeding 50 cfs are conveyed west in a roadside ditch north of WCR 54. Overtopping of WCR 54 may occur in a large storm event, however the longitudinal slope of the road to the west (toward the Big Thompson River) will direct water away from the proposed site and will find a safe overflow route through the agricultural field west of Lakota Lakes property. The existing ditch on the west side of the site is capable of handling the maximum conveyance of the 42"x24" CMP. A 50-cfs maximum conveyance from this structure produces a flow depth in the ditch of 3.6- feet. The ditch is capable of passing a 134 cfs storm flow, but will never see this magnitude of flow due to the limitations on the upstream culvert previously mentioned. Ditch cross sections are provided in Appendix C of this report. Basin OS-5 (2.2 acres) lies outside the Lakota Lakes property boundary _ on the east side of the site. The runoff from this basin (5-year = 1.5 cfs, 100-year = 7.4 cfs) will contribute to the flows captured by the borrow ditch on the northeast side of the road. The flow will combine with the runoff of onsite basin S-2 and be conveyed to the wetland area located near the southeast corner of the site. Total flow in the eastern-most borrow ditch is 4.4 cfs for the 5-year event and 16.5 cfs for the 100-year event. The ditch is sized to carry the 100-year event plus 1-foot of freeboard. • Table 3.2 below shows a summary of the amount of offsite runoff. The runoff from Basin OS-1 was determined using the CUHP method so as not to underestimate the flow. The runoff flow rates from all other basins were — determined using the rational method. Lakota Lakes Final Drainage Page 7 of 10 March, 2004 Lakota Lakes Offsite Runoff Flow(cfs) Basin Minor Major OS-1 17.0 313.0 OS-2 0.8 15.0 OS-3 0.5 11.0 OS-4 1.3 24.6 OS-5 1.5 7.4 Table 3.2— Summary of offsite flows. 3.3 DETENTION Due to the proximity of the proposed development to the Big Thompson River, storm water detention will not be required. A large gravel mining excavation will remain as an onsite pond feature. This pond will detain localized runoff, but is not intended to act as a detention facility for on or offsite flows. Runoff from the proposed site will naturally flow overland to — the onsite pond and to the river. Channelized flow from the borrow ditches and lot line swales will also be routed to the pond and a wetland area in the southeast corner of the site. 3.4 EROSION CONTROL Erosion control will be managed using best management practices set forth by the Urban Storm Drainage Criteria Manual. Any required NPDES permits shall be obtained prior to construction. Lakota Lakes Final Drainage Page 8 of 10 March, 2004 4.0 SUMMARY The summary of runoff flows for the proposed site are provided in the table below. Lakota Lakes Final Drainage Flow(cis) Basin Historic Minor Historic Major Proposed Minor Proposed Major S-1 0.2 3.0 0.2 3.0 S-2 0.1 2.9 2.9 9.2 S-3 0.1 1.4 2.7 5.8 S-4 1.7 34.5 33.3 104.9 Table 4.0—Summary of historic and proposed site flows Lakota Lakes Final Drainage Page 9 of 10 March, 2004 5.0 CONCLUSIONS Historically, the storm runoff from offsite basins north of the site was highly controlled by irrigation structures. This fact remains unchanged today. Although several large drainage basins upgradient of the proposed site theoretically produce 364 cfs of storm flow for the 100-year event, there is no physical _ evidence of drainage channels to carry this kind of flow or the erosive affects produced by this kind of flow. (Photographs are provided in Appendix D.) We therefore must conclude that most if not all of the storm water produced by these offsite basins is captured for irrigation or livestock watering. This report assumes that this situation is not the case and that all of the runoff — must be accounted for as it affects the site. An analysis of the only culvert conveying storm flows under WCR 54 indicates that the existing allowable headwater will limit flows crossing the road to roughly 50 cfs. Flows exceeding this rate will rise onto WCR 54 and sheet flow west, as well as overtop WCR 15, finding the roadside ditch that will route flows safely away from the site and to the Big Thompson River. The existing ditch on the west side of the proposed site has sufficient capacity to handle the maximum 50 cfs flow from the 42"x24" CMP and convey this flow to — the river with no adverse affect to the proposed site or surrounding area. The onsite terrain of the proposed site slopes generally southwest toward the river. The historic flow pattern for the site will be maintained. An updated floodplain study for the site indicates that none of the lots are significantly impacted by the 100-year floodplain boundary. The boundary encroaches on