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Home My WebLink About20120532.tiff SITE SPECIFIC DEVELOPMENT PLAN AND USE BY SPECIAL REVIEW (USR) APPLICATION 0 FOR PLANNING DEPARTMENT USE DATE RECEIVED: RECEIPT#/AMOUNT# /$ CASE#ASSIGNED: APPLICATION RECEIVED BY PLANNER ASSIGNED: Parcel Number 0 8 0 1 . 1 0 . 3 . 0 0 . 0 4 7 (12 digit number-found on Tax I.D.information,obtainable at the Weld County Assessor's Office,or www.co.weld.co.us) Legal Description Lot A of Recorded Exemption RE-3889 , Section 10 , Township 6 North, Range 64 West Zone District:AG , Total Acreage:19.558 , Flood Plain: , Geological Hazard: Airport Overlay District: FEE OWNER(S)OF THE PROPERTY: 1f Name:Doug Jergens — 4X,°`0_3 `e-rse99ri0.-\.cow Lcp NDllmr-�Swmr- Work Phone# Home Phone# Email Address:27435 Weld County Road 70 Address: City/State/Zip Code Gill, CO 80624 Name:Amy Jergens Work Phone# Home Phone# Email Address:27435 Weld County Road 70 Address: City/State/Zip Code Gill, CO 80624 Name: • Work Phone# Home Phone# Email Address: Address: City/State/Zip Code APPLICANT OR AUTHORIZED AGENT(See Below:Authorization must accompany applications signed by Authorized Agent) Name: Work Phone# Home Phone# Email Address: Address: City/State/Zip Code PROPOSED USE: The proposed use is to convert a portion of the existing pole barn into examination rooms as well as a room capable of conducting equine surgery. The occupants currently operate a mobile Veterinary service,this would allow them to examine and treat equine patients at the current address. I (We)hereby depose and state under penalties of perjury that all statements, proposals, and/or plans submitted with or contained within the application are true and correct to the best of my(our)knowledge. Signatures of all fee owners of property must sign this application. If an Authorized Agent signs, a letter of authorization from all fee owners must be included with the application. If a corporation is the fee owner, notarized evidence must be in,�luded indicating that the signatory has to legal authority to sign or the co oration. li 242,4/ �/s /i Signature •wner or A riz Agent Dace Signal e/wn r uthorized Agent DAte • / EXHIBIT i 2- 2012-0532 LI5)21/-Wa5 SITE SPECIFIC DEVELOPMENT PLAN AND USE BY SPECIAL • REVIEW (USR) QUESTIONNAIRE The following questions are to be answered and submitted as part of the USR application. If a question does not pertain to your use, please respond with"not applicable",with an explanation as to why the question is not applicable. 1. Explain, in detail, the proposed use of the property. 2. Explain how this proposal is consistent with the intent of the Weld County Code, Chapter 22 of the Comprehensive Plan. 3. Explain how this proposal is consistent with the intent of the Weld County Code, Chapter 23(Zoning)and the zone district in which it is located. 4. What type of uses surround the site (explain how the proposed use is consistent and compatible with surrounding land uses). 5. Describe, in detail,the following: a. Number of people who will use this site b. Number of employees proposed to be employed at this site c. Hours of operation d. Type and number of structures to be erected (built)on this site e. Type and number of animals, if any,to be on this site • f. Kind of vehicles(type, size,weight)that will access this site and how often g. Who will provide fire protection to the site h. Water source on the property(both domestic and irrigation) Sewage disposal system on the property(existing and proposed) j. If storage or warehousing is proposed, what type of items will be stored 6. Explain the proposed landscaping for the site. The landscaping shall be separately submitted as a landscape plan map as part of the application submittal. 7. Explain any proposed reclamation procedures when termination of the Use by Special Review activity occurs. 8. Explain how the storm water drainage will be handled on the site. 9. Explain how long it will take to construct this site and when construction and landscaping is scheduled to begin. 