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Home My WebLink AboutPEDERSEN TOYOTA EXPANSION - PDP - PDP140007 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTJune 4, 2014 Mr. Wes Lamarque Fort Collins Utilities – Stormwater 700 Wood Street Fort Collins, CO 80522 Re: Pedersen Toyota – Preliminary Storm Drainage Report Dear Wes, Please accept the following letter report on behalf of the Heath Construction and Pedersen Toyota for the Pedersen Toyota expansion and site redevelopment to demonstrate the site’s ability to comply with the City’s stormwater requirements. INTRODUCTION The project site will consist of the existing Pedersen Toyota showroom and sales office located at the northwest corner of S. College Avenue and Kensington Drive and the Mini-U-Storage site located at the northeast corner of S. Mason Street and Kensington Drive. These two existing sites are bound by S. Mason Street to the west, Kensington Drive to the south, S. College Avenue to the east, and the existing Target retail store to the north. The proposed project will consist of demolition of the Mini- U-Storage improvements and limited redevelopment of the Pedersen Toyota site to expand the existing Toyota showroom and service center, and ultimately construct a parking garage for vehicle inventory with vehicle detailing and retail shops. Potential phasing of the parking garage is being considered but is not anticipated to affect the drainage design. EXISTING CONDITIONS Both the existing Mini-U-Storage and Pedersen Toyota site have existing stormwater management infrastructure onsite controlling the stormwater release rates. The Mini-U-Storage site utilizes a combination of detention ponds and parking lot surface ponding as runoff storage with an orifice plate installed within an inlet to control the release rate. The Mini-U- Storage site was designed with a release rate of 0.88 cfs and a detention volume of 20,200 cu-ft (0.46 ac-ft). The drainage outfall for the site is the existing 18” storm drain located north of the site. The existing site is currently 82% impervious. The existing Pedersen Toyota site utilizes parking lot surface ponding as runoff storage with an orifice plate installed within an inlet to control the release rate. The Pedersen Toyota site was designed with a release rate of 1.38 cfs and a required detention volume of 20,866 cu-ft (0.48 ac-ft). The drainage outfall for the site is the existing 36” storm drain located east of the site along S. College Avenue. The existing site is currently 87% impervious. Pedersen Toyota – Preliminary Storm Drainage Report June 4, 2014 Page 2 of 4 The historical release rates, stated above, are referenced for the stormwater release rates for the proposed improvements. All calculations and exhibits are attached, including the previous grading & drainage plans for the Mini-U-Storage and Pedersen Toyota sites. PROPOSED DEVELOPMENT The project proposes to redevelop the existing Mini-U-Storage site and redevelop limited areas of the Pedersen Toyota site to expand the showroom and service center and ultimately construct a parking garage, with vehicle detailing and retail shops, to provide additional vehicle inventory storage. The two properties will be replatted into one lot. The detention and water quality requirements will be provided through the use of a detention pond in the northwest corner of the site and a permeable paving area within the northeast parking lot. The northwest detention and water quality pond is proposed to be designed as an extended detention basin per City of Fort Collins and Urban Drainage standards. All of the developed Basin D1 will drain to this pond and will consist of the parking garage upper deck drainage, vehicle detailing and retail shop roof drainage, and parking/access drainage. The pond is designed with a release rate equal to the existing Mini-U-Storage release rate, 0.88 cfs, and utilizes the existing 18” storm drain as the site’s drainage outfall. The developed percent impervious is 76% for Basin D1, which is a reduction compared to the existing percent impervious. Basin D1 requires 0.32 acre-ft of storage for detention and water quality. The north side of the existing Pedersen Toyota site is going to be improved to accommodate the expanded service center. The service center footprint absorbs some of the existing parking lot detention area and requires the storm infrastructure to be adjusted. The existing parking lot detention depth is 18” and the proposed improvements will reduce this ponding depth to be 12” during a 100-yr storm event, to meet current standards. To be able to achieve the required detention volume, along with the new rainfall data and the existing release rate, the necessary storage for Basin D2 will be provided within the drainage course of the permeable paver section. Along with the detention volume, the permeable pavers will also provide water quality enhancement and proposed to satisfy the Low Impact Development (LID) techniques for this redevelopment site. The developed percent impervious is 80%, which is a reduction in compared to the existing percent impervious. Basin D2 requires 0.53 acre-ft of detention storage which will be achieved with 0.07 acre-ft of parking lot surface storage and the remaining within the paver section. The Midtown Plan requires improvements for the S. Mason Street, Kensington Drive, and S. College Avenue with dedication of additional right-of-way and detached sidewalks. This dedication increased the areas draining to the respected streets. Though the