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HomeMy WebLinkAboutDrainage Reports - 09/02/2015 (2)DRAINAGE REPORT FOR Parking at 620 S. Lemay Avenue 620 S. Lemay Fort Collins, CO 80524 Prepared for: CS Design, Inc. 2519 S. Shields St. #129 Fort Collins, CO 80526 Prepared by: �� QUALITY `x ENGINEERING www.quality-engineering.com 1501 Academy Court, #201 Fort Collins, Colorado 80524 (970)416-7891 QE Project No: 1060-003 Date: June 02, 2015 n I Parking at 620 S. Lemay Avenue FINAL DRAINAGE REPORT ENGINEER'S CERTIFICATION I hereby certify that this Final Drainage Report for the design of stormwater management facilities for the Parking at 620 S. Lemay Avenue Project 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. PG OLIC S E'V0 0 .026 m 9 �FFSS/ONA%- I Cody Ge6endorf4JP.lV Registered Professional Engineer State of Colorado No. 41326 I. Table of Contents ' I. GENERAL LOCATION AND DESCRIPTION.........................................1 A. Location.................................................................................................................... 1 ' B. Description of Property........................................................................................... 1 II. DRAINAGE BASINS AND SUB-BASINS..................................................2 ' A. Major Basin Description.................................................................................:....... 2 B. Sub -Basin Description............................................................................................. 2 III. DRAINAGE CRITERIA...............................................................................3 ' A. Regulations............................................................................................................... 3- B. Implementation of the "Four Step Process".......................................................... 3 ' C. Development Criteria Reference and Constraints ................................................ 4 D. Hydrological Criteria............................................................................................... 4 ' E. Hydraulic Criteria................................................................................................... 5 F. Modifications of Criteria......................................................................................... 5 ' IV. DRAINAGE FACILITY DESIGN...............................................................5 A. General Concept....................................................................................................... 5 B. Specific Details......................................................................................................... 6 C. Rain Garden/Detention Pond.................................................................................. 6 V. CONCLUSIONS.............................................................................................7 A. Compliance with Standards:.................................................................................. 7 B. Drainage Concept..................................................................................................... 7 VI. REFERENCES...............................................................................................7 ' VH. APPENDICES ' A. Hydrologic Computations Vicinity Map ' FEMA FIRM Exhibit USGS Soil Map Fort Collins Rainfall Intensity Curve t 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 ' B. Hydraulic Computations ' Rain Garden Outlet Area Inlet Calculations Rain Garden Outlet Pipe Calculations ' C. Water Quality Design Calculations ' UD BMP Rain Garden Calculations D. Standard Operating Procedures ' Standard Operating Procedures I r 1 1 1 11 1 I. GENERAL LOCATION AND DESCRIPTION A. Location The proposed site is located in the northwest quarter (NW '/4) of the northwest quarter (NW '/4) 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 southeast corner of Poudre River Drive and Hoffman Mill Road. More generally, the property is located at the northeast corner of Lemay Avenue and Riverside Avenue. The property address is 620 S. Lemay Avenue, Fort Collins, Colorado, 80524. (Please see the vicinity map located in the Appendix A). B. Description