10. Explain where storage and/or stockpile of wastes will occur on this site. • • Site Specific Development Plan and Use by Special Review Questionnaire Jergens'Equine 1. Explain the proposed use of the Property: The proposed use of this property is to use specific areas of the property as an area for the current residents to conduct veterinary services on the property. The current residents are DR.Amy Jergens DVM and Doug Jergens a licensed equine Dentist. There is a currently a pole building located on the property which will be finished to house examination and veterinary treatment areas as well as a lab area and rest room. 2. Explain how this proposal is consistent with the intent of the Weld County Code, Chapter 22. Weld County Code Chapter 22-2-20 Agricultures Goals and Policies, B.A. Goal 2.,A. Policy 2.2 states "Allow commercial and industrial uses, which are directly related to or dependent upon agriculture, to locate within agricultural areas when the impact to surrounding properties is minimal or mitigated and where adequate services and infrastructure are currently available or reasonably obtainable. These commercial and industrial uses should be encouraged to locate in areas that minimize the removal of agricultural land from production." The proposed use of this property to allow for veterinary use to treat equine patients meets the above stated goal. 3. Explain how this proposal is consistent with the intent of the Weld County Code, Chapter 23 and the zone district in which it is located. Weld County Code, Chapter 23, Agriculture Zone District: The following BUILDINGS, STRUCTURES and USES may be constructed, occupied, operated and maintained in the A(Agricultural) Zone District upon approval of a Use by Special Review Permit in accordance with the requirements and procedures set forth in Article II, Division 4 of the Weld County Code. B. • Agricultural Service establishments primarily engaged in performing agricultural, animal husbandry or horticultural services on a fee or contract basis, including: 5. Veterinary Clinics and Hospitals. 4. What type of uses surround the site: Surrounding the site are mostly agriculture properties. There are multiple USR permits in the vicinity with multiple dairies, and one indoor arena facility with a USR permit to hold public events. This type of use would provide a service to many of the neighboring properties for veterinary care of their animals. 5. A. number of people who will use the site: 2 owners and 2 employees B. Number of employees proposed to be employed at the site: 2 C. Hours of operation: Standard business operating hours of 8:00 AM to 5:00 PM are being proposed for this facility. D. Type and number of structures to be erected: No new structures will be erected: The existing pole building will be finished to include the needed facilities for this operation. Please see attached building layout. E. Type and number of Animals to be on this site: The owners currently have horses and cattle on site in conformance with weld county code. The veterinary facility will allow horses to come in for treatment and leave with a maximum of 4 stalls being available for longer term recovery if needed. F. Kind of vehicles that will access this site and how often: The veterinary operation will remain primarily mobile, but will allow clients to bring horses on site for treatment in certain circumstances, such as orthopedic surgeries. This will involve clients bringing • • horses to the site with pickup trucks and trailers, there will also be one delivery truck per week bringing in Veterinary supplies. G. Who will provide fire protection for the site: This residence currently falls in the Galeton Fire protection district. H.Water Source on the property: Domestic water source is currently provided by North Weld County Water District and will continue to provide water. There is no irrigation water on the property. I. Sewage disposal system on the property: The residence is