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HomeMy WebLinkAboutDrainage Reports - 05/26/2016 (2)City` offt: Collins p ; . d Plans App►nved By D04C 5/6- iIesco Project & Construction Services Drainage Memorandum Date: May 13, 2016 Project: Timberline Center 2133 Timberline — Lot 11 / 3rd Filing — Lot 1 Attn: Stormwater Staff City of Fort Collins Utilities Stormwater Engineering 700 Wood Street Fort Collins, CO 80521 To Whom It May Concern: 1315 Oakridge Drive, Suite 120 Fort Collins, CO 80525 ditescoservices.com The purpose of this drainage memorandum is to summarize the proposed drainage design changes as compared to the original Final Drainage and Erosion Control Reportfor the Timberline Center Subdivision as prepared by North Star Design; February 2006 - (North Star Report), describe project conformance to LID standards, and provide an erosion control report. Site Imperviousness: Lot 1, 3rd Filing of the Timberline Center Subdivision changed since the original North Star Report which was approved by the City of Fort Collins (COFC) on May 23, 2006. The original lot configuration for that filing served a drive through bank and associated parking. Both the lot and site design have been adjusted to serve an office building/restaurant use with associated parking areas. There is no increase in impervious area from the approved 2006 report. In fact, there is a net decrease of approximately 4,500 square feet. The summary of impervious and pervious areas for both the North Star Report and this submitted memorandum are tabulated below in Table 1 and shown visually in Appendix A. TABLE 1: Impervious/Pervious Area Summary 2133 Timberline Lot 1- Current Design Impervious Area Summary Area Description Area -SF Asphalt 20,728 Sidewalks 3,990 Building Footprint 10,325 Total Area 35,043 2133 Timberline Lot 1- 2006 Approved Design Impervious Area Summary Area Description Area -SF Asphalt 32,550 Sidewalk/Building 7,050 Total Area 39,600 Page 1 of 3 2133 Timberline Lot 1- Current Design 2133 Timberline Lot 1- 2006 Aooroved Design Pervious Area Summary Area Description Area -SF Islands At Parking Lot 815 Islands at Sidewalk 1,182 Planters at Building 5,942 Open Area/Detention Pond 21,458 Total Area 29,397 Impervious Percentage 1 54.4% Pervious Area Summary Area Description Area -SF Islands At Parking Lot 1,753 Islands at Sidewalk 1,377 Open Area/Detention Pond 21,676 Total Area 24,840 Impervious Percentage I 61.S% As the new site plan and design provides additional landscaped area when compared to the initial 2006 site design, this site remains in compliance with the original approved North Star Report. Additionally, a site specific Erosion Control Report has been developed for Lot 11 and is included in Appendix B. Drainage Basin Compliance: The site slopes from the west to east from the high point ridge designed as part of the Ascent site plans which is exactly consistent with the grading plan presented in the North Star Report. As there is lower impervious area in the new site plan than originally shown in the North Star Report, this site does not increase runoff quantity to the respective design point. Low Impact Development Compliance: Low Impact Development (LID) requirements per Section 3.1 of the Urban Drainage and Flood Control District Manual (Fort Collins 2012 Amendments) (UDFCD) include Section 3.1(a)(1) - a higher degree of water quality treatment for 50% of new impervious area and Section 3.1(a)(2) - 