of Property The property is parcel number 8718200035 of the Poudre River Business Park and is currently 0.99 acres of undeveloped land surrounded by undeveloped property to the north and east, medical offices to the northwest, Concentra Urgent Care to the west, and East Laurel St. to the south. Hoffman Mill Road is located directly west of the property and acts as its only access. Both existing Hoffman Mill Road and Poudre River Drive are paved with curb, gutter, sidewalk, and utilities installed. Hoffman Mill Road to the southwest and E. Laurel Street to the south of the property are unpaved, gravel roads. E. Laurel Street is a private street. The existing property is mainly natural vegetation that has no general drainage patterns. It appears that onsite flows pond and infiltrate, without leaving the site. Existing Hoffman Mill Road drains north to the existing inlet, where it is conveyed to the Poudre River. Existing Poudre River Drive drains east towards the existing storm inlet, where it joins flows from Hoffman Mill Road. There are generally no offsite flows that drain toward the property. The entire site is located entirely outside of any 100-year flood plain (see FIRMETTE in Appendix A). According to the NRCS soils. map survey, the native soils consist of the Type `B" soils. These soils consist of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils produce moderate infiltration rates when thoroughly wet. There are no irrigation facilities located within the proposed site area. The proposed development will consist of the construction of a 37 space parking lot that will act as overflow parking for the Concentra Urgent Care directly across Hoffman Mill Road. The parking lot will be paved asphalt with curb and gutter. Parking stalls will consist of pervious pavers. A rain garden will be installed on the northwest corner of the proposed site. 1 II. DRAINAGE BASINS AND SUB -BASINS A. Major Basin Description The proposed site is located within the Cache la Poudre River Basin. The basin is a major tributary to the South Platte River and the major confluence of many of Fort Collins' sub - basins. As determined in the Final Drainage Report for Poudre River Business Park, First Filing, onsite detention is not required due to the close proximity to the Cache la Poudre River. The Poudre River Business Park, First Filing development installed the storm drain system along Poudre River Drive, including the curb inlets and storm pipe that conveys flow north to the Poudre River. This 24" ADS pipe (downstream of the 620 S. Lemay system) has a capacity of 23 cfs. Once the pipe reaches capacity, onsite detention will be required for future developments within the Poudre River Business Park. The Poudre River Business Park, First Filing uses 7.98 cfs of the 23 cfs. The Poudre River Business Park, Second Filing produces an additional 5.92 cfs of flow into this system. The Poudre River Business Park, Third Filing produces an additional 1.0 cfs into this system. The total receiving flow of the storm system from the first three filings is 14.9 cfs; allowing for an additional 8.1 cfs of flow into the existing storm system before the system is at capacity and onsite detention is. required. B. Sub -Basin Description Historically, most of the site ponds and infiltrates within the property. The surrounding roads are at a high elevation than the proposed site, so no historic flows drain to these roads. ' The developed site is delineated into one sub -basin, with a rain garden designed to provide the required water quality capture volume. ' Sub -basin B1, (0.99 acres), consists of asphalt/concrete, landscaped area, and natural vegetation. Rainfall travels via overland flow from the center of the parking area to the exterior of the lot, where it will concentrate in valley pans and will be conveyed to the rain ' garden where the WQCV is treated. Overland flow will also infiltrate the permeable pavers in the parking stalls, where it will be treated. Sub -basin OS accounts for the south half of the Poudre River Drive extension. Rainfall in this basin will travel via overland flow where it will concentrate in gutter flow and travel west to the existing curb inlet on the southeast side of Poudre River Drive and Hoffman Mill Road. Sub -basin OS2 accounts for the Hoffman Mill Road extension. Rainfall in this basin will ' travel via overland flow where it will concentrate in gutter flow and travel south where it will meet the existing Hoffman Mill Road and will be conveyed as it has historically. 