currently supplied by a septic system. There will be one new restroom facility proposed and new septic system will be applied for upon approval of this permit. J. There will be now storage or warehousing on site. 6. Explain the proposed landscaping for the site: The proposed use does not affect the current landscaping and no new structures are being erected,therefore there is no landscaping planned for this site. 7. Explain proposed reclamation procedures when termination of the Use by Special Review activity occurs: The site will be reclaimed by any applicable state and local laws upon termination of the Use by Special Review activities if necessary. 8. Explain how storm water drainage will be handled on site: This plan does not require new grading for parking facilities or change of natural drainage as it currently occurs. There is also no request for new buildings that would affect historic drainage patterns in the area therefore no additional drainage systems are proposed. 9. Explain how long it will take to construct the site: Upon approval of this permit, construction will begin and will take approximately 3 months to complete. • 10. Explain where Storage and Stockpile of wastes will occur: There will no storage or stockpiling of wastes on site, all waste will be disposed of according to applicable state and local laws. Typical trash removal will be handled by a disposal company of the owners' choice in the area. • • FOR COMMERCIAL SITES,PLEASE COMPLETE THE FOLLOWING INFORMATION BUSINESS EMERGENCY INFORMATION: Business Name:Jergens Equine Phone: Address:27435 WCR 70 City, ST,Zip:Gill, CO 80624 Business Owner:Doug Jergens, Amy Jergens Phone: Home Address:same City, ST,Zip: List three persons in the order to be called in the event of an emergency: NAME TITLE ADDRESS PHONE Doug Jergens Owner 970-590-7012 Amy Jergens Owner 970-518-6398 Cana(°,ct. Lostrel, o iha 4er 92a-573- aFa6 Business Hours:8:00 AM to 5:00 PM Days:Monday-Friday Type of Alarm: None Burglar Holdup Fire Silent Audible • Name and address of Alarm Company: Location of Safe: MISCELLANEOUS INFORMATION: Number of entry/exit doors in this building:* ?- Location(s): s°att% We S t Co enter ) lo tek,t•rc.f Is alcohol stored in building?" Location(s): Are drugs stored in building?y Location(s):Equine prescription drugs only in designated areas of building Are weapons stored in building?" Location(s): The following programs are offered as a public service of the Weld County Sheriffs Office. Please indicate the programs of interest. Physical Security Check Crime Prevention Presentation UTILITY SHUT OFF LOCATIONS: Main Electrical: AI fig o c W'crr ? a �t fa-ol .,S Gas Shut Off: ct pr a pant cot C Exterior Water Shutoff: O2a � F- 5+ oc o\ r: LA cif o 4 rcoal Interior Water Shutoff: £ H ft, G/c ct L u n n tr c 4 , h s c ✓'% t • it ev CO) Weld County Public Works Dept. s� 1111HStreet ACCESS PERMIT co P.O.Box 758 G '.ere*' Greeley,CO 80632 APPLICATION FORM • 6C/c NIOP Phone: (970)304-6496 Fax:(970)304-6497 Applicant Property Owner(If different than Applicant) Name Cody Hollingsworth Name Doug and Amy Jergens Company Western Integrity Agency Address 27435 WCR 70 Address P.O. Box 1043 City Gill State CO Zip 80624 City Stillwater State OK Zip L9 74076 Phone / �o-59 0-70 I 1 Business Phone 970-690-6041 Fax Fax E-mail d ot~S 3 e.ry-ar 0' n.e' I .Le n— cody@westem-integnty.com y©western-integrity.com ♦=Existing Access A=Proposed Access Parcel Location&Sketch . The access is on WCR 7D Nearest Intersection:WCR 70 &WCR 55 5 5 WCR approx. 1/2 mile east Distance from Intersection Parcel Number 0801110300047 IVe„aG N. Section/Township/Range 10/6N/64W -1 Is there an existing access to the property?