basin areas increased, there was a reduction in the percent impervious due to the inclusion of a landscaped parkway associated with the detached sidewalk along S. Mason Street and Kensington Drive. The basin area increased slightly along S. College Avenue, and since a wider sidewalk is required, the percent impervious did increase. Historically, the runoff associated with the adjacent right-of-ways drain to street inlets within S. Mason Street and S. College Avenue. An analysis was completed to review the impacts of the required dedication of right-of-way. Slight increases in runoff are anticipated and due to the limited Pedersen Toyota – Preliminary Storm Drainage Report June 4, 2014 Page 3 of 4 change in runoff rates, improvements or adjustments to the existing right-of-way storm drain infrastructure is not anticipated. During a 100-yr storm event, S. Mason Street has an increase of 0.28 cfs, which drains to the inlet on the east side of Mason, just north of the existing Mini-U-Storage site. Basin D4, associated with Kensington Drive, and Basin D5, associated with S. College Avenue, drain to the existing inlet on S. College Avenue (Design Point D5), just east of the existing Pedersen Toyota showroom. In reference to the attenuated flows from Basin D4 and D5, draining to Design Point D5, there is an increase of 0.22 cfs. This is 3% increase in the 100-yr storm runoff rate and is considered negligible. The current onsite drainage infrastructure was designed referencing the pre-1997 rainfall data and the proposed improvements associated with the redevelopment of the Mini-U-Storage and Pedersen Toyota site will improve the performance of the site drainage, including incorporation of the new rainfall data, and should satisfy the City’s storm drainage criteria. 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, we have looked at many options, along with the site redevelopment constraints, to satisfy these requirements. The proposed extended detention basin (EDB), which is considered “somewhat” of a LID technique per Urban Drainage, located in the northwest corner of the site and the permeable pavers located within the northeast parking area will detain and treat all of Basins D1 & D2. To achieve the required detention volumes and release rates for Basin D1, an EDB is able satisfied those requirements while providing water quality enhancement. Underdrains, clean-outs, and a Standard Operations Plan will be provided at final design to assist in ensuring that these BMPs will adequately perform over time. EROSION CONTROL Erosion and sedimentation will be controlled on-site by use of silt fences, culvert inlet protection, a gravel construction entrance, and seeding and mulch. 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. Pedersen Toyota – Preliminary Storm Drainage Report June 4, 2014 Page 4 of 4 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 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) 674-3300 extension 8917. Sincerely, Jason T. Claeys, P.E., LEED AP Interwest Consulting Group Attachments Site Descriptions, Characteristics & References Hydrologic Soil Group—Larimer County Area, Colorado (Pedersen Toyota) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 3/27/2014 Page 1 of 4 4486030 4486050 4486070 4486090 4486110 4486130 4486150 4486170 4486190 4486030 4486050 4486070 4486090 4486110 4486130 4486150 4486170 4486190 493240 493260 493280 493300 493320 493340 493360 493380 493400 493420 493440 493460 493480 493240 493260 493280 493300 493320 493340 493360 493380 493400 493420 493440 493460 493480 40° 31' 35'' N 105° 4' 47'' W 40° 31' 35'' N 105° 4' 36'' W 40° 31' 29'' N 105° 4' 47'' W 40° 31' 29'' N 105° 4' 36'' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 50 100 200 300 Feet 0 15 30 60 90 Meters Map Scale: 1:1,210 if printed on A landscape (11" x 8.5") sheet. 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: http://websoilsurvey.nrcs.usda.gov 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 of the version date(s) listed below. Soil Survey Area: Larimer County Area, Colorado 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 3 Altvan-Satanta loams, 0 to 3 percent slopes B 1.1 18.7% 4 Altvan-Satanta loams, 3 to 9 percent slopes B 3.8 62.9% 74 Nunn clay loam, 1 to 3 percent slopes C 1.1 18.4% Totals for Area of Interest 6.1 100.0% 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. Hydrologic Soil Group—Larimer County Area, Colorado Pedersen Toyota Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 3/27/2014 Page 3 of 4 Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Hydrologic Soil Group—Larimer County Area, Colorado Pedersen Toyota Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 3/27/2014 Page 4 of 4 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 Intensity (in/hr) City of Fort Collins Rainfall Intensity-Duration-Frequency Curve 2-yr (FTC) 10-yr (FTC) 100-yr (FTC) 2-yr (UD) 10-yr (UD) 100-yr (UD) 100-yr 10-yr 0.0 1.0 2.0 3.0 4.0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 65.0 Duration (min) 2-yr 10-yr Duration (minutes) 2-yr Intensity (in/hr) 10-yr Intensity (in/hr) 100-yr Intensity (in/hr) Duration (minutes) 2-yr Intensity (in/hr) 10-yr Intensity (in/hr) 100-yr Intensity (in/hr) 5 2.85 4.87 9.95 33 1.22 2.08 4.24 6 2.67 4.56 9.31 34 1.19 2.04 4.16 7 2.52 4.31 8.80 35 1.17 2.00 4.08 8 2.40 4.10 8.38 36 1.15 1.96 4.01 9 2.30 3.93 8.03 37 1.13 1.93 3.93 10 2.21 3.78 7.72 38 1.11 1.89 3.87 11 2.13 3.63 7.42 39 1.09 1.86 3.80 12 2.05 3.50 7.16 40 1.07 1.83 3.74 13 1.98 3.39 6.92 41 1.05 1.80 3.68 14 