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Home My WebLink AboutDrainage Reports - 02/18/20161 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 January 26, 2016 Mr. Dan Mogen City of Fort Collins Storm Water Utility 700 Wood Street Fort Collins, CO 80522 INTERWI T CONSULTI N G GROUP City of Fo Collins Approved Plans Approved by' Date: Z/1/2_0« Re: Drainage Memorandum — Wood Street Vehicle Storage Facilities Dear Dan, Please accept the following letter on behalf of the City of Fort Collins Utility Services Building Department to demonstrate each of the sites referenced above compliance with current City Code. Please note that a separate erosion control / stormwater management report has been prepared for this combined project and erosion control is not addressed in this letter. Also included with this letter are the standard operating procedures for the proposed rain garden. INTRODUCTION This combined project consists of two new buildings on the City of Fort Collins Utility Services Department's property. The first building is known as. the Light and Power Building located at 700 Wood Street. The second building is known as the Water Services Building located at 701 Wood Street. The 700 Wood Street site is bounded on the west by Wood Street, the south by Elm Street, and the north and east by existing City of Fort Collins Utility Services Department infrastructure. The proposed building will be used for vehicle storage and is located in the existing service yard parking area that is currently 100% asphalt pavement. The 701 Wood Street site is bounded on the east by Wood Street, the south by W. Vine Drive, the west by existing City of Fort Collins Utility Services Department infrastructure, and the north by an existing detention pond. The proposed building will be used for vehicle storage and is located off the west edge of the existing concrete drive for the vehicle storage building. EXISTING CONDITIONS The 700 Wood Street building addition will be located -in the existing asphalt parking/equipment storage area. Existing runoff from this area currently sheet flows across existing pavement to the northeast corner of the property where it enters an existing water quality / detention pond. In walking the area of the existing offsite pond with city staff it was noted that the pond was well ' Mr. Basil Hamdan January 26, 2016 Page 2 of 3 ' established and appeared to have wetland vegetation near the outlet which discharges to the Poudre River. Additional modifications to this pond were determined to be potentially detrimental to the pond and vegetation. ' The 701 Wood Street building addition will be located west of the existing vehicle storage ' building and align with the edge of concrete. Existing runoff from the dirt parking area currently sheet flows to the north where it is ultimately conveyed to an existing water quality / detention pond located at the north end of the property that was designed as part of the previous Vehicle ' Storage Building project. While the area is currently an existing dirt parking area, this building was master planned and included with the design of the extended detention pond by TST in 2004. PROPOSED DEVELOPMENT ' 700 Wood Street The 700 Wood Street building addition will consist of an 11,520 sf building which will be located in the existing service yard parking area that is currently 100% asphalt pavement. The ' proposed building will have a 20 foot concrete apron on both the west and east side and new asphalt will be used to patch the limits of removal required for general construction and utility connections. ' Per previous conversations with city staff on this project regarding detention and water quality, the 700 Wood Street building addition is not required to provide storm water quantity detention ' or pervious Low Impact Development (LID) treatment. The proposed impervious area is replacing existing impervious area resulting in no additional runoff. The City Stormwater department recently installed an LID / water quality system for the parking lot located directly west of the building addition. It is proposed to credit the LID / water quality treatment that this parking lot now receives in exchange for this new building. Approximately 89,000 sf of parking lot is now being treated to the west of the development area and there is approximately 23,000 sf ' of new disturbed area associated with the building and utility construction. Therefore