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Home My WebLink AboutCOUNTRY CLUB CORNERS SIXTH FILING (CARWASH) - PDP - PDP170003 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT1218 W. ASH, STE. A, WINDSOR, COLORADO 80550 TEL. 970.674.3300 – FAX 970.674.3303 January 25, 2017 Mr. Shane Boyle Fort Collins Utilities – Stormwater 700 Wood Street Fort Collins, CO 80522 Re: Country Club Corners Sixth Filing – Lot 1 Preliminary Storm Drainage Letter Dear Shane, Please accept the following letter describing the storm drainage intent demonstrating the proposed site improvement’s ability to comply with the City’s stormwater requirements. INTRODUCTION The Country Club Corners Sixth Filing – Lot 1 proposes to construct a drive through carwash along with the supporting utility infrastructure, site accesses (pedestrian/vehicular), along with modifying the existing interim detention pond to accommodate the proposed improvements. The site is located within commercial plaza located in the southeast corner of N. College Ave (Hwy 287) and E. Willox Lane, north of Bristlecone Dr, and west of Blue Spruce Drive. Lot 1 of Country Club Corners Sixth Filing is a replat of Lot 8, Country Club Corners Third Filing PUD, and Lot 1, Country Club Corners Fifth Fill, located in the Northwest Quarter Section 1, Township 7 North, Range 69 West of the 6th P.M., City of Fort Collins, County of Larimer, State of Colorado. A vicinity map is attached for reference. The carwash site is located with Lot 1 and the interim detention pond is proposed to be located within Lot 2 of Country Club Corners Sixth Filing. Lot 1 is approximately 1.09 acres, and Lot 2 is approximately 1.09 acres. A significant portion of both lots will be disturbed with the proposed improvements, for a total area of 2.18± acres. The proposed improvements will be completed in one phase of construction. EXISTING CONDITIONS The project site is located within the Northeast College Corridor Outfall (NECCO) drainage basin and detention is not required. An existing storm drainage infrastructure is described in the following drainage reports and/or utility plans: • Country Club Corners Third Filing P.U.D. (1995) • Lot 3, Replat No. 1 of Country Club Corners Third Filing P.U.D. (1996) • Country Club Corners Fourth Filing P.U.D. (1997) • Country Club Corners Fifth Filing (2002) The original drainage plan was established with the Country Club Corners Third Filing PUD. This filing proposed that the storm drainage infrastructure be constructed in two phases, with the swale to Evergreen Pond as the ultimate outfall for both phases. References are attached. Phase 1 established an interim detention pond with a temporary outfall pipe, and Phase 2 is to complete the storm drain outfall within Bristlecone Dr to the Evergreen Pond swale. No dedicated onsite detention facilities are required with the Country Club Corners Sixth Filing – Lot 1 Preliminary Storm Drainage Letter January 25, 2017 Page 2 of 4 completion of Phase 2 of the storm drainage infrastructure. Phase 1 utilized a temporary 24” HDPE outfall pipe and swale to drain the pond. The remaining filings listed above either modified the interim detention pond or enclosed the temporary outfall swale in a pipe. The Phase 2 of the storm drain system has not be completed. Unfortunately, no mechanism was established with the original PUD to complete the extensive infrastructure needed to complete the drainage outfall. The last modification to the interim detention pond is described within the Country Club Corners Fourth Filing PUD. The project is not located within a FEMA mapped 100-yr floodplain. PROPOSED DEVELOPMENT The improvements associated with Lot 1 will consist of constructing a 4,680 sqft drive through carwash with supporting utility infrastructure and pedestrian/vehicle accesses. The interim detention pond will be reconfigured to accommodate the carwash improvements. Without