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HomeMy WebLinkAboutDrainage Reports - 02/05/2015DRAINAGE REPOT Collins proo veedd Bye FOR Date �? -5- Touchstone Addition 1217 Riverside Avenue Fort Collins, CO 80524 Prepared for: (Go OGLESBY d e .. g n Oglesby Design, LLC 123 North College Ave., Suite 390 Fort Collins, CO 80524 (970)416-8876 Prepared by: ❑QUALITY `x ENGINEERING www.quality-engineering.com 1501 Academy Court, #201 Fort Collins, Colorado 80524 (970)416-7891 QE Project No: 7022-001 Date: February 2, 2015 G Touchstone Addition FINAL DRAINAGE REPORT ENGINEER'S CERTIFICATION I hereby certify that this Final Drainage Report for the design of stormwater management facilities for the Touchstone addition was prepared by me, or under my direct supervision, in accordance with the provisions of the City of Fort Collins Storm Drainage Design Criteria and Construction Standards for the owners thereof. oPND O L/C6,L 0A ' Io 41326 m� 90� N r 1 Cody Geis dorfer,'P.E. Registered Professional Engineer State of Colorado No. 41326 I. Table of Contents I. GENERAL LOCATION AND DESCRIPTION.........................................1 A. Location...................................................................::............................................... I B. Description of Property...........................................................................................1 II. DRAINAGE BASINS AND SUB-BASINS..................................................2 A. Major Basin Description.......................................................................................... 2 B. Sub -Basin Description............................................................................................. 2 M. DRAINAGE CRITERIA...............................................................................3 A. Regulations............................................................................................................... 3 B. Development Criteria Reference and Constraints ................................................ 3 C. Hydrological Criteria............................................................................................... 3 D. Hydraulic Criteria................................................................................................... 4 E. Modifications of Criteria......................................................................................... 4 IV. DRAINAGE FACILITY DESIGN...............................................................4 A. General Concept....................................................................................................... 4 B. Specific Details......................................................................................................... 5 V. CONCLUSIONS.............................................................................................6 A. Compliance with Standards....................:............................................................... 6 B. Drainage Concept...............................................................:..................................... 6 VI. REFERENCES ........................... :.............................................. I ..................... 