we request that the existing LID system to the west be accepted as providing alternate compliance for the proposed development area. 701 Wood Street The 701 Wood Street building addition will consist of a 5,600 sf building addition. This building ' and associated improvements were included in the "City of Fort Collins — Utilities, Fleet and Facility Services — Final Drainage and Erosion Control Report", prepared by The Engineering Company, dated July 12, 2004. This report and calculations anticipated these proposed t improvements within their Basin 101 and master planned the water quality/extended detention basin (located north of the proposed building) accordingly. Please reference the appendix for excerpts from this report. The new building slab will generally abut the existing concrete pavement along the east face of the building. Although the existing pond to the north provided water quality capture volume and detention storage for this future building location, the development will comply with the more recent LID code. Mr. Basil Hamdan January 26, 2016 Page 3 of 3 Since there is no new drivable impervious area associated with this project, pervious pavement treatment is not required. For the building addition itself a rain garden is proposed along the west side of the building. All runoff from the building roof drains will discharge on grade along the western face of the building and flow into the proposed rain garden. The rain garden has been sized to treat 100% of the water quality capture volume associated with the tributary basin (runoff from the proposed roof and any runoff generated by the rain garden itself). Additional storage for storm water quantity volume has not been included as this volume was accounted for with the original pond located to the north. Please refer to the attached calculations for rain garden sizing. Overflow from the raingarden will be routed via underdrain to the existing 18" RCP that runs along the western property line of the site. This pipe then discharges into the existing detention / water quality pond. Thank you for reviewing the proposed stormwater improvements for the two building additions. If you have any questions or comments please contact me at (970) 460-1091. Skylar Brower, P.E. Colorado Professional Engineer No. 44248 Attachments Project References Grading Plan & Drainage Basin Map Hydrologic Calculations Rain Garden Sizing Standard Operating Procedures Stormwater Detention and Infiltration Design Data Sheet s/atin� •ENG�? ReGviiew�edBy: Robert Almirall, P.E. Colorado Professional Engineer No. 33441 C a N CITY OF FORT COLLINS' UTILITIES, FLEET AND 'FACILITIES _SERVICES Final' Drainage and"Erosion Control -Report July142,1004 The E ngmwmg _Cp. :Fort Collins,: CO. Project No. 03402.05 F:\2003 Projects\03-102 Fort Collins AllerLingle\05 Vehicle Stgmge\REPQftTTina1 Drainage Reportdoc, pis unofficial copy was downloaded on Jan-25-2016 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com M. PROPOSED CONDITIONS A. Developed 'Drainage Basins Five main basins have been analyzed for this drainage report. The basins were delineated in order to generate basins tributary to the major drainage components analyzed with- ModSwmm and the .Extras. component of:the EPA's:SWNfM model. The City of Fort Collins GIS contour data was used to delineate these basins: The first basin delineated, Basin 0&1, is. the basin tributary to the pond on the Equipment Services Building site. The flows in this basin are conveyed via overland and gutter flow into the pond itself. The runoff from the second basin is conveyedvia overland and gutter flow to the I S:-inch ADS pipe on the ESB site. This basin is knowwas"Basin OS-2. 'Basin 101 is that area tributary to the pond m `Lot t1x3 This basin was further, divided mto 5 sub- basins :as flows are.o. conveyed,;around both sides of ,the building Ilocated in the middle of Lot 1 and along Wood 1S reei and those. flows are routed into the pond. .Basin 102. is that area tributary to the inlet on Lot 2.. This inlet. is currently a flared' end! section :at the north end' of ,the swale in Lot 2. The basin includes a large area outside of the City's property. Portions of :this :area were included in Basin 501 in the Old'. Town Master Drainage Planfor reasons explained earlier. Basin 103 is that :area tributary to Lot 3. This area will' be captured. in a future pond' to be located in the northwest portion of Lot, B. Street Capacities and Inlet Sizing .Street capacity calculations and inlet .computations were: ;completed utilizing the program UD-Inlet version L,00 developed by James C. -Y.. Gou of the University of Colorado at Denver. The clogging factorsfound in the Fort Collins SDDCCS were used for alt inlets, sized with UD-Inlet. 