the southern fringes of Lots 6 and 7 where no building will occur. A 100-year rise in river elevation or a 100-year storm event occurring at the site will not cause inundation of any proposed lots or structures built on those lots. Runoff rates will increase with the development of the site. The proposed development will not however impede natural water courses. Peak flows are controlled by borrow ditches on either side of the site access road that directs collected runoff to an onsite pond, a wetland area, and the river to the south. _ Localized grading around proposed building footprints is recommended. The finished floor elevation of each building will be raised one foot to promote positive drainage away from each building foundation. By providing a raised finished floor elevation, a drainage swale will be established at each lot line that will convey roof and gutter drainage away from the homes to the onsite pond, wetland area, and river. Annual maintenance of the existing ditch on the west side of the site is recommended to remove the seasonal growth of grasses and weeds and maintain the existing ditch berms. _ Lakota Lakes Final Drainage Page 10 of 10 APPENDIX A FIGURES i koeni�� r) - 1.9 2 0 J.. __ ... eRvsrr , ...- ... .. _ •............. i .„ L . i . ! .....is, • . , i --., _.• L _ _ ii,t --.•.__ _ ,.4809 V// � � '' t- • -r // A -\ 2 9 r VfA4*2• 0 0 iii .�.�� ., ` ./ i r 4-838 / /t/ i a ,:.. •O a �.J L �I Hardman i, i i ° 'i T- WE!i!anhiirTc114 Erwiranrrynntel& VICINITY MAP 2003-002 �"� !0355 W.Calf..Silt,ErseWpwrtng 223 �r-1 OOO� Lal4PWPOIS GO ewes ph 303-4.38-0951 LAKOTA LAKES DEVELOPMENT fir 303_..38 , W W W. �,.rf.,c r APPENDIX B HYDROLOGIC CALCULATIONS _ ^ HYDROLOGIC ZONES IN THE STATE OF COLORADO Identify the hydrologic zone for your project site: Zone 1, 2, 3 or 4. Geographic Regions in the State of Colorado Zone 1: South Platte, Republican, Arkansas, and Cimarron River Basins Zone 2: San Juan, Upper Rio Grande, Upper Colorado, and Gunnison River Basins, and Green River Basin below Confluence with the Yampa River — Zone 3: Yampa and Green River Basins above confluence of Green and Yampa Rivers Zone 4: North Platte River Basins Definition of these four zones is below: I 4 i 344 j +) ^ • 4.4 i e 3.4 COLORADO rtre :c+ .ea ww w roe Design Parameters for Various Zones Zone 1- hr 2- hr 3- hr a b c d e f m n r q 1 0.2180 0.7090 0.0000 1.8970 0.4390 -0.0080 0.3420 0.6580 0.5970 0.4030 2 -0.0110 0.9420 0.0000 0.4940 0.7550 0.0000 0.3410 0.6590 0.5690 0.4310 3 0.0190 0.7110 0.0010 0.3380 0.6700 0.0010 0.2500 0.7500 0.4670 0.5330 4 0.0280 0.8900 0.0000 0.6710 0.7570 -0.0030 0.2500 0.7500 0.4670 0.5330 Duration in minutes 5.00 10.00 15.00 30.00 Ratio to one-hr Depth 0.29 0.45 0.57 0.79 UD-Rainzone Design Storms, ZONES 3/17/2004, 10:24 AM — IDF TABLE FOR ZONE ONE IN THE STATE OF COLORADO Zone 1:South Platte, Republican, Arkansas, and Cimarron River Basins Project: Lakota Lakes Enter the elevation at the center of the watershed: Elev= 4,800 (input) 1. Precipitation-Duration-Frequency Table Enter the 6-hour and 24-hour rainfall depths from the NOAA Atlas 2 Volume III in rightmost blue columns Return Rainfall Depth in Inches at Time Duration Period 5-mm 10-min 15-min 30-mM 1-hr 2-hr 3-hr 6-hr 24-hr (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) output output output output output output output input input 2-yr 0.29 0.45 0.56 0.78 0.99 1.13 1.23 1.40 1.80 5-yr 0.40 0.63 0.80 1.10 1.40 1.53 1.64 1.80 2.40 10-yr 0.48 0.75 0.95 1.31 1.66 1.85 1.98 2.20 2.80 25-yr 0.58 0.90 1.14 1.58 2.00 2.24 2.42 2.70 3.40 50-yr 0.67 1.04 1.32 1.83 2.32 2.52 2.67 2.90 3.80 100-yr 0.76 1.18 1.49 2.07 2.62 2.88 3.08 3.40 4.60 Note: Refer to NOAA Atlas 2 Volume Ill isopluvial maps for 6-hr and 24-hr rainfall depths. 2. Rainfall Intensity-Duration-Frequency Table Return Rainfall Intensity in Inches Per Hour at Time Duration Period 5-min 10-mM 15-min 30-mM 1-hr 2-hr 3-hr 6-hr 24-hr (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) output output output output output output output output output 2-yr 3.45 2.67 2.26 1.56 0.99 0.57 0.41 0.23 0.08 5-yr 4.86 3.77 3.18 2.21 1.40 0.77 0.55 0.30 0.10 10-yr 5.79 4.49 3.79 2.63 1.66 0.92 0.66 0.37 0.12 25-yr 6.96 5.40 4.56 3.16 2.00 1.12 0.81 0.45 0.14 50-yr 8.06 6.26 5.28 3.66 2.32 1.26 0.89 0.48 0.16 100-yr 9.10 7.06 5.96 4.13 2.62 1.44 1.03 0.57 0.19 UD-Rainzone Design Storms, Z-1 3/17/2004, 10:23 AM One-Hour Rainfall Depth Design Chart 3.00 — 2.62 • 2.50 2.32 • ZOO 2.00 ♦ -- - N d L U 1.66 • m 1.50 A 1.40 • C e 1.00 0.99 0.50 0.00 - 2-yr 5-yr 10-yr 25-yr 50-yr ..-.... . . 