7 I. GENERAL LOCATION AND DESCRIPTION A. Location ' The proposed site is located in the northwest quarter (NW 1/a) of Section 18, Township 7 North, Range 68 West of the 6th P.M. in Larimer County, Colorado. Specifically, the property is located at the end of Rivendal Drive, more generally, the southeast corner of South Lemay Avenue and Riverside Avenue. The property address is 1217 Riverside Avenue, Fort Collins, Colorado 80524 and is further described by the Riverside Commercial Planned unit Development Second Filing as Lots 4 and 4A. Please see ' vicinity map located in the Appendix. B. Description of Property The property (Lots 4 and 4A) are currently 0.42 acres of developed land surrounded by ' commercial properties to the west, east and south as well as parking and Riverside Avenue to the east. The area to be developed is an existing gravel building pad and consists of approximately 0.08 acres. Directly north of the property is Rivendal Drive. ' Rivendal Drive., the parking lot and Riverside Ave. are both currently paved with curb, gutter, sidewalk, and utilities installed. The existing property includes parking, sidewalk, an -existing building and landscaping. The site currently is crowned and drains generally to the north and south at approximately a 1 to 2 percent slope towards Rivendal Drive and the south parking lot, respectively. ' Southern flows drain toward an area inlet just south of the site and continues southeast via storm pipe until it is met by Riverside Ave. Northern Flows drain toward Rivendal Drive and out to Riverside Avenue. There are generally no offsite flows that drain ' towards the property. The entire site is located in FEMA Flood Zone X, entirely outside of any 100-year flood plain (see FIRMETTE in Appendix). ' According to the NRCS soils map survey, the native soils consist of Type `B" soils. Type B soils exhibit moderate to high infiltration and moderate to low runoff characteristics. (See NRCS soil map in Appendix). ' There are no irrigation facilities located within the proposed site area. ' The proposed development will consist of the construction of a 1,600 square foot building addition that will serve as additional office space for Touchstone. The existing building is approximately 3,876 square feet. II. DRAINAGE BASINS AND SUB -BASINS A. Major Basin Description The Touchstone Medical Center Expansion site is located at the edge of the Spring Creek Basin according to the City of Fort Collins Master Drainage Plan. Spring Creek is a major watercourse that flows from Spring Canyon Dam at Horsetooth Reservoir to its confluence with the Poudre River. The Spring Creek drainage basin encompasses nearly nine square miles in central Fort Collins. The basin is dominated by residential development, but it also includes open space, parks and isolated areas of commercial and industrial development. We understand that storage requirements for the spring creek basin are to detain to 2-year historic after a 1,000 square foot allowable for new impervious areas. B. Sub -Basin Description Historically, the entire existing site drains to the north and south side of the property via sheet flow at a slope of 1 to 2 percent. Northern flows exit the property to Rivendal Drive as sheet flow and are conveyed via curb and gutter to Riverside Avenue. From there, it will be conveyed southeast to Spring Creek. Spring Creek ultimately discharges into the Poudre River. Southern flows will exist the property to the business access road where it is then transported south to an area inlet. This concentrated flow is then carried via storm pipe east until it is met by Riverside Avenue where it will continue just as flows from the north. The developed building pad portion of the site has been delineated into two sub -basins to quantify overall developed flows and one smaller sub -basin to quantify water quality and detention requirements with a rain garden designed to provide both the required water quality capture volume and 100-year detention volume. Sub -basin 1, 0.08 acres, encompasses the disturbed area of lot 4A. Runoff from this basin is conveyed historically towards the north and south. Sub -basin la, 0.0367 acres, includes just the flow from the 1600 square feet of the building expansion for which detention is required. This sub -basin is conveyed north to