the completion of the originally proposed storm drain system, the interim detention pond will need to remain and will be located within Lot 2 of the Country Club Corners Sixth Filing. At the time the outfall is complete, dedicated onsite detention facilities are not required. To determine the appropriate detention volume required, the basins draining to the interim pond were reanalyzed with the current rainfall depths along with confirming the ponds release rate. The capacity of the existing 30” RCP within Bristlecone Dr limits the pond release rate. The pond was originally designed with a 6.60 cfs release rate based on the available capacity of 25 cfs within the 30” RCP determined within the Country Club Corners Third Filing PUD drainage report. By allowing a little head on the pipe, the pipe capacity was confirmed to allow 32.5 cfs. It is anticipated that if the pipe was to surcharge, the existing just north of Bristlecone Dr would provide hydraulic relief. The street capacity of Bristlecone Dr was also confirmed to have capacity available to convey any potential flow from surcharged inlets. It is recommended that the existing storm drain vault covers be replaced with locking lids to reduce the chance of dislodging. Based on these capacities, the pond release rate could be increased to 14.1 cfs. The preliminary pond represented within these calculations has a release rate of 13.49 cfs, requiring 1.67 acre-ft of storage. To accommodate the carwash improvements, the portion of the existing storm drain within Lot 1 will be realigned. Preliminary sizing calculations are provide with reference to the Country Club Corners Third Filing PUD drainage report for off site flows. The project is required to implement Low Impact Development (LID) techniques to provide water quality enhancement. A bioretention rain garden is proposed to treat at least 75% of the proposed impervious area. There is some offsite drainage from the west that sheet flows to the carwash site. These flows will be directed to the interim detention pond without being conveyed to the proposed rain garden utilizing a curb cut near the carwash entrance. Approximately 2,250 sqft of the private drive along the east of the site drains to the rain garden. The remaining eastern private drive that drains to the carwash site is conveyed to the interim detention pond through a combination of curb cuts and a swale. The carwash site is divided into 3 basins: Basin 101 consists of majority of the site improvements. This basin drains to and is treated by the rain garden along the eastern property line. The basin is approximately 0.82 acres and is 71.2% impervious with an estimated 100-yr runoff rate of 6.86 cfs. Runoff from the rain garden is directed to the relocated 36” storm drain along the eastern property line than to the interim detention pond. Country Club Corners Sixth Filing – Lot 1 Preliminary Storm Drainage Letter January 25, 2017 Page 3 of 4 Basin 102 consist of the proposed carwash building and the carwash entry/exit drives. This basin is approximately 0.19 acres and is 68.5% impervious with an estimated 100-yr runoff rate of 1.75 cfs. Runoff from the basin in collected by a series of area inlets and directed to the storm drain manhole proposed to be located north of the carwash building. Basing 103 consist of the west portion of Lot 1 that is not conveyed to the rain garden. This basin is approximately 0.09 acres and is 43.4% impervious with an estimated 100-yr runoff rate of 0.56 cfs. Runoff from this basin is directed to the interim detention pond via surface from and a curb cut in the carwash site entry drive. All calculations and exhibits are attached for reference. LOW IMPACT DEVELOPMENT TECHNIQUES In reference to the code requirements for implementation of Low Impact Development (LID) techniques, the use of a bioretention rain garden is necessary to satisfy these requirements. The rain