❑1'ES NO❑ N,/„ 3 Number of Existing Accesses 1 r2 1065--++01 ham • Road Surface Time&Construction Information r Asphalt I 1 Gravel a Treated 0 Other 5 7 WCR 1, EE S Amid! .nrtP �._�_ Culvert Size&Type 2 Materials used to construct Access Construction Start Date Finish Date Proposed Use °Temporary(Tracking Pad Required)/$75 ()Single Residential/$75 O Industrial/$150 Q Small Commercial or Oil&Gas/$75 °Large Commercial/$150 °Subdivision/$150 °Field(Agriculture Only)/Exempt '''' Is this access associated with a Planning Process? QNo kJSR ORE OPUD 41)1(20N— Required _ Required Attached Documents \\ / ` -Traffic Control Plan -Certificate of Insurance -Access Pictures(From the Left,Right,&into the access) By accepting this permit,the undersigned Applicant,under penalty of perjury,verifies that they have received all pages of the permit application;they have read and understand all of the permit requirements and provisions set forth on all pages;that they have the authority to sign for and bind the Applicant,if the Applicant is a corporation or other entity;and that by virtue of their signature the Applicant is bound by and agrees to comply with all said permit requirements and provisions,all Weld County ordinances,and state laws regarding facilities construction. p / Signature D Printed Name 6 0 I f )eJ F).7ersenroate AI /// Approval or Denia will be ss� In tnimum of 5 days. Approved by Revised Date 6/29/10 • • Waste Management Plan — Doug and Amy Jergens USR Application 1. Typical trash and refuse will be disposed of using a refuse company such as Waste Management. 2. In the event animal removal is needed Weld County Rendering will be contact to pick up and remove the animal. 3. All floor drains installed in the treatment area and surgery are will deposit into the Septic System engineered to have the proper capacity for such a facility. Dust Management Plan- Doug and Amy Jergens USR Application 1. Should the driveway or parking are become dusty do to traffic, the applicant agrees to wet the designated area down to control dust. • • • Ne rt-rafC , 1— C November 9, 2011 Doug Jergens 27435 WCR 70 Gill, CO 80624 Dear Doug: Please find enclosed the revised plots of the site drawing with the water quality control feature indicated. This entails leaving a 30ft wide buffer along the North and East edges of the property in which you will not be able to build future structures in. In the event that you need to construct in this area you may need to amend your permit. The other documentation is the design documentation and I would maintain this in your file and provide it upon request to the county. Consider the fees for this revision included in the paid invoice. If you have any changes or concerns as always please don't hesitate to contact me. • Sincerely, crfrieky, PE Agricultural Engineer Enclosures: 24x36 site layout Grass Buffer Documentation • .: , L. ,..., 19 661 ,....� ._ _____ 8605 S . Dr. ... `" -6,209 20997 County Rd Greeley,co 634 then9 ineerin9 online.com Calhan,CO 80808 1' ' r1 oMm¢ � 85 I I L p `oo __'�- 60. • ��I �� - Ir , (\.___.‘, -. 4 ti II 1 i \. 4a1;I Pack,Tcwer i II, _ — ' r I 4;3 _— _ /� 1 _ � - twev r I Ppo l 9 i I - ii '11 f� 1Q 11 � H5� ._ _ _ - _ __ __I�- ! I � �� r 8 // l 3 ov Hoearvrd4 -� ' I I awe ' 4928 •a a864 . 'id t i '2u 4746 • 4,14 6.qs 4� / I._,." ( l x`4:5' 0 d � i )oJ i2D0➢' 4000' V / y .�w 50� DOUG JERGENS Date: 27435 WCR 70 8/18/2011 • NO/Nrrk'/NG LLC PART OF THE S OF THE SW Z OF SECTION 10,T Sheet No. 8605 17th St Dr,Greeley,CO 719-661-6209 6N, R 64 W OF THE 6TH P.M. LOT A, RE 3889 1 OF 1 4100' • rr PROPOSED PROPOSED D POSE 14' X14' / 18'X14' 10'PROPOSED RECOVERY / SURGERY XB ROOM ROOM / I,/ CSI = PROPOSED 5' X 5' r< BATHROOM PROPOSED TREATMENT PROPOSED AREA 12'X 12' TREATMENT AREA \/ \ PROPOSED EXISTING 12'X 12' 12'X 12' STALL STALL 80.00' I. • PROPOSED EXISTING -12' X 12' 12'X 12' STALL STALL EXISTING 12'X 12' STALL PROPOSED _ 24' X 12' TACK ROOM - EXISTING 12'X 12' STALL EXISTING 16' X 16' OVERHEAD DOOR 0 10'Imm �' DOUG JERGENS Date: 27435 WCR 70 8/30/2011 N6/NttK/N6,LLG PART OF THE S% OF THE SW 1/4 OF SECTION 10,T Sheet No. 8605 17th St Dr,Greeley,CO 719-661-6209 6N, R 64 W OF THE 6TH P.M. LOT A, RE 3889 1 OF 1 30FT GRASSED BUFFER UTILISED AS WATER QUALITY CONTROL FEATURE(NO BUILD AREA) • p�p EXISTING BUILDING EXISTING FENCE