the properly sized rain garden where flow is captured and to meet the City of Fort Collins' required WQCV. As the soils for the site are fairly permeable, an underdrain has not been provided. Instead, the captured flow will infiltrate through the rain garden medium and eventually into the water table. Off -site flows do not enter the site. This will not change after the site has been developed. DRAINAGE CRITERIA A. Regulations Drainage design criteria specified in the City of Fort Collins Storm Drainage Design Criteria and Construction Standards manual (FCSDCM) and the Urban Storm Drainage Criteria Manual, Volume 3 by the Urban Drainage and Flood Control District (UDFCD) have been referenced in the preparation of this study. ' B. Development Criteria Reference and Constraints The criteria used as the basis for analysis and design of stormwater management ' improvements for this site are those found in the references cited. To the knowledge of the author, there are no other capital drainage improvements planned ' for this portion of Riverside Business Park, aside from those referred to above, that would constrain or otherwise influence the design of the stormwater improvements for this site. C. Hydrological Criteria Stormwater runoff from the respective sub -basins of the Touchstone site is analyzed for ' storms with 2-year and 100-year return frequencies. Due to the relatively small aggregate area of the tributary drainage sub -basins, the Rational ' Method was chosen for use in the design of the stormwater management improvements. The Rational Method provides that: ' Q = CIA; where: Q = Design flow in cubic feet per second (cfs) ' C = Coefficient of runoff for the area under consideration I = Rainfall intensity for the design storm duration (in/hr) A = Area of the drainage sub -basin under consideration (ac) ' Peak flows were calculated using the Rational Method for the 2-year and 100-year storm events. This software uses the local 1-hour rainfall depth and Fort Collins rainfall ' intensities developed calculate rainfall intensities as a function of the time of concentration. These values were obtained by the City of Fort Collins Rainfall Intensity -Duration - Frequency (IDF) curve/table; Figure 3-1 and Table 3-la, and can be found in the Appendix. ' Additionally, per City of Fort Collins, the coefficients have been multiplied by the appropriate storm factors. Percent imperviousness values were taken from Table RO-3, Recommended Percentage Imperviousness Values, USDCM (See Appendix). Soils of hydrologic soil type `B" dominate the site. Onsite runoff was calculated to determine the runoff differential between existing and developed conditions for use in sizing the rain garden as required per Wes Lamarque at the city of Fort Collins Engineering Department. The hydrologic basin parameters and runoff rates are show in the Appendices. The Modified FAA Detention Method as outlined in the USDCM Control was used to compute the required 100-year storage volume requirement for the site. The USDFCD software UD-Detention v2.34 was used to calculate the required detention storage volume as well as tabulate a stage -discharge relationship for the water quality capture volume and outlet structure. The USDFCD software UD-BMP v3.03 was used to calculate the required WQCV and the size for the proposed rain garden. The design worksheets included in the Appendices to this Final Drainage Report present documentation of the hydrologic calculations for the on -site storm drainage systems. D. Hydraulic Criteria Within this development, all runoff will be conveyed on the surface, initially as sheet flow and subsequently as concentrated flow in curbs and gutters. The assessment of required capacity and the sizing of the respective