25% of new paved areas must be pervious. As an alternative to these requirements, per City of Fort Collins Ordinance No. 007, 2016; 75% of a newly developed area may be treated using a combination of LID techniques to achieve compliance. A summary LID Compliance Table in Appendix C is provided for clarity. This project meets the 75% treatment requirement through the following means: The project is proposing a total impervious area of 35,043 square feet (0.80 Acres) through a combination of traditional asphalt pavement, curb and gutter, sidewalks, ramps, pans and building roof area. At 75% treatment, this requires a treated area of 26,282 square feet (0.603 Acres). These areas will be treated through a combined method of rain garden/bioretention treatment, bio-swale treatment, and release of partial roof collection area (east half of building) to roof drain bioretention areas. Appendix C shows areas highlighted and delineated for treatment types. Rain Garden Treatment— A combined area of 13,125 square feet (0.30 Acres) of impervious pavement, sidewalk, and roof area are routed to a 1-foot curb cut into a 480 square foot partial -infiltration rain garden adjacent to the northwest corner of the building envelope. The gutter at the curb cut will be lowered, similar to a curb inlet throat, to route water into the rain garden. The flat area of the rain garden is 14-inches below the gutter flowline elevation at the curb cut and an area inlet will be installed Page 2 of 3 in the rain garden with a rim elevation equal to one foot above the rain garden flat area elevation to maintain a maximum of 1-foot of standing water in the garden and prevent sheet flow over the curb surrounding the garden. Once the rain garden is full, any additional flow will be routed in the gutter past the garden to the north into an existing curb inlet. Calculations for the sizing of this rain garden are provided in Appendix C. Bio-Swale Treatment— A combined area of 8,015 square feet (0.18 acres) of impervious area are routed to a bio-swale with a bioretention media cross section with 100-year storm event capacity. The Swale is 12-feet wide with 4:1 side slopes and 1% longitudinal slope. All contributing drainage is routed through the front of the drainage swale and progresses through approximately 100 linear feet of swale before outfalling into the existing water quantity detention basin. The central channel of the swale is 3-feet wide and includes a biorention and filtration media cross section. The bio-swale will be hand seeded and protected with a biodegradable erosion control mat. The run-on area to swale area is 6.7 using the 12-foot channel measurement and 26.7 using the 3-foot wide central media channel measurement. Calculations for the ratio are provided in Appendix C. Roof Drain Bioretention Areas —The east side of the building roof, an area of 6,112 square feet (0.14 acres) will be routed through roof drains to the roof drain bioretention areas. This storm water will filter through smaller rain garden areas with growth media and filter rock to a perforated subdrain system which outlets into the detention basin. Splash blocks placed at the downspouts of the roof drains will route water into the rain gardens and provide energy dissipation. Overflow of the gardens will sheet flow into the detention basin. Calculations for the sizing of these bioretention areas are provided in Appendix C. In summary, this project complies