1 ' The total additional` flow to the existing storm sewer system is 5.55 cfs; less than the maximum allowable increase of 8.1 cfs. Therefore, the downstream existing storm system will still be under capacity even with the inclusion of the entire 100-year flow. ' Currently, offsite flows do not enter the site property. This will not change after the site has been developed. III. 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. Implementation of the "Four Step Process" ' The overall stormwater management strategy employed with this parking lot expansion project utilizes the "Four Step Process" to minimize adverse impacts of urbanization on receiving waters. The following is a description of how the proposed development has incorporated each step. ' Step 1 — Employ Runoff Reduction Practices. The first consideration taken in trying to reduce the stormwater impacts of this development is the site selection itself. By selecting a site with historically undetained runoff, the burden of development will be significantly less with a WQCV pond. Also, for Basin B1, permeable pavers and rain gardens are used to convey the runoff from impervious surfaces, reducing the effects of imperviousness. ' Step 2 — Implement BMPs That Provide a Water Quality Capture Volume (WQCV) with Slow Release. Urban development will cause stormwater runoff to increase from the site. The primary water quality will occur in the rain garden on the northwest side of the lot. ' Refer to the map pocket for rain garden and permeable paver details and cross -sections. The rain garden and permeable pavers will increase water quality and promote infiltration. Step 3 — Stabilize Drainageways. The Poudre River is the governing drainageway for the proposed site. The proposed project indirectly helps achieve a better stabilized drainageway nonetheless. By improving the water quality and increasing infiltration, the likelihood of bed and bank erosion from this site is greatly reduced. Step 4 — Implement Site Specific and Other Source Control BMPs. The Parking at 620 S. Lemay Avenue site contains a plethora of source control BMPs. ' Permeabl'e Pavement Systems: Flow from the parking lot will directly flow into the void area of the pavers avoiding any extra pollutant -flow contact time. Additional flow from the sidewalks will be captured by the pavers and be treated before an underdrain system ' transfers flow to the Rain Garden. Rain Garden: All Unconnected Impervious Areas (UTA) are drained through the on -site rain garden, reducing the impact of the impervious areas on water quality. The rain garden will increase the •water quality of released flows, and will aid in the infiltration of these capture flows. C. 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 the Poudre River Business Park; aside from those referred to above, that ' would constrain or otherwise influence the design of the stormwater improvements for this site. ' D. Hydrological' Criteria Stormwater runoff from the respective sub -basins of the 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, UDCM (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 by the FCSDM. The hydrologic basin parameters and runoff rates are included in the Appendices and include quantification of the allowable volume reduction. ' 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. ' E. Hydraulic Criteria ' Within this development, all runoff will be conveyed on the surface, initially as sheet flow and subsequently as concentrated flow in shallow pans 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. The surface runoff will culminate into the rain garden at the northwest portion of the site. ' The pond outlet will consist of a 100-year drop inlet outlet structure. Flows above the required WQCV will be released into the storm system via this outlet. ' F. Modifications of Criteria There are no modifications or variances requested in connection with the design of the ' stormwater management for the Parking at 620 S. Lemay Avenue site development. ' IV. DRAINAGE FACILITY DESIGN A. General Concept ■ The storm drainage system is designed to safely convey developed storm flows by sheet flow and concentrated pan, underdrain, and gutter flow to the rain garden located at the ' northwest corner of the property. The rain garden has been sized for the total required WQCV and will safely release all flows greater than this into the storm system, as intended to per the Poudre River Business Park, Filing One. 