components of the drainage system are based on the anticipated runoff from the 100-year storm event. Where the site grading design in localized areas precludes continuous surface migration of runoff to the rain garden, appropriately sized outflow structures are included to convey the accumulated runoff from these localized collection points to historical exit points. E. Modifications of Criteria There are no modifications or variances requested in connection with the design of the stormwater management for the Touchstone addition. IV. DRAINAGE FACILITY DESIGN A. General Concept The storm drainage system is designed to safely convey developed storm flows by sheet flow and concentrated gutter flow to the rain garden located at the northeast corner of the property. The rain garden will be sized for the total required 100-year storage volume and the water quality capture volume requirements for the entire site; however, the runoff from the proposed patio and sidewalk will be conveyed to the existing access road, and continue on as it has historically. These flows are considered insignificant due to the relatively small change in flow for the site. The detention pond outlet structure is the ultimate release point off of the site and will be release at the historic 2-year rate of 1.36 cfs per acre, or 0.5 cfs. Runoff from the site will be conveyed into the rain garden for water quality and detention requirements. This runoff will be released offsite at the historical rate for the additional impervious area only, as required by the City of Fort Collins. The design worksheets included in the Appendices to this Final Drainage Report present details of the hydrologic and hydraulic calculations pertinent to the design of the on -site storm drainage system. A drainage plan, showing the proposed development of the site and developed drainage patterns is included in the map pocket following the Appendices. B. Specific Details ' There are a number of collection and conveyance scenarios within the drainage regime associated with this development. The respective scenarios are described below. Sub -basin 1 (0.08 acres) encompasses the planned construction area of lot 4A. Runoff from this basin is conveyed historically towards the east and into the access road. The total, site - generated, 2 and 100-year peak discharge from the 0.08 acre site is 0.17 cfs and 0.78 cfs, respectively. Sub -basin la (0.0367 acres) includes just the flow from the 1600 square feet of the building expansion for which detention is required. Runoff from the roof will sheet flow until it is carried to the rain garden via an appropriately sized gutter. The 2 and 100-year peak discharges into the rain garden are 0.10 cfs and 0.36 cfs, respectively. The required 47.7 cubic feet of WQCV will infiltrate the various layers of the...garden and regenerate the ground water, while the additional flow created by the 100-year storm will be captured and released at the historic 2-year rate. This outlet will consist of a 2.23" orifice plate restricting the ultimate release rate to equal or less than the allowable release rate of 1.36 cfs per acre. Flow will be released through a curb cut and will continue as it would historically. ' The rain garden has been designed to accommodate volume and release requirements for the new impervious area of the Touchstone Addition. The 100-year detention requirement for the site is 209 cubic feet. The site will require the aforementioned 47.7 cubic feet of WQCV. The controlling detention volume required is the 100-year detention of 209 cubic feet. C u Rain Garden Storage Pond Summary Water 100-YR 100-YR Quality Pond Volume Volume 100-YR WQCV Spillway Outlet Capture Freeboard Outlet Type Required Provided Elevation Volume Elevation Elevation (ft) Size (ac-ft). (ac-ft) (ac-ft) 0.005 0.005 4956.47 0.001 4955.94 4956.47 0 Orifice The rain garden can be easily accessed from the north along Rivendal Drive to allow for maintenance access. The rain garden has been designed to drain the WQCV in the 12-hour allotted time frame. Additionally, a portion of the 100-year volume will infiltrate into the ground surface at 0.6 in/hr (1.2 in/hr before the applied 2.0 factor of safety). The additional volume will be released at the historical rate through the aforementioned orifice plate. There will be no new facilities required offsite for the conveyance of the minor or major flows. V. CONCLUSIONS A. Compliance with Standards The drainage design for the Touchstone addition is in compliance with the requirements of the City of Fort Collins Storm Drainage Design Criteria and Construction Standards Manual as well as the City's floodplain regulations. The criteria and recommendations of the Urban Storm Drainage Criteria Manual are also reflected in the design of the drainage systems. B. Drainage Concept The drainage design for the Touchstone addition will be adequate to safely convey onsite and offsite flows through the development. The design will attenuate the 100-year developed site flow down to the 1.36 cfs per acre release rate as required by the City of Fort Collins. Development of the site, as proposed, should have a beneficial impact on water quality in downstream drainage facilities and drainage ways by reducing and delaying the initial discharge of runoff from the site such that sediments and other potential pollutants typically carried by this first flush are removed from the flow. VI. REFERENCES "City of Fort Collins Stormwater Criteria Manual", City of Fort Collins, Adopted December 2011 . "City of Fort Collins Municipal Code", Chapter 10 — Flood Protection and Prevention City of Fort Collins, 1987 Urban Storm Drainage Criteria Manual, Volumes 1, 2, and 3, Urban Drainage and Flood Control District, April 2008 VII APPENDICES A. Hydrologic Computations Vicinity Map FEMA FIRM Exhibit USGS Soil Map Fort Collins Rainfall Intensity Curve Fort Collins Rainfall Intensity Table Table RO-3 Recommended Percentage Imperviousness Values Rational Method Calculated Composite C Tables Rational Method Calculated Imperviousness Rational Method Calculated Flows m z D r v LEMAY AVE D O -a 0 � �IS �O � Ltd cgti ' I ATSON 4T9 O m AFT STREET zY sT9F a co0.4 V FT O� J 0 sT9 N O O z a F r MTI z ^� m N I� O �O ~ ~ROBERTSON STREET m m �a a m (n aka m 0 HoOSPITAL LANE m X�0 pC o m 0 a c a a c a" LUKE STREET �C��r m aC �c O N �R m � m z 6� m m Z d PATTON S TREET 2 \\ o H`JIW3 3. e ALFORD STREET 9p-s-r-p6ES a� ,�a 9�BAKER STREET4- RIVE ~ Qf— O z—_m E9m o jS 3R3n� ` no' a� F O m S f a im �r� R7Jill i mZ z r mm3�� a m C O ,'ate O N O C� OR d og a r Sg '0 0 n O v m m135. a w i ��� 7 -5 O� CrJ y� D 0 S 0 g �qo c� r 3'32y.m �s� TON O C R o� m m ° 2-€ 9 o r o 8a93g ;� �g �Oy z o p m _ pnq m yg$[ gg gg R7 O Z m m' 3 D m m x r :5 3 R m �:i'�" <'A Z e Y 3 Ts o 00 MS $ F 5 cn 00 m d x x O 3 p°z3 wfG SAS ' S m — m j m 3=a^ � 1 m II 'I> 105^ 329W ' O n m �Z 7 C O N C $ i6 y A •• m 2 N N � r V ' � g D x N ' O N C o < 0 a m 0 W. C m C In m cn m -0 m � N m � 00 I05^ 3 13'W § 4491510 -WK- 0 441: 590 4491630 k 91670 4491710 pu zz 10Y' SA'w O. O_ O O 0 C 0 N r 1 Z 3. m� mn D0 �CD m 0 O 0 m 0 105" 31S W 4491750 X z ! ■ Cl O O | ! ! | I I \ / Li / Li Li / Li / w ` z` ` ` ©\ ` ` ` ® k , , e e 6 e e e / \ 0 {\ k o ■ ■ ■ ■ �a ` ° - 0 ) ƒ !