100 yr Return Period UD-Rainzone Design Storms, Z-1 3/17/2004, 10:23 AM I Weld County Rainfall Intensity/Duration/Frequency Curves 10 I ' I 9 — I i 8 -- t -- I — L in 7 r t V C 6 - - r —2-Year \ f ---5-Year 10-year Z5 t � — i —25-year W 50 Year I 4 -- 100-Year J J ., Q I U. 3 r I Z , CZ i I 2 f 1 I I_ � I I I I I l 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 STORM DURATION (minutes) - DRAINAGE CRITERIA MANUAL RUNOFF •- TABLE 3-1 (42) RECOMMENDED .RUNOFF COEFFICIENTS AND PERCENT IMPERVIOUS - LAND USE OR PERCENT FREQUENCY SURFACE CHARACTERISTICS IMPERVIOUS 2 5 10 100 - Business: Commercial Areas 95 .87 .87 .88 .89 Neighborhood Areas 70 . 60 .65 .70 .80 Residential: Single-Family * .40 .45 .50 .60 - Multi-Unit (detached) 50 .45 .50 .60 .70 Multi-Unit (attached) 70 .60 .65 .70 .80 ' 1/2 Acre Lot or Larger * .30 .35 .40 .60 Apartments 70 .65 .70 .70 .80 Industrial : - Light Areas 80 . 71 . 72 .76 .82 Heavy Acres 90 . 80 .80 .85 .90 - Parks, Cemetaries: 7 . 10 . 18 .25 .45 Playgrounds: 13 . 15 .20 .30 .50 - Schools: 50 .45 .50 .60 .70 Railroad Yard Areas 20 .20 .25 35 .45 Undeveloped Areas: Historic Flow Analysis- 2 (See "Lawns") Greenbelts, Agricultural - Offsite Flow Analysis 45 .43 .47 .55 .65 (when land use not defined) Streets: Paved 100 .87 .88 .90 .93 - Gravel (Packed) 40 .40 .45 .50 .60' Drive lks: 96 .87 .87 88 .89 Roofs: 90 .80 .85 - 90 90 Lawns Sandy Soil 0 .00 .01 .05 .20 Lawns Cla ey Soil 0 .05 . 15 .25 .50 - NOTE: .These Rational Formula coefficients may not be valid for large basins. - *See Figure 2-1 for percent impervious. Runoff Coefficients for Rational Equation Table Runoff Coefficients for Rational Equation* Hydrologic Soil Group Land Use, Crop, and Management A B C D CULTIVATED, with crop rotations Row Crops, poor management .55 .65 .70 .75 Row Crops, conservation mgmt .50 .55 .65 .70 Small Grains, poor management .35 .40 .45 .50 Small Grains, conservation mgmt .20 .22 .25 .30 Meadow .30 .35 .40 .45 PASTURE, permanent w/moderate grazing . 10 .20 .25 .30 WOODS, permanent, mature, no grazing .06 .13 .16 .20 Urban residential 30 percent of area impervious . 30 .40 .45 .50 70 percent of area. impervious .50 .60 .70 .80 -- Hydrologic Soil Group Descriptions: A -- Well-drained sand and gravel; high permeability. B -- Moderate to well-drained; moderately fine to moderately coarse texture; moderate permeability. — C -- Poor to moderately well-drained; moderately fine to fine texture; slow permeability. D-- Poorly drained, clay soils with high swelling potential, permanent high water table, claypan,or shallow soils over nearly impervious layer(s). DRAINAGE CRITERIA MANUAL RUNOFF 50 30 / / i 20 3 r w o A — a. 10 e — o > w v v V 0 3. t 0.— 0 �i �t oe byre co N 5 ? �" ' 40 3r V V W A. .1 c! y¢ 470o O y yr yr' ? 0 a 4' 4 D 4- .4.. C o =rye V let O 3 o a. yr cc 2 r. ro S W Ye 0 R t-- 4QQ Cr a r �o S — 1 a� .5 .1 .2 .3 .5 1 2 3 5 10 20 VELOCITY IN FEET PER SECOND - FIGURE 3-2. ESTIMATE OF AVERAGE FLOW VELOCITY FOR - USE WITH THE RATIONAL FORMULA. * MOST FREQUENTLY OCCURRING "UNDEVELOPED" - LAND SURFACES IN THE DENVER REGION. REFERENCE: "Urban Hydrology For Small Watersheds" Technical .— Release No. 55, USDA, SCS Jan. 1975. 5-1-84 URBAN DRAINAGE & FLOOD CONTROL DISTRICT OS-1(10yr-100yr) 1 U.D.F.C.D. CUHP RUNOFF ANALYSIS EXECUTED ON DATE 3/ 5/2004 AT TIME 9:48 CUHPF/PC RELEASE 2A (32-BIT VER) SEPTEMBER 10, 1998 PRINT OPTION NUMBER SELECTED FOR THIS BASIN IS 1 Lakes Ranch Development _ BASIN ID: 1 -- BASIN COMMENT: OS-1 AREA LENGTH OF BASIN DIST TO CENTROID IMPERV. AREA SLOPE UNIT DURATION (SQMI) (MI) (MI) (PCT) (FT/FT) (MIN) . 55 1.44 .74 2.00 .0244 5.00 COEFFICIENT COEFFICIENT (REFLECTING TIME TO PEAK) (RELATED TO PEAK RATE OF RUNOFF) .156 .305 - THIS BASIN USES TRADITIONAL DRAINAGE PRACTICES FRACTION OF PERVIOUS FRACTION OF IMPERVIOUS - AREA RECEIVING AREA DIRECTLY CONNECTED IMPERVIOUS DRAINAGE TO DRAINAGE SYSTEM ( DEFAULT ) ( DEFAULT ) R= .06 D= .04 CALCULATED UNIT HYDROGRAPH TIME TO PEAK PEAK RATE OF RUNOFF UNIT HYDROGRAPH PEAK VOLUME OF RUNOFF (MIN) (CFS/SQMI) (CFS) (AF) 25.94 500.09 275.05 29.33 WIDTH AT 50 = 60. MIN. WIDTH AT 75 = 31. MIN. K50 = .26 K75 = .35 RAINFALL LOSSES INPUT W/ BASIN DATA MAX. PERVIOUS RET. = .60 IN. MAX. IMPERVIOUS RET. = .30 IN. INFILTRATION = 3.00 IN./HR. DECAY = .00180/SECOND FNINFL = .50 IN./HR. TIME UNIT TIME UNIT TIME UNIT - HYDROGRAPH HYDROGRAPH HYDROGRAPH 0. 0. 90. 100. 180. 23. - 5. 46. 95. 92. 185. 22. 10. 131. 100. 85. 190. 20. 15. 207. 105. 79. 195. 18. 20. 257. 110. 73. 200. 17. 25. 275. 115. 67. 205. 16. 30. 269. 120. 62. 210. 14. 35. 249. 125. 57. 215. 13. 40. 226. 130. 53. 220. 12. - 45. 209. 135. 48. 225. 11. 50. 195. 140. 45. 230. 10. 55. 181. 145. 41. 235. 10. 60. 167. 150. 38. 240. 9. - 65. 153. 155. 35. 245. 8. Page 1 OS-1(10yr-100yr) 70. 139. I 160. 32. I 250. 8. I 75. 128. I 165. 30. I 255. 0. I 80. 118. I 170. 28. I 0. 0. I 85. 109. I 175. 25. I 0. 