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:. C ' 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 B1, (0.99 acres), consists of asphalt/concrete, landscaped area, and natural ' vegetation. Rainfall travels via overland flow from the center of the parking area to the exterior of the lot, where it will concentrate in valley pans and will be conveyed to the rain garden at a minimum of 0.6% slope, where the WQCV is treated. Overland flow will also ' infiltrate the permeable pavers in the parking stalls, where it will be treated. The 100-year flow is released via a 24" drop inlet into the back of the existing curb inlet located on the south side of Poudre River Drive. After treatment within the rain garden and the permeable ' pavers, the WQCV will also be released into the back of the curb inlet, where it will be eventually be conveyed to the Poudre River. Sub -basin B 1 produces a 100-year flow of 4.29 cfs. if the paver system overflows due to clogging, the runoff will be directed to the ' rain garden where it will be treated and released through the outlet structure. Sub -basin OS 1 accounts for the south half of the Poudre River Drive extension. Rainfall in ' this basin will travel via overland flow where it will concentrate in gutter flow and travel west to the existing curb inlet on the southeast side of Poudre River Drive and Hoffman Mill Road. From this inlet, flow will be conveyed through the existing system to the Poudre River. Sub -basin OS produces a 100-year flow of 1.26 cfs. Sub -basin OS2 accounts for the Hoffman Mill Road extension. Rainfall in this basin will ' travel via overland flow where it will "concentrate in gutter flow and travel south where it meets the existing Hoffman Mill Road. From this point, it will be conveyed as it has historically. Sub -basin OS2 produces a 100-year flow of 0.88 cfs. C. Rain Garden The rain garden has been designed to accommodate volume and release requirements for the proposed site in its entirety. The WQCV required is 490 cubic feet. The WQCV infiltrates ' completely through the rain garden media. At a depth of 5 inches, the rain garden requires a flat surface area of 327 square feet; a flat surface area of 390 square feet has been provided. The outlet structure has been designed to release the flows above the WQCV into the storm ' sewer system. A 6" PVC underdrain will be installed beneath the rain garden. A detail of this rain garden has been provided in the attached map pockets. ' The entire overflow from the rain garden and the permeable pavers will be conveyed through the rain garden outlet structure and to the existing storm system to the north. This existing storm sewer system has the capacity to convey the entire 100-year flow from the proposed development. There will be no new facilities required offsite for the conveyance of the minor or major flows to the Poudre River. V. CONCLUSIONS 1 1 1 VI. 1 1 1 1 A. Compliance with Standards The drainage design for the Parking at 620 S. Lemay Avenue 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 Parking at 620 S. Lemay Avenue will be adequate to safely convey onsite and offsite flows through the development. 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. 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. APPENDICIES APPENDIX 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 No Text W m W Gi d F g W= lu Eof t 10Op E � __ ➢� m� 17J V! S _� 1�� a 900 Q' Z o o w sg8� LO ; o V _g W"gym 11po ` 4ZmE�_ O L �n Z W Q fn L�. Q LL,� �$ J 1 CC Z Ooz L? &0T� OJ a LL LA. R � e., O 3$ v LLE g ee ®ee ee ®®® a ® e @C2 E mvE35 Cl Lo e��de �3`oaLL ";t':'�ii'',;%Y/i3 ! 