1.92 3.29 6.71 42 1.04 1.77 3.62 15 1.87 3.19 6.52 43 1.02 1.74 3.56 16 1.81 3.08 6.30 44 1.01 1.72 3.51 17 1.75 2.99 6.10 45 0.99 1.69 3.46 18 1.70 2.90 5.92 46 0.98 1.67 3.41 19 1.65 2.82 5.75 47 0.96 1.64 3.36 20 1.61 2.74 5.60 48 0.95 1.62 3.31 21 1.56 2.67 5.46 49 0.94 1.60 3.27 22 1.53 2.61 5.32 50 0.92 1.58 3.23 23 1.49 2.55 5.20 51 0.91 1.56 3.18 24 1.46 2.49 5.09 52 0.90 1.54 3.14 25 1.43 2.44 4.98 53 0.89 1.52 3.10 26 1.40 2.39 4.87 54 0.88 1.50 3.07 27 1.37 2.34 4.78 55 0.87 1.48 3.03 28 1.34 2.29 4.69 56 0.86 1.47 2.99 29 1.32 2.25 4.60 57 0.85 1.45 2.96 30 1.30 2.21 4.52 58 0.84 1.43 2.92 31 1.27 2.16 4.42 59 0.83 1.42 2.89 32 1.24 2.12 4.33 60 0.82 1.40 2.86 Figure 3-1a City of Fort Collins Rainfall Intensity-Duration-Frequency Table for using the Rational Method Duration 2-yr 10-yr 100-yr 2-yr ∆∆∆∆ 10-yr ∆∆∆∆ 100-yr ∆∆∆∆ 5 2.85 4.87 9.95 2.78 -0.07 4.74 -0.13 9.68 -0.27 6 2.67 4.56 9.31 2.64 -0.03 4.51 -0.05 9.20 -0.11 7 2.52 4.31 8.80 2.52 0.00 4.30 -0.01 8.78 -0.02 8 2.40 4.10 8.38 2.41 0.01 4.11 0.01 8.39 0.01 9 2.30 3.93 8.03 2.31 0.01 3.94 0.01 8.04 0.01 10 2.21 3.78 7.72 2.21 0.00 3.78 0.00 7.72 0.00 11 2.13 3.63 7.42 2.13 0.00 3.64 0.01 7.43 0.01 2-yr 0.82 12 2.05 3.50 7.16 2.05 0.00 3.51 0.01 7.16 0.00 10-yr 1.40 13 1.98 3.39 6.92 1.98 0.00 3.39 0.00 6.92 0.00 100-yr 2.86 14 1.92 3.29 6.71 1.92 0.00 3.28 -0.01 6.69 -0.02 15 1.87 3.19 6.52 1.86 -0.01 3.17 -0.02 6.48 -0.04 16 1.81 3.08 6.30 1.80 -0.01 3.08 0.00 6.28 -0.02 C 1 28.5 17 1.75 2.99 6.10 1.75 0.00 2.99 0.00 6.10 0.00 C 2 10 18 1.70 2.90 5.92 1.70 0.00 2.90 0.00 5.93 0.01 C 3 0.786651 19 1.65 2.82 5.75 1.65 0.00 2.82 0.00 5.77 0.02 20 1.61 2.74 5.60 1.61 0.00 2.75 0.01 5.61 0.01 21 1.56 2.67 5.46 1.57 0.01 2.68 0.01 5.47 0.01 22 1.53 2.61 5.32 1.53 0.00 2.61 0.00 5.34 0.02 23 1.49 2.55 5.20 1.49 0.00 2.55 0.00 5.21 0.01 24 1.46 2.49 5.09 1.46 0.00 2.49 0.00 5.09 0.00 25 1.43 2.44 4.98 1.43 0.00 2.43 -0.01 4.97 -0.01 26 1.40 2.39 4.87 1.39 -0.01 2.38 -0.01 4.86 -0.01 27 1.37 2.34 4.78 1.36 -0.01 2.33 -0.01 4.76 -0.02 28 1.34 2.29 4.69 1.34 0.00 2.28 -0.01 4.66 -0.03 29 1.32 2.25 4.60 1.31 -0.01 2.24 -0.01 4.57 -0.03 30 1.30 2.21 4.52 1.28 -0.02 2.19 -0.02 4.48 -0.04 31 1.27 2.16 4.42 1.26 -0.01 2.15 -0.01 4.39 -0.03 32 1.24 2.12 4.33 1.24 0.00 2.11 -0.01 4.31 -0.02 33 1.22 2.08 4.24 1.21 -0.01 2.07 -0.01 4.23 -0.01 34 1.19 2.04 4.16 1.19 0.00 2.03 -0.01 4.15 -0.01 Coefficients Intensity (in/hr) Urban Drainage Intensity (in/hr) City of Fort Collins Urban Drainage Inputs Urban Drainage Intensity Equation 1-hr Rainfall Depths (P 1 ) City of Fort Collins Rainfall Intensity-Duration-Frequency Table Use of Urban Drainage Intensity Equation for CoFC IDF Values This cell was determined using Solver to best match intensities given from the Fort Collins IDF values. C 3 2 1 1 ( c ) C t C P I + = 34 1.19 2.04 4.16 1.19 0.00 2.03 -0.01 4.15 -0.01 35 1.17 2.00 4.08 1.17 0.00 2.00 0.00 4.08 0.00 36 1.15 1.96 4.01 1.15 0.00 1.96 0.00 4.01 0.00 37 1.13 1.93 3.93 1.13 0.00 1.93 0.00 3.94 0.01 2-year 5-yr 10-yr 25-yr 50-yr 100-yr 5 0.29 0.40 0.49 0.63 0.79 1.00 10 0.33 0.45 0.56 0.72 0.90 1.14 15 0.38 0.53 0.65 0.84 1.05 1.33 20 0.64 0.89 1.09 1.41 1.77 2.23 25 0.81 1.13 1.39 1.80 2.25 2.84 30 1.57 2.19 2.69 3.48 4.36 5.49 35 2.85 3.97 4.87 6.30 7.90 9.95 40 1.18 1.64 2.02 2.61 3.27 4.12 45 0.71 0.99 1.21 1.57 1.97 2.48 50 0.42 0.58 0.71 0.92 1.16 1.46 55 0.35 0.49 0.60 0.77 0.97 1.22 60 0.30 0.42 0.52 0.67 0.84 1.06 65 0.20 0.28 0.39 0.62 0.79 1.00 70 0.19 0.27 0.37 0.59 0.75 0.95 75 0.18 0.25 0.35 0.56 0.72 0.91 80 0.17 0.24 0.34 0.54 0.69 0.87 85 0.17 0.23 0.32 0.52 0.66 0.84 90 0.16 0.22 0.31 0.50 0.64 0.81 95 0.15 0.21 0.30 0.48 0.62 0.78 100 0.15 0.20 0.29 0.47 0.60 0.75 105 0.14 0.19 0.28 0.45 0.58 0.73 110 0.14 0.19 0.27 0.44 0.56 0.71 115 0.13 0.18 0.26 0.42 0.54 0.69 120 0.13 0.18 0.25 0.41 0.53 0.67 City of Fort Collins Design Storms for using SWMM Figure 3-1c Time (min) Intensity (in/hr) These are the 1-hour storm 2-year 5-yr 10-yr 25-yr 50-yr 100-yr 1-hr 0.82 1.14 1.40 1.81 2.27 2.86 2-hr 0.98 1.36 1.71 2.31 2.91 3.67 Storm Duration Rainfall Depth (in) Note: The City of Fort Collins SWWM input hyetopgrah is used to calculate the 1-hr and 2-hr storm rainfall depths for the different storm events. These are the 1-hour storm depths that are used in the Urban Drainage intensity equation, derived from the CoFC Hyetograph. Historic & Developed Rational Calculations Pedersen Toyota DRAINAGE SUMMARY Design Engineer: Design Firm: Project Number: Date: IMPERVIOUS SUMMARY: Description % Impervious Existing 81.8% Proposed 72.3% Difference -9.4% DRAINAGE SUMMARY: Area (acres) % Imprevious 100-yr Peak Runoff (cfs) Area (acres) % Imprevious 100-yr Peak Runoff (cfs) H1/D1 2.08 82.3% 11.23 1.66 75.7% 9.22 -2.02 Ex Mini-U-Storage H2/D2 2.68 87.2% 16.06 2.93 79.7% 16.70 0.63 Ex Pedersen Toyota H3/D3 0.34 92.8% 2.33 0.54 58.4% 2.61 0.28 S. Mason Street H4/D4 0.33 83.5% 2.25 0.42 72.4% 2.67 0.42 Kensington Drive H5/D5 0.83 74.6% 4.91 0.84 77.1% 4.98 0.07 S. College Avenue H6/D6 0.18 39.8% 0.81 0.04 0.0% 0.16 -0.64 North Offiste Totals 6.44 81.8% 37.60 6.44 72.3% 36.34 -1.26 H4&H5/D4&D5 1.16 77.1% 7.10 1.27 75.5% 7.32 0.22 College & Kensington Basins Notes Historical Proposed Hist vs. Dev Peak Runoff Difference J.Claeys Interwest Consulting Group 1180-027-00 May 28, 2014 SOUTH COLLEGE AVENUE (HWY 287) KENSINGTON DRIVE SOUTH MASON STREET PREPARED FOR PROJ. NO. DATE: SCALE (H): SCALE (V): CHECKED BY: DESIGNED BY: PROJECT NAME PEDERSEN TOYOTA EXISTING DRAINAGE EXHIBIT 05/28/14 1"=60' N/A JTC RA 1180-027-00 1 of 2 SCALE 