with applicable Urban Drainage and Flood Control District Manual (Fort Collins 2012 Amendments) requirements. The total LID treatment area of 0.61 acres is in excess of the required treatment area of 0.60 acres. If you have any questions regarding this submittal, please do not hesitate to contact me by email at bill.renz@ditescoservices.com or by phone at 970-219-0157. Thank you for your attention and assistance in this matter. Sincerely, O R,19,9 OHO M yF'.4tk� #32976 J_ Bill Renz, El Keith Meyer, PE � • (2.16;�,; Enc. Appendix A — Impervious Areas Comparison -0,%0NAL �%%Ns Appendix B — Erosion Control Report Appendix C— 3'd Filing Lot 1 LID Treatment Areas and Calculations Page 3 of 3 2133 TIMBERLINE - 3rd FILING - LOT 1 Appendix A Impervious Areas Comparison LE ggiyy8 [I\3 r� C \ 4- mc. � l C 5�— bra C 1 /t- , 5 C m � b y C� O Cy 4 4 Y U p y Y E x�3=a a a Nq C 4 L b V� V Q N D O m M g C ` q C C q q 6 b 0 f I r _ rTUBOVAE ix. Call �ij 3� e _-t• 90 Em C MMC TCD ' ./TWBERUNC p1t0.1EGT 1 - cn KS Y 0. LLB R l Iie � 9dE � \ aaaa ait .i BIB x i aj t xlval06 ,�'B M E / a — 1 ry I � N� O �G N 1� � b� X - 1• �p� 6 a d a d i ■.. As En. Av xe. AT y t = � � 1 (- lit a �� I� 2133 TIMBERLINE - 3rd FILING - LOT 1 Appendix B Erosion Control Report 2133 TIMBERLINE - LOT 11 PROJECT ECR APPENDIX A — EROSION CONTROL REPORT A. Proposed Construction Area i. Developed Conditions — The proposed site is located at the northwest corner of the Timberline Rd. and Nancy Gray Ave., in Fort Collins. Currently, the proposed site development area contains an established detention pond and outlet along the eastern edge of the site. The proposed building will have an 85' setback from Timberline road. Vegetative Cover has been established in the detention pond. ii. Rainfall Erodibility — Rainfall erosion will be controlled through use of temporary construction BMPs until permanent vegetative cover has reached 70% percent of groundcover. Opportunities for rainfall erosion include sheet flow across the site during earthwork operations and utility installations. iii. Proposed Rainfall Erosion and Sediment Control Methods — Primary methods will include silt fence installation on the east and south lot limits and inlet and channel protection with gravel bags to both slow and filter runoff water before it enters any structures or channel outletting to the detention pond. A stabilized construction entrance will be utilized at the site ingress/egress point. iv. Site Phasing and BMP Installation Schedule —The site construction will take place in the following order: 1. Installation of site BMPs i. Stabilized Construction Entrance ii. Silt Fence iii. Inlet protection on existing inlets 2. Site Utility Installation i. Installation of inlet control in new inlets and channels as they are finished 3. Building Foundation and Earthwork 4. Vertical building construction and ongoing utilities 5. Finished site grading, hardscaping and paving 6. Landscaping and Irrigation installation B. Stormwater Management Controls i. SWMP Administrator 1. During construction, the SWMP administrator will be the earthwork and utility contractor. Until such time as that contractor has been selected, the SWMP Administrator will be Bill Renz, Project Manager-Ditesco. He will be responsible Page 1 of 5 2133 TIMBERLINE - LOT 11 PROJECT ECR for developing, implementing, maintaining, and revising the SWMP and will address all aspects of the site SWMP. i. Bill Renz — Ditesco Project Manager 1315 Oakridge Drive, Suite 120 Fort Collins, CO 80525 970.219.0157 ii. Identification of Potential Pollution Sources 1. All disturbed and stored soils — there will be disturbed soils onsite through excavation and vehicle/equipment movement. Soils will be stockpiled/permanently embanked onsite. Excess soil will be transported offsite. Soil stockpiles left undisturbed for a period greater than 30 days will be mulched and seeded. 