1!i /, �! G Q, / ;/r/' Q• �Q p �/O i t O p CO✓� / /a♦ � / <!/ , 3 ;ice. n'' \ %'/'i.F/'� 5/N/N // •:)%. 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D U N s cc 0 m O n N O m E ai am0Btmmy to m`o n omi�°m p m m 2 my E m- m E y m C� Q(9 oL U� c J Qo mN m ;Nmc �$ m mamE u m m E t Uww m 0m 0 m,`�m0Jo- D c o' E U) 'o wT mm m oEo m0 cO mon ,vE aomm a�anoc > t 3 Nmom mE 00 ` NL ._ , 'DOc o3mm LgyD om �J m m mcmmi "�O m om 0 o m U) m m e0 � EE m maO T m D L m m D m N J m -1 O m U m U) m m m y m m > J m a« N L N C m E m O m> D Z T 0 D Q U m d= m l3/1 m o .,NN o N E m�L O MW D amFa oc m;rn Na Q� na _o -u):.' 3-om0 mo _�' m `m Lac m;��co� mE Eemmc oUcwm °� ym JT S o`°�c rnaE.$ m� mt0 i n> fn m mm E rn w 0 n m m E m m m m m mm D om$ n m 0 J moyD@ tmo? o� m mo romE cmm. -w E 0. mi a E N U n v¢ o F- « N N `o N F- o E o a m m tl N > m T m c m T d m O U L c m m a m m U O 0 U Z N qO K - a O m tl 1 1 c m tl � m n m n p m m m m m m N m D C O C m 0 z N O 0 d M O m tl Q O T N C m O O d Q p1 Q m m U O Z Dl Q 'Q m U U la p1 Q m m m C C C n n 'p Y 1n 0® M m tl p LJ LI f y • p d O N N y Q m N V m Z Hydrologic Soil Group—Larimer County Area, Colorado Hydrologic Soil Group Hydrologic Soil Group— Summary by Map Unit— Larimer County Area; Colorado (C0644) Map unit symbol Map unit name Rating Acres, in'AOf' Percent of A0I . 64 94 Loveland clay loam, 0 to 1 percent slopes Satanta loam, 0 to 1 percent slopes C B 1.3 7.1 15.6%1 84.4% Totals for Area of Interest 8.5 100.0% Description Hydrologic soil groups are based on estimates of runoff potenbal..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 (A/D, B/D, and C/D). 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 (A/D, B/D, or C/D), 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 Gasses. ' Rating Options Aggregation Method. Dominant Condition ODA Natural Resources Web Soil Survey 3/2/2015 �� Conservation Service National Cooperative Soil Survey Page 3 of 4 Hydrologic Soil Group—Larimer County Area, Colorado ' Component Percent Cutoff. None Specified Tie -break Rule: Higher r usoA Natural Resources Web Soil Survey 3/2/2015 �_� Conservation Service National Cooperative Soil Survey Page 4 of 4 C) cr 1 3� .- UI rn O v 1 f - LL LL O C N a a 1 L — p 1 O y O O O O O O O O O O O Cl O O O O O O O O O O O o O O� 00 r CO to 'et C-i N O (Jti/U1) Al!sualul O N I• • •• • 0 04 w City of Fort Collins Rainfall Intensity -Duration -Frequency Table for using the Rational Method (5 minutes - 30 minutes) Figure 3-1 a Duration (minutes) 2-year Intensity in/hr 1'0-year Intensity in/hr 100-year Intensity in/hr 5.00 2.85 4.87 9.95 6.00 2.67 4.56 j 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 j 7.42 12.00 j 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 18.00 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 j 5.09 25.00 j 1.43 2.44 4.98 j 26.00 1.40 2.39 4.87 27.00 1.37 2.34 4.78 j 28.00 1.34 2.29 4.69 29.00 1:32 2.25 4.60 30.00 1.30 2.21 4.52 DRAINAGE CRITERIA MANUAL (V. 1) RUNOFF Table 110-3—Recommended Percentage Imperviousness Values Land Use or —7Percentage Surface Characteristics 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 +"(1.31i3 —1.441 z + 1.135i — 0.12) for CA >— 0, otherwise CA = 0 CCD = KCD + (0.858i3 — 0.786iz + 0.774i+ 0.04) CB = (CA + CcD)I2 (RO-6) (RO-7) 2007-01 Urban Drainage and Flood Control District RO-9 n n II II II II I 1 ' Z O ' y� � 3 Z Q w m Z V W a� Y Q a N W Q 1 E a u°w 1 1 1 u x _ � u O V m rn m m d O 0 0 6 O N p O IL E 0 u � u > d ct o o ti v ao 0 0 o a o 0 0 0 c E o u m d N a L Ol Ol ti •-I u Y R O 0 0 0 N l u Ln O n r n C 3 � W h -. Vp O n n 0 n 0 u ` 0ccU b N O d N d W N in in � IC —o O 7 mtn N L u d 41 a O ^ d b C N U Y C O v N u u cc m Ln a it r a N W 0] 00 N co c 0 a ti ry m c a ❑ ❑ ❑ m O a Q N N r N C H u O ti GJ i V 00 w a a a E (o (U a y o rn m r m cn ti @ O o 0 0 M O Q VI u CD m O '71 IN V Ch V7 C) C) N T C 4 3 O J d `u p O O O O n O O O O O O O K V M o O O O O O O > ro C Q. i O X W Gl > O! VI 0 v V aj p ` p O O p m N 0 0 y 0 0 0 0 m u C O v 0J `u m n r, ui J O O a p a+ f0 Z- L O. a I C_ N Ln N 0 m lJ co0 O O m C 'o m a o 0 a O E +i S T L C }C. 6 a v II 1 Z _O O X N W z V M Z Y ' 3 a 0 0_ 1L } Ca N W ' (Q J N O N lD LF 1 m N N > m imn, a r9r m b 5 ry 8. n n m ry o m 000.