garden will promote infiltration while capturing fine sediment that drains off of the impervious areas. A Standard Operations Procedure will be provided at final design to assist in ensuring that these BMPs will adequately perform over time. Below is a description of the 4 step process for selecting structural BMPs: Urban Drainage and Flood Control District (UDFCD) recommends a Four Step Process for receiving water protection that focuses on reducing runoff volumes, treating the water quality capture volume (WQCV), stabilizing drainageways and implementing long-term source controls. The Four Step Process applies to the management of smaller, frequently occurring events. Step 1: Employ Runoff Reduction Practices To reduce runoff peaks, volumes, and pollutant loads from urbanizing areas, implement Low Impact Development (LID) strategies, including Minimizing Directly Connected Impervious Areas (MDCIA). Runoff throughout the site is mainly conveyed to the rain garden via overland sheet flow, curb & gutter, and drain pans. The rain garden will slow runoff, promote infiltration, and filter runoff prior to being released into the adjacent storm drain system. Step 2: Implement BMPs that Provide a Water Quality Capture Volume with Slow Release The rain garden is designed to provide water quality capture volume per Urban Drainage’s recommendations and calculations. The captured runoff is design for a 12-hr drain time. Step 3: Stabilize Drainageways Natural Drainageways are subject to bed and bank erosion due to increases in frequency, duration, rate and volume of runoff during and following development. Because the site will drain to an existing storm system, bank stabilization is unnecessary with this project. Step 4: Implement Site Specific and Other Source Control BMPs Country Club Corners Sixth Filing – Lot 1 Preliminary Storm Drainage Letter January 25, 2017 Page 4 of 4 Proactively controlling pollutants at their source by preventing pollution rather than removing contaminants once they have entered the stormwater system or receiving waters is important when protecting storm systems and receiving waters. This can be accomplished through site specific needs such as construction site runoff control, post-construction runoff control and pollution prevention / good housekeeping. It will be the responsibility of the contractor to develop a procedural best management practice for the site. All calculations are attached for reference. EROSION CONTROL Erosion and sedimentation will be controlled on-site by use of sediment control logs, inlet protection, a gravel construction entrance, seeding, mulch, and turf. The measures are designed to limit the overall sediment yield increase due to construction as required by the City of Fort Collins. During overlot and final grading the soil will be roughened and furrowed perpendicular to the prevailing winds. During the performance of the work required by these specifications or any operations appurtenant thereto, whether on right-of-way provided by the City or elsewhere, the contractor shall furnish all labor, equipment, materials, and means required. The Contractor shall carry out proper efficient measures wherever and as necessary to reduce dust nuisance, and to prevent dust nuisance that has originated from his operations from damaging crops, orchards, cultivated fields, and dwellings, or causing naissance to persons. The Contractor will be held liable for any damage resulting from dust originating from his operations under these specifications on right-of-way or elsewhere. It is unlawful to track or cause to be tracked mud or other debris onto city streets or rights-of-way. Wherever construction vehicles access routes or intersect paved public roads, previsions must be made to minimize the transport of sediment by runoff or vehicles tracking onto the paved surface. Stabilized construction entrances are required with base