® !0 E e \ \ \ \ } k [ } ,�`-f|ea2 2 R» ®® 2fEka CD §`ƒD0\ ƒ\D ({\ > ` \B' ( w \U®m_ �& 0� - umGa - ) #°(») ; _ƒ CD (a /}} -D 0 TD aSE ( £ a|-<0 _( i] | § |t7D k CD Z\ Q %>/[ƒk\({ �f0 \|\}\\/{ /\K}/ () )\ @ / ƒ»®,»`,Rƒ; ( L /0) \0C�� ID { 2 i §kc �) ;f0 m{ / w Uk &CD/// / |) - ;If 0{- /ƒ0CUf/ <� D � m 0 z 0 � � z 0 X � � e 3 z TOUCHSTONE HEALTH Hydrologic Soil Group-.arimer County Area, Colorado Hydrologic Soil Group Hydrologic Soil Group— Summary by Map Unit — Larimer County Area, Colorado (CO614) Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 53 Kim loam, 1 to 3 percent slopes B 1.4 12.1% 94 Satanta loam, 0 to 1 percent slopes B 10.4 87.9% Totals for Area of Interest 11.8 100.0% Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long -duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (AID, BID, and CID). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink -swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. ' If a soil is assigned to a dual hydrologic group (AID, BID, or CID), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Rating Options Aggregation Method: Dominant Condition QD Natural Resources Web Soil Survey 11/25/2014 Conservation Service National Cooperative Soil Survey Page 3 of 4 Hydrologic Soil Group—Larimer County Area, Colorado TOUCHSTONE HEALTH Component Percent Cutoff.- None Specified Tie -break Rule: Higher USDA Natural Resources Web Soil Survey 11/25/2014 ;�" Conservation Service National Cooperative Soil Survey Page 4 of 4 O N T— 0 n O N IOE (ay/ui) Apsua;ul IA d 7 c E rz O m R r` 3 W City of Fort Collins Rainfall Intensity -Duration -Frequency Table for using the Rational Method (5 minutes - 30 minutes) Figure 3-1a Duration (minutes) 2-year Intensity in/hr 10-year Intensity in/hr 100-year Intensity in/hr 5.00 2.85 4.87 9.95 6.00 2.67 4.56 9.31 7.00 2.52 4.31 8.80 8.00 2.40 4.10 8.38 9.00 2.30 3.93 8.03 10.00 2.21 3.78 7.72 11.00 2.13 3.63 7.42 12.00 2.05 3.50 7.16 13.00 1.98 3.39 6.92 14.00 1.92 3.29 6.71 15.00 1.87 3.19 6.52 16.00 1.81 3.08 6.30 17.00 1.75 2.99 6.10 1 &00 1.70 2.90 5.92 19.00 1.65 2.82 5.75 20.00 1.61 2.74 5.60 21.00 1.56 2.67 5.46 22.00 1.53 2.61 5.32 23.00 1.49 2.55 5.20 24.00 1.46 2.49 5.09 25.00 1.43 2.44 4.98 26.00 1.40 2.39 4.87 27.00 1.37 2.34 4.78 28.00 1.34 2.29 4.69 29.00 1.32 2.25 4.60 30.00 1 1.30 2.21 4.52 DRAINAGE CRITERIA MANUAL (V. 1) Table RO-3—Recommended Percentage Imperviousness Values Land Use or Surface Characteristics Percentage Imperviousness Business: Commercial areas 95 Neighborhood areas 85 Residential: Single-family Multi -unit (detached) 60 Multi -unit (attached) 75 Half -acre lot or larger Apartments 80 Industrial: Light areas 80 Heavy areas 90 Parks, cemeteries 5 Playgrounds 10 Schools 50 Railroad yard areas 15 Undeveloped Areas: Historic flow analysis 2 Greenbelts, agricultural 2 Off -site flow analysis (when land use not defined) 45 Streets: Paved 100 Gravel (packed) 40 Drive and walks 90 Roofs 90 Lawns, sandy soil 0 Lawns, clayey soil 0 * See Figures RO-3 through RO-5 for percentage imperviousness. CA = KA + (1.31i 3 —1.44i z + 1.135i — 0.12) for CA >: 0, otherwise CA _ 0 CCD = KCD + (0.858i3 — 0.786i2 + 0.774i + 0.04) CB = (CA + CcD)12 RUNOFF (RO-6) (RO-7) 2007-01 Urban Drainage and Flood Control District RO-9 0 0 n 0 J A O J 0 0 o_ 0 N m v m m OG v O m w d N D v S U II D 0 O 0 0 O 0 O o bm � Ol` n N n J n lD 0 0 0 0 m O 0 O D O 00 0 O A O � W n 'm N ci 0 0 0 0 0 0 ui m o N O A N pip A a n o 0 o o 0 00 0 CD N 0 od N _ d f 0 0 0 0 O O O O O .0 O O O O O 0 O O O O N 0 0 O O 0 O O 0 0 n o+ W 00 W OO � W o 3 3 0 0 p 0 J 0 0 V '0 0 ^ to O� 0 O m f ri A n 0 3 o N o o m w w n o0 A Y n r- rD CA v N v w v ~ m d m N 00 O 0 0 w m m w L N D N U S � d O G O U O D 0 0 C O p N n N N 0 O n fD fD O O 0 0 N 0 O 0 0 o 0 o D m o d v n O < rD O X N G1 G O O M O O 7 00 61 < o a oW iD � T. O � m n O N O O O O ° O W CT)Ql O W O O CDn N ko 4 V V U O N N N O O O O O 00 O 0 O O O O O O O n N N o O O O ° W 0 oo 0 W o o n v (D — D m V N Ql rn V .