1" = 0 60' 30 60 LEGEND BASIN LABEL DESIGN POINT BASIN BOUNDARY FLOW PATH Pedersen Toyota HISTORIC 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 April 2008) BASINS: C2 C5 C10 C100 C2 C5 C10 C100 0.89 0.90 0.92 0.96 0.89 0.90 0.92 0.96 0.71 0.73 0.75 0.81 0.73 0.75 0.77 0.83 0.71 0.73 0.75 0.81 0.73 0.75 0.77 0.83 0.23 0.30 0.36 0.50 0.28 0.35 0.42 0.58 0.02 0.08 0.15 0.35 0.04 0.15 0.25 0.50 C2 C5 C10 C100 H1 C 90,711 2.08 37,981 40,789 0 0 11,941 82.3% 0.62 0.65 0.69 0.76 H2 C 116,796 2.68 79,480 24,481 422 0 12,414 87.2% 0.69 0.71 0.74 0.81 H3 C 14,677 0.34 13,626 0 0 0 1,051 92.8% 0.77 0.78 0.81 0.87 H4 C 14,428 0.33 12,054 0 0 0 2,374 83.5% 0.64 0.66 0.70 0.77 H5 C 36,307 0.83 24,523 0 2,836 0 8,948 74.6% 0.54 0.57 0.61 0.71 H6 C 7,818 0.18 0 3,457 0 0 4,361 39.8% 0.28 0.35 0.42 0.58 Total - 280,737 6.44 167,664 68,726 3,257 0 41,089 81.8% 0.62 0.64 0.68 0.76 H4 & H5 C 50,735 1.16 36,577 0 2,836 0 11,322 77.1% 0.56 0.60 0.63 0.72 Pavers 40% J.Claeys Interwest Consulting Group 1180-027-00 May 28, 2014 % Impervious values from Table RO-3 in the Urban Storm Drainage Criteria Manual for Hydrologic Soil Classifications Land Use % Impervious Hydrologic Soil Classification B Runoff Coefficient Hydrologic Soil Classification C Runoff Coefficient Roof 90% Walk 90% Paved 100% Lawns, clayey soil 0% Sub-basin Designation Soil Type Atotal (sq feet) Atotal (acres) Apaved (sq feet) Aroof (sq feet) Awalk (sq feet) Apavers (sq feet) Alawn (sq feet) Weighted % Pedersen Toyota HISTORIC TIME OF CONCENTRATION Design Engineer: Design Firm: Project Number: Date: DESIGN CRITERIA: Urban Storm Drainage Criteria Manual by Urban Drainage and Flood Control District, June 2001 (Revised April 2008) EQUATIONS: -Equation RO-3 -Equation RO-4 -Urbanized Check Equation RO-5 -Equation RO-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 tc = 5 min for urbanized basins BASINS: Type of Travel Surface Cv H1 H1 0.65 2.08 120 0.0288 6.35 477 0.0044 Paved Areas 20 1.33 6.00 12.34 13.32 12.34 H2 H2 0.71 2.68 176 0.0203 7.50 391 0.0086 Paved Areas 20 1.86 3.51 11.01 13.15 11.01 H3 H3 0.78 0.34 49 0.0170 3.40 451 0.0042 Paved Areas 20 1.29 5.81 9.21 12.78 9.21 H4 H4 0.66 0.33 49 0.0251 4.11 427 0.0158 Paved Areas 20 2.52 2.83 6.94 12.64 6.94 H5 H5 0.57 0.83 44 0.0225 4.92 295 0.0061 Paved Areas 20 1.56 3.15 8.08 11.89 8.08 H6 H6 0.35 0.18 137 0.0446 9.80 47 0.0268 Paved Areas 20 3.27 0.24 10.04 11.02 10.04 H5 H4 & H5 0.60 1.16 44 0.0225 4.70 295 0.0061 Paved Areas 20 1.56 3.15 7.85 11.89 7.85 REMARKS tc Urban Check Final tc (min) tc=ti+tt SLOPE (min) (ft/ft) VEL. (ft/s) tt (min) SLOPE (ft/ft) ti (min) LENGTH Table RO-2 (ft) TRAVEL TIME (tt) DESIGN POINT Sub-basin C5 AREA (acres) LENGTH (ft) SUB-BASIN DATA INITIAL/OVERLAND TIME (ti) J.Claeys Interwest Consulting Group 1180-027-00 May 28, 2014 ( ) 0 .33 Pedersen Toyota HISTORIC PEAK RUNOFF Design Engineer: Design Firm: Project Number: Date: DESIGN CRITERIA: Urban Storm Drainage Criteria Manual by Urban Drainage and Flood Control District, June 2001 (Revised April 2008) EQUATIONS: Q n = n-yr peak discharge (cfs) I = rainfall intensity (in/hr) C n = n -yr runoff coefficient P 1 = one-hour point rainfall depth (in) I n = n -yr rainfall intensity (in/hr) t c = time of concentration (min) A n = Basin drainage area (ac) P 1-2yr = 0.82 in P 1-5yr = 1.14 in P 1-10yr = 1.40 in P 1-100yr = 2.86 in BASINS: Runoff Coeff. (C2) C(A) (acres) Intensity (in/hr) Q (ft3/s) 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) H1 H1 2.08 12.34 0.62 1.30 2.03 2.63 0.65 1.36 2.82 3.82 0.69 1.43 3.46 4.94 0.76 1.59 7.08 11.23 H2 H2 2.68 11.01 0.69 1.84 2.13 3.92 0.71 1.90 2.96 5.63 0.74 1.98 3.64 7.21 0.81 2.16 7.43 16.06 H3 H3 0.34 9.21 0.77 0.26 2.29 0.59 0.78 0.26 3.18 0.84 0.81 0.27 3.90 1.07 0.87 0.29 7.97 2.33 H4 H4 0.33 6.94 0.64 0.21 2.52 0.53 0.66 0.22 3.51 0.77 0.70 0.23 4.31 1.00 0.77 0.26 8.80 2.25 H5 H5 0.83 8.08 0.54 0.45 2.40 1.07 0.57 0.48 3.33 1.59 0.61 0.51 4.09 2.09 0.71 0.59 8.36 4.91 H6 H6 0.18 10.04 0.28 0.05 2.21 0.11 0.35 0.06 3.07 0.19 0.42 0.07 3.77 0.28 0.58 0.10 7.71 0.81 Total 6.44 8.86 12.85 16.59 37.60 H5 H4 & H5 1.16 7.85 0.56 0.66 2.42 1.59 0.60 0.69 3.37 2.34 0.63 0.74 4.13 3.05 0.72 0.84 8.45 7.10 5-yr Peak Runoff 100-yr Peak Runoff J.Claeys Interwest Consulting Group 1180-027-00 May 28, 2014 Design Point SOUTH COLLEGE AVENUE (HWY 287) KENSINGTON DRIVE SOUTH MASON STREET PREPARED FOR PROJ. NO. DATE: SCALE (H): SCALE (V): CHECKED BY: DESIGNED BY: PROJECT NAME PEDERSEN TOYOTA PROPOSED DRAINAGE EXHIBIT 05/28/14 1"=60' N/A JTC RA 1180-027-00 2 of 2 SCALE 1" = 0 60' 30 60 LEGEND BASIN LABEL DESIGN POINT BASIN BOUNDARY FLOW PATH Pedersen Toyota 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 April 2008) BASINS: C2 C5 C10 C100 C2 C5 C10 C100 0.89 0.90 0.92 0.96 0.89 0.90 0.92 0.96 0.71 0.73 0.75 0.81 0.73 0.75 0.77 0.83 0.71 0.73 0.75 0.81 0.73 0.75 0.77 0.83 0.23 0.30 0.36 0.50 0.28 0.35 0.42 0.58 0.02 0.08 0.15 0.35 0.04 0.15 0.25 0.50 C2 C5 C10 C100 D1 C 72,461 1.66 11,744 47,266 634 0 12,817 75.7% 0.55 0.58 0.62 0.71 D2 C 127,738 2.93 61,837 37,158 953 14,053 13,737 79.7% 0.59 0.62 0.66 0.74 D3 C 23,708 0.54 11,498 0 2,613 0 9,596 58.4% 0.39 0.45 0.50 0.63 D4 C 18,447 0.42 11,677 0 1,857 0 4,913 72.4% 0.51 0.55 0.59 0.69 D5 C 36,762 0.84 24,628 0 4,114 0 8,020 77.1% 0.56 0.60 0.63 0.72 D6 C 1,604 0.04 0 0 0 0 1,604 0.0% 0.04 0.15 0.25 0.50 Total - 280,720 6.44 121,384 84,425 10,172 14,053 50,686 72.3% 0.51 0.55 0.59 0.69 D4 & D5 C 55,209 1.27 36,305 0 5,971 0 12,933 75.5% 0.55 0.58 0.62 0.71 J.Claeys Interwest Consulting Group 