EXISTING CORRAL EXISTING EDGE OF DIRT ROAD .01 F / PROPERTY BOUNDARY EXISTING CULVERT p FLOW DIRECTION ———> p> B PASTURE 0 ARENA • Ra NEIGHBOR'S STRUCTURE 5e }� 04,1= 00 / 193 a25T// - ir i1 1 I P(IRRIGATION) 134 *476' t 14' NEIGHBOR'S STRUCTURE �JI ADJACENT OWNER'S POND 0 211' 400 DOUG JERGENS Date: 8/30/2011 27435 WCR 70 REV 11/9/2011 N6/VEER/N6 LLG PART OF THE S Y2 OF THE SW 1/4 OF SECTION 10, T Sheet No. 8605 17th St Dr, Greeley, CO 719-661-6209 6N, R 64 W OF THE 6TH P.M. LOT A, RE 3889 1 OF 1 Design Procedure Form: BMP Selection Tool Sheet 1 of 1 . Designer: Travis Hertneky Company: THEngineering Date: November 9,2011 Project: Doug Jergens Location: 27435 WCR 70,Gill,CO 80624 Choose One 1. To identify potential BMPs,what best describes the type of site? 0 Conventional Sites Q Hiobly Urbanized Sites SKIP S 2 O Linear Construction in Urbanized Areas Choose One — Q YES 0 NO 3. Is the site comprised of Hydrologic Soil Group A or B soils? r Choose One O YES O NO r Choose One 4. Is the tributary impervious area'greater than 1 acre? rC YES O NO 5. Is the depth of bedrock greater than 5 feet? r Choose One — ®YES 0 NO 6 Is the tributary impervious area'greater than 5 acres? Choose One— 0 YES SKIP 9 7 NO • Choose One 0 YES V NO B. Is the BMP in a developing watershed? Choose One OYES SKIP 19'10 ®NO Choose One— 0 YES 0 M Choose One — r oYES 0 NO 11. Step 1 of Four Step Process: Grass Swale MDCIA/Volume Reduction(Not WQCV)BMPs Grass Buffer Permeable Pavement-Full Infiltration(5,61 Green Roof(3,6) 12. Step 2 of Four Step Process: Permeable Pavement-Full Infiltration(5,6) W OCV BMPs Bioretention-Full Infiltration(5,6) Extended Dry Detention Basin Sand Filter Extended Detention-Full Infiltration(5) Green Roof(3,6) Regional Water Quality Treatment(4) Notes: 1.'Tributary impervious area'refers to the impervious area draining to the BMP.not the total area of the project site• . 3.In the Front Range of Colorado,irrgation,at least periodically in dry times.will be required to sustain a green roof. 4.If a regional facility will be used to provide the WQCV,some degree of onsite treatment/MDCIA will still likely be required. 5.No Infiltration=underdrain and liner,Partial Infiltration=underdrain and no liner,Full Infiltration=no underdrain and no liner. 6 Consider this BMP for a portion of your site. It's best suited for impervious tributary areas of approximately one acre or less. UD-BMP_v3_01.xis,BMP Selection Tool 11/9/2011.2.56 PM Design Procedure Form: Grass Buffer(GB) Sheet 1 of 1 • Designer: Travis Hertneky Company: THEngineering Date: November 9,2011 Project: Doug Jergens Location: 27435 WCR 70,Gill,CO 80624 1. Design Discharge A) 2-Year Peak Flow Rate of the Area Draining to the Grass Buffer O2= 1.7 cfs 2. Minimum Width of Grass Buffer W0= 35 ft 3 Length of Grass Buffer(14'or greater recommended) L;= 30 ft 4. Buffer Slope(in the direction of flow.not to exceed 0 1 ft f ft) SG= 0.019 ft I ft 5. Flow Characteristics(sheet or concentrated) r Choose One A) Does runoff flow into the grass buffer across the I a Yes (!%No entire width of the buffer CONCENTRATED FLOW — Choose One • 6. Flow Distribution for Concentrated Flows Q Noe(sheet flow) ()Slotted Curbing a Level Spreader O Other(Explain): Historically flood irrigated and level field 7 Soil Preparation (Describe soil amendment) Native-soil.no disturbance 8 Vegetation(Check the type used or describe"Other") Choose One Q Existing xeric Turf Grass Q litigated Turf Grass n Other(Explain): Native dryland pasture mix Choose One 9. Irrigation C)Temporary ('Select None if existing buffer area has 80%vegetation O Permanent AND will not be disturbed during construction.) Q None' — Choose One 10. Outflow Collection(Check the type used or describe"Other") 0 Grass Swale O Street Gutter 0 Storm Sewer Inlet �?Other(Explain): adjacent farmground • Notes. UD-BMP v3_01.xIs,GB 11/9/2011,2 56 PM • • Area-Weighting for Runoff Coefficient Calculation Project Title: Doug Jergens Catchment ID: 27435 WCR 70, Gill, CO 80624 Illustration