-• Ql N .... N d 3 10 M v O N CD < ' 0 0 0 o C 3 N 7 N N n (D on 0 3 4 i 3 0 6 Y m Y Y m Y M J a p p o W 0 pp W ml 'Sq i� 9 a J T m iO V N N A 8 J N T O O O n 0 ^ S N W W m O N N mm NN .r oA N O O N N N CIO W W A b N N N 3 j� yN V N N J Oi J O ti 3 m Y N a s 3 m q O V W W � o :g S $s SS aeb n Z4 qq ti q m p m 3 A n 0 0 88 00 r 00 o o #w 88 3 N N 3G N N N 3 VNV y n � p3 N N pN 8 O pN O S n 3 S w N N N N Ibm N N T r A a A A P S i b 1m b Q �bp N N N N N 0 0 p p O V YOi 1+ y Q O O OL 0 � E G0 0 0 V v N B. Hydraulic Computations ' Detention Volume by the Modified FAA Method Stage -Discharge Sizing of Orifice n U LI ' DETENTION VOLUME BY THE MODIFIED FAA METHOD ' Basin m: Developed 100-Year (For catchments leas than 160 acres only. For larger cetchlnents, use hydrognph routing nethod) (NOTE: for catchments larger than 90 acres, CUHP hydrograph and routing are recolmlended) Determination of MINOR Detention VolunY Using Modified FAA Method Determination of MAJOR Detention Volunas Using Modified FAA Method . Design Infamatlon finguO: D eof D,aueape l,ryeaio,ares4 I,. Cffichnart D,ok Area A.. Pntlelabl+rnen NRC65o90rore TtVe. Reluan PoMdla DeYdbn Cereal T- Tmeoi Cwcaeeionawaon,w Tc. A9n u,ft Rsbw Rd* 0- Oretolr pm ip9abn P,- Da=IGl N4afaw mF Far@ada I.C,•PACarTj-CP Coeffnen One C,. Coaakd@rt Tee Ca CoeaaenTYne C4- 90.N -:::Pervert A,B.C,aD was(2, S. 1a. 25, N,o, 100) modes asNcoe RMa Design mfonlYtion fleoutl: CetlmeKDreluepe l,reaviouaaas 1.- 90.00 Mreen uage Noe A- 0.W29 @cops Colamert Don Prvda lopmeorwcs So90mlp Trye- 8 A. B, C. or Rerun Period for anemion Corael T IN yeYa(2, 5, 10, 25, N, errlW) Tole of C ncerlrWcn of WaaraMd To - 5.00 modes AbwdOio lira Re4aas RYa 0 1263T ae/acn Om Pncip0a0on Pr 2.88 Yrhs Osslgn Wh,Y9 OF F.1% Iv C,' PAC»T^n DoeffrveN Ore C,- U.so C ra Two Ca- 10 Coeilioblt Thal ra. 01e9 0.032E .eras B sm 12WT OM 2850 10 O.T89 Raga Coelhieu �C. 0.71 Idioe Pook Runll op-hLo. a-06 cfs AOowaOle PeakO Rase Opou-_OM_tla Yod.FMYkwrSbraq VOWnrsv 12 eugelNt MW.FMMluorSn Va . 0000 scrNt 1-FAer RaNe9 Oaalionl,pemerdallrneafe Value He re e..51or 5#batez Determination of Average Oudim from the Basin ICalculatedl: Ruotf Cc lert C- 0.81 I,dker Peakrimell OP- . 0.26 d. Abe+bb Peek(AgbwRm OpoN-_OA4 tls Yed.FM Yalor $long VOWnp. 195 cuw hers NW. 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Mad. FM Ylnor Sharpe VoNms(&a )a flows YaO.FM Ya)er Stonq Volume(acMt)• 0m41 UDFCD DETENTION BASIN VOLUME ESTIMATING WORKBOOK Version 2.33, Released August 2013 1W-YeaD bedUD-0aYmbn Y2.33_Wuel Real Area). Moddfed FM 101IM14,128PM Orifice Flow Calculations Project: Touchstone Number: 7022-001 Calculations By: GLF Date: 12/11/2014 Orifice ID: Orifice 1 Grate Dimensions and Information: Grate Type: 2.23 Inch Orifice Plate Diameter (W): 0.1858 ft Open Area (A): 0.0271 ftZ Reduction Factor (F): 50% Orifice Flow: Results: Number of Orifices: 1 Design Flow Q = 0.05 cfs H = 0.5 ft Use the orifice equation Q;o = C*A*(2*g*H)1/2 C = Ideal Capacity C = Orifice discharge Coefficient = 0.65 A = Orifice area (ft2) - open area of grate g = Graviational constant = 32.2 ft/sZ H = Head on grate centroid, ponding depth (ft) QG = Reduced Inlet Capacity = Q;*(1-F) 4-0 = 0.10 cfs Quo = 0.05 cfs `ALLOW 0.05 cfs QACTU, = 0.05 cfs C. Water Quality Design Calculations UD BMP Rain Garden Calculations Design ProcedureForm: Rain Garden (RG) Sheet 1 012 Designer: GLF Company: QUALITY ENGINEERING Date: December 11, 2014 Project: 1217 RIVERSIDE AVE (One rg north) Location: FORT COLLINS, COLORADO 1. Basin Storage Volume , A) Effective Imperviousness of Tributary Area, I, 1, = 90.0 % (100%it all paved and roofed areas upstream of rain garden) B) Trbutary Area's Imperviousness Ratio (i = IJ700) i = 0.900 - C) Water Quality Caphre Volume (WOCV) for a 12-hour Drain Time WQCV = - 0.32 watershed inches (WOCV=0.8' (0.91' P- 