1180-027-00 May 28, 2014 % Impervious values from Table RO-3 in the Urban Storm Drainage Criteria Manual for Hydrologic Soil Classifications Sub-basin Designation Apaved (sq feet) Atotal (acres) Atotal (sq feet) Soil Type Land Use % Impervious Hydrologic Soil Classification B Runoff Coefficient Hydrologic Soil Classification C Runoff Coefficient Paved 100% Roof 90% COMPOSITE Weighted % Impervious Alawn (sq feet) Apavers (sq feet) Lawns, clayey soil Awalk (sq feet) Aroof (sq feet) Pedersen Toyota DEVELOPED TIME OF CONCENTRATION Design Engineer: Design Firm: Project Number: Date: DESIGN CRITERIA: Urban Storm Drainage Criteria Manual by Urban Drainage and Flood Control District, June 2001 (Revised April 2008) EQUATIONS: -Equation RO-3 -Equation RO-4 -Urbanized Check Equation RO-5 -Equation RO-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 tc = 5 min for urbanized basins BASINS: Type of Travel Surface Cv D1 D1 0.58 1.66 50 0.0100 6.72 456 0.0150 Paved Areas 20 2.45 3.10 9.82 12.81 9.82 D2 D2 0.62 2.93 153 0.0432 6.65 418 0.0101 Paved Areas 20 2.01 3.47 10.12 13.17 10.12 D3 D3 0.45 0.54 45 0.0323 5.46 422 0.0053 Paved Areas 20 1.46 4.83 10.29 12.60 10.29 D4 D4 0.55 0.42 34 0.0474 3.49 408 0.0162 Paved Areas 20 2.55 2.67 6.16 12.46 6.16 D5 D5 0.60 0.84 37 0.0146 4.96 301 0.0048 Paved Areas 20 1.38 3.64 8.59 11.88 8.59 D6 D6 0.15 0.04 53 0.0638 6.86 52 0.0352 Paved Areas 20 3.75 0.23 7.09 10.58 7.09 D5 D4 & D5 0.58 1.27 37 0.0146 5.11 301 0.0048 Paved Areas 20 1.38 3.64 8.74 11.88 8.74 J.Claeys Interwest Consulting Group 1180-027-00 May 28, 2014 SLOPE (ft/ft) ti (min) LENGTH Table RO-2 (ft) SUB-BASIN DATA INITIAL/OVERLAND TIME (ti) DESIGN POINT Sub-basin C5 AREA (acres) LENGTH (ft) TRAVEL TIME (tt) REMARKS tc Urban Check Final tc (min) tc=ti+tt SLOPE (min) (ft/ft) VEL. (ft/s) tt (min) ( ) 0 .33 Pedersen Toyota DEVELOPED PEAK RUNOFF Design Engineer: Design Firm: Project Number: Date: DESIGN CRITERIA: Urban Storm Drainage Criteria Manual by Urban Drainage and Flood Control District, June 2001 (Revised April 2008) EQUATIONS: Q n = n-yr peak discharge (cfs) I = rainfall intensity (in/hr) C n = n -yr runoff coefficient P 1 = one-hour point rainfall depth (in) I n = n -yr rainfall intensity (in/hr) t c = time of concentration (min) A n = Basin drainage area (ac) P 1-2yr = 0.82 in P 1-5yr = 1.14 in P 1-10yr = 1.40 in P 1-100yr = 2.86 in BASINS: Runoff Coeff. (C2) C(A) (acres) Intensity (in/hr) Q (ft3/s) 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) D1 D1 1.66 9.82 0.55 0.91 2.23 2.03 0.58 0.97 3.10 3.00 0.62 1.03 3.81 3.94 0.71 1.19 7.78 9.22 D2 D2 2.93 10.12 0.59 1.73 2.20 3.82 0.62 1.82 3.06 5.59 0.66 1.93 3.76 7.26 0.74 2.17 7.69 16.70 D3 D3 0.54 10.29 0.39 0.21 2.19 0.47 0.45 0.24 3.04 0.74 0.50 0.27 3.74 1.02 0.63 0.34 7.64 2.61 D4 D4 0.42 6.16 0.51 0.22 2.62 0.57 0.55 0.23 3.64 0.85 0.59 0.25 4.47 1.12 0.69 0.29 9.13 2.67 D5 D5 0.84 8.59 0.56 0.47 2.34 1.11 0.60 0.50 3.26 1.64 0.63 0.53 4.00 2.14 0.72 0.61 8.18 4.98 D6 D6 0.04 7.09 0.04 0.00 2.51 0.00 0.15 0.01 3.48 0.02 0.25 0.01 4.28 0.04 0.50 0.02 8.74 0.16 Total 6.44 8.01 11.83 15.52 36.34 D5 D4 & D5 1.27 8.74 0.55 0.69 2.33 1.61 0.58 0.74 3.24 2.38 0.62 0.79 3.98 3.12 0.71 0.90 8.13 7.32 100-yr Peak Runoff J.Claeys Interwest Consulting Group 1180-027-00 May 28, 2014 10-yr Peak Runoff Design Detention Calculations Pedersen Toyota Pond Summary (Basin D1) Design Engineer: Design Firm: Project Number: Date: Pond Summary Table 0.05 5030.04 16.74 4 3/16 0.88 0.32 5033.02 J.Claeys Interwest Consulting Group 2598.1 May 28, 2014 100-yr Detention Volume (acre-ft) 100-yr Water Surface Elev. (ft) Detention Pond Summary Table Water Quality Capture Volume (acre-ft) WQCV Water Surface Elev. (ft) 100-yr Pond Max Inflow (cfs) 100-yr Site Release Rate (cfs) Outlet Orifice Size (in) 1180-027-00 PondCalcs.xls - Pond Summary Page 1 of 4 Interwest Consulting Group Project: Basin ID: Design Information (Input): Design Information (Input): Catchment Drainage Imperviousness Ia = 75.70 percent Catchment Drainage Imperviousness I a = 75.70 percent Catchment Drainage Area A = 1.660 acres Catchment Drainage Area A = 1.660 acres Predevelopment NRCS Soil Group Type = C A, B, C, or D Predevelopment NRCS Soil Group Type = C A, B, C, or D Return Period for Detention Control T = 2 years (2, 5, 10, 25, 50, or 100) Return Period for Detention Control T = 100 years (2, 5, 10, 25, 50, or 100) Time of Concentration of Watershed Tc = 10 minutes Time of Concentration of Watershed Tc = 10 minutes Allowable Unit Release Rate q = 0.53 cfs/acre Allowable Unit Release Rate q = 0.53 cfs/acre One-hour Precipitation P1 = 0.82 inches One-hour Precipitation P 1 = 2.86 inches Design Rainfall IDF Formula i = C1* P 1/(C2 +Tc)^C 3 Design Rainfall IDF Formula i = C1 * P1/(C 2+Tc )^C3 Coefficient One C1 = 28.50 Coefficient One C 1 = 28.50 Coefficient Two C2 = 10 Coefficient Two C 2 = 10 Coefficient Three C3 = 0.787 Coefficient Three C 3 = 0.787 Determination of Average Outflow from the Basin (Calculated): Determination of Average Outflow from the Basin (Calculated): Runoff Coefficient C = 0.55 Runoff Coefficient C = 0.71 Inflow Peak Runoff Qp-in = 2.04 cfs Inflow Peak Runoff Qp-in = 9.17 cfs Allowable Peak Outflow Rate Qp-out = 0.88 cfs Allowable Peak Outflow Rate Qp-out = 0.88 cfs Mod. FAA Minor Storage Volume = 1,060 cubic feet Mod. FAA Major Storage Volume = 11,743 cubic feet Mod. FAA Minor Storage Volume = 0.024 acre-ft Mod. FAA Major Storage Volume = 0.270 acre-ft 15 <- Enter Rainfall Duration Incremental Increase Value Here (e.g. 5 for 5-Minutes) Rainfall Rainfall