+ h m g o ry m m c c y 6 W Q N c .ri6d Y c > N v m W W ry ry C E F p p Q H N N F R C F � W O O G v1 W f 0 ° P o Y E A L f f U u _ O X v M � �• O 4 W � o •= ^ W Q e a A E e o N f E c o � ''•' mmm d f Q aF n 0 N Y y yUy� e JI N N Oml m E u° � ii o 000 0 u o $ ino o c m c o E N N O m O c O ° 71 i O p f a ' APPENDIX B: Hydraulic Computations ' Rain Garden Outlet Area Inlet Calculation Rain Garden Outlet Pipe Calculation tD tV O aD IO N V leh) �aede� M CV I 0 O C O cc CO (n O LQ 0 M O N O T O T O (3) 40 ti (0 In M N T O O O O O O O O O (4) uOIJen913 C Hydraulic Analysis Report Project Data Project Title: Designer: Project Date: Wednesday, March 04, 2015 Project Units: U.S. Customary Units Notes: Channel Analysis: RAIN GARDEN OUTLET PIPE Notes: Input Parameters Channel Type: Circular Pipe Diameter: 1.2500 ft Longitudinal Slope: 0.0249 ft/ft Manning's n: 0.0120 Flow: 4.2900 cfs Result Parameters Depth: 0.5409 ft Area of Flow: 0.5088 ft12 Wetted Perimeter: 1.7947 ft Average Velocity: 8.4323 ft/s Top Width: 1.2386 ft Froude Number: 2.3186 Critical Depth: 0.8386 ft Critical Velocity: 4.9010 ft/s Critical Slope: 0.0060 ft/ft Critical Top Width: 1.1747 ft Calculated Max Shear Stress: 0.8404 Ib/ft^2 Calculated Avg Shear Stress: 0.4404 Ib/ft^2 I APPENDIX C: Water Quality Design Calculations UD BMP Rain Garden Calculations Design Procedure Form: Rain Garden (RG) Designer: NAP Company: QUALITY ENGINEERING Date: March 4, 2015 ' Project: 620 S. LEMAY AVE-PARKING EXPANSION Location: FORT COLLINS, COLORADO 1. Basin Storage Volume A) Effective Imperviousness of Tributary Area, I, 1, = 4t0 % (100% it all paved and roofed areas upstream of rain garden) B) Tributary Area's Imperviousness Ratio (i = 1,100) 1 = 0.410 C) Water Quality Capture Volume (WOCV) for a 12 hour Drain Time WQCV _ 0.15 watershed inches (WQCV= 0.8' (0.91' i'- 1.19' i'a 0.78' i) D) Contributing Watershed Area (including ram garden area) Area - 43,124 sq 0 E) Water Quality Capture Volume (WQCV) Design Volume Vwxy = cu It Vol = (WQCV / 12) ' Area F) For Watersheds Outside of the Denver Region, Depth of dfi - 0,43 in Average Runoff Producing Storm G) For Watersheds Outside of the Denver Region. Vwe oraEe = 524.6 cu If Water Quality Capture Volume (WQCV) Design Volume H) User Irgwt of Water Quality Capture Volume (WQCV) Design Vdume Vwccvu n = cu it (Only 0 a ddfe o WQCV Design Volume ,s desired) 2 Basin Geometry A) WQCV Depth (12-inch maximum) Dwav - 5 in B) Ram Garden Side Slopes (Z = 4 min., henz. disc per unit verficall Z - 4.tX1 it ! I^, (Use '0* 0 ram garden has ventral walls) C) Mimimum Flat Sudace Area Ate„ = 350 sq it D) Actual Flat Surface Area A,, _ 390 sq It E) Area at Design Depth (Top Surface Area) A,,= = 2445 sq 0 F) Rain Garden Total Volume V— 591 cu N (Vr- ((AT. * A„d,d) 1 2) ' Depth) 3. Growing Media rr �QQ l8' Rain Garden Grrnang Medu C) Other !Esplam): 4. Undendram System Cho One Q YES A) Are underdrains provided? Q NO B) Underdrain system orifice diameter for 12 Four drain bme i) Distance From Lowest Elevation of the Storage y= 1.0 it Volume to the Center of the Orifice in Volume to Dram in 12 Hours Vd,z= sa a10 tii) Orifice Diameter, 3/8' Minimum Do = 0.61 in -- --Sheet 1 of 2 UD-BMP_RAIN GARDEN.xlsm. RG 3142015, 3:49 PM Design Procedure Form: Rain Garden (RG) Sheet 2 of 2 Designer MAP Company: QUALITY ENGINEERING Date: March 4, 2015 Project: 620 S. LEMAY AVEPARKING EXPANSION LocaLon. FORT COLLINS. COLORADO Dune One 5- Impermeable Geomembrane Lmer and Geotextde Separator Fabnc OYES A) Is an impermeable liner provided due to proximity © NO of structures or groundwater comaminatwn7 lhoose One 6. Inlet, Outlet Control Q Sheet Row- No Energy Dr pation Required A) Inlet Control Q Cmrertrawd Fk x Energy Desipadm Provided 7, Vegetation O SQd (Plan for "quent weed cormd) QQ Randrrgs Q Sand Csaaat m other High Infittmorin Sod Choose One 8. Irrigation C YES A) Will the rain garden be imgated� O NO Notes: UD-BMP RAIN GARDEN.xlsm. FIG 3i4)2015, 3:49 PM APPENDIX D: Standard Operating Procedures Standard Operating Procedures STANDARD OPERATING PROCEDURES (SOPS) Parking at 620 S. Lemay Avenue, Fort Collins, CO A. PURPOSE ' In order for physical stormwater Best Management Practices (BMPs) to be effective, proper maintenance is critical. 