material consisting of 6” coarse aggregate. The contractor will be responsible for clearing mud tracked onto city streets on a daily basis. All temporary and permanent erosion and sediment control practices must be maintained and repaired as needed to assure continued performance of their intended function. Silt fence and sediment control logs will require periodic replacement. Maintenance is the responsibility of the contractor. All disturbed areas must be seeded and mulched within 30 days of project start. Vegetation shall not be considered established until a ground cover is achieved which is demonstrated to be mature enough to control soil erosion to the satisfaction of the City Inspector and to survive severe weather condition. Thank you in advance for your time and if you have any questions or comments please contact me at (970) 347-8917. Sincerely, Jason T. Claeys, P.E., LEED AP Interwest Consulting Group Attachments SITE Vicinity Map Scale: 1" = 1000' PROJECT DATUM: NAVD88 CITY OF FORT COLLINS BENCHMARK #42-97 ON TOP OF A STORM INLET STRUCTURE ON THE EAST SIDE OF REDWOOD ST., 400 FEET SOUTH OF WILLOX LANE. ELEV= 4969.93 CITY OF FORT COLLINS BENCHMARK #V401 AT THE JUNCTION OF U.S. HIGHWAY 287 AND BRISTLECONE DRIVE, 194.9 FT EAST OF THE CENTERLINE OF THE NORTH BOUND LANES OF THE HIGHWAY, 48.2 FT NORTH OF THE CENTER OF THE DRIVE, AND 3.6 FT NORTH OF A UTILITY POLE AND POWERLINE CROSSING THE DRIVE ELEV= 4977.81 PLEASE NOTE: THIS PLAN SET IS USING NAVD88 FOR A VERTICAL DATUM. IF NGVD29 UNADJUSTED IS REQUIRED FOR ANY PURPOSE, THE FOLLOWING EQUATIONS SHOULD BE USED: NGVD UNADJUSTED = 4969.93 (NAVD88) - 3.18 NGVD UNADJUSTED = 4977.81 (NAVD88) - 3.17 HORIZONTAL DATUM: COLORADO STATE PLAN COORDINATES NAD 83(2007) DATUM. HORIZONTAL CONTROL BASED VRS. Hydrologic Soil Group—Larimer County Area, Colorado (Country Club Corners Sixth Filing - Lot 1) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/19/2017 Page 1 of 4 4495250 4495260 4495270 4495280 4495290 4495300 4495310 4495320 4495250 4495260 4495270 4495280 4495290 4495300 4495310 4495320 493600 493610 493620 493630 493640 493650 493660 493670 493680 493690 493700 493710 493600 493610 493620 493630 493640 493650 493660 493670 493680 493690 493700 493710 40° 36' 31'' N 105° 4' 32'' W 40° 36' 31'' N 105° 4' 27'' W 40° 36' 28'' N 105° 4' 32'' W 40° 36' 28'' N 105° 4' 27'' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 25 50 100 150 Feet 0 5 10 20 30 Meters Map Scale: 1:580 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Rating Polygons A A/D B B/D C C/D D Not rated or not available Soil Rating Lines A A/D B B/D C C/D D Not rated or not available Soil Rating Points A A/D B B/D C C/D D Not rated or not available Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as Hydrologic Soil Group Hydrologic Soil Group— Summary by Map Unit — Larimer County Area, Colorado (CO644) Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 73 Nunn clay loam, 0 to 1 percent slopes C 1.7 100.0% Totals for Area of Interest 1.7 100.0% Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (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 classes. Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Hydrologic Soil Group—Larimer County Area, Colorado Country Club Corners Sixth Filing - Lot 1 Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/19/2017 Page 3 of 4 Tie-break Rule: Higher Hydrologic Soil Group—Larimer County Area, Colorado Country Club Corners Sixth Filing - Lot 1 Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/19/2017 Page 4 of 4 References from Country Club Corners Third Filing Country Club Corners Sixth Filing - Lot 1 DEVELOPED IMPERVIOUS AREA CALCULATION Design Engineer: Design Firm: Project Number: Date: DESIGN CRITERIA: Urban Storm Drainage Criteria Manual by Urban Drainage and Flood Control District, June 2001 (Revised January 2016) BASINS: % Impervious Runoff Coefficient C Return Period Frequency