0. I 1 BASIN ID: 1 -- BASIN COMMENT: OS-1 **** STORM NO. = 1 **** DATE OR RETURN PERIOD = 5-year 1===TOTAL PERV AREA==I=DIR CON IMP AREA--I RECEIVING PERV AREA 1 98.% OF TOTAL I 0.% OF TOTAL I 6.% OF TOTAL TIME INCR I MAX DEP EFF %EFFIDEP LOSS EFF %EFFIINCR MAX DEP WQCV EFF %EFFITOTAL MIN PREC I INF STOR PREC PRECISTOR PREC PRECIPREC INF STOR STOR PREC PRECI 5. .03 I .20 .00 .00 .00 1 .03 .00 .00 .00 I .03 .20 .00 .00 .00 .00 I - .000 10. .05 I .13 .00 .00 .00 1 .05 .00 .00 .00 I .05 .13 .00 .00 .00 .00 .000 15. .12 I .10 .03 .00 .00 1 .12 .00 .00 .00 I .12 .10 .03 .00 .00 .00 _ .000 20. .21 I .07 .14 .00 .00 1 .10 .01 .11 .00 I .25 .07 .18 .00 .00 .00 .000 25. .35 I .06 .29 .00 .00 1 .00 .02 .33 .00 I .46 .06 .40 .00 .01 .00 I _ .001 30. .18 I .05 .13 .00 .00 1 .00 .01 .17 .00 I .24 .05 .00 .00 .19 .01 .011 35. .08 I .05 .01 .02 .02 1 .00 .00 .08 .00 I .11 .05 .00 .00 .06 .00 I .022 40. .06 I .05 .00 .02 .02 1 .00 .00 .06 .00 I .08 .05 .00 .00 .04 .00 .017 45. .05 I .04 .00 .01 .01 1 .00 .00 .05 .00 I .07 .04 .00 .00 .02 .00 .007 50. .05 I .04 .00 .01 .01 1 .00 .00 .05 .00 I .07 .04 .00 .00 .02 .00 I .008 55. .04 I .04 .00 .00 .00 1 .00 .00 .04 .00 I .06 .04 .00 .00 .01 .00 I .001 60. .04 I .04 .00 .00 .00 1 .00 .00 .04 .00 I .06 .04 .00 .00 .01 .00 1 .001 65. .04 I .04 .00 .00 .00 1 .00 .00 .04 .00 I .06 .04 .00 .00 .01 .00 I .001 70. .04 I .04 .00 .00 .00 1 .00 .00 .04 .00 1 .06 .04 .00 .00 .01 .00 I .001 75. .04 I .04 .00 .00 .00 1 .00 .00 .03 .00 I .05 .04 .00 .00 .00 .00 I .000 80. .03 I .04 .00 .00 .00 1 .00 .00 .03 .00 I .04 .04 .00 .00 .00 .00 I .000 85. .03 I .04 .00 .00 .00 1 .00 .00 .03 .00 I .04 .04 .00 .00 .00 .00 I .000 - 90. .03 1 .04 .00 .00 .00 1 .00 .00 .03 .00 I .04 .04 .00 .00 .00 .00 I .000 95. .03 I .04 .00 .00 .00 1 .00 .00 .03 .00 I .04 .04 .00 .00 .00 .00 I .000 100. .02 I .04 .00 .00 .00 1 .00 .00 .02 .00 I .03 .04 .00 .00 .00 .00 I .000 105. .02 I .04 .00 .00 .00 1 .00 .00 .02 .00 I .03 .04 .00 .00 .00 .00 I .000 110. .02 I .04 .00 .00 .00 1 .00 .00 .02 .00 I .03 .04 .00 .00 .00 .00 I .000 115. .02 I .04 .00 .00 .00 1 .00 .00 .02 .00 I .03 .04 .00 .00 .00 .00 I .000 120. .02 I .04 .00 .00 .00 1 .00 .00 .02 .00 I .02 .04 .00 .00 .00 .00 I Page 2 OS-1(l0yr-100yr) .000 1.62 .60 .05 .05 .30 .07 1.25 .00 2.05 .60 .00 .40 .02 .070 TIME STORM TIME STORM TIME STORM - (MIN.) HYDROGRAPH (MIN.) HYDROGRAPH (MIN.) HYDROGRAPH 5. 0. 80. 15. 155. 4. 10. 0. 85. 14. 160. 4. 15. 0. 90. 13. 165. 4. 20. 0. 95. 12. 170. 3. 25. 0. 100. 11. 175. 3. 30. 1. 105. 10. 180. 3. 35. 3. 110. 9. 185. 3. 40. 6. 115. 8. 190. 2. 45. 10. 120. 8. 195. 2. 50. 14. 125. 7. 200. 2. - 55. 16. 130. 7. 205. 2. 60. 17. 135. 6. 210. 2. 65. 17. 140. 6. 215. 2. 70. 16. 145. 5. 220. 2. - 75. 16. 150. 5. 225. 1. TOTAL PRECIP. = 1.62 (1-HOUR RAIN = 1.40) EXCESS PRECIP. = .070 - --� INCHES VOLUME OF EXCESS PRECIP = 2.06 ACRE-FEET PEAK Q = 17. CFS TIME OF PEAK = 60. MIN. INFILT.= 3.00 IN/HR DECAY = .00180 FNINF = . 50 IN/HR - MAX.PERV.RET.= .60 IN. MAX.IMP.RET.= .30 IN. 1 BASIN ID: 1 -- BASIN COMMENT: OS-1 **** STORM NO. = 2 **** DATE OR RETURN PERIOD = 10-year — I===TOTAL PERV AREA==I=DIR CON IMP AREA--I RECEIVING PERV AREA I I 98.% OF TOTAL I 0.% OF TOTAL I 6.% OF TOTAL I TIME INCR I MAX DEP EFF %EFFIDEP LOSS EFF %EFFIINCR MAX DEP WQCV EFF %EFFITOTAL - MIN PREC I INF STOR PREC PRECISTOR PREC PRECIPREC INF STOR STOR PREC PRECI 5. .03 I .20 .00 .00 .00 1 .03 .00 .00 .00 I .03 .20 .00 .00 .00 .00 .000 10. .06 I .13 .00 .00 .00 1 .06 .00 .00 .00 I .06 .13 .00 .00 .00 .00 - .000 15. .14 1 .10 .04 .00 .00 1 .14 .00 .00 .00 1 .14 .10 .04 .00 .00 .00 .000 20. .25 I .07 .18 .00 .00 1 .07 .01 .17 .00 I .31 .07 .23 .00 .00 .00 - .000 25. .41 I .06 .35 .00 .00 1 .00 .02 .39 .00 1 .55 .06 . 33 .00 .17 .01 .010 30. .20 1 .05 .03 .12 .11 1 .00 .01 .19 .00 I .26 .05 .00 .00 .21 .01 - .121 35. .09 I .05 .00 .05 .04 1 .00 .00 .09 .00 I .12 .05 .00 .00 .08 .00 .046 `1 40. .07 I .05 .00 .03 .02 1 .00 .00 .07 .00 I .09 .05 .00 .00 .05 .00 - .027 Page 3 ,.., 05-1(l0yr-100yr) 45. .06 I .04 .00 .02 .02 .00 .00 .06 .00 I .08 .04 .00 .00 .04 .00 I .020 50. .05 I .04 .00 .01 .01 1 .00 .00 .05 .00 I .07 .04 .00 .00 .03 .00 I .011 55. .05 I .04 .00 .01 .01 .00 .00 .05 .00 I .07 .04 .00 .00 .03 .00 I _ .012 60. .05 I .04 .00 .01 .01 1 .00 .00 .05 .00 I .07 .04 .00 .00 .03 .00 I .012 65. .05 I .04 .00 .01 .01 .00 .00 .05 .00 I .07 .04 .00 .00 .03 .00 I _ .012 70. .05 I .04 .00 .01 .01 1 .00 .00 .05 .00 I .07 .04 .00 .00 .03 .00 I .012 75. .05 I .04 .00 .01 .01 1 .00 .00 .05 .00 I .07 .04 .00 .00 .03 .00 I _ .012 80. .04 I .04 .00 .00 .00 1 .00 .00 .04 .00 I .06 .04 .00 .00 .01 .00 I .001 85. .03 I .04 .00 .00 .00 1 .00 .00 .03 .00 I .04 .04 .00 .00 .00 .00 I .000 90. .03 I .04 .00 .00 .00 1 .00 .00 .03 .00 I .04 .04 .00 .00 .00 .00 I .000 95. .03 I .04 .00 .00 .00 1 .00 .00 .03 .00 I .04 .04 .00 .00 .00 .00 I _ .000 100. .03 I .04 .00 .00 .00 1 .00 .00 .03 .00 I .04 .04 .00 .00 .00 .00 I .000 105. .03 I .04 .00 .00 .00 1 .00 .00 .03 .00 I .04 .04 .00 .00 .00 .00 I _ .000 110. .03 I .04 .00 .00 .00 1 .00 .00 .03 .00 I .04 .04 .00 .00 .00 .00 I .000 115. .03 I .04 .00 .00 .00 1 .00 .00 .03 .00 I .04 .04 .00 .00 .00 .00 I .000 _ 120. .02 I .04 .00 .00 .00 1 .00 .00 .02 .00 I .03 .04 .00 .00 .00 .00 I .000 1.92 .60 .27 .25 .30 .08 1. 