se ------` LEGEND: Flow Direction here S Catchment Subarea 3 Boundary Instructions: For each catchment subarea,enter values for A and C. Subarea Area Runoff Product ID acres Coeff. A C* CA • input input input output Shed 0.08 100.00 7.62 House 0.06 100.00 6.03 Concrete 0.02 100.00 2.13 Driveway 0.51 90.00 45.90 Pervious 17.70 0.00 0.00 Sum: 18.37 Sum: 61.68 Area-Weighted Runoff Coefficient(sum CA/sum A)= 3.36 *See sheet"Design Info"for inperviousness-based runoff coefficient values. • UD-Rational v1.02a.xls, Weighted C 11/9/2011, 2:56 PM • CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title: Doug Jergens Catchment ID: 27435 WCR 70,Gill,CO 80624 I. Catchment Hydrologic Data Catchment ID= 1 Area= 18.37 Acres Percent Imperviousness= 3.36 NRCS Soil Type= B A, 5,C,or D II. Rainfall Information I(inch/hr)=Cl *P1 /(C2+Td)AC3 Design Storm Return Period,Tr= 2 years (input return period for design storm) C1 = 28.50 (input the value of C1) C2= 10.00 (input the value of C2) C3= 0.786 (input the value of C3) P1= 0.93 inches (input one-hr precipitation--see Sheet"Design Info") III. Analysis of Flow Time(Time of Concentration)for a Catchment Runoff Coefficient,C= 0.03 Overide Runoff Coefficient,C= (enter an overide C value if desired,or leave blank to accept calculated C.) 5-yr. Runoff Coefficient,C-5= 0.09 Overide 5-yr.Runoff Coefficient,C= (enter an overide C-5 value if desired,or leave blank to accept calculated C-5.) Illustration overland LEGEND Reach I Dow Reach O Beginning Flaw Direction Reach 3 Catchment Boundary NRCS Land Heavy Tillage/ Short Nearly Grassed Paved Areas 8 Type Meadow Field Pasture/ Bare Swales/ Shallow Paved Swales Lawns Ground Waterways (Sheet Flow) Conveyance 2.5 5 7 J 10 15 20 Calculations: Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey- Velocity Time Coeff ance V Tf fUft ft C-5 fps minutes input input output input output output Overland 1.9300 420 0.09 N/A 1.06 6.60 1 2 3 4 5 Sum 420 Computed Tc= 6.60 Regional Tc= 12.33 User-Entered Tc= 6.60 IV. Peak Runoff Prediction Rainfall Intensity at Computed Tc, I= 2.91 inch/hr Peak Flowrate,Qp= 1.74 cfs Rainfall Intensity at Regional Tc, I= 2.31 inch/hr Peak Flowrate, Qp= 1.38 cfs • Rainfall Intensity at User-Defined Tc, I= 2.91 inch/hr Peak Flowrate,Qp= 1.74 cfs UD-Rational v1.02a.xls,Tc and PeakQ 11/9/2011, 2:56 PM Grass Buffer T-1 • Description r 5'.n • i `_ Grass buffers are densely vegetated '.... y strips of grass designed to accept sheet . •„r flow from upgradient development. x ' ' d a" Properly designed grass buffers play a 4qt; i� s' key role in LID, enabling infiltration and - . •` slowing runoff. Grass buffers provide F., , ,y filtration (straining) of sediment. .1\., Buffers differ from swales in that they - are designed to accommodate overland g sheet flow rather than concentrated or channelized flow. " "c Site Selection ` , Grass buffers can be incorporated into a wide range of development settings. Photograph GB-I. A flush curb allows roadway runoff to sheet flow Runoff can be directly accepted from a through the grass buffer. Flows are then further treated by the grass Swale. Photo courtesy of Muller Engineering parking lot, roadway, or the roof of a structure, provided the flow is distributed in a uniform manner over the width of the buffer. This can be achieved through the use of flush curbs, slotted curbs, or level spreaders where needed. Grass buffers are often used in conjunction with grass swales. They are well suited for use in riparian zones to assist in stabilizing channel banks adjacent to major drainageways and receiving waters. These areas can also • sometimes serve multiple functions such as recreation. Hydrologic Soil Groups A and B provide the best infiltration Grass Buffer capacity for grass buffers. For Type C and D soils, buffers still serve to provide filtration (straining) although infiltration rates are Functions lower. LID/Volume Red. Yes WQCV Capture No Designing for Maintenance WQCV±Flood Control No Fact Sheet Includes Recommended