'The program is available through the Urban Drainage:and Flood Control' District and analyzes the flow characteristics in the street to determine the inlet's maximum_fl'ow capture. All flows that were not captured, in on -grade inlets were routed to;the next d'ownst eam.inlet as shown in the hydrology calculations found:i iAppendix B. A trench style inlet was designed using, the Neenah web -site and data from, Neenah. This grate was - designed assuming that all the flow in. the.actuall gutter passed the inletand went to the next inlet. 'The inlet was modeled assuming that all. but' 4 lineal' feet of the inlet was clogged, rendering a conservative interception amount for the 357foot wide inlet. Alt computations and printouts for inlet sizing can be found iii Appendix C. 4 is unofficial copy was downloaded on Jan-25-2016 from the City of Fort Collins Public Records Website: http://citydocs.fegov.com Storm Sewer Analysis. The main storm sewer for the systemWds analyzed With ithe sofiwaaze Storm Wdter Managemelat. ModeI (SVAM version 4.4g. The EXTRANmode ofthisprogram was used, to analyze the maibr storm sewer sysferh:. This softare is capable of modeling backwater conditions.in thesystem as it routes,hydrographs; through the network of pipes and stora output ge.pond& Theinputandou tit.fil6scan.be.,fdund'*:M.AppeiidixG: and H for the,interim-and ultimate conditions, respectively. The local .storm -sewer system was analyzed' with Hydraflow. Tlu'sisasimple program that;routesflows through the storm sewer system and determines the condition ;of the flow and; applies the: appropriate: equations and headloss. All' storm:sewer:analyzed with this program: were given a tail -water boundary '!, condj#On equal''to the -down stream 100-YOT water surface: elevation: 'Ile, locaV storm sewer system mclb&s all inlets and pipes that drain directly to thepondon site:and tie into. the -storm of site. All system output can: be found inAppendix,C. Riprap was sized for each storm sewer, outlet. using criteria set forth, by the: City ,of Fort Collins,and by, Urban Storm*Driiinage. Manuals. Calculations can:be f6undInAppendix D. 5 �his unofficial copy was downloaded on Jan-25-2016 from the City of Fort Collins Public Records Website: hitp://citydocs.fcgov.com i_ 1V - MODELING A. Hydrologic Modeling The City of Fort Collins requires a unique hydrologic model, "MODSWMM" to generate the hydrographs used for routing in the stormwater system. This model, is based on the program UDSWMM I?C, a DOS based public domain software. that generates and routes hydrographs in a fairly simplistic stormwater system. The "MODSWMM" model was developed by Ted Combs 'in order to make UDSW1%4M2PC program more user friendly. Neither model may not be used for hydraulic routing when there is a backwater condition. This project :includes the analysis of a series of detention ponds that create a backwater effect, thereby ttqumng the use of a separate hydraulic inodel. The MODSWMM program was therefore used' to generate 'input hydrographs for use in the :interim condition and ultimate condtion hydraulic :models: The MODSWMM input and output file can be fouridih tlppendixR . The interim conditions model requiredthe input of 3 hydrographs; two hydrographs=for the City of Fort. Collins Equipment Services. Building site at 835 Wood- 'Street, (Basins 'OS-1 and 0S-2)• and •one hydrograph for the pond on Lot 1. The hydrograph used for the pond on Lot I was the result of the direct connection of •the hydrographs;generatedfor, Lot. I •(Basin. 101)and Lot 2 (Basin .102) of the_ Fort Collins Utilities, Fleet and, Facilities Services site. At this time, the conveyance element between Lots 1 and 2 is 4 incapable c able •of handling the 100-year storm event. (This prpe will be replaced with tliee-- evelopme if ofLot-, P _ (� l the meantime, tfie pond will'be capable`of-handling all�ofthe runoff generated- on Lots-'1 and whetherr all the. flowis deliver�e here or not. 4 The ultimate conditions model requires the input:of 5 separate hydrographs. This model:was generated with hydrographs for the existing ;pond on :Lot 1 (Basin 101), the swale on Lot_2 (Basin 1:02) and :the future pond on Lot..1(Basin 103). 