54 .00 2.45 .60 .00 .73 .04 .295 TIME STORM TIME STORM TIME STORM (MIN.) HYDROGRAPH (MIN.) HYDROGRAPH (MIN.) HYDROGRAPH - 5. 0. 100. 46. 195. 10. 10. 0. 105. 43. 200. 9. 15. 0. 110. 39. 205. 8. - 20. 0. 115. 36. 210. 8. 25. 0. 120. 34. 215. 7. 30. 7. 125. 31. 220. 7. 35. 20. 130. 28. 225. 6. - 40. 35. 135. 26. 230. 6. 45. 48. 140. 24. 235. 5. 50. 56. 145. 22. 240. 5. 55. 61. 150. 21. 245. 4. - 60. 62. 155. 19. 250. 4. 65. 61. 160. 17. 255. 4. 70. 60. 165. 16. 260. 3. 75. 60. 170. 15. 265. 3. - 80. 59. 175. 14. 270. 3. 85. 57. 180. 13. 275. 3. 90. 54. 185. 12. 280. 2. 95. 50. 190. 11. 285. 1. Page 4 OS-1(10yr-100yr) TOTAL PRECIP. = 1.92 (1-HOUR RAIN = 1.66) EXCESS PRECIP. = .295 INCHES VOLUME OF EXCESS PRECIP = 8.67 ACRE-FEET PEAK Q = 62. CFS TIME OF PEAK = 60. MIN. INFILT.= 3.00 IN/HR DECAY = .00180 FNINF = .50 IN/HR MAX.PERV.RET.= .60 IN. MAX.IMP.RET.= .30 IN. 1 BASIN ID: 1 -- BASIN COMMENT: OS-1 *** STORM NO. = 3 **** DATE OR RETURN PERIOD = 100-year 1===TOTAL PERV AREA==I=DIR CON IMP AREA--I RECEIVING PERV AREA I I 98.% OF TOTAL I 0.% OF TOTAL I 6.% OF TOTAL I TIME INCR I MAX DEP EFF %EFFIDEP LOSS EFF %EFFIINCR MAX DEP WQCV EFF %EFFITOTAL MIN PREC I INF STOR PREC PRECISTOR PREC PRECIPREC INF STOR STOR PREC PRECI 5. .03 I .20 .00 .00 .00 1 .03 .00 .00 .00 I .03 .20 .00 .00 .00 .00 I .000 10. .08 I .13 .00 .00 .00 1 .08 .00 .00 .00 I .08 .13 .00 .00 .00 .00 I .000 15. .12 I .10 .02 .00 .00 .12 .00 .00 .00 I .12 .10 .02 .00 .00 .00 I .000 20. .21 I .07 .14 .00 .00 1 .07 .01 .13 .00 I .25 .07 .18 .00 .00 .00 I .000 25. .37 I .06 .31 .00 .00 1 .00 .02 .35 .00 I .49 .06 .39 .00 .03 .00 I .002 _ 30. .65 I .05 .13 .47 .44 1 .00 .03 .62 .00 I .87 .05 .00 .00 .82 .05 .481 I 35. .37 I .05 .00 .32 .29 1 .00 .02 .35 .00 I .49 .05 .00 .00 .44 .02 .319 I 40. .21 I .05 .00 .16 .15 1 .00 .01 .20 .00 I .28 .05 .00 .00 .23 .01 I .165 45. .16 I .04 .00 .12 .11 1 .00 .01 .15 .00 I .22 .04 .00 .00 .17 .01 I .119 50. .13 I .04 .00 .09 .08 1 .00 .01 .12 .00 I .17 .04 .00 .00 .13 .01 .089 I 55. .10 I .04 .00 .06 .06 1 .00 .01 .10 .00 I .14 .04 .00 .00 .10 .01 .063 I 60. .10 I .04 .00 .06 .06 1 .00 .01 .10 .00 I .14 .04 .00 .00 .10 .01 06 I 65. .10 I .04 .00 .06 .06 1 .00 .01 .10 .00 I .14 .04 .00 .00 .10 .01 .064 I 70. .05 I .04 .00 .01 .01 1 .00 .00 .05 .00 I .07 .04 .00 .00 .03 .00 I - .011 75. .05 I .04 .00 .01 .01 1 .00 .00 .05 .00 I .07 .04 .00 .00 .03 .00 I .011 80. .03 I .04 .00 .00 .00 1 .00 .00 .03 .00 I .04 .04 .00 .00 .00 .00 .000 I 85. .03 I .04 .00 .00 .00 1 .00 .00 .03 .00 I .04 .04 .00 .00 .00 .00 .000 I 90. .03 I .04 .00 .00 .00 1 .00 .00 .03 .00 I .04 .04 .00 .00 .00 .00 I - .000 95. .03 I .04 .00 .00 .00 1 .00 .00 .03 .00 I .04 .04 .00 .00 .00 .00 .000 I 100. .03 I .04 .00 .00 .00 1 .00 .00 .03 .00 I .04 .04 .00 .00 .00 .00 I - .000 105. .03 I .04 .00 .00 .00 1 .00 .00 .03 .00 I .04 .04 .00 .00 .00 .00 I „ .000 110. .03 I .04 .00 .00 .00 1 .00 .00 .03 .00 I .04 .04 .00 .00 .00 .00 I — .000 Page 5 05-1(l0yr-100yr) 115. .03 I .04 .00 .00 .00 1 .00 .00 .03 .00 I .04 .04 .00 .00 .00 .00 I - .000 120. .03 I .04 .00 .00 .00 1 .00 .00 .03 .00 I .04 .04 .00 .00 .00 .00 I .000 3.03 .60 1.37 1.27 .30 .14 2.59 .00 3.92 .60 .00 2.17 .12 1.389 TIME STORM TIME STORM TIME STORM - (MIN.) HYDROGRAPH (MIN.) HYDROGRAPH (MIN.) HYDROGRAPH 5. 0. 105. 196. 205. 39. 10. 0. 110. 181. 210. 36. - 15. 0. 115. 166. 215. 33. 20. 0. 120. 153. 220. 30. 25. 0. 125. 141. 225. 28. 30. 22. 130. 130. 230. 26. _ 35. 78. 135. 120. 235. 24. 40. 150. 140. 111. 240. 22. 45. 218. 145. 102. 245. 20. 50. 269. 150. 94. 250. 19. - 55. 299. 155. 87. 255. 17. 60. 312. 160. 80. 260. 16. 65. 313. 165. 74. 265. 15. 70. 309. 170. 68. 270. 14. 75. 301. 175. 63. 275. 13. - 80. 288. 180. 58. 280. 8. 85. 271. 185. 54. 285. 5. 90. 252. 190. 49. 290. 4. 95. 232. 195. 46. 295. 3. 100. 213. 200. 42. 300. 2. TOTAL PRECIP. = 3.03 (1-HOUR RAIN = 2.62) EXCESS PRECIP. = 1.389 INCHES VOLUME OF EXCESS PRECIP = 40.75 ACRE-FEET PEAK Q = 313. CFS TIME OF PEAK = 65. MIN. INFILT.= 3.00 IN/HR DECAY = .00180 FNINF = . 50 IN/HR - MAX.PERV.RET.= .60 IN. MAX.IMP.RET.