ongoing maintenance practices for all BMPs are EURV Guidance No provided in Chapter 6 of this manual. During design the Typical Effectiveness for Targeted following should be considered to ensure ease of maintenance Pollutants3 over the long-term: Sediment/Solids Good • Where appropriate(where vehicle safety would not be Nutrients Moderate impacted), install the top of the buffer 1 to 3 inches below the Total Metals Good adjacent pavement so that growth of vegetation and Bacteria Poor accumulation of sediment at the edge of the strip does not Other Considerations prevent runoff from entering the buffer. Alternatively, a Life-cycle Costs Low sloped edge can be used adjacent to vehicular traffic areas. • Amend soils to encourage deep roots and reduce irrigation Based primarily on data from the International Stormwater BMP Database requirements, as well as promote infiltration. ‘‘ ��./,n� • November 2010 Urban Drainage and Flood Control District GB-1 Urban Storm Drainage Criteria Manual Volume 3 Grass Buffer T-1 • 4. Buffer Slope: The design slope of a grass buffer in the Use of Grass Buffers direction of flow should not exceed 10%. Generally, a minimum slope of 2% or more in turf is adequate to Sheet flow of stormwater through a facilitate positive drainage. For slopes less than 2%, grassed area provides some benefit in consider including an underdrain system to mitigate pollutant removal and volume nuisance drainage. reduction even when the geometry of the BMP does not meet the criteria 5. Flow Characteristics (sheet or concentrated): provided in this Fact Sheet. These Concentrated flows can occur when the width of the criteria provide a design procedure watershed differs from that of the grass buffer. that should be used when possible; Additionally, when the product of the watershed flow however, when site constraints are length and the interface slope (the slope of the watershed limiting, this treatment concept is normal to flow at the grass buffer)exceeds approximately still encouraged. one, flows may become concentrated. Use the following equations to determine flow characteristics: Sheet Flow: FL(SI) ≤ 1 Equation GB-2 Concentrated Flow: FL(SI) > 1 Equation GB-3 Where: FL =watershed flow length (ft) SI = interface slope(normal to flow)(ft/ft) • 6. Flow Distribution: Flows delivered to a grass buffer must be sheet flows. Slotted or flush curbing, permeable pavements, or other devices can be used to spread flows. The grass buffer should have relatively consistent slopes to avoid concentrating flows within the buffer. A level spreader should he used when flows are concentrated. A level spreader can be a slotted drain designed to discharge flow through the slot as shown in Photo GB-2. It could be an exfiltration trench filled with gravel, which allows water to infiltrate prior to discharging over a level concrete or rock curb. There are many ways to design and construct a level spreader. They can also be used in series when the length of the , buffer allows flows to re- l. - nr concentrate. See Figure GB-2 for various level spreader sections. must u . . P P��tAli t � , p ' ��"' I c �I� P it � y� t p \ 1 iiI ti i f Y, "{ pt / t Rt' 1 `�� y�,itof e a �. r • Photograph GB-2. This level spreader carries concentrated flows into a slotted pipe encased in concrete to distribute flows evenly to the grass buffer shown left in the photo. Photo courtesy of Bill Wenk. November 2010 Urban Drainage and Flood Control District GB-3 Urban Storm Drainage Criteria Manual Volume 3 Grass Buffer T-1 • Turf grasses such as Kentucky bluegrass are often selected due to these qualities'. Dense native turf grasses may also be selected where a more natural look is desirable. Once established, these provide the benefit of lower irrigation requirements. See the Revegetation chapter in Volume 2 of this manual with regard to seed mix selection, planting and ground preparation. Depending on soils and anticipated flows, consider erosion control measures until vegetation has been established. 