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, homeowner's association (HOA), or property manager. B. BMPS SUBJECT TO SOP REQUIREMENTS ' The following stormwater facilities contained within the Parking at 620 S. Lemay Avenue project are subject to SOP requirements: ' - Rain Garden Detention Basin (RG) Storm Sewers and Tree Roots ' - Permeable Pavers (PP) The location of said facilities can be found on the Site Plan, Landscape Plans, and Utility Plans for Parking at 620 S. Lemay Avenue. ' C. SITE -SPECIFIC STANDARD OPERATING PROCEDURES ' 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, latest revision. The Storm Sewer maintenance procedures follow. The Storm Sewer Lines.(Table 1.), Rain Garden (Table 2), and Permeable Pavers (Table 3) maintenance plans are as follows: ' Storm Sewer Lines Maintenance Plan The storm sewer lines are located in close proximity to many trees. The situation is unavoidable; ' therefore, special maintenance has been identified to ensure these storm drain systems perform as they were designed. In addition, Inlets and outlet rip -rap will need to be maintained. 1 1 Page 1 of 2 u Table 1— Routine Storm Sewer Line Maintenance Required Action Maintenance Obiective Freauency of Action Use a video camera to inspect the Routine -Annual inspection of condition of the storm sewer hydraulic and structural facilities. Line Inspections pipes. Cleanout pipes as needed. Also check for obvious problems If the integrity of the pipe is during routine maintenance visits, compromised, then repair the 'damaged especially for plugging of outlets. sections . Inspect and clean inlet weirs and Routine — Annual inspection of Inlet Inspections boxes of any debris. inlets to ensure proper operation and prevent plugging. Riprap Outlet Protection Maintain riprap (rock) storm Routine — Annual inspection of Inspections sewer outlet protection to ensure riprap to replace dislodged stones, proper operation. remove debris, etc. ' Rain Garden Maintenance Plan Table 2 — Routine EDB Maintenance (Summary from Table EDB-1, Chapter 6 of UDFCD) Required Action Maintenance Ob'ective Frequency of Action Occasional mowing to limit unwanted vegetation. Maintain Lawn mowing and Lawn care irrigated turf grass as 2 to 4 inches Routine - Depending on aesthetic tall and non -irrigated native turf requirements. grasses at 4 to 6 inches. Removal of sediment, debris, and Routine - Including just before Sediment, Debris, and Litter litter from the entire pond to annual storm seasons (April and removal minimize outlet clogging and May), end of storm season after improve aesthetics. leaves have fallen, and following significant rainfall events. Non -routine - Performed when sediment accumulation occupies 20 percent of the WQCV. This may vary Major Pond Sediment removal' Remove accumulated sediment from considerably, but expect to do this the bottom of the basin. every 10 to 20 years, as necessary per inspection if no construction activities take place in the tributary watershed. More often if they do. Inspect basins to insure that the basin continues to function as initially intended. Examine the outlet for Inspections clogging, erosion, slumping, Every two to five years. excessive sedimentation levels, overgrowth, embankment and spillway integrity and damage to any structural element. Page 2 of 2 ' Permeable Paver Maintenance Plan Table 3 — Routine EDB Maintenance (Summary from Table PPS-1, Chapter 6 of UDFCD) Re uired Action Maintenance Ob'ective Freguency of Action Remove snow and'ice from the pavement system by plowing. Snow Removal Conventional plowing should not Routine — After all snow storms. cause damage to the pavement. Do not use sand. Removal of sediment, debris, and Routine — Broom sweep Debris Removal, Sweeping, and litter from the pavement system to frequently (weekly or monthly) Vacuuming minimize clogging and improve and vacuum sweep as needed aesthetics. (monthly or yearly). If surface is completely clogged and rendering a minimal surface infiltration rate, restoration of surface Full and Partial Replacement