2. Vehicle tracking of sediments — most vehicle and equipment travel will risk sediment tracking until final pavement is installed. A stabilized construction entrance will be used for the site. Surrounding roadways will be swept if sediment is tracked onto the roadway. 3. Management of contaminated soils — soils may be contaminated through spills during fueling operation or equipment oil leaks. The contractor will keep spill kits onsite during the project and will excavate and remove contaminated kit materials and soil and dispose through the proper waste stream. 4. Loading and unloading operations — Loading and unloading operations will take place within the site for materials to be incorporated in the project. Vehicles will use the stabilized entrance for ingress/egress. 5. Outdoor storage activities (building materials, fertilizers, chemicals, etc.) Storage of materials will be in a designated area. Any chemicals used during construction, concrete cure, etc., will be stored on secondary containment. 6. Vehicle and equipment maintenance and fueling — Maintenance and fueling will be done in the field at the location of the equipment on grade. Spills will be addressed through item 3 of this section. 7. Significant dust or particulate generating processes — dust may be generated from vehicle tracking or portions of backfill operation. The site will be kept from producing dust through watering of any exposed soils. 8. Routine maintenance activities involving fertilizers, pesticides, detergents, fuels, solvents, oils, etc. — Fueling, lubrication, and maintenance operations will take place within the project limits on grade. No fertilizers pesticides or detergents are planned for use on site. 9. On -site waste management practices (waste piles, liquid wastes, dumpsters, etc.) Roll -off Dumpsters will be utilized for the site and will be hauled off at Page 2 of 5 2133 TIMBERLINE - LOT 11 PROJECT ECR regular intervals. Any liquid waste generated will be contained. Concrete process water will be addressed through the next item in the section. 10. Concrete truck/equipment washing, including the concrete truck chute and associated fixtures and equipment — A concrete wash out will be utilized for all concrete placement operations. A sign will be posted clearly showing the washout location. 11. Dedicated asphalt and concrete batch plants — no asphalt or concrete batch plants will be erected onsite. 12. Non -industrial waste sources such as worker trash and portable toilets — Portable toilets will be staged onsite. Trash receptacles will be emptied regularly. 