'It al'so: included hydrographs for the existing inlet north of the Lot '1 pond (Basin,064), and -for the existing detention pond.to .the north (Basin OS-1), :bothlocated' on ,the City of Fort Collins Equipment Services Building site;at 835 Wood Street. B. Hydradlic Modeling 7 The software Storm Water Management Model (SWMM) version 4.4g, available :through -the Environmental Protection Agency's (EPA) *e-bstte, was tised. to model the hydraulics of this stormwater 4 system. The Extran node of this -program was used to model the backwater conditions of the project that are created by the series of ponds and storm sewer. 1. Interim -Conditions Model The interim conditions model: was .generated to represent the conditions after the development of Lot 1 of the Fort Collins, Utilities, Fleet and Facilities Services site and prior to stormwater improvements for 's unofficial copy was downloaded on Jan_25-2016 from the City of Fort Collins Public Records Website_http://citydoes.fcgov.com development on Lots 2 or .3. �e percent -imperviousness used to generate the input hydrographs ,d :assume build-out-of-all_the_basins_but are assumed -to tie undevelopa-the utiTiry impr veemen :associated w1th •the development of the basin are not co�lmp ete—This model also pf des watergual --i e Lot_l pond_ for developed flows originating within all three of the Fort Collins -Utilities,- leet-and' Tzcilities-Se�vic ot�s A schematic of the model and the input and output files for atus model can ;be found. in Appendix G. Construction. deficiencies, such as an undulating .outlet pipe, located in the existing outlet for the "north pond on the ESB site (EXTRAN ID,107) made it clear that anew outlet pipe should be constructed with adequate capacity to deliver flows to the Cache La Poudre River. Therefore, the interim conditions model` U was set up by modeling the "north pond" outlet (EXTRAN ID 308) with a 24" RCP and no orifice plate. The stage -storage information for the'"north,pbnd" was not altered' from the existing data. Through, trial' and error, the 100-year'water surface ;of the"'site pond" in Lot 1 of the site (EXTRAN ID 101) was found to have encroached into the right-of-way for Wood Street. The :pond was therefore re -graded to ensure -that the pondwould contain the required.storage volume for the ultimate condition inside the lot. This stage :storage information also incorporated the storage data for the water quality capture volume: The Interim Conditions model- was generated with the re -graded stage -storage information. The outlet for this�pond had.also been constructed improperly. Portions of the pipe were constructed with,a reverse slope. Instead of tearing :out the. existing pipe and replacing it, the outlet for the pond was redesigned toL incorporate some changes to: the ESB site and to minimise damage to the existing landscaping. The existing ADS inlet.on.�the ESB site is proposed to be torn out and replaced.with:a type 13 grated inlet. This should reduce the cross slope on the driveand reduce the amount of ponding on site. The interim conditions model shows adequate storage in -both the "site pond" (101) and the: "north pond" (107). The new maximum water surface elevation for the `-'site pond" (101) is 4984.25 (MSEL) and 4982.36 for the ``north pond" ,(107) in. the.interiti conditions. The new inlet located on the ESB' site has eliminated the:, previous,ponding problems. 2: Utiniate Condittorss Model a' The ultimate conditions model was generated ,to, represent the: conditions after. the development and construction of all stormwater facilities -,of all tht a lots on the Fort Collins Utilities, Fleet and Facilities. Services site. The development of Lot 3_will require the construction of anothea detention northwest portion of"the to This pond has •been•preliminarily graded and has beengiven, stage storage data based on this. grading. The location'of which can 6e. found on the drainage exhibit: This pond is not intended to "detain" runoff but rather to create available -head to "push" the runoff downstream. 