Inflow Adjustment Average Outflow Storage Rainfall Rainfall Inflow Adjustment Average Outflow Storage Duration Intensity Volume Factor Outflow Volume Volume Duration Intensity Volume Factor Outflow Volume Volume minutes inches / hr acre-feet "m" cfs acre-feet acre-feet minutes inches / hr acre-feet "m" cfs acre-feet acre-feet (input) (output) (output) (output) (output) (output) (output) (input) (output) (output) (output) (output) (output) (output) 5 2.78 0.017 1.00 0.88 0.006 0.011 5 9.68 0.079 1.00 0.88 0.006 0.073 20 1.61 0.040 0.75 0.66 0.018 0.022 20 5.61 0.182 0.75 0.66 0.018 0.164 35 1.17 0.051 0.64 0.56 0.027 0.024 35 4.08 0.232 0.64 0.56 0.027 0.205 50 0.93 0.059 0.60 0.53 0.036 0.022 50 3.25 0.264 0.60 0.53 0.036 0.228 65 0.78 0.064 0.58 0.51 0.045 0.019 65 2.73 0.288 0.58 0.51 0.045 0.243 80 0.68 0.068 0.56 0.49 0.054 0.014 80 2.37 0.307 0.56 0.49 0.054 0.253 95 0.60 0.072 0.55 0.49 0.064 0.008 95 2.10 0.323 0.55 0.49 0.064 0.260 110 0.54 0.075 0.54 0.48 0.073 0.002 110 1.89 0.337 0.54 0.48 0.073 0.264 125 0.49 0.077 0.54 0.47 0.082 -0.004 125 1.72 0.349 0.54 0.47 0.082 0.267 140 0.45 0.080 0.54 0.47 0.091 -0.011 140 1.58 0.360 0.54 0.47 0.091 0.269 155 0.42 0.082 0.53 0.47 0.100 -0.018 155 1.47 0.369 0.53 0.47 0.100 0.270 170 0.39 0.084 0.53 0.47 0.109 -0.025 170 1.37 0.378 0.53 0.47 0.109 0.269 185 0.37 0.086 0.53 0.46 0.118 -0.032 185 1.29 0.387 0.53 0.46 0.118 0.269 200 0.35 0.088 0.52 0.46 0.127 -0.040 200 1.21 0.394 0.52 0.46 0.127 0.267 215 0.33 0.089 0.52 0.46 0.136 -0.047 215 1.15 0.402 0.52 0.46 0.136 0.265 230 0.31 0.091 0.52 0.46 0.145 -0.055 230 1.09 0.408 0.52 0.46 0.145 0.263 245 0.30 0.092 0.52 0.46 0.154 -0.062 245 1.04 0.415 0.52 0.46 0.154 0.260 260 0.29 0.093 0.52 0.46 0.164 -0.070 260 1.00 0.421 0.52 0.46 0.164 0.257 275 0.27 0.095 0.52 0.46 0.173 -0.078 275 0.96 0.426 0.52 0.46 0.173 0.254 290 0.26 0.096 0.52 0.45 0.182 -0.086 290 0.92 0.432 0.52 0.45 0.182 0.250 305 0.25 0.097 0.52 0.45 0.191 -0.094 305 0.88 0.437 0.52 0.45 0.191 0.246 320 0.24 0.098 0.52 0.45 0.200 -0.102 320 0.85 0.442 0.52 0.45 0.200 0.242 335 0.24 0.099 0.51 0.45 0.209 -0.110 335 0.82 0.447 0.51 0.45 0.209 0.238 350 0.23 0.100 0.51 0.45 0.218 -0.118 350 0.79 0.452 0.51 0.45 0.218 0.234 Pedersen Toyota Water Quality Pond and Outlet Sizing (Basin D1) Design Engineer: Design Firm: Project Number: Date: DESIGN CRITERIA: REQUIRED WATER QUALITY CAPTURE VOLUME (WQCV): Tributary Area, A 1.66 acres Composite. Imperviousness, I 75.7% WQCV (watershed inches) 0.303 inches 40-Hour Drain Time (Fig SQ-2) Required WQCV 0.050 acre-feet Including 20% for Sedimentation WATER QUALITY OUTLET SIZING (Per USDCM, Volume 3): Design Water Quality Depth, DWQ 1.29 ft Determine K40 K40 = 0.013DWQ 2 + 0.22DWQ - 0.10 0.206 Maximum Area per Row, a a = WQCV / K40 0.245 square inches Number of Rows, nr 3 rows Number of Columns, nc (See Table 6a-1 for Max.) 1 columns Choose Hole Diameter 1/2 inches Use USDCM Volume 3, Figure 5 0.500 inches Total Area per Row, Ao 0.20 square inches Total Outlet Area, Aot 0.59 square inches Does design work? Yes Minimum Steel Plate Thickness 1/4 inch (Not Used) Number of Rows, nr 2 rows Choose Rectangular Hole Width (w/ 2" Height) 0 inches Use USDCM Volume 3, Figure 5 0.000 inches Total Outlet Area, Aot 0.00 square inches Does design work? Yes Minimum Steel Plate Thickness 1/4 inch Urban Storm Drainage Criteria Manual (USDCM) Volume III, Urban Drainage and Flood Control District, June 2001 (Updated November 2010) Circular Perforation Sizing Rectangular Perforation Sizing J.Claeys Interwest Consulting Group 1180-027-00 May 28, 2014 * * 1 . 2 12 Area WQCV Volume       = 1180-027-00 PondCalcs.xls - WQCV & Outlet Structure Page 2 of 4 Interwest Consulting Group Pedersen Toyota Water Quality Pond and Outlet Sizing (Basin D1) Design Engineer: Design Firm: Project Number: Date: J.Claeys Interwest Consulting Group 1180-027-00 May 28, 2014 WATER QUALITY TRASH RACK SIZING (Per USDCM, Volume 3) Required Open Area, At At =0.5*[77(e -0.124D )]*Aot 21 square inches Min. Distance between Columns, Sc 2 inches Width of Trash Rack and Concrete Opening per Column 3 inches Use USDCM Volume 3, Table 6a-1 Total Width, Wconc 3 inches Height of Trash Rack Screen, Htr 15 8/16 inches Check - Larger than Required Type of Screen S.S. #93 VEE Wire (US Filter) Screen Opening Slot Dimension 0.139" (US Filter) Support Rod Type (See Table 6a-2) Spacing of Support Rod (O.C.) 3/4 inches O.C. Total Screen Thickness (See Table 6a-2) 0.31 inches Carbon Steel Frame Type (See Table 6a-2) (Not Used) Required Open Area, At (including 50% clogging) At =0.5*[77(e -0.124D )]*Aot 0 square inches Width of Trash Rack Opening, Wopening 1 inches Use USDCM Volume 3, Table 6b-1 Width of Concrete Opening, Wconc 12 inches Min Height of Trash Rack Screen, Htr (including 2' 4" below lowest openings) 28.00 inches Type of Screen Kelmp KRP Series Aluminum Bar Gate (or Equal) Screen Opening Slot Dimension 3/16" Bars on 1-3/16" Centers Minimum Bearing Bar Size (See Table 6b-2) Rectangular Perforation Trash Rack Sizing 1 in x 3/16 in #156 VEE 3/8in x 1.0in flat bar Circular Perforation Trash Rack Sizing 1180-027-00 PondCalcs.xls - WQCV & Outlet Structure Page 3 of 4 Interwest Consulting Group Pedersen Toyota Critical Pond Elevations (Basin D1) Design Engineer: Design Firm: Project Number: Date: DESIGN CRITERIA Urban Storm Drainage Criteria Manual, Urban Drainage and Flood Control District, June 2001 (Revised April 2008) 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) 5028.75 0.000 0.000 0.00 0.000 5029.0 1546 0.035 