Adjustment Factor (Cf) 100% 0.95 2-year to 10-year 1.00 90% 0.95 100-year 1.25 90% 0.95 40% 0.50 0% 0.25 C2 to C10 C100 101 35,609 0.817 25,162 0 221 0 10,227 71.2% 0.75 0.94 102 8,183 0.188 1,389 4,680 0 0 2,113 68.5% 0.77 0.96 103 3,788 0.087 1,642 0 0 0 2,146 43.4% 0.55 0.69 Overall 47,579 1.092 28,193 4,680 221 0 14,486 68.5% 0.74 0.92 J.Claeys Interwest Consulting Group 1303-158-00 January 25, 2017 % Impervious values from Table RO-3 in the Urban Storm Drainage Criteria Manual Runoff Coefficients and Frequency Adjustment Factors for City of Fort Collins - Storm Water Criteria Manual Land Use Paved Roof Walks Gravel/Pavers Lawns (Heavy, 2-7% Slope) Sub-basin Designation Atotal (sq feet) Atotal (acres) Weighted % Impervious Apaved COMPOSITE (sq feet) Aroof (sq feet) Awalk (sq feet) Agravel/pavers (sq feet) Country Club Corners Sixth Filing - Lot 1 DEVELOPED TIME OF CONCENTRATION Design Engineer: Design Firm: Project Number: Date: DESIGN CRITERIA: EQUATIONS: -Equation 6-2 -Equation 6-4 -Urbanized Check Equation 6-5 -Equation 6-3 CONSTRAINTS: 300 ft - Overland flow shall not exceed for developed condition 500 ft - Overland flow shall not exceed for undeveloped condition Final t c = minimum of t i + t t and urbanized basin check recommended minimum t c = 5 min for urbanized basins BASINS Type of Travel Surface Cv 1 101 71.2% 0.75 0.723 60 0.0146 4.41 256 0.0101 Paved Areas 20 2.01 2.12 6.54 0.0109 9.05 6.54 2 102 68.5% 0.77 0.438 35 0.0209 2.83 99 0.0100 Paved Areas 20 2.00 0.82 5.00 0.0129 8.42 5.00 3 103 43.4% 0.55 1.161 24 0.0200 3.90 150 0.0038 Paved Areas 20 1.23 2.03 5.92 0.0060 13.16 5.92 SUB-BASIN DATA % Impervious Urban Check tc (min) OVERALL SLOPE (ft/ft) TRAVEL TIME (tt) SLOPE (ft/ft) VELOCITY (ft/s) tt (min) AREA (acres) LENGTH (ft) REMARKS Final tc (min) tc =ti +tt (min) J.Claeys Interwest Consulting Group 1303-158-00 January 25, 2017 SLOPE (ft/ft) Urban Storm Drainage Criteria Manual by Urban Drainage and Flood Control District, June 2001 (Revised January 2016) ti (min) LENGTH Table RO-2 (ft) Country Club Corners Sixth Filing - Lot 1 DEVELOPED PEAK RUNOFF Design Engineer: Design Firm: Project Number: Date: DESIGN CRITERIA: Town of Timnth - Design Criteria Manual (2016) Urban Storm Drainage Criteria Manual by Urban Drainage and Flood Control District, June 2001 (Revised August 2006) EQUATIONS: I = rainfall intensity (in/hr) Q n = n -yr peak discharge (cfs) P 1 = one-hour point rainfall depth (in) C n = n -yr runoff coefficient t c = time of concentration (min) I n = n -yr rainfall intensity (in/hr) P 1-5yr = 1.14 in A n = Basin drainage area (ac) P 1-10yr = 1.40 in P 1-100yr = 2.86 in BASIN SUMMARY: Runoff Coeff. (C5) C(A) (acres) Intensity (in/hr) Q (ft3/s) Runoff Coeff. (C10) C(A) (acres) Intensity (in/hr) Q (ft3/s) Runoff Coeff. (C100) C(A) (acres) Intensity (in/hr) Q (ft3/s) 1 101 0.817 6.54 0.75 0.61 3.57 2.19 0.75 0.61 4.39 2.69 0.94 0.77 8.97 6.86 2 102 0.188 5.00 0.77 0.14 3.86 0.56 0.77 0.14 4.74 0.68 0.96 0.18 9.68 1.75 3 103 0.087 5.92 0.55 0.05 3.68 0.18 0.55 0.05 4.52 0.22 0.69 0.06 9.24 0.56 Design Point Sub-basin Area (acres) tc (min) 5-yr Peak Runoff 100-yr Peak Runoff J.Claeys Interwest Consulting Group 1303-158-00 January 25, 2017 10-yr Peak Runoff Q n = C n I n A n 0.786651) 1 ( 10 ) 28 . 5 t c P I + = Country Club Corners Sixth Filing - Lot 1 Low Impact Development Design Engineer: Design Firm: Project Number: Date: DESIGN CRITERIA Low Impact Development Summary Pavement Area Summary 28,193 sqft 0 sqft 0.0% Developed Area Summary 47,579 sqft Total New Impervious area: 33,094 sqft Total Impervious Area required for Treatment (75%): 24,820 sqft 0 sqft 0 sqft 0 sqft 25,162 sqft 25,162 sqft 76.0% City of Fort Collins - Ordinance No. 007, 2016 - Treat at least 75% of any newly developed or redeveloped area using one or a combination of LID techniques, or - Treat at least 50% of any newly developed or redeveloped area using one or a