1.19' it+0.78' ) D) ContrbutN Watershed Area (including rain garden area) Area = 1,600 sq it E) Water Quality Capture Volume (WOCV) Design Volume Vwocv = - cu it Vol = (WOCV / 12)' Area F) For Watersheds Outside of the Derwer Region, Depth of de - 0.43 in Average Ruwff Producing Storm G) For Watersheds Outside of the Denver Region, Vwacv ova - 42.8 cu it Water Quality Capture Volume (WOCV) Design Volume H) User Input of Water Quality Capture Volume (WOCV) Design Volume Vwocv user - Cu it (Only if a different WQCV Design Volume is desired) 2. Basin Geometry A) WQCV Depth (124nch maximum) Dwocv = 12 in B) Rain Garden Side Slopes (Z - 4 min., horiz. dist per unit vertical) Z = 4.00 ft / ft (Use'0' if rain garden has vertical walls) C) Mimimum Flat Surface Area Aar, 29 sq it D) Actual Flat Surface Area A� = 55 sq If E) Area at Design Depth (Top Surface Area) Ar, = 370 sq ft F) Rain Garden Tota! Volume V7- M cu it (Vr- ((AT. + A .b j / 2)' Depth) 3. Growing Media 18' Rain Garden Growing Media CC Oil- (E*aN): 4. Underdrain System Chooso C e A) Are underdrams provided? YES NO B) Underdrain system orifice diameter for 12 hour dram time ) Distance From Lowest Elevation of the Storage y = WA ft Volume to the Center of the orifice m7 Volume to Drain in 12 Hours Vol,z= WA cu ft um) Orifice Diameter, 3/8' Mnwnum Do = WA _ in UD-BMP_RAIN GARDEN (North RG with vertical walls), RG 12/11/2014, 1:24 PM UD-BMP_RAIN GARDEN (North RG with vertical walls), RG 12/11/2014, 124 PM HISTORIC BASIN FLOWS BASIN DESIGNATION AREA (AC) 2 IEAR COMP. 'C 100 YEAR COMP. 'C Oz (CS) 01,m ((p§) OE9@E POINT BASIN NUMBER Dt E1 0.08 0.50 0.63 1 0.11 1 0.51 E1A E1A 0.037 1 0.50 1 0.63 0.05 0.23 PROPOSED BASIN FLOWS BASIN DESIGNATION BAR! MIMBER AREA (AC) 3 YFAR COMP. 'C 1 Me IEAA COMP. 'C O1 (CFSI) O,.ro (6� DESIGN POINT Pt B1 O.OB OJB 0.98 O.O 0. B PIA ERA 0.037 0.95 1.DO 0.10 0. EnsnxO WATER sFANS EL51N. SMITARY MINCE mmxp r etc awlTAnr eewen uxF 5 S S 5 9 gl4sr. nar Mutt gAmdT FarnEaTr Fear FNSTwc wAma CAP - \ — DMIRAtrtll ro Rm taarc F1r51N0 VIIVIe$ µp 1&I.pCA1F ilECE44NY I \ �q y b D f l �� �kkkk IgE Ei06TN& &tlgBMp �I n+gau —5 5 Rrll WRN _ \ I I Y,/ I I PI4OPOaElA1100 df ADpItON Fq•s&t/' at I B1A E1A ( I / An Garden Storage Pond Summary her took New" Oog1Y VeYme Vtlume ack waC/ Faillwry � gaet ap:.e aaMeE pwiW or.a4en Elentix, Denliwi awnisoe nde (a°AI kafq KA) 1 ANSI 4956,47 D onhe 3]a' Owl aW III a%6A7 —w— DRIVE RIVENDAL kpRNATE DRIVEL i5—• —5 —9 fICE PLATE� a „ r--- I I I � -- I Rock - I I 1 I 1 � I f I Q R Lq I I I� I Bill I I in I If ETA a �_ 111rA FAaI ewxwwY 1 sMv I I} k. I I� I I � I I I I l 1►� �1► j�' �j►� , t � Q �I� �I Ir` , I II I ' II II II II II II II II _ II LL I" N r FOR O kI ED VTILItt INFORM II I • TMRIDE(3) BUSINESBD BEFORE YOU DIG CALL 811 (anleMn 4ttic CENTEJILITY NOTIFICATION 2R OF COLORADO Hill Slid Storage & Release Table Ertlre Slte Rnln Fla 81 &istin 2-Yr Flow 011 Rs F.ISFI 106vr Now asl ds Oevelo tli ttflow 01 Rs Developed!1NYr Flaw 078 Rs Ro a WMELl&B1A Ealsfi 3-ttFloo, I a05 ds EaIHI 1WYr Flow ai3 Rs Developed TYr Flow D.1 Rs Developed ID)l Now OWN, MW Nea Dete,Nan Rekme Nu aaS ds Fe Nln 2 Yr rvpn gmlem ftle Rleae Rek aa: as (Difference between developed took Yr'Entire SIR' flow (0.78 dal and the 10DW-Rand Area"flow (035ds) which we are capturing) TotalM la dMlecu Rate 0.47ds (Nonbu dingreleax rate(0.414 Detentionreleaser (aMdt)l Raduaton in Now ID.01 a1a (wxerence between Existing 1E4Yr How last us) and the Total developed release Me Hart d3 CITY OF FORT COLLINS, COLORADO UTILITY PLAN APPROVAL CHECKED BY - rru e.unum unun wrt NECKED DY: nmwm uMr w CHECKED In CHECKED W.- al Z !m FF--W�3 w' J ZI€ Q C7 _a�aa OWE I W O a= CL V i�tlV Z rc c�eclav n ew Ilmolm a,: dM DRNw1 m MF WED D]. 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