of infiltration can be achieved by Non -routine —Perform as needed. Pavement or Infill Material removing the first I" of soiled aggregate infill with a vacuum sweeper. After cleaning, refill with clean a e ate infill material. Page 3 of 2 HISTORIC BASIN FLOWS BABIN DESIGNATION MFA (aA) 1 rFAA coup. Y Im xAl1 mn Y (ate (UqD pE9GN PUNT BASN NUMBER % fl a90 0.1! QIP Q11 6,ya PROPOSED BASIN FLOWS BASIN DESIGNATION AREA (40 1 K ccw Y I 1W xIA MtP. Y e1 (CF3) 9 (W IW DESIGN PUNT BASIN NUMBER DI BI 0.M 0.H EL"¢W .1p M O51 W376 1 0.110 1 099 OR 1.18 D) oS1 aN am 09] D.b Da IAO A55 • IEIai11N0 RFLNNIf WPA0.1Y fF DIIIIEi PIPE . al 6e RMM fyNO ROwS ILDm 10 Wll£i ARE CONCENTRA URGENT CARE PARIONG EXPANSION UD ReInGvI New lm Mau5A2a 1] .R Re wrca AenMuml mrou5a.arolerrearea rt (ANNQ raen tARarreMea by DDTmtmara Fttlpan TR m TOM Im RMeRArearreacea Perwim PaIii mnn Nm Pmment Area ll R Re Irea MnImum AMaor PONuaPmmM 1 .N. rc,orvmr3enlmn Rm-marcerorPmrSeWmri u ro3:lm rmlma .R rcaefPmr5vRM 1R a! .h RmgnaroarorPmrletllmRu [a 3:1N maRa 1.911 .R Amawrmr3eEBonn ;91a .R RumonanaTorPrvxSealmnu w3:1N mina 6W .R Amao PmrRWonea m .h Runronama%rPmr%MmW(u w3Ak mIM 303 ,h Taetl PwwaPmmeMAma AS3 R Rain Garden Su YAeEY VNIN3R waw.w Tota leo-n "aobe" Seam 01M1%Fd vam Mwae wo.n 15nCV "'"' IYwae bRl s.wsn R.raw Pwnl laM IaRI Rne lard pinll 9 aR1 I a9LIi am DRAINAGE LEGEND BASIN NAME V 2-YR RUNOFF COEFFICIENT D-YR RUNOFF COEFFICIENT RES) D1 DESIGN POINT BASIN BOUNDARY PROPOSED ROW DIRECTION IJIMRIESesFiial 01, PAYER UNDERDRAIN L.I.D. 1`FLEGEND O �•� y RAIN GARDEN B-B SEDIMENT rOREBAY SCALE: Y=5'' PERMEABLE PAVERS A -A RAIN GARDEN SCALE: 1'=5' 1'=2O IBUSINESS 4FORE�URIEDUTILIT`YINFORMATION TNRiEE (3) BUSINESS DAYS BEFORE YOU DIG CALL 811 YOU Ia3 �WIL"NOTIFICAMN CENTER OF COLORA9DNOn (UNCC). wAw.uxa oac CITY OF FORT COLLINS, COLORADO UTILITY PLAN APPROVAL um 2 LL Q = c� C O]w W Y=� yQo N W f Q�O jyU YI I^ O LL a� S 2 J 4 0 PRELIMINARY NOT FOR CONSTRUCTION wEcxw m. m NVW DR.WNEDrm. Nw DATE, 02 JUNE J015 EGlE 6 NKNUD PROIER No lm- C4.0 sN1n 6 w 17 2830AG _ _X 00 Dfallmile mmurr PIMARW PE WHETMWa6 nWVNM gar. ��'4 �F IaDsx-zwrcW ww, Y rxxamrtis �T. rbww.e�e�elewIDwi OIIE mTK 1MNT ID`TxaOWTFDHtlC S1gM11 E BIAN n ..AAAEowo®m NNUp /4�NnK 461 all �r 0 CLASS A BEDDING CLASS B BEDDING MN]I YDM AS 9EOIm IPrI Ia1r or llOxl a9l alafe wuNu.r d rna... m.rmrp MINE a� CLASS C BEDDING' ROCK EXCAVATION �RYOI rN A9 aFOtd�_ �,.r�.>�r aimisl`�`aalx nrr ppp 110�`imlo2`�rVix i. 7?a',}i''. a r alp FFY NfIG® 4 nial.i -1 IRY M aL.,lp ORNm fLr/C® aMYM r.46� .rr� wan �a UNSTABLE SUBGRAVE SUBDRAIN DETAIL IL.fi1 Wl6 �l ...,. lOPE�� %/ 1.mw 19L r-+.Z e r SOE pp� o ° _ B, t iM�aAMmq weal D.A® T n auaL — wlRn RIE11 4 rr ..LM rtlavLldM 9o11m A4 11n r na1`IW liwzNnOVCgn ®� IFW W) [t 1. Slur md. ai9i ri As scum w .wn 116P A 11[ fIOY 9IWQ Ma1MW'IYJI SINOMQ; 6.a1 i'®19 wLWa' f� OUDiIq¢ STORMWATET3 BEDDING REQUIREMENTS Cltt Of CQ1AS $TDRMWATER DETAIL DATE. 1D: 1/. TuITT me1TIES C\DN$TRUCTIDN DETAILS D-1 m owwx W. sc m e' fAFE9(WID a -Eflai 2 WQCV i MANHOLE WTBI Sa°Ponchn9 l%pM SLOTTED UD EL. =a95Im BOTTOM OIOSWALEC I -III —III —III —III I I SEE BIOSWALE DETAIL (THIS PAGE) FOR BEDDING/STORAGE REQUIREMENTS EL.=aesY9P 6" PERFORATED PVC SUBDRAIN 15" N-12 ADS PIPE 0 2.5% BIOSWALE OVERFLOW DETAIL in imam 30 mn I �. ..w.= HOPE Irgpervl0Ua EL. a4954.00 Ibembrane 6g1'PoMInq Dp111 (Re�'UI2U Mr C' LAN V OBB RulMing Pabtedpn) inimum 12' Thick Layer of Bloratention Sand Media i (we 0loretentlan sand Ne lla speclnWtlon from EL 4953M ❑ty dfort WINE) Inlmum 6' Thkk layer of Minimum bI3DTF4� 95250 Pea Gravel Diaphragm No. 4Above and Del: / 1P TIYJt dC00T Na.a Above and ftm \ Wx PVE Rpa `'N is afV^g.a �uMisWlbed/Sell PrbidM PVC Mpe Im. El. a 4951.84 N07E 1. Tx6 sfK s1dAn s use ro UaI[w a TILE REIN GARDEN.GARDEN.tlLy.Y. (MODIFED) BIORETENTION/BIOSWALE CROSS SECTION T"OR LADS an cowxs STORMWATER APFII9 2a' DETAIL CONSTRUCTION DETAILS DATL: W: D. -53 um r.-.a. DPAx21 er: . socDl 0U9 Z9 Y g WHIZ � >� LL181 Ld Z8� oa 'CIO, Z)Z dw 2 N LL ai to �¢ IX 4 p h LZN J C�p � qLi c3 C4 wg] W rD 2 W ,1 ca x 2mLL O h aQ S PRELIMINARY NOT FOR CONSTRUCTION CMK O PL ABA DMI'm W. MV DMaN W. W mm 02 AM 2015 SPLE: AS WE IMYECT W. 1 W-= C8.5 suT 16 oP 17