combination of LID techniques when 25% of private driveable surfaces are permeable. J.Claeys Interwest Consulting Group 1303-158-00 January 25, 2017 Urban Storm Drainage Criteria Manual, Urban Drainage and Flood Control District, January 2010 Total New Paved Area: Permeable Paver Area: Total Newly Developed Area: Proposed Area of Pavers: Additional Area Treated by Pavers: Total Area Treated by Pavers: Total Area Treated by LID: Percent Site Impervious Area Treated by LID: Percent Pavement Area as Permeable Pavers: Impervious Area Treated by Rain Garden: Sheet 1 of 2 Designer: Company: Date: Project: Location: 1. Basin Storage Volume A) Effective Imperviousness of Tributary Area, Ia Ia = 71.2 % (100% if all paved and roofed areas upstream of rain garden) B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.712 C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.22 watershed inches (WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i) D) Contributing Watershed Area (including rain garden area) Area = 35,609 sq ft E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = cu ft Vol = (WQCV / 12) * Area F) For Watersheds Outside of the Denver Region, Depth of d6 = 0.43 in Average Runoff Producing Storm G) For Watersheds Outside of the Denver Region, VWQCV OTHER = 666.0 cu ft 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 = 12 in B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 4.00 ft / ft (Use "0" if rain garden has vertical walls) C) Mimimum Flat Surface Area AMin = 507 sq ft D) Actual Flat Surface Area AActual = 512 sq ft E) Area at Design Depth (Top Surface Area) ATop = 1170 sq ft F) Rain Garden Total Volume VT= 841 cu ft (VT= ((ATop + AActual) / 2) * Depth) 3. Growing Media CoFC Rain Garden Section (12" Growing Media, 6" Pea Gravel, 10" CDOT Class 2) 4. Underdrain System A) Are underdrains provided? B) Underdrain system orifice diameter for 12 hour drain time i) Distance From Lowest Elevation of the Storage y = 2.0 ft Volume to the Center of the Orifice ii) Volume to Drain in 12 Hours Vol12 = 666 cu ft iii) Orifice Diameter, 3/8" Minimum DO = 3/5 in Design Procedure Form: Rain Garden (RG) J.Claeys Interwest Consulting Group January 25, 2017 Country Club Corners Sixth Filing - Lot 1 Choose One Choose One 18" Rain Garden Growing Media Other (Explain): YES NO 1303-158-00 UD-BMP_v3.05.xlsm, RG 1/23/2017, 6:02 PM Sheet 2 of 2 Designer: Company: Date: Project: Location: 5. Impermeable Geomembrane Liner and Geotextile Separator Fabric A) Is an impermeable liner provided due to proximity of structures or groundwater contamination? 6. Inlet / Outlet Control A) Inlet Control 7. Vegetation 8. Irrigation A) Will the rain garden be irrigated? Notes: Design Procedure Form: Rain Garden (RG) J.Claeys Interwest Consulting Group January 25, 2017 Country Club Corners Sixth Filing - Lot 1 Choose One Choose One Choose One Sheet Flow- No Energy Dissipation Required Concentrated Flow- Energy Dissipation Provided Plantings Seed (Plan for frequent weed control) Sand Grown or Other High Infiltration Sod Choose One YES NO YES NO 1303-158-00 UD-BMP_v3.05.xlsm, RG 1/23/2017, 6:02 PM Design Engineer: Design Firm: Project Number: Date: DESIGN CRITERIA Detention Volume Calculation 0.9 1.25 1.00 ft3 acre-ft 11.69 acres 72,806 1.671 13.49 cfs Time (min) 100-yr Intensity (I , in/hr) Q100 (cfs) Accumulative Runoff Volume (ft3) Release Volume (ft3) Detained Volume (ft3) Detained Volume (acre-ft) 0 0.00 0.00 0.00 0.00 0.00 0.0000 5 9.95 116.32 34,894.65 4,047.00 30,847.65 0.7082 10 7.72 90.25 54,148.08 8,094.00 46,054.08 1.0573 15 6.52 76.22 68,596.92 12,141.00 56,455.92 1.2960 20 5.60 65.46 78,556.80 16,188.00 62,368.80 1.4318 25 4.98 58.22 87,324.30 20,235.00 67,089.30 1.5402 30 4.52 52.84 95,109.84 24,282.00 70,827.84 1.6260 35 4.08 47.70 100,159.92 28,329.00 71,830.92 1.6490 40 3.74 43.72 104,929.44 32,376.00 72,553.44 1.6656 45 3.46 40.45 109,207.98 36,423.00 72,784.98 