'This is the case for all ;ponds modeled as the water is "pushed" out to the Cache La Poudre River. The ponds are necessitated by the capacities of existing downstream structures. As in -the -Interim Con- itions model) water quality for fu11 developmen-i—ofthe site ig-provided"in-the-storage pond -onto is unofficial copy was downloaded on Jan-25-2016 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com The tributary basin for the pond in Lot 3 is extended past Arthur's Ditch. This does conflict with the "Old Town Master Plan. As discussed previously, if the ditch were piped or running full. during a rainfall event, runoff would enter the Fort Collins Utilities,, Fleet and! Facilities Services site. The results of the Ultimate Conditions model show the water surface- for the pond in Lot 1 rising slightly from the Interim Conditions model but all flows remain contained within the system The only location that still has a slight flooding problem is the inlet on the ESB site. The depth of water in, this.location is less ;than one-half of a foot. However, when flooding does occur; the flows will not- approach the building. If the inlet plugs, the flows will pond until the runoff crosses the entrance to the sitearid eJiters- the'" northpond." The Ultimate Conditions Model ,also shows that an i8 inch ,pipe ,is required from the new pond in Lot 3 to the connection at the "swale" in Lot'2. The existing 1,8-inch ;pipe from Lot 2 to Lot I is replaced by a 36- inch pipe. The Ultimate Conditions Model' shows -that the maximum water surface elevatiorf on the,:pond in Lot 1 a&lringthe 100-year storm event will, be approximately 4985.00 (MSEL). No orifice plates are being ,proposed for use on :any pond outlet for any condition as this system was created as a backwater problem rather than:a restricted release rate issue. All input and output for this model can be found. in Appendix H.. 8 is unofficial copy was downloaded on Jan-25-2016 from the City of Fort Collins Public Records,Web-site:-htt,p://.citydocs.fcgov.com C-Value'PetenrinatJbn Project: !Ft. Collins Vehicle Maintenance_ Building Job No.: 03-102.00 'Date:. 30-Jan-04 By: A:'Kauffman General Unfo Industrial Residential' C Value. :' 1%Imp 0.8 . 0.5 --80;. --40- — Sub -Basin ID Total Area (ft`) Total Area (ac)' Industrial Area (ft`)� Residential ! Area W) Composite IC Value Percent Impervious _North OS-1. 140,118. 322 140,1:18 = 0i80-` ; 80"/0 Inlet° OS 2 '' ` 11',5;886 2.66 1'15,886 - 0;80 _80_°k` i Site a1;01' zj I 422;709 9.70 422,709' _ - 10 80� �80°l0- . Swale 102, _ ; 355,158: _ _ 8:55 88,789 266,368 , 0.58 50% Future 1;03 460,819"; t0:58 t15,205 345;61b { 0:58 50'/0 101a 64,627 1'.48 64,627 - 0.80 809�° 101b 30,329 0.70 30,329 - _ - _- 0.80 . ' I 80% _ 101 c_- _ - .52,685 - . 1.21 " 52,685 - - 0.80" 80% - T01tl` 18;466-. 0.42 18'466 - 0.80 80% 1 U;1 s- i 5.7,711 1.32 Z7;.711 1 I, - 0:80 _; :_ 8A%° 1 10.1.f 110 J 07 L 2.53, 11.0,107. _ - 0.80' 80% s unofficial copy was downloaded on Jan-25-2016 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com a CL n 47 w a3 Cl) Z CAP) 0 9:1. ------ 0 0' 0) 0 00 p to :-j w iQ q 0) n ID a. 0 o b. C. o.. o 0 P P P a0WC8W 0W0 4 W =L �o a 6 o o o o 6 o � 6 6 � cp F fl, I %4, 10 CO: to o co W IQ R P, 1p lu" 4 .4 CA3 4�jco c) (D n (" a Ch o -P. CD :3 a co a AOa00o CD 0. 0 0 0 o 6 0:0 C, 41 .9� w 111 'a 00 CIP p CD sal ;b ion" in b 6 6 4" m m 0 IMP 0) 4m (n (TO 0) to N ro p io co :tl bO 4!. :�4 W .41 0 io 0'- 0 (A bo POP �P, - N IV A b) tIi A . f IT4 w 0 co, Ul cn co w j n co Ln 2 �li EF.�i � 0 co 0) .9. -4 60 .,pp.W . -4 , Z n 0 co -acb (n colchica CD CA 0 AwOcncnu�LTj c"li-4 4 (D ca U s ' 9) PA CD CO -_4 0 0 cD U. co Co Ln W zo (q � b . - . 2 d C) C_ 0 0 moo 0 yi Z m 0 Fit 3 L 0 b 5 (milk ;CD CD Flow CglcuWons "qt Ft. Collins Vehicle Maintenance Building Jdb'No.:- 03-.102:60 Date: 30-Jan-04 BY: - A., Kauffman Floware based on the equation 0 = C Cf I A Where CX=' 1.00for the 2and lO, year events 1.25for the 100,year event 1: = 24:2211,41.047j'"') 2.Year =41'.44/(10tT,)I'-n7q' loyear =84:682/(10+Te") 100-year Design POW Sub basin IlD ; Area (A) (66 C Value' Time.ofConcentration; Rainfall Intensity,fl) DI Charge from;B2sln. Minor 'Major (mini (min) 2-yr : (In/hr) I i 1p;y�, (InMr), 100-yr On/hr) Zyr (cft), lc-yr (ds), f 100-YT (ds)i .North OS-1 3.22 - OM 13A -7,0 -WA- '3A' '8.8 '-NfA: 8.7 28.4 Infet(OS:2 2.65' -0.80- 19.1 9.A NA 2.8 8.1NA 6.0 21.4 Site (101);- .9.7.0., 0.80 -22:3-- A 10.5 N/A 2.6 1 7.6 NIA 20.1 718- S vale '1 02 -1 1.15 �0.58 747W ---35:T-- -NIA- 1-.13Y 4.0 7 N/A 7.7 23.5 10.58 0.58 55A 4jU- NIA 11.5- -3.7,- N/A. AU '27.9 8 101a,� N 1.48 0.80 -15A� 6Z NIA LN/A 3.2 '9.0 N/A -3*.6 7 13.4 q:Future,103 'b ---101b,--,'- --0.,70-- -0.80, 15A 6's. 1 �&Z 8.9 NIA, 1.8: -1 6:Z C C 101 c _, 101c -1 -1.2T *0.80 '194-1 i -7.4:- 'NIA , 'NIA 12.8. .6 T- N/Ar 2.7 .1 10.4 A 101d 0.42 1 0.80 10.2 1 - 4.8, NIA 34, 9.9 N/A, I . le .4101 e! VIT5" rVII&AP" I ZINIAIM '3 3 1 E9.27 NIA- i 1 Ii- il �2 '12! 