13. Other areas or procedures where potential spills can occur — No other areas qualify for this section. C. Dryland Vegetation I. All areas will be hardscaped, sodded, or mulched. Existing open areas have already been seeded. D. Detailed Sequence of Construction Activities i. It is anticipated that this project will begin construction during 2016 and will be completed within a year. ii. Installation of site BMPs 1. Stabilized Construction Entrance 2. Silt Fence 3. Inlet protection on existing inlets . iii. Site Utility Installation 1. Installation of drainage facilities 2. Installation of inlet control/BMPs in new inlets and channels as they are finished iv. Building Foundation and Earthwork v. Vertical building construction and ongoing utilities vi. Finished site grading, hardscaping and paving vii. Landscaping and Irrigation installation 1. Seeding and mulching 2. Tree planting 3. Shrub planting viii. Vegetative cover establishment period ix. Removal of silt fence and inlet protection x. BMPs will be inspected for effectiveness and maintained after each runoff event and every 14 days at a minimum during construction. E. Erosion Control Security Calculations • Page 3 of 5 2133 TIMBERLINE - LOT 11 PROJECT ECR Example Erosion and Sediment Control Escrow/Security Calculation for The City of Fort Collins Project: Timberline Lot 11 EROSION CONTROL BMPs Silt Fence (SF) Inlet Protection (IP) Concrete Washout (CW) Vehicle Tracking Control (VTC) (add all other BMPs for the site in this list) BMP Amount Disturbed Acres: 1.31 Estimated Unit Total Units Quantity Price Price LF 440 $2.50 $1,100.00 EA 3 $150.00 $450.00 EA 1 $750.00 $750.00 EA 1 $1,100.00 $1,100.00 Sub -Total: $3,400.00 1.5 x Sub -Total: $5,100.00 Amount of security. $5,100.00 Reseeding Amount Total Acres x Price/acre: $1,299.99 Unit Price of Seeding per acre: $995.00 Sub -Total: $1,299.99 1.5 x Sub -Total: $1,949.98 Amount to Re -seed. $1,949.98 Miniumum Escrow Amount Minimum escrow amount. $3,000.00 Erosion Control Escrow. $5,100.00 `The amount of the security must be based on one and one-hallftimes the estimate of the cost to install the approved measures, or one and one-half ibnes the cost to re -vegetate the disturbed land to dry land grasses based upon unit cost determined by the City's Annual Revegetation and Stabilization Bid, whichever is greater. 1n no instance, will the amount of security be less than one thousand five hundred dollars (f1,500) for residential development or three thousand dollars ($3,000) for commercial development" . Page 4 of 5 1 � REE L N m P 0 U 0 w ? 0 N CO Ci a w x N I I u7 R w 0 s Z I I DESIGN BY OTHER / 20' 0 20• ao' so' g (FOR REFERENCE ONLY) .,t "Im �,. SCALE: 1• =20' L IT.. AIMIF For 33ASA MMM NFIN O W w LOT B LOT 9 / opp LOT ID a TIMBERLINE CENTER TIMBERLINE CENTER L - TIMBE'RUNE CENTER `A LEGEND: D; Z O uUi Mti EN J$ FNOMRESM PROPOSED CONTOUR 2 NSI IP 4 V RPC US }lBR0,N91 O FNG rvnLS 34ae5, EXISTING CONTOUR M9TI U RR 1■n I= *A m. III --lY m >tt SF PROPOSECmTOUR DESIGN (BY OTHERS) A9AS _.. O A $ S 7 PROPOSED CURB k CUTTER Q v I I V — — EXISTING STORM SEWER __ a — i Z �r� d{ dJJ� 0 Ae!G PROPERTY BOUNDARY �O/ Y K Y APPROXIMATE LIMITS OF CONSTRUC110N OCR LL W PROPOSED RAN GARDEN )' Y > , I VEHICLE 1RACNINC CONTROL PAID VTC mED (SEE SHEET Not) O I w m O I II 1 SILT FENCE SF —�— \ VWRPC ID89]BBR iGANNE i 1 Y I w 0 INLET PROTECTION IP UTLLIN DRAINAGE. ACCESS EASEMENT CAPKL SOON: GS 46 NOTES: -- I EROSION TRIO _ 1 I SEE GRACING AND EROSION CONTRIOLC302 NOTE, TI ;MEET COC T7 AS WELL AS DETAILS ON SHEET G303, 3' 3 CONRtAMP SHALL PREVENT SEDIMENT FROM ENTERING I I UT31i'/ SIORMWA'ER FACILITIES. AND ^ L IMPLEMENT THE s APPROPRIATE MEASURES ACCORDING THE THE COrvSTRUCTION E SECUDI INC ANO LEVEL OF SITE STAENLIATION. 