= .30 IN. Page 6 HYDROLOGIC COMPUTATION FORM Historic Condition (Rational Method) Location: Lakota Lakes Ranch Development Computed by: WCK Checked by: WCK Date: 3/17/2004 Design Storm: 5-yr Sub-Basin Data _ Runoff Coefficient Overland Time(Ti) Travel Time(Tt) Tc Check Runoff ic- 05 2 o _8 E c c, o o a a U on U U b c m £ - = c c E C O J CL ~ CO o lY 0 o 'CO C, a, a) al .c... Ti) T + c co U O `U U U .C i- J 5 I- 'y a a 'in A E a, Co N a • Cl COa R d 0 11 N J l0 m ia ia l0 8 o O O O O a yo L O N U o o C N m Design Pt. m C 0 O O , O O O .j co F O co > it I— I— , i— it S a a (acres) (acres) (feet) (%) (min.) , (feet) (%) (feet/sec) (min.) (min.) (feet) (minj jmin.) , (in/hour) (cfs) (cfs) Q-1 OS-1 352.24 35224 3.Q01 = - 0.02 - 0.06, < e'021° - 1 = 704, 300 :-- 2.0 - - :':26.7 6080 3 2d 0.7, 144.8 171.8-- F. 6380 ..el 45.4: 45.4 X1.70 120 Iret,17.0 .0-2 OS-2 ° 12.57 364.81 '0.01 -0.02 X0.06 - e 0.21- _n. 0.25 -:; 300 "3.1 23.1 _ 1054 1.2 0.8 23.4 -46.5= - 1354, %4'17.5 '".'. ` 17.5' ::300 =0.8 .--,--4 0-3 OS-3 822 373.03 `?0.01 - 0.02 b= 0.06-' 0.21 0.16 300 5.6 1t0_ 253 - 4.3 _0.8 5.3 24.2 <"553 13.1 13.1 = '330 " =0.5 , 0-4 0S-4 20.19 393.22 < 0.01 0.02 0:06 0,21 0.40 300 5.0 19.7 830 1.9' 0.9 15.4; 35.1 1130 4:- 16.3 16.3 3.10 - `1.3 t'_- . 1 S-I 2.30 2.30 0.01 0.02 ' - `,0.06 0.21 -10.05 142 3.5 15.3 516 1.0 0.4 . :21.5 36.8: 658' = 43.7 13.7 . 3.30 0.2 2 S-2 2.50 --7 2.50 '0.01 a- 0.02 _ . "0.06 `0.21 0.05 34 = - 2.0 - t0 1392 1.0 " .---1.0_ 232, 32.2 "1426r -'-17.9 17.9 - 2.90 *'='0.1 3 S-3 1.20 3.70 '0.01 0.02 0.06 021 ' 0.02: 30' : 2.0 8.5, 1392, ` 1.0 `- 1.0 23.2` 31.7 1422' s 'x-`-17.9 17.9 2.90 701 i 4 OS-5 2.20 5.90 >0.01 0.02 0.06 ' 021 `0.04, 63 e 1.0 15.4 523 `1.0 « 1.0_ 8.7,- 24.1 :=6863-:-'-- 13.3 13.3 3.3 0.1 5 S-4 26.10 26.10 0.01 0.02 0.06 021 0.52 300 1.0 33.7 295 1.0 1.0_ 4.9 38.6- -'595-17‘ : :13.3 - 13.3 33 1.7 427.52 F:tProject DatalLand Development Projects!Ebel\RationalDesignQ(Histonc).x/s 3/17/2004 8:11 AM HYDROLOGIC COMPUTATION FORM Historic Condition (Rational Method) Location: Lakota Lakes Ranch Development Computed by: WCK Checked by: WCK Date: 3117/2004 Design Storm: 100-yr Sub-Basin Data Runoff Coefficient Overland Time(Ti) Travel Time(Tt) Tc Check Runoff X N N is c 2 o 8 E Of co a_ O O_ 0 U U 0 U o o v rn + ra D m E m d + m i.T. rt U v v v r a) c m H J J r .N d a o fu E m m ta o c a to 0. 0 11 m H A m at at co O 0 0 0 0 Q 0 .c ° ) o o O C m 0 Design Pt. m ¢ 0 ti 0 ci 0 ci -4 CO I- 0 CO > 1= F- F F- iL c a a (acres) (acres) (feet) (%) (min.) (feet) (%) (feet/sec) (min.) (min.) (feet) (min.) (min.) (in/hour) (cfs) (cfs) 4/4034 .- . 06,-1-1,-, re 352.24.,,. 352.24. 0.01- =ES-02 ::.t. 0.06 X0.21 ?, 73.97 U.' 300 . . .. 2.0 - 26.7 6080E ` 2.4 - 0.7 -::4-4-4144.8. 171.5; " 6380 x45.4--J5--,45.4:0 3.30 r, 244.1 . 313.0 ,0.2 `': 0S-2 x,'12.57 ,-.' 364.81 ,.=4401 rt..0,0/ 0.06 41.21 . 2.64 300 3.1 23;1 -21054:":"/--. - 1.6:,''''f,-.."....-/0.8, /4'23.41--;;---7----/-46.5 1354: ,_';'-47.5` f=17.5 -r°5.70 . `- -15.0 . 1,"-_-,-,e,- t'.0-3.a OS-3 : '__-8,22 37303 .6.01 , 0.02 0.06 0.21 1.73 300 5.6 .19.0 F,253 13 0.8 r. 5.3 ,24.2 °- 553; 131 - 13.1'` 6.40` 11.0 0-4 ._ -OS-4 20.19 393.22 0.01 .)-k -0.02 4- . 0.06 ` . 0.21 . 4.24 300 5.0 19.7 .'2"."8304,2 1.9. ` . 0.9 r,1-15.C12)`.,.,'4'.:•:,:::::35.1'- 1130` ' .16.3 " 16.3;.- 5.80` ' 24.6 -? 1 ,`4 `"2 S-1 2.30;'"`-) =2.30 ':0.01 k=0.02 - 0.06 0.21 0A8 142 3.5 `15.3` ." . 516 r ^. 1.0 :04 . 21.5 ti 36.8 658 13.7 -_. ..13.7 6.20 - - 3.0=-. Z ^",: --- 52-_ _ 2.50 . ::2.50'..a,01---74;a.02 E E. 0.06 0.21E!. . 70.53`, x34 2.0 . ,.-9n ,4- -1392 -... '-- 1.0 1.0 . i-232,.a: 32.2.- 1426` -.17.9 . 1.17.9'_" ,,' :5.60' x2.9: `.'3 -- S-3 4:1.20 ^ =3.7017 0.01 . ;0.02 = : OA6' -0.21 .: , . 0.25 <-- , 30 2.0 8.5 , ,1392 '- -14.0.-.)-------4.0>41%14.2-23.2 t' -x`31.7 1422 17.9 ., -1-7;9:44:2,. -5.60? ='1.4 ' • E ,4 t OS-5 - 2.20 : -5.90 .�:0.01 ='_`�" 0.02 x. '-0.06 021 "-0.46/t. 63 1.0 15.4 "-;-523,.: 1,0 ., s: 1;0 " . .8.7 : 24.1 586; / -13.3 . 13.3 . , 6.3; -2.9 5 S-4_ : 26.10 • <2630 ':0.01 : ,*;0.02 - 0.06 021 5.48 300 1.0 33.7 -.4‘.295`71- .1.0 - `-''1.0 =` . 4.9 -138.6, ' 595 13.3 13.3 0 ' 6.3 `34;5` ` 427.52 F F:IProject DatalLand Development Projects\Data\RationalDesignO(Historic).xls 3/17/2004 8:11 AM HYDROLOGIC COMPUTATION FORM Developed Condition (Rational Method) Location: Lakota Lakes Ranch Development Computed by: WCK Checked by: WCK Date: 3/17/2004 Design Storm: 5-yr Sub-Basin Data Runoff Coefficient Overland Time(Ti) Travel Time(Tt) Tc Check Runoff % N I. L m o _o E rn A 0 0 = o U U U U o a) ci,v a - m c c c c o U _ ,. + c U Cl U U L G ' J ^ I- I a o 7 N o 'a J Ti N m d m CD a c a O II .�. II o N (0 N o o o o Q eo -c o m U o u c ai o Design Pt. to Q O O O O O O J (n I- O co > r H, H H IL tl t1 (acres) (acres) (feet) (%) (min.) (feet) (%) (feet/sec) (min.) (min.) (feet) (min.) (min.) (in/hour) (cfs) (cfs) till 0-1 ry OS-I 35224: 352.24 'Q_01 .,.:=_0.020.4-4.'4;0.06 _-_021,-;:l.= --7.04 = ,- 300 2.0 . 