1011 2.53 0.� 14.9 - 1 &9'- 1.9 32 8.1 3.8- 7 6.4, J1 , - 20.61 Ft. Collins Vehicle Wirt. Build. 03-162.00 is unofficial copy was downloaded on Jan-25-2016 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com Pagel of 2 — I I' aop - V \ Ar L ` \qR 8 r/7CrJ f ^Is- jL Ij 75 �I / -__l VEHICLE STORAGE BUILDING UTILITY SERVICES DEPARTMENT CITY OF FORT COLLINS. COLORADO ''il 1 � / 1 LOT 1 I SERVICE CENTER FOURTH SUED/V/S/ON I N0.97079757 / / — — — — — \— — — — — \ NNNECT O IX 18" RP Ir NYLOPLAST DRAN BASN DOMED GRAEC WS EX JB" IX Q00' W/ 8" INSERTA 18INV`00.2 8" WW00.8 MM-0.9 w INV SS}00,w DE O $-1.I/A I ANs)-m.50 R?�rtt<rr — rrrr rrrrrrr — — �rrrrrrrrrrrr r rrrrrrr rrrrrrrrl UMITS O RNN GARDEN piOMNG MESA (2' MDE X 111' LONG) CA1T]I IX —GRA— — — — AT PROPERTY ME I I I 15 V 8" HDPE IX DQ00' , DL PROPERTY ME 14.5' DRNMADE O S�1.01 DE _ =aY0 �H9_ 3,y{L jtg — ,�0— GHQ_ ALIGNMENT 3H0 3H0 \ 1--E�__. —3 3N0 — — — — — — — — — — — — — — / /_._._._.----- // RSM 015�0� �_— . .----- 8' DRADIADE ._. _. _. _.- — ._._. _._._._. _. _._.. AUGNIN-._._._.-. . . — — — — — -- — — — — --- _._.-.-.-.-.-.-._._._ _ _ _ _ - - - -. _._._._ _ _ .-. SOD / I- — I EXTERIOR �EX PROPFAtt UNE --04.110 04.10 ..I RIOR _ 5=0.5; PENF RPE— _IX 044,Y0 —IX �- —� —� J OA10 / \ \ \ EXIEPoOIIE1Ni1R011 IN1TF01R I a.zo / w a EXCEPTION FROM BLANKET "75 I WREMOR / / / 04.70 \ DRAINAGE & UTILITY EASE. / REC. NO. 20040123441 ss ETl REGURED w BAD( I �/ PROPOSED BUILDING sx / / \ \ 0.190.89 FFE VARIES, SEE SPOTS BREAK UNE J I 25'E%CEPRAI iROM �BLAN BRAwAGE a lik In sLAe I I unutt Esur lI M�OSEDANNWO 04.40 I I ( W TRAIwER / 04.23 03.r0 W — / \ \ \ \ \ \ \ \ \\ I \ \ 01.20 -`------- �DGnG — - --�-- / MGIF ---- _�------------------5004 I LOT 1 A E.VS1W0 FOIE i� EA151{VI EDGE SERVICE CENTER THIRDSUBDIVISION OF 02YE'A97E REC NO.97079756 NOTES 1. ONSITE IMPROVEMENTS WILL BE PRIVATELY OWNED AND MAINTAINED. 2. ALL EARTH WORK AND PAVEMENT CONSTRUCTION SHALL BE IN ACCORDANCE WITH THE GEOTECHNICAL REPORT FOR THE SITE AND LCUASS AS APPLICABLE. 3.. ALL SPOT SHOTS SHOWN ARE FINISH GRADE UNLESS OTHERWISE NOTED. 4, THE CONTRACTOR SHALL BE RESPONSIBLE FOR PROVIDING ADEQUATE AND APPROPRIATE EROSION CONTROL MEASURES IN THE CONSTRUCTION AREA. THE CONTRACTOR SHALL INSTALL TEMPORARY BMPS AS NEEDED TO CONTAIN SEDIMENT AND POLLUTANTS ON THE JOB SITE. S. STEM WALL REQUIRED ALONG WEST FACE OF BUILDING TO ALLOW GRADES HIGHER THAN PROPOSED FINISH FLOOR ELEVATION. 6. DRAINAGE BASIN SHOWN FORTRIBUTARYAREATOTHE PROPOSED RAIN GARDEN. LEGEND - -XXXX- i EXISTING MINOR CONTOUR - -XXXX- EXISTING MAJOR CONTOUR �XXXX-� PROPOSED MINOR CONTOUR ----X(XX� PROPOSED MAJOR CONTOUR PROPOSED DRAINAGE BASIN DIVIDE LINE A DRAINAGE BASIN NUMBER 0.31 D.7 BASINCOEFFICIENTUODYR) DRAINAGE BASIN AREA W W - GRA VEL - WATER [[ SERVICE$ SRE T am� 0¢ 3 $ ^ &a G . VivEo LIGHT ANG PoWERSITE k S�om - ; QLL ° ELM ET. BYCAMOPE6T. pQ <MFAPYP. 5 s KEY MAP N W F J N 5 unN ULL11 w Do � y W � (0N 0 10 5 0 10 20 Z U SCALE: 1'= 10' O J U) N W J m 0 0Zo d U p -jm W I- 3 0 W D. °OVO 0 LL n�LL (L 00 00 F U CALL UTILITY NOTIFICATION CENTER OF COLORADO 811 LALL 2-BUSNESS DAYS IN ADVANCE BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UMIDES. CITY OF FORT COLLINS, COLORADO UTILITY PLAN APPROVAL 1 APPROVED: - I CRT! ENGINEER DALE CHECKED BY: WATER a WASTEWATER UTLItt DATE ' PRELIMINARY CHECKED BY: CHECKED BY: STORMWAMR UTIUTY PARKS-; RECREATION DATE DAIS pROJ. NO. 1246095 NOT FOR CONSTRUCTION CHECKED BY: 7AFRC ENGINEER DAIS JC DF 10 CHECKED BY: NATURAL RESOURCES DAIS \k `§]) k� 2� !e - 0 /+\2 _ 3� Q ®| _ [( &; m �� 77 777 a� § {%()\ }\ ) ; -ƒ oa , (0 - �laa§ 2 0,�\ 0 § / U) Design Procedure Form: Rain Garden (RG) Sheet 1 of 2 Designer: so Company: Interwest Consulting Group Date: February 17, 2016 Project: 701 Wood Street Location: 1. Basin Storage Volume A) Effective Imperviousness of Tributary Area, I, Ir = 65.0 (100 % it all paved and roofed areas upstream of rain garden) B) Tributary Area's Imperviousness Ratio (i = 1,/100) i =i 0.650 ,',' C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV =i 6.26 -1watershed inches (WQCV= 0.8' (0.91' i'- 1.19 , i2+ 0.78 - i) D) Contributing Watershed Area (including rain garden area) Area = 8,490 sq It E) Water Quality Capture Volume (WQCV) Design Volume VwoCv =( 144 cu It Vol = (WQCV / 12)' Area F) For Watersheds Outside of the Denver Region, Depth of de = in Average Runoff Producing Storm G) For Watersheds Outside of the Denver Region, VWocv oniER =, ��cu it Water Quality Capture Volume (WQCV) Design Volume H) User Input of Water Quality Capture Volume (WQCV) Design Volume VW0CV USER = cu it (Only if a different WQCV Design Volume is desired) 2. Basin Geometry A) WQCV Depth (12-inch maximum) Dwccv = 5 in B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 4.00 ft / ff (Use "0" if rain garden has vertical walls) C) Mimimum Flat Surface Area AMn =(— 96 sq It D) Actual Flat Surface Area A� = 122 sq it E) Area at Design Depth (Top Surface Area) AT. = sq It See sheet 18 for F) Rain Garden Total Volume Vr=i ---ICU It volume calculation (Vr= ((Arm + AAda) / 2) ' Depth) 3. Growing Media Choose One 1* 18" Rain Garden Growing Media Q Other (Explain): Standard City of Fort Collins Spec 4. Underdrain System A) Are underdrains provided? Ctroose orre 0 YES Q NO B) Underdrain system orifice diameter for 12 lour drain time i) Distance From Lowest Elevation of the Storage y= ff Volume to the Center of the Orifice No orifice control plate ii) Volume to Drain in 12 Hours V0112= N/A --�cu it proposed, release rate based loff of 4" underdrain capacity iii) Orifice Diameter, 3/8" Minimum Do =(— VA i in Rain Garden Basin.xls, RG ' 2/17/2016, 1:44 PM Design Procedure Form: Rain Garden (RG) Sheet 2 of 2 Designer: sb Company: Interwest Consulting Group Date: February 17, 2016 Project: 701 Wood Street Location: 5. Impermeable Geomembrane Liner and Geotextile Separator Fabric A) Is an impermeable liner provided due to proximity of structures or groundwater contamination? Choose One — O YES Q NO 6. Inlet / Outlet Control A) Inlet Control r Choose One I Q Sheet Flow- No Energy Dtssipaeon Required I 0 Concentrated Flow- Energy D'�ssipation Provided 7. Vegetation Choose One Q Seed (Plan for frequent weed control) Q Plantings O Sand Grown or Other High Infiltration Sod 8. Irrigation A) Will the rain garden be irrigated? Choose One p YES Q NO Notes: Rain Garden Basin.xls, FIG 2/17/2016, 1:44 PM 701 Wood Street Proposed Rain Garden Volume LOCATION: 701 Wood Street Rain Garden PROJECT NO: 1221-130-00 COMPUTATIONS BY: sb SUBMITTED BY: INTERWEST CONSULTING GROUP DATE: 11/11/2015 V = 1/3 d (A + B + sgrt(A'B)) where V = volume between contours, ft3 d = depth between contours, ft A = surface area of contour MAX PONDING SPILL ELEV Stage (Elev) Surface Area (Ft^2) Incremental Storage (cf) Total Storage (cf) 5003.5 0 0.00 0.00 5003.6 357 11.90 11.90 5003.7 507 42.98 54.88 5003.8 670 1 58.66 113.54 5003.9 1 842 1 75.44 1 188.98 5004.0 1026 93.25 282.23 WATER QUALITY CAPTURE VOLUME REQD: 144 (cf) WATER QUALITY CAPTURE VOLUME PROVIDED: 189 (cf) RG Volume.xls STANDARD OPERATING PROCEDURES (SOPS) 700 & 701 Wood Street — Utility Services Department Building Additions Fort Collins, CO A. PURPOSE In order for physical stormwater Best Management Practices (BMPs) to be effective, proper maintenance is essential. Maintenance includes both routinely scheduled activities, as well as non -routine repairs that may be required after large storms, or as a result of other unforeseen problems. Standard Operating Procedures (SOPS) should clearly identify BMP maintenance responsibility. BMP maintenance is typically the responsibility of the entity owning the BMP. Identifying who is responsible for maintenance of BMPs and ensuring that an adequate budget is allocated for maintenance is critical to the long-term success of BMPs. Maintenance responsibility may be assigned either publicly or privately. For this project, the privately owned BMPs shown in Section B below are to be maintained by the property owner or property manager. 0 B. SITE -SPECIFIC SOPS The following private stormwater facilities contained within 701 Wood Street building addition are subject to SOP requirements: ' Bioretention Pond/Rain Garden The location of said facilities can be found on the Utility Plan for The Colony Inspection and maintenance ' procedures and frequencies, specific maintenance requirements and activities, as well as BMP-specific constraints and considerations shall follow the guidelines outlined in Volume 3 of the Urban Drainage and Flood Control District (UDFCD) Urban Storm Drainage Criteria Manual. rFor this project, all BMP's are to be maintained by the property owner or property manager contracted with the property owner. SOP