3 IIN ALI. CITY, STATE. AND FEDERALDDITION To REOUIREMENTSINCOWNTIUCTOR SAU ALSO TAKE T EXTAN D,AECARRENCY Oµ EXISTINGPREVENTATIVE MEASURES RDUE TTOTHE Z . — PROPOSED EASEMENT w I ` A RE. Al SIXTHIS., GRAPHICAL SYM90LS MAY NOT BE TO SCALE. EROSION CONTFICIL PILAFF IS SCHEMATIC IN JNOR ARE UCD THEY TION. Z e pIII GS I _ S THIS EROSIONECESSARILY CONTRO LAN SERVES ONLYASA GUIDELINE TO THE OR STACINC/1"ASING OF THE BEEN DESIGN BY OTHER -..� _ LOT 1 ".' I EXlsrwarvnDE I O ONNPiNIS PL�H�EX ECTED e�oIONAL, sl °� DIFFNRNwN Z � (FOR REFERENCE ONLY) I r/TO cGNCRETE WAu I EE TIMBERLINE CENTER _ ! WAY SHALL THIS PLAN REPLACE THE CONTRACTORS 0f II I �I W OBLIGATIONS FOR PERMITRNC (ON. STATE DISCHARGE PERMIT. w Q THIRD FILING I I Z ETC.) OR COMPLIANCE WITH GOVERNING AUTHORITIES, IT N --GI j OR PERMITBE THE HOLDEN TO ENSURE EROSION CONTROILITY OF THE L MEAOR SURES m L_L LOT Y TIMBERLINE CENTER tt W I� $=NB FILINL I i I (F��o I' FF=4946.80 J' I C m ARE PROPERLv MAINTAINED AND FOLLOWED t I I I l I 6. iTHEE 9 RPOUNDNG SURFACE TYPEPROTECTION SHAI� BE D AND CONOTED, AS EPONS( A.. TO L STAKE -DRIVEN WATTLES FOR BARE SOIL. SAND BAGS OR E >e I I I I r GRAVEL SOCKS FOR PAVEMENT. ETC.) 4 I I I 1 O T. CON1RAClOR IS RE5PONSIBI.E FOR STABILIZING ALL SLOPES. N PAR rICULANLY MUSE STEEPER MANE &I CRIMP MULCHING, rO I I I HYDRO MULCHWO, EROSION MATS. TELWORARY PRIGATIGN, AND ADO TION& WATTLES ON SILL FENCING MAY EB NECESSARY 10 ESTABLISH VEGETATIVE COVER AND STABILIZE J _ ILL^. rya Wei q I L THE SLWE B. THE LIMITS OL DISIURBANCEAIMITS 0' CONSIRUCNON (BCCNOARY LINE FOR MIS PROJECT IS MC PROPERTY GS 1 S 9 SEE LANDSCAPE PLANES FOR AODITIONa. I"NATION ON L PLATING, RCVECETATION, HARDSCAPC AND ONCP PERMANENT s 1 T SITE STABILISATION MENiOOS. S I C 91h I I IC. THE TOP Or FOUNDATION ELEVATIONS SHOWN ARE ABOVE THE MINIMUM REQUIRED FOR THE TOO -YEAR STOW LAJ VanLglig, � RE e P" rg. I 5 q+ i On �JIO TIUSH ENCLOSURE ! Pw I Y r _ I _. TROT TOOT_ :I �G K9A5 I IF rr L dY``` O OIO cIPB Iplrlul.T' nl lry <<A9AE AFAT--J - •'= E CIIL of Foll lnllln>. I -I IIII ,IIII, ^" SF FNGMRESM fNOMRESM oO _ FNDw REBAR O .+RPC Ls latro.KSI HRPC Ls vta9.11sl E. TII..ETl P1..\N ai'I'12()\ aE. Q ON IN LS]I99IAE APPROVED: II, iII.IU•.� - 4UC0 CALL UTILITYNORFICATKMI CENTER OF , COLORADO 1 CHECKED BY �� II I� ,., �I �- c ..._ ,..,I I, T II o=xo I UU 3 OUTLET A;CHECKED BY: SPRING CRREX FARMS' NORTH n o �v eF RRn whETAblIOW CHECKED B1': Perk. kRPcreNCiPn _- C811 bobs you dig. uN P rur[m own w ,WFAva w ar r CHECKED BY: ma MMPF. a vnwrt TOI IHF INVITE 6 IRRAggIrM yLyMR VIMI[8 CHECKED BY: 2133 TIMBERLINE - 3rd FILING - LOT 1 Appendix C - LID Treatment Areas d'lesc0 �. Filing - LID Cala and Summary TE DATE:Project 52133 / 3/ 016erline-Lotl-3rd & Construction Services FILE/JOB#: PAGE: 1 OF 1 Bio Swale Characteristics Area Description Area (sf) Area (AC) Ratio (sf/sf) Tributary Area (Run On) 8015 0.184 Area of Bioswale (12' full width) 1200 0.028 Area of Bioswale Cobble (3' center) 300 0.007 Ratio of Run Area On to Swale Area 8,015/1,200 6.7 Ratio of Run Area On to Swale Media Area 8,015/300 26.7 Low Impact Development (LID) Compliance Table LID COMPLIANCE TABLE QTY UNIT QTY UNIT New Impervious Area Traditional Pavement Area 20,728 SF 0.476 AC Other Impervious Surfaces (Roofs, Concrete Walks, Etc.) 14,315 SF 0.329 AC Required Minimum Impervious Area to be Treated (75%) 26,282 SF 0.603 AC Rain Garden UD Treatment Rain Garden Area 480 SF 0.011 AC Run-on area for Rain Garden 13,125 SF 0.301 AC Run-on area ratio for Rain Garden (sf/sf) 27.3 Impervious Area Treated by Rain Garden 13,125 SF 