0.003 0.25 0.003 5030.0 2382 0.055 0.045 1.25 0.048 5031.0 3338 0.077 0.065 2.25 0.113 5032.0 4418 0.101 0.089 3.25 0.202 5033.0 5670 0.130 0.115 4.25 0.317 5034.0 6518 0.150 0.140 5.25 0.457 0.05 5030.04 ft 0.32 5033.02 ft J.Claeys Interwest Consulting Group 1180-027-00 Acre-Ft Interpolates to an Elev. of Acre-Ft Interpolates to an Elev. of Required Water Quality Capture Volume = Required 100-yr Detention Volume (including WQCV) = May 28, 2014 5028.00 5029.00 5030.00 5031.00 5032.00 5033.00 5034.00 5035.00 0.0 0.1 0.2 0.3 0.4 0.5 ELEVATION (FT) DETENTION POND VOLUME (AC-FT) DETENTION POND VOLUME VERSUS ELEVATION ( ) 3 AAAADepth 1 2 1 2 V + + = 1180-027-00 PondCalcs.xls - Pond Stage Storage Page 4 of 4 Interwest Consulting Group Pedersen Toyota Parking Lot Detention (Basin D2) Design Engineer: Design Firm: Project Number: Date: DESIGN CRITERIA Urban Storm Drainage Criteria Manual, Urban Drainage and Flood Control District, January 2010 Detention Volume Volume (pond volume calculated using the prismoidal formula): CONTOUR (FT) AREA (FT 2 ) AREA (ACRE) VOLUME (ACRE-FT) DEPTH (FT) CUMULATIVE VOLUME (ACRE-FT) 5029.12 0.000 0.000 0.00 0.000 5030.12 9008 0.207 0.069 1.00 0.069 Basin D2 Release Rate 1.38 cfs Required Detention Volume 0.526 ac-ft Surface Detention Volume 0.069 ac-ft Paver Detention Volume Required 0.457 ac-ft Paver Surface Area 14,053 sf % Voids w/in Paver Aggregates 40% Avg Paver Depth 3.54 ft Parking Lot Detention Volume Interwest Consulting Group J.Claeys 1180-027-00 May 28, 2014 ( ) 3 AAAADepth 1 2 1 2 V + + = Project: Basin ID: Design Information (Input): Design Information (Input): Catchment Drainage Imperviousness Ia = 79.70 percent Catchment Drainage Imperviousness I a = 79.70 percent Catchment Drainage Area A = 2.930 acres Catchment Drainage Area A = 2.930 acres Predevelopment NRCS Soil Group Type = C A, B, C, or D Predevelopment NRCS Soil Group Type = C A, B, C, or D Return Period for Detention Control T = 2 years (2, 5, 10, 25, 50, or 100) Return Period for Detention Control T = 100 years (2, 5, 10, 25, 50, or 100) Time of Concentration of Watershed Tc = 10 minutes Time of Concentration of Watershed Tc = 10 minutes Allowable Unit Release Rate q = 0.47 cfs/acre Allowable Unit Release Rate q = 0.47 cfs/acre One-hour Precipitation P1 = 0.82 inches One-hour Precipitation P 1 = 2.86 inches Design Rainfall IDF Formula i = C1* P 1/(C2 +Tc)^C 3 Design Rainfall IDF Formula i = C1 * P1/(C 2+Tc )^C3 Coefficient One C1 = 28.50 Coefficient One C 1 = 28.50 Coefficient Two C2 = 10 Coefficient Two C 2 = 10 Coefficient Three C3 = 0.787 Coefficient Three C 3 = 0.787 Determination of Average Outflow from the Basin (Calculated): Determination of Average Outflow from the Basin (Calculated): Runoff Coefficient C = 0.59 Runoff Coefficient C = 0.74 Inflow Peak Runoff Qp-in = 3.81 cfs Inflow Peak Runoff Qp-in = 16.67 cfs Allowable Peak Outflow Rate Qp-out = 1.38 cfs Allowable Peak Outflow Rate Qp-out = 1.38 cfs Mod. FAA Minor Storage Volume = 2,379 cubic feet Mod. FAA Major Storage Volume = 22,909 cubic feet Mod. FAA Minor Storage Volume = 0.055 acre-ft Mod. FAA Major Storage Volume = 0.526 acre-ft 15 <- Enter Rainfall Duration Incremental Increase Value Here (e.g. 5 for 5-Minutes) Rainfall Rainfall Inflow Adjustment Average Outflow Storage Rainfall Rainfall Inflow Adjustment Average Outflow Storage Duration Intensity Volume Factor Outflow Volume Volume Duration Intensity Volume Factor Outflow Volume Volume minutes inches / hr acre-feet "m" cfs acre-feet acre-feet minutes inches / hr acre-feet "m" cfs acre-feet acre-feet (input) (output) (output) (output) (output) (output) (output) (input) (output) (output) (output) (output) (output) (output) 5 2.78 0.033 1.00 1.38 0.010 0.024 5 9.68 0.145 1.00 1.38 0.010 0.135 20 1.61 0.077 0.75 1.04 0.029 0.048 20 5.61 0.335 0.75 1.04 0.029 0.307 35 1.17 0.098 0.64 0.89 0.043 0.055 35 4.08 0.427 0.64 0.89 0.043 0.384 50 0.93 0.111 0.60 0.83 0.057 0.054 50 3.25 0.486 0.60 0.83 0.057 0.429 65 0.78 0.121 0.58 0.80 0.071 0.050 65 2.73 0.530 0.58 0.80 0.071 0.459 80 0.68 0.129 0.56 0.78 0.086 0.044 80 2.37 0.565 0.56 0.78 0.086 0.479 95 0.60 0.136 0.55 0.76 0.100 0.036 95 2.10 0.594 0.55 0.76 0.100 0.495 110 0.54 0.142 0.55 0.75 0.114 0.027 110 1.89 0.620 0.55 0.75 0.114 0.506 125 0.49 0.147 0.54 0.75 0.128 0.018 125 1.72 0.642 0.54 0.75 0.128 0.513 140 0.45 0.151 0.54 0.74 0.143 0.009 140 1.58 0.662 0.54 0.74 0.143 0.519 155 0.42 0.155 0.53 0.74 0.157 -0.002 155 1.47 0.680 0.53 0.74 0.157 0.523 170 0.39 0.159 0.53 0.73 0.171 -0.012 170 1.37 0.696 0.53 0.73 0.171 0.525 185 0.37 0.163 0.53 0.73 0.185 -0.023 185 1.29 0.711 0.53 0.73 0.185 0.526 200 0.35 0.166 0.53 0.72 0.200 -0.034 200 1.21 0.725 0.53 0.72 0.200 0.526 215 0.33 0.169 0.52 0.72 0.214 -0.045 215 1.15 0.739 0.52 0.72 0.214 0.525 230 0.31 0.172 0.52 0.72 0.228 -0.057 230 1.09 0.751 0.52 0.72 0.228 0.523 245 0.30 0.174 0.52 0.72 0.242 -0.068 245 1.04 0.763 0.52 0.72 0.242 0.520 260 0.29 0.177 0.52 0.72 0.257 -0.080 260 1.00 0.774 0.52 0.72 0.257 0.517 275 0.27 0.179 0.52 0.72 0.271 -0.092 275 0.96 0.785 0.52 0.72 0.271 0.514 290 0.26 0.182 0.52 0.71 0.285 -0.104 290 0.92 0.795 0.52 0.71 0.285 0.509 305 0.25 0.184 0.52 0.71 0.300 -0.116 305 0.88 0.804 0.52 0.71 0.300 0.505 320 0.24 0.186 0.52 0.71 0.314 -0.128 320 0.85 0.813 0.52 0.71 0.314 0.500 335 0.24 0.188 0.52 0.71 0.328 -0.140 335 0.82 0.822 0.52 0.71 0.328 0.494 350 0.23 0.190 0.51 0.71 0.342 -0.152 350 0.79 0.831 0.51 0.71 0.342 0.489 365 0.22 0.192 0.51 0.71 0.357 -0.165 365 0.77 0.839 0.51 0.71 0.357 0.483 380 0.21 0.194 0.51 