26.7. 6080 2.4 0:7. 144:8 . ,-171.5 _- '4380. :..x'45.4 ,.. --:45.4--" 1.70 = 12.0 .: 17.0 921 .:0.25 - 300 3.1 23.1 1054 1.2 0.8;2.Y.' -23.4 X46.5 ' 1354.:_ -.,17:5'- ;* 17.5. -:3.00 08---4=-,,-.....-... O2 OS-2 12.57: '364.81 0:01 t �Y02 = Oi06., ` - 300 5.6 19.0 253 1.3 0.8 _5.3 ,..'. 242; 553 13.1 13.1 .-3.30 0.5 0-3 <OS-3 , =8.22 373.03: " 0:01 " 0:02 = - 0.06 = 0.21 0.16 0-4 0S-4 . 20.19 393.22' 0.01 - 0.02 . 0.06 -`021 0.40 v ... 300 5.0 19.7 830 1.9 0.9 15.4 35.1 1130 16.3 16.3 3.10 1.3 - 19.6 1 S-1 2.30 2.30 0.01 . ` 0.02 -..0.06 . -0.21 : . 0.05 142 3.5 15.3 516 1.0 0.4 21.5 36.8 -658, ` --'13.7. 13.7 3.30 0.2 0.2 2 8-2 -- ". 2.50 2.50 : 0.34 : -0.40- 0.48- e0.65' =1.01 ,-:t-, 34 2.0 5.8 1392 1.0 1.0 232 ,;:." 29.0 1426 :- 17.9 17.9 , ' ` 2.90 2.9 7k 3 .. 8-3 ' 1.20 3.70 ,,.:0.75 7.. 0.78 `D.81' 0.87'. 0.93 30 2.0 2.5 - 1392 1.0 1.0 23.2 4 4..:."' 25.7 1422 =:, '17.9 17.9 " 2.90 — 2.7 a"..t.- 4 . OS-5 "2.20 5.90 0.11 -020 ,- 0.30 0.53 - � 0.45 . - 63 1.0 12.8` 523 -1.0 1.0 -x:8.7- �=",.21.5 586,.4`. =13.3,- 13.3. 3.3 1.5 7.1 5 S-4 26.10 26.10 0:31 0.39 0.46 0.64 10.09 300 1.0 222 295 1.0 1.0 4.9 27.2 595 133 13.3 3.3 33.3 33.3 427.52 F:IProject Datatand Development ProjectslEberliRationalDesignQ(Developed).xls 3/17/2004 8:23 AM I HYDROLOGIC COMPUTATION FORM Developed Condition (Rational Method) Location: Lakota Lakes Ranch Development Computed by: WCK Checked by: WCK Date: 3/17/2004 Design Storm: 100-yr Sub-Basin Data Runoff Coefficient Overland Time(Ti) Travel Time(Tt) Tc Check Runoff m rt..' 0 E a o o a a U c c U o c m C m j a) c c c c m ~ m o x re a c m u d � .� y c 0 F - co tm- .N a a c ,� O) m c m .m J C Y Y 'y m g m m m m c o. m O. o n T. '� m m m m ro O O O o a a) oTi) o a c m m Design Pt. m a v a a a a a _I rn P a co > I=, i- I- I— is. c a a (acres) (acres) (feet) (%) (min.) (feet) (°/0) (feet/sec) (min.) (mini (feet) , (min.) (min.) (in/hour) (cfs) (cfs) - 0.02 ` 0.06 0.21 =:. m 7397 r ;«i300 ' : 2.0 1 26.7 :6080 , 2.4: 0.7 144.8 171.5 -,6380 -- 45.4. 45.4 r".".";"---330 -: '244.1 -^1. 313.0 02 ..: OS-2 OS-1 312.57` ' 362 84 0.01 - 46.5 1354 1r 17.5;"_-.1'117.5 , 5.70 " ' =45.0 ._ . 0-3 - -O - 0-2 12.57 364.8(. =0.01 0.02 ' 0:06 . , 0.21 =: :«�64 "x300 �.3-1-:, 23.f � 1054` ; 1.6 0.8- 23.4 242 553 13.1 .13.1 ., 6.40 11.0 3-3 - 822 373.03 -' -0.03 0.02 ..,, 0.06 021 x '(.73 _ 300 ,. :5.6 19.0 `' 253 1.3 0.8 5.3 0.4 OS-4 20.19 . 393.22 0.01 0.02 0.06 0.21 . .4.24. .. m 7.... ": " _.3.0= 19.7 830 1.9 0.9 15.4 .-.35.1 1130 16.3 ' 16.3 5.80 .24.6 . .. .---c . 363.6 I t S-1 2.30 2.30 0.01 -.70102 0.06 0.21 6 ,' ` -048 _;1142. : _ --;:3.5 15.3 .. •i 516 4.0 0,4 21.5_ _ 36.8 . 658 13.7 . 13.7 .,..:6.20 , 3.0 ' 3.0 2 S-2 ==;2.50 '- 2.50 034 0.401- 0.48 0.65 )162 -1.4:-:;-... ?34 -4,.....-2:4-2.0, -= 5.8', ?1392 1.0 1.0 =232' 29.0 1426 17.97. _- =17.9 m.7 ^.5.60 - 1== 9.1 , `3 : S-3 1.20 - - 'r 3.70 0.75 .. -0.78 . . 0.81 0.87 :"11-.041.114-1:1112'30 -22.6 --i2.5 - . 1392 1.0 1.0, 23.2 "' . '25.7 1422 - --.17.9 .Cr- 17.9` .' .`5.60 ' 5.8 °- - -4 ; O5-5 220' 5.90 0.11 020 0.30 0.53 -' , .'..n1.1.7,3, .. 63 .- t.0 . ` 12.8 523 1.0 1.0 " 8.7 21.5 586 13.3 13.3 6.3 7.4 , . • <. I 22.3 5 -S-4 26.10 26.10 0.31 r ' 0.39 0.46 0.64 16.65 " 101)---.., 1.0` 22.2 295 1.0 1.0 4.9 27.2 595 13.3 13.3 z 6.3 ' 2.104.9 . . 104.9 427.52 F:1Project Dataland Development ProjectslEbe&MationalDesignQ(Developed).xls 3/17/2004 8:23 AM APPENDIX C HYDRAULIC CALCULATIONS _ 7 - CHART 3 —151 a 97 —3000 EXAMPLE - Site-76"e 48' - o•3ooctc (2) —R6a 87 _ =2000 (3) NWA NW - 40 - D (feet) (I ) - -4.0 -121 x 77 = (t) 2.8 112 - (2) 2.2 8.8 - 4.0 - 3.0 — - 113x72 -1000 (31 2.3 9.2 .. - _-3.0 - 800 •o in leer _ - - 106x68 - 3 _„.. __ �. -600 / -- _ - 2.0 �- - 98 a63 - 500 - - -2.0 - 91x58 - 40%-- - 2.0 _ ` to _ :100 = - 1.5 1.5 — W - 83x53 / �` ..---_ � -- = 200 = _ I.5 - - = -16a 48 _ - W — - _ To use scale (2)or(3) N LL U) - draw a straight line ¢ - _ d - 68 x 43 U - 100 through known values LL - ot size and discharge 0 a 2 -'80 to intersect scale(I). -1.0 -1.0 Fran. point on scale(I) N - LO - - 0 - 60 a 38 E.-60 project horizontally to ¢ - .9 -'9 LL W - solution on either scale W 9 • • N `. 53 x34 _ _ 40 = -.8 -.8 v x=e w - 49x32 0 - 30 W - • z o — O- - 45x29 _ 20 ¢ - - - HW/D ENTRANCE f - N '.42 x 27 SCALE TYPE ; 10 (I) Square edge with W - 38 x 24 _8 headwott = - - - (2) Groove end with -6 headwall — -5 13) Grove end ='5 -4 projecting - - -30x19 _3 - 2 —T - 8 D - -I.0 — 23x14 Z • HEADWATER DEPTH FOR OVAL CONCRETE PIPE CULVERTS LONG AXIS HORIZONTAL • WITH INLET CONTROL BUREAU OF PUBLIC ROADS JAN. 1963 5-23 Western Ditch Capacity @ max headwater Cross Section for Irregular Channel Project Description Project File f:\cad projects\eberl final drainage\hd\flowmaster\ebed.fm2 Worksheet Western Ditch Capacity @ max headwater Flow Element Irregular Channel Method Manning's Formula Solve For Water Elevation Section Data Wtd. Mannings Coefficient 0.030 Channel Slope 0.010000 ft/ft Water Surface Elevation 3.62 ft Discharge 50.00 cfs 5. 