1.6709 50 3.23 37.76 113,276.10 40,470.00 72,806.10 1.6714 55 3.03 35.42 116,888.31 44,517.00 72,371.31 1.6614 60 2.86 33.43 120,360.24 48,564.00 71,796.24 1.6482 65 2.72 31.80 124,007.52 52,611.00 71,396.52 1.6390 70 2.59 30.28 127,163.82 56,658.00 70,505.82 1.6186 75 2.48 28.99 130,460.40 60,705.00 69,755.40 1.6014 80 2.38 27.82 133,546.56 64,752.00 68,794.56 1.5793 85 2.29 26.77 136,527.51 68,799.00 67,728.51 1.5548 90 2.21 25.83 139,508.46 72,846.00 66,662.46 1.5304 95 2.13 24.90 141,928.29 76,893.00 65,035.29 1.4930 100 2.06 24.08 144,488.40 80,940.00 63,548.40 1.4589 105 2.00 23.38 147,294.00 84,987.00 62,307.00 1.4304 110 1.94 22.68 149,678.76 89,034.00 60,644.76 1.3922 115 1.89 22.09 152,449.29 93,081.00 59,368.29 1.3629 120 1.84 21.51 154,869.12 97,128.00 57,741.12 1.3256 125 1.79 20.93 156,938.25 101,175.00 55,763.25 1.2801 130 1.75 20.46 159,568.50 105,222.00 54,346.50 1.2476 135 1.71 19.99 161,918.19 109,269.00 52,649.19 1.2087 140 1.67 19.52 163,987.32 113,316.00 50,671.32 1.1633 145 1.63 19.05 165,775.89 117,363.00 48,412.89 1.1114 Country Club Corners Sixth Filing Critical Pond Elevations Design Engineer: Design Firm: Project Number: Date: DESIGN CRITERIA Urban Storm Drainage Criteria Manual, Urban Drainage and Flood Control District, June 2001 (Revised January 2016) Stage Storage Volume (pond volume calculated using the prismoidal formula): CONTOUR (FT) AREA (FT2) AREA (ACRE) VOLUME (ACRE-FT) DEPTH (FT) CUMULATIVE VOLUME (ACRE-FT) 4973.15 0 0.000 0.000 0.00 0.000 4974.0 3641 0.084 0.024 0.85 0.024 4975.0 15055 0.346 0.200 1.85 0.223 4976.0 29283 0.672 0.500 2.85 0.723 4977.0 34157 0.784 0.727 3.85 1.451 4978.0 37138 0.853 0.818 4.85 2.269 0.000 N/A ft 1.671 4977.27 ft J.Claeys Interwest Consulting Group 1303-158-00 Acre-Ft Interpolates to an Elev. of Required 100-yr Detention Volume (including WQCV) = January 25, 2017 Required Water Quality Capture Volume (WQCV) = Acre-Ft Interpolates to an Elev. of ( ) 3 AAAADepth 1 2 1 2 V + + = 1303-158-00 PondCalcs.xls - Pond Stage Storage Page 1 of 1 Interwest Consulting Group Bristlecone Ex 30" RCP Capacity Project: Inlet ID: Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb TBACK = 10.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb) SBACK = 0.020 ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020) nBACK = 0.020 Height of Curb at Gutter Flow Line HCURB = 6.00 inches Distance from Curb Face to Street Crown TCROWN = 20.0 ft Gutter Width W = 2.00 ft Street Transverse Slope SX = 0.020 ft/ft Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft) SW = 0.083 ft/ft Street Longitudinal Slope - Enter 0 for sump condition SO = 0.004 ft/ft Manning's Roughness for Street Section (typically between 0.012 and 0.020) nSTREET = 0.016 Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm TMAX = 18.5 20.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 6.0 12.0 inches Allow Flow Depth at Street Crown (leave blank for no) check = yes Maximum Capacity for 1/2 Street based On Allowable Spread Minor Storm Major Storm Water Depth without Gutter Depression (Eq. ST-2) y = 4.44 4.80 inches Vertical Depth between Gutter Lip and Gutter Flowline (usually 2") dC = 2.0 2.0 inches Gutter Depression (dC - (W * Sx * 12)) a = 1.51 1.51 inches Water Depth at Gutter Flowline d = 5.95 6.31 inches Allowable Spread for Discharge outside the Gutter Section W (T - W) TX = 16.5 18.0 ft Gutter Flow to Design Flow Ratio by FHWA HEC-22 method (Eq. ST-7) EO = 0.321 0.296 Discharge outside the Gutter Section W, carried in Section TX QX = 5.8 7.3 cfs Discharge within the Gutter Section W (QT - QX) QW = 2.7 3.1 cfs Discharge Behind the Curb (e.g., sidewalk, driveways, & lawns) QBACK = 0.0 0.0 cfs Maximum Flow Based On Allowable Spread QT = 8.5 10.3 cfs Flow Velocity within the Gutter Section V = 3.3 3.5 fps V*d Product: Flow Velocity times Gutter Flowline Depth V*d = 1.6 1.8 Maximum Capacity for 1/2 Street based on Allowable Depth