0.301 AC Blo Swale LID Treatment Bio Swale Area (3' Width) 300 SF 0.007 AC Run-on area for Bio Swale 8,015 SF 0.194 AC Run-on area ratio for Bio Swale (sf/sf) 26.7 Impervious Area Treated by Bio Swale 8,015 SF 0.184 AC Impervious Area Treated by Roof Drain Bioretention East Roof Bioretention Area 528 SF 0.012 AC Run-on area for Roof Drain Bioretention 6,112 SF 0.140 AC Run-on area ratio for Roof Drain Bioretention (sf/sfl 11.6 Impervious Area Treated by Bioretention 5,315 SF 0.122 AC Total Impervious Area ' 35,043 SF 0.804 AC Total Impervious Area Treated 26,455 SF 0.607 AC Total Impervious Area Treated Percentage 75.49% 0V0N 3NIIN38NII Hinos LJ wt z�Y m�ri A r ``t 6E6I W Ya co co a) Q E co 5w rw A t3 8 9 ,Mrs r9 u Design Procedure Form: Rain Garden (RG) II Sheet 1 of 2 Designer: Keith Meyer Company: oftil Date: May 13, 2016 Project: 2133 Timberline WEST Rain Garden Location: 213 Timberline Lot 1, 3rd Filing, Fort Collins, CO 1. Basin Storage Volume A) Effective Imperviousness of Tributary Area, I, I, = 96,5 % (100 % if all paved and roofed areas upstream of rain garden) B) Tributary Area's Imperviousness Ratio (i = I,1100) i = 0.965 C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.37 watershed inches (WQCV= 0.8' (0.91' i'- 1.19 " i'+ 0.78 - i) D) Contributing Watershed Area (including rain garden area) Area = 13,605 sq It E) Water Quality Capture Volume (WQCV) Design Volume Vwocv = cu ft Vol = (WQCV / 12) " Area F) For Watersheds Outside of the Denver Region, Depth of EIS = 0.43 in Average Runoff Producing Storm G) For Watersheds Outside of the Denver Region, Vwocv CT R = 419.0 cu it Water Quality Capture Volume (WQCV) Design Volume H) User Input of Water Quality Capture Volume (WQCV) Design Volume Vwocv USER = cu It (Only f a different WQCV Design Volume is desired) 2. Basin Geometry A) WQCV Depth (12-inch maximum) Dwocv = 12 in B) Rain Garden Side Slopes (Z = 4 min., hor¢. dist per unit vertical) Z = 4.00 ft / ft (Use'0' it rain garden has vertical walls) C) Mimimum Flat Surface Area AMa = 262 sq it D) Actual Flat Surface Area A, ,,,a = 269 sq ft E) Area at Design Depth (Top Surface Area) ATw = 480 sq It bioretention media porosity used to achieve total volume of F) Rain Garden Total Volume Vi= 375 tuft (VT= ((Arw+A�) / 2)' Depth) 427.5 cf. (see note 2 below) 3. Growing Media Choose one O 18" Rain Garden Growing Media (g Other (Explain): 12" provided minimally planted 4. Underdrain System Choose One © YES A) Are underdrains provided? O too B) Underdrain system orifice diameter for 12 hour drain time I) Distance From Lowest Elevation of the Storage y= 1 A It Volume to the Center of the Orifice ii) Volume to Drain in 12 Hours Volt,= 419 cu R iii) Orifice Diameter, 3/8' Minimum Do = 1/2 in UD - Rain Garden Calcs West of Bldg, RG 5/14/2016. 212 PM Design Procedure Form: Rain Garden (RG) Sheet 2 of 2 Designer: Keith Meyer Company: Ditesco Date: May 13, 2016 Project: 2133 Timberline WEST Rain Garden Location: 213 Timberline Lot 1, 3rd Filing, Fort Collins, CO 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 rEs ND 6. Inlet / Outlet Control A) Inlet Control Choose One Q Sheet Flow- No Energy Dissipation Required QQ Concentrated Flow- Energy Dlssipaton Provided 7. Vegetation Choose One Q Seed (Plan for frequent weed control) QQ Plantings O Sand Grown or Other High Inflltretlon Sod 8. Irrigation A) Will the rain garden be Irrigated? Choose One OYES O No 7 Notes: 1. Side slopes of rain garden to be