4.5 4.0 _ v 3.5 3.0 t 2 2.5 m m W — 2.0 1.5 • 1.0 0.5 0.0 0.0 2.0 4.0 6.0 8.0 10.0 Station (ft) 03/17/04 FlowMaster v5.13 09:19:33 AM Haestad Methods,Inc. 37 Brookside Road Waterbury, CT 06708 (203)755-1666 Page 1 of 1 Western Ditch Full Flow Capacity Cross Section for Irregular Channel Project Description Project File - f:\cad projects\eberl final drainage\hd\flowmaster\eberl.fm2 Worksheet Western Ditch Full Flow Capacity Flow Element Irregular Channel Method Manning's Formula Solve For Water Elevation Section Data Wtd. Mannings Coefficient 0.030 Channel Slope 0.010000 ft/ft Water Surface Elevation 5.00 ft Discharge 134.00 cfs 5.5 5. — 4.5 4.0 3.5 w 3.0 c - 0 m 2.5 W 2.0 1.5 1.0 0.5 0.0 0.0 2.0 4.0 6.0 8.0 10.0 Station (ft) 03/17/04 FlowMaster v5 13 09:20:11 AM Haestad Methods,Inc. 37 Brookside Road Waterbury,CT 06708 (203)755-1666 Page 1 of 1 Access Road Borrow Ditch (east) Cross Section for Triangular Channel Project Description Project File f:\cad projects\eberl final drainage\hd\flowmaster\eberl.fm2 Worksheet Borrow Ditch (east) Flow Element Triangular Channel Method Manning's Formula Solve For Channel Depth Section Data Mannings Coefficient 0.030 Channel Slope 0.010000 f fft Depth 1.18 ft Left Side Slope 2.000000 H : V Right Side Slope 2.000000 H : V Discharge 9.10 cfs • a • 1.18 ft t 1 V H 1.0 NTS 73/05/04 FlowMaster v5.13 13:05:13 PM Haestad Methods, Inc. 37 Brookside Road Waterbury.CT 06708 (203) 755-1666 Page 1 of 1 _ East Fenceline Ditch Cross Section Cross Section for Triangular Channel Project Description Project File f:\cad projects\eberl final drainage\hd\flowmaster\eberl.fm2 Worksheet Borrow Ditch (east2) Flow Element Triangular Channel Method Manning's Formula Solve For Channel Depth _ Section Data Mannings Coefficient 0.030 Channel Slope 0.010000 ft/ft Depth 1.48 ft Left Side Slope 2.000000 H : V Right Side Slope 2.000000 H :V Discharge 16.50 cfs • 1.48 ft 1N V H 1.0 NTS 3/05/04 FlowMaster v5.13 3:01:50 PM Haestad Methods, Inc. 37 Brookside Road Waterbury.CT 06708 (203)755-1666 Page 1 of 1 _ Access Road Borrow Ditch (west) Cross Section for Triangular Channel Project Description Project File f:\cad projects\eberl final drainage\hd\flowmaster\eberl.fm2 Worksheet Borrow Ditch (west) Flow Element Triangular Channel Method Manning's Formula Solve For Channel Depth _ Section Data Mannings Coefficient 0.030 Channel Slope 0.010000 ft/ft Depth 1.00 ft Left Side Slope 2.000000 H : V Right Side Slope 2.000000 H : V Discharge 5.80 cfs • 1.00 ft 1 VD H 1.0 NTS 'J3/05/0d FlowMaster v5.13 )3:05:52 PM Haestad Methods, Inc. 37 Brookside Road Waterbury,CT 06708 (203)755-1666 Page 1 of 1 APPENDIX D PHOTOGRAPHS ,ry 4 I, , twcr: 0 PHOTO I 42"x24" n4O ♦ rn DRAINAGE A G DITCH LY11 rA �v vn '! nj ` (WEST SIDE OF SITE, LOOKING SOUTH) e xs 7ff . • ._ ds PHOTO 2 FLOW CONTROL STRUCTURE (NORTH OF WCR 54, EAST OF WCR 15) PHOTO 3 LAKOTA LAKES SITE /HILL AND BRUSH DITCH (LOOKING SOUTHWEST) \ • -. tot*—44F F . / " ' 4t to 'I r PHOTO 4 IRRIGATION CONROL STRUCTURE (NORTH END OF BASIN OS-4) I PHOTO 5 IRRIGATION CONTROL STRUCTURE ALONG WCR 15 (LOOKING WEST) • .. I S PHOTO 6 RAILROAD TRESTLE NORTH OF DESIGN POINT 0-1 (LOOKING EAST NE) fi • • PHOTO 7 GREAT WESTERN RAILROAD AND BASIN 0-4 (LOOKING SE) F h • ake- PHOTO 8 BASIN OS-4 AND IR=RIGATION CONTROL STRUCTURES (LOOKING SOUTH ALONG WRC 15) < f as�''yPX r fit — - A f v rywiis1 ,' — ' H va '. ,z{ / I. PHOTO 9 30" CMP IRRIGATION CONTROL STRUC'TURI (LOOKING NORTH IN BASIN OS-4) y fig' tY 'M'mm2 r t . C1 - _. .1 ,>r L PHOTO 10 IRRIGATION CONTROL STRUCTURES (LOOKING EAST (a)INTERSECTION OF WCR'S 15 AND 54) vas. 4. s vxt-lye cx PHOTO 11 NORTH EDGE OF PROPOSED LAKOTA LAKES SITE (LOOKING WEST ALONG WCR 54) APPENDIX E REFERENCES REFERENCES Colorado Urban Storm Drainage Criteria Manual, Volume 1, Urban Drainage and Flood Control District, June 2001. _ Precipitation Atlas of the Western United States, NOAA Atlas 2, Volume III National Oceanic and Atmospheric Administration, U.S. Department of Commerce, Colorado 1973. Weld County Land Use Code, Section 24, Subdivisions, Article VII, Design Standards, Weld County, Colorado, July, 2003. Hydraulic Charts for the Selection of Highway Culverts, Hydraulic Engineering Circular No. 5, Hydraulics Branch, Bridge Division, Office of Engineering and Operations, Bureau of Public Roads, Washington, D.C. 20235, December, 1965. A Policy on the Geometric Design of Highways and Streets, American Association of State Highway and Transportation Officials (AASHTO), 1990. Hello