Minor Storm Major Storm Theoretical Water Spread TTH = 18.7 43.7 ft Theoretical Spread for Discharge outside the Gutter Section W (T - W) TX TH = 16.7 41.7 ft Gutter Flow to Design Flow Ratio by FHWA HEC-22 method (Eq. ST-7) EO = 0.318 0.130 Theoretical Discharge outside the Gutter Section W, carried in Section TX TH QX TH = 5.9 68.2 cfs Actual Discharge outside the Gutter Section W, (limited by distance TCROWN) QX = 5.9 53.1 cfs Discharge within the Gutter Section W (Qd - QX) QW = 2.8 10.2 cfs Discharge Behind the Curb (e.g., sidewalk, driveways, & lawns) QBACK = 0.0 10.4 cfs Total Discharge for Major & Minor Storm (Pre-Safety Factor) Q = 8.7 73.7 cfs Average Flow Velocity Within the Gutter Section V = 3.3 5.6 fps V*d Product: Flow Velocity Times Gutter Flowline Depth V*d = 1.7 5.6 Slope-Based Depth Safety Reduction Factor for Major & Minor (d > 6") Storm R = 1.00 1.00 Max Flow Based on Allowable Depth (Safety Factor Applied) Qd = 8.7 73.7 cfs Resultant Flow Depth at Gutter Flowline (Safety Factor Applied) d = 6.00 12.00 inches Resultant Flow Depth at Street Crown (Safety Factor Applied) dCROWN = 0.00 5.69 inches MINOR STORM Allowable Capacity is based on Spread Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow = 8.5 73.7 cfs Version 4.04 Released November 2016 ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) Country Club Corners 6th Filing Bristlecone Capacity Minor storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management' Major storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management' UD-Inlet_v4.04.xlsm, Bristlecone Capacity 1/25/2017, 9:59 AM Full Street Capacity = 2(73.7) = 147.4 cfs Per Country Club Corners Filing 3, Full Street Capacity = 43.22 cfs With approximated 32.5 cfs (25 cfs orignially) available within 30" RCP, there is a total street+pipe capacity within Bristlecone of 179.9 cfs 150 1.60 18.70 168,336.00 121,410.00 46,926.00 1.0773 155 1.57 18.35 170,685.69 125,457.00 45,228.69 1.0383 160 1.54 18.00 172,824.96 129,504.00 43,320.96 0.9945 165 1.51 17.65 174,753.81 133,551.00 41,202.81 0.9459 170 1.48 17.30 176,472.24 137,598.00 38,874.24 0.8924 175 1.45 16.95 177,980.25 141,645.00 36,335.25 0.8341 180 1.42 16.60 179,277.84 145,692.00 33,585.84 0.7710 185 1.40 16.37 181,662.60 149,739.00 31,923.60 0.7329 190 1.38 16.13 183,907.08 153,786.00 30,121.08 0.6915 195 1.36 15.90 186,011.28 157,833.00 28,178.28 0.6469 200 1.34 15.66 187,975.20 161,880.00 26,095.20 0.5991 205 1.32 15.43 189,798.84 165,927.00 23,871.84 0.5480 210 1.30 15.20 191,482.20 169,974.00 21,508.20 0.4938 215 1.28 14.96 193,025.28 174,021.00 19,004.28 0.4363 220 1.26 14.73 194,428.08 178,068.00 16,360.08 0.3756 225 1.24 14.50 195,690.60 182,115.00 13,575.60 0.3117 230 1.22 14.26 196,812.84 186,162.00 10,650.84 0.2445 235 1.21 14.14 199,443.09 190,209.00 9,234.09 0.2120 240 1.20 14.03 202,003.20 194,256.00 7,747.20 0.1779 Adjusted Runoff Coefficient (CC f ) Area (A ) Allowed Release Rate Required Detention Urban Storm Drainage Criteria Manual, Urban Drainage and Flood Control District, June 2001 (Revised April 2008) City of Fort Collins - Storm Water Criteria Manual January 25, 2017 Runoff Coefficient (C ) Frequency Factor (C f ) 100-yr Detention Volume - FAA Method Country Club Corners Sizth Filing J.Claeys Interwest Consulting 1308-158-00 Interim Detention Pond INITIAL/OVERLAND TIME (ti) DESIGN POINT Sub-basin C5 ( ) 0 .33 0 . 395 1 . 1 5 S C L ti − = t c = t i + t t 0 . 5 V = C v S w V L tt 60 = �� = 18 − 15� + � 60 24� + 12 � Alawn (sq feet) of the version date(s) listed below. Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 11, Sep 23, 2016 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Apr 22, 2011—Apr 28, 2011 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Hydrologic Soil Group—Larimer County Area, Colorado (Country Club Corners Sixth Filing - Lot 1) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/19/2017 Page 2 of 4