installed at 4:1 max with a 0.35' vertkal drop at bottom back of curb to provide required Oat area in excess of 262 SF. . For Item 2.F above additional storage volume achieved thro h use of orosi of rowth media t 14°/ r Sioretention Guide T-3 Sheet B-5. Additional 67h' added - .5ft'+375ft'=427.5ft°> r d 419ft3 3. Table R0.3 Volume 1 - Run used to calculate im er - - Dements a for tributary area. UD Fo Design Procedure Form: Rain Garden (RG) Sheet 1 of 2 Designer: Keith Meyer Company: Ditesco I Date: May 13, 2016 Project: 2133 Timberline Fast Rain Gardens Location: 213 Timberline Lot 1, 3rd Filing, Fort Collins, CO 1. Basin Storage Volume A) Effective Imperviousness of Tributary Area, I, I, = 90.0 % (100% if all paved and roofed areas upstream of rain garden) B) Tributary Area's Imperviousness Ratio (i = IJ100) I = 0.900 C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.32 watershed inches (WQCV= 0.8' (0.91" i3- 1.19 • ?+0.78" i) D) Contributing Watershed Area (including rain garden area) Area = 5,524 sq It E) Water Quality Capture Volume (WQCV) Design Volume Vwacv = cu it Vol = (WQCV 112) " Area F) For Watersheds Outside of the Denver Region, Depth of dr = 0.43 in Average Runoff Producing Storm G) For Watersheds Outside of the Denver Region, VWMV OTHER = 147.9 W R Water Quality Capture Volume (WQCV) Design Volume H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV useR = cu ft (Only if a different WQCV Design Volume is desired) 2. Basin Geometry A) WQCV Depth (12-inch maximum) DwQcv = 6 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 Am. = 99 sq it D) Actual Flat Surface Area A,v,,,� = 141 sq It E) Area at Design Depth (Top Surface Area) ATw = 528 sq ft F) Rain Garden Total Volume VT= 167 cu It (VT= ((AT. + Aa. /2)'Depth) 3. Growing Media Choose One 0 18" Rain Garden Growing Media Q Other (Explain): B" provided; minimally planted 4. Underdram System A) Are untlertlrains provided? Choose One O NO B) Underdrain system orifice diameter for 12 hour drain time i) Distance From Lowest Elevation of the Storage y= 1.2 R Volume to the Center of the OMce ii) Volume to Drain in 12 Hours Vol,,= 148 cu ft iii) Orifice Diameter, 3/8" Minimum Do = 113 in LESS THAN MINIMUPo L...-'IAV TSP UD - Rain Garden Calcs East of Bldg, RG 5/14/2016, 2 14 PM Design Procedure Form: Rain Garden (RG) Sheet 2 of 2 Designer: Keith Meyer Company: Ditesco Date: May 13, 2016 Project: 2133 Timberline East Rain Gardens Location: 213 Timberline Lot 1, 3rd Filing, Fort Collins, CO 5. Impermeable Geomembrane Liner and Geotextile Separator Fabric Choose One - Q YES A) Is an impermeable liner provided due to proximity Q NO of structures or groundwater contamination? 6 Inlet / Outlet Control II�� Choose One Q Sheet Flow- No Energy Dissipation Required A) Inlet Control Q Concentrated Flow- Energy Dissipation Provided 7. Vegetation Choose One Q Seed (Plan for frequent weed rontrolJ QQ Plantings Q Sand Grown or Other Hlgh Irdlltratlan Sad 8. Irrigation Choose One - OYES A) Will the rain garden be irrigated? Q to Notes: 1. Rain Gardens split into 5 mini-bioretention areas serving all 5 east roof drains. There is 28.2 sf of growth media per location = 141 sf. 2. Table RO-3 Volume 1 - Runoff) used to calculate Impervious rcenta a for tributary area. 3. Flat area of rain garden will not be irngatT14F Partial liner provided against building foundation but not under rain ganders. UO - Rain Garden Calcs East of Bldg, RG 5/14/2016, 2 14 FM