Maintenance Summary Table ' Stormwater Facility/BMP Ownership/Responsibility UDFCD Maintenance Reference Bioretention Pond/Rain Garden Private / Property Owner Follow guidelines for Bioretention Page 1 of 2 Bioretention Pond/Rain Garden Maintenance Plan Routine Maintenance Table (Summary from Chapter 6 of UDFCD Volume 3) Required Maintenance Objective Frequency of Action Action Determine if the bioretention area is Inspection providing acceptable infiltration, and outlet structures are not obstructed. Check for erosion and repair as necessary. Debris and Remove debris and litter from the infiltrating Litter Removal surface to minimize clogging of the media. Remove debris and litter from the overflow structure. Mowing & Maintain healthy, weed -free vegetation. Plant Care Routine - Inspect the infiltrating surface at least twice annually following precipitation events. Check for obvious problems during routine maintenance visits, especially for plugging of outlets and erosion. Routine - Including just before annual storm seasons (April and May), end of storm season after leaves have fallen (October), and following significant rainfall events. Routine - Mowing of manicured grasses may vary from as frequently as weekly during the summer, to no mowing during the winter. Mow as desired or as needed for weed control. Non -Routine — Performed as needed depending on planting scheme and cover. Weeds should be removed before they flower. Irrigation Adjust irrigation throughout the growing Scheduling season to provide the proper irrigation Non -Routine — Check for broken sprinkler heads and and application rate to maintain healthy repair as needed. Maintenance vegetation. Replacement Replace wood mulch only when needed to of Wood maintain a mulch depth of up to Non -Routine — Inspect mulch conditions at least twice Mulch approximately 3 inches. Excess mulch will annually following precipitation events. need to be removed. Sediment Non -routine — Maintenance activities to restore Removal and Maintain adequate infiltration rates to drain infiltration capacity of bioretention facilities will vary Growing pond within 24 hours. with the degree and nature of the clogging. The Media frequency of media replacement will depend on site - Replacement specific pollutant loading characteristics. Page 2 of 2 Stormwater Detention and Infiltration Design Data Sheet Stormwater Facility Name: Vehicle Storage Water Services - Rain Garden Facility Location &Jurisdiction: City of Fort Collins Utilities Department User (Input) Watershed Characteristics Watershed Slope = 0.010 ft/ft Watershed Length -to -Width Ratio = 3.10 L:W Watershed Area = 0.20 acres Watershed Imperviousness = 65.0% percent Percentage Hydrologic Soil Group A = percent Percentage Hydrologic Soil Group B = 100.0% percent Percentage Hydrologic Soil Groups C/D =1 1percent User Input: Detention Basin Characteristics WQCV Design Drain Time = 12.00 hours After completing and printing this worksheet to a pdf, go to: ' https://maperture.digitaidatiservices.com/gvh/?viewer=cswdii create a new stormwater facility, and attach the pdf of this worksheet to that record. Design Storm Return Period = Two -Hour Rainfall Depth Calculated Runoff Volume: OPTIONAL Override Runoff Volume: Inflow Hydrograph Volume ' Time to Drain 97`Yo of Inflow Volume Time to Drain 99% of Inflow Volume Maximum Ponding Depth Maximum Ponded Area Maximum Volume Stored Rnnro�l Llv.l.nory nl. Rno,Nc 'ull Release WQCV 2 Year 5 Year 10 Year 25 Year 50 Year 100 Year 0.53 0.98 1.36 1.71 2.31 2.91 3.67 0.003 0.010 0.016 0.021 0.031 0.041 0.054 0.003 0.010 0.015 0.020 0.030 0.040 0.053 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0.01 0.05 0.08 0.11 1 0.16 0.21 0.27 0,001 0,004 0,007 0.008 1 0.010 0.012 0.014 0.000 0.000 0.000 0.000 1 0.001 0.001 0.002 n icre-ft icre-ft acre-ft lours icurs t cres cre-ft IStormwater Detention and Infiltration Design Data Sheet.xlsm, Design Data 1/27/2016, 4:02 PM Stormwater Detention and Infiltration Design Data Sheet 1.2 t 100YR IN 100YR OUT �50YR IN 1 50YR OUT _ I \ 25YR IN0.8 / \ - 25YR OUT 10YR IN / L - - - 10YR OUT / ♦ \ \ \ 'G —SYR IN s • • . . 5YR OUT ' 2YR IN / % \ 2YR OUT \ \ 0.4 % — WQCV IN % - / \ \ • WQCV OUT / ♦ % \ 0.2 0 - 0.1 03 — 100VR 0.25 1 0.2 Z r 6 W O C 0.15 _ O 6 0.1 0-05 1 0 0.1 1 1 TIME [hr] __ _ ____. _. _ _ _. __ _. _ DRAIN TIME [hr] IStormwater Detention and Infiltration Design Data Sheet.xlsm, Design Data 10 10 100 1/27/2016, 4:02 PM