9. Irrigation: Grass buffers should be equipped with irrigation systems to promote establishment and survival in Colorado's semi-arid environment. Systems may be temporary or permanent, depending on the type of vegetation selected. Irrigation application rates and schedules should be developed and adjusted throughout the establishment and growing season to meet the needs of the selected plant species. Initially,native grasses require the same irrigation requirements as bluegrass. After the grass is established, irrigation requirements for native grasses can be reduced. Irrigation practices have a significant effect on the function of the grass buffer. Overwatering decreases the permeability of the soil, reducing the infiltration capacity and contributing to nuisance baseflows. Conversely, under watering may result in delays in establishment of the vegetation in the short term and unhealthy vegetation that provides less filtering and increased susceptibility to erosion and rilling over the long term. 10. Outflow Collection: Provide a means for downstream conveyance. A grass swale can be used for this purpose, providing additional LID benefits. Construction Considerations Success of grass buffers depends not only on a good design and long-term maintenance, but also on • installing the facility in a manner that enables the BMP to function as designed. Construction considerations include: • The final grade of the buffer is critical. Oftentimes, following soil amendment and placement of sod, the final grade is too high to accept sheet flow. The buffer should be inspected prior to placement of seed or sod to ensure appropriate grading. • Perform soil amending,fine grading, and seeding only after tributary areas have been stabilized and utility work crossing the buffer has been completed. • When using sod tiles stagger the ends of the tiles to prevent the formation of channels along the joints. Use a roller on the sod to ensure there are no air pockets between the sod and soil. • Avoid over compaction of soils in the buffer area during construction to preserve infiltration capacities. • Erosion and sediment control measures on upgradient disturbed areas must be maintained to prevent excessive sediment loading to grass buffer. Although Kentucky bluegrass has relatively high irrigation requirements to maintain a lush,green aesthetic. it also withstands drought conditions by going dormant. Over-irrigation of Kentucky bluegrass is a common problem along the Colorado Front Range, and it can be healthy, although less lush,with much less irrigation than is typically applied. November 2010 Urban Drainage and Flood Control District GB-5 Urban Storm Drainage Criteria Manual Volume 3 Grass Buffer T-1 • CORRUGATED SLOTTED DRAIN PIPE GRASS BUFFER AGGREGATE RASE COURSE SECTION Q LEVEL SPREADER FOR PIPE FLOWS PIPE AND HEADWALL BEYOND GRASS BUFFER SLOTTED CURB DRAIN PAN WITH CURBS SECTION LEVEL SPREADER FOR PIPE FLOWS GRASS BUFFER UNDERDRAIN, SEE SECTION 5 (OR PROVIDE SMALL OPENING IN WALL) • SECTION LEVEL SPREADER FOR SURFACE FLOWS GRASS BUFFER UNDERDRAIN, SEE SECTION 5 (OPTIONAL) SECTION LEVEL SPREADER FOR SMALL SURFACE FLOWS CDOT CLASS C FILTER MATERIAL OR OTHER COMPATIBLE MATERIAL SUCH AS PASHTO #57 OR #67 COOT " VARIES, MIN 8° CLASS C FILTER �)♦I 4., MATERIAL 1 PER TABLE SLOTTED PIPE PER TABLE GS-3 GS-2' 1. SEE BMP FACT SHEET T-2. GRASS SWALE SECTION n UNDERDRAIN • Figure GB-2. Typical Level Spreader Details November 2010 Urban Drainage and Flood Control District GB-7 Urban Storm Drainage Criteria Manual Volume 3 Grass Buffer T-1 • References Barrett, M., Lantin, A. and S. Austrheim-Smith. 2004. Stormwater Pollutant Removal in Roadside Vegetated Buffer Strips. Prepared for the Transportation Research Board: Washington, DC. California Stormwater Quality Association (CASQA). 2003. California Stormwater BMP Handbook, Vegetated Buffer Strip. • • November 2010 Urban Drainage and Flood Control District GB-9 Urban Storm Drainage Criteria Manual Volume 3 Hello