0.71 0.371 -0.177 380 0.75 0.847 0.51 0.71 0.371 0.476 395 0.21 0.195 0.51 0.71 0.385 -0.190 395 0.72 0.855 0.51 0.71 0.385 0.470 410 0.20 0.197 0.51 0.71 0.399 -0.202 410 0.70 0.862 0.51 0.71 0.399 0.463 425 0.20 0.199 0.51 0.71 0.414 -0.215 425 0.68 0.869 0.51 0.71 0.414 0.456 440 0.19 0.200 0.51 0.71 0.428 -0.227 440 0.67 0.876 0.51 0.71 0.428 0.449 455 0.19 0.202 0.51 0.71 0.442 -0.240 455 0.65 0.883 0.51 0.71 0.442 0.441 470 0.18 0.203 0.51 0.70 0.456 -0.253 470 0.63 0.890 0.51 0.70 0.456 0.433 485 0.18 0.205 0.51 0.70 0.471 -0.266 485 0.62 0.896 0.51 0.70 0.471 0.426 500 0.17 0.206 0.51 0.70 0.485 -0.279 500 0.60 0.902 0.51 0.70 0.485 0.418 515 0.17 0.208 0.51 0.70 0.499 -0.291 515 0.59 0.909 0.51 0.70 0.499 0.409 530 0.17 0.209 0.51 0.70 0.513 -0.304 530 0.58 0.915 0.51 0.70 0.513 0.401 545 0.16 0.210 0.51 0.70 0.528 -0.317 545 0.57 0.920 0.51 0.70 0.528 0.393 560 0.16 0.212 0.51 0.70 0.542 -0.330 560 0.55 0.926 0.51 0.70 0.542 0.384 575 0.16 0.213 0.51 0.70 0.556 -0.343 575 0.54 0.932 0.51 0.70 0.556 0.376 590 0.15 0.214 0.51 0.70 0.570 -0.356 590 0.53 0.937 0.51 0.70 0.570 0.367 605 0.15 0.215 0.51 0.70 0.585 -0.369 605 0.52 0.942 0.51 0.70 0.585 0.358 620 0.15 0.217 0.51 0.70 0.599 -0.382 620 0.51 0.948 0.51 0.70 0.599 0.349 635 0.14 0.218 0.51 0.70 0.613 -0.395 635 0.50 0.953 0.51 0.70 0.613 0.340 650 0.14 0.219 0.51 0.70 0.627 -0.408 650 0.49 0.958 0.51 0.70 0.627 0.330 665 0.14 0.220 0.51 0.70 0.642 -0.422 665 0.48 0.963 0.51 0.70 0.642 0.321 680 0.14 0.221 0.51 0.70 0.656 -0.435 680 0.48 0.968 0.51 0.70 0.656 0.312 695 0.13 0.222 0.51 0.70 0.670 -0.448 695 0.47 0.972 0.51 0.70 0.670 0.302 710 0.13 0.223 0.51 0.70 0.684 -0.461 710 0.46 0.977 0.51 0.70 0.684 0.293 725 0.13 0.224 0.51 0.70 0.699 -0.474 725 0.45 0.982 0.51 0.70 0.699 0.283 740 0.13 0.225 0.51 0.70 0.713 -0.488 740 0.45 0.986 0.51 0.70 0.713 0.273 755 0.13 0.226 0.51 0.70 0.727 -0.501 755 0.44 0.991 0.51 0.70 0.727 0.263 770 0.12 0.227 0.51 0.70 0.741 -0.514 770 0.43 0.995 0.51 0.70 0.741 0.253 785 0.12 0.228 0.51 0.70 0.756 -0.527 785 0.43 0.999 0.51 0.70 0.756 0.244 800 0.12 0.229 0.51 0.70 0.770 -0.541 800 0.42 1.003 0.51 0.70 0.770 0.233 815 0.12 0.230 0.51 0.70 0.784 -0.554 815 0.41 1.008 0.51 0.70 0.784 0.223 830 0.12 0.231 0.51 0.70 0.798 -0.567 830 0.41 1.012 0.51 0.70 0.798 0.213 845 0.12 0.232 0.51 0.70 0.813 -0.581 845 0.40 1.016 0.51 0.70 0.813 0.203 860 0.11 0.233 0.51 0.70 0.827 -0.594 860 0.40 1.020 0.51 0.70 0.827 0.193 875 0.11 0.234 0.51 0.70 0.841 -0.607 875 0.39 1.024 0.51 0.70 0.841 0.182 890 0.11 0.235 0.51 0.70 0.856 -0.621 890 0.39 1.028 0.51 0.70 0.856 0.172 905 0.11 0.236 0.51 0.70 0.870 -0.634 905 0.38 1.031 0.51 0.70 0.870 0.162 Mod. FAA Minor Storage Volume (cubic ft.) = 2,379 Mod. FAA Major Storage Volume (cubic ft.) = 22,909 Mod. FAA Minor Storage Volume (acre-ft.) = 0.0546 Mod. FAA Major Storage Volume (acre-ft.) = 0.5259 Determination of MAJOR Detention Volume Using Modified FAA Method (For catchments less than 160 acres only. For larger catchments, use hydrograph routing method) (NOTE: for catchments larger than 90 acres, CUHP hydrograph and routing are recommended) UDFCD DETENTION BASIN VOLUME ESTIMATING WORKBOOK Version 2.34, Released November 2013 Determination of MINOR Detention Volume Using Modified FAA Method DETENTION VOLUME BY THE MODIFIED FAA METHOD Petersen Toyota D2 1180-027-00 Basin D2 Detention Volume - Existing Release Rate.xls, Modified FAA 5/27/2014, 8:19 PM Existing Release Rate Required Detention Volume 365 0.22 0.101 0.51 0.45 0.227 -0.126 365 0.77 0.456 0.51 0.45 0.227 0.229 380 0.21 0.102 0.51 0.45 0.236 -0.134 380 0.75 0.460 0.51 0.45 0.236 0.224 395 0.21 0.103 0.51 0.45 0.245 -0.142 395 0.72 0.465 0.51 0.45 0.245 0.219 410 0.20 0.104 0.51 0.45 0.254 -0.150 410 0.70 0.469 0.51 0.45 0.254 0.214 425 0.20 0.105 0.51 0.45 0.264 -0.159 425 0.68 0.473 0.51 0.45 0.264 0.209 440 0.19 0.106 0.51 0.45 0.273 -0.167 440 0.67 0.476 0.51 0.45 0.273 0.204 455 0.19 0.107 0.51 0.45 0.282 -0.175 455 0.65 0.480 0.51 0.45 0.282 0.198 470 0.18 0.107 0.51 0.45 0.291 -0.183 470 0.63 0.484 0.51 0.45 0.291 0.193 485 0.18 0.108 0.51 0.45 0.300 -0.192 485 0.62 0.487 0.51 0.45 0.300 0.187 500 0.17 0.109 0.51 0.45 0.309 -0.200 500 0.60 0.491 0.51 0.45 0.309 0.182 515 0.17 0.110 0.51 0.45 0.318 -0.208 515 0.59 0.494 0.51 0.45 0.318 0.176 530 0.17 0.110 0.51 0.45 0.327 -0.217 530 0.58 0.497 0.51 0.45 0.327 0.170 545 0.16 0.111 0.51 0.45 0.336 -0.225 545 0.57 0.500 0.51 0.45 0.336 0.164 560 0.16 0.112 0.51 0.45 0.345 -0.234 560 0.55 0.503 0.51 0.45 0.345 0.158 575 0.16 0.112 0.51 0.45 0.354 -0.242 575 0.54 0.506 0.51 0.45 0.354 0.152 590 0.15 0.113 0.51 0.45 0.364 -0.250 590 0.53 0.509 0.51 0.45 0.364 0.146 605 0.15 0.114 0.51 0.45 0.373 -0.259 605 0.52 0.512 0.51 0.45 0.373 0.140 620 0.15 0.114 0.51 0.45 0.382 -0.267 620 0.51 0.515 0.51 0.45 0.382 0.133 635 0.14 0.115 0.51 0.45 0.391 -0.276 635 0.50 0.518 0.51 0.45 0.391 0.127 650 0.14 0.116 0.51 0.45 0.400 -0.284 650 0.49 0.521 0.51 0.45 0.400 0.121 665 0.14 0.116 0.51 0.45 0.409 -0.293 665 0.48 0.523 0.51 0.45 0.409 0.114 680 0.14 0.117 0.51 0.45 0.418 -0.301 680 0.48 0.526 0.51 0.45 0.418 0.108 695 0.13 0.117 0.51 0.45 0.427 -0.310 695 0.47 0.529 0.51 0.45 0.427 0.101 710 0.13 0.118 0.51 0.45 0.436 -0.318 710 0.46 0.531 0.51 0.45 0.436 0.095 725 0.13 0.119 0.51 0.45 0.445 -0.327 725 0.45 0.534 0.51 0.45 0.445 0.088 740 0.13 0.119 0.51 0.45 0.454 -0.335 740 0.45 0.536 0.51 0.45 0.454 0.082 755 0.13 0.120 0.51 0.45 0.464 -0.344 755 0.44 0.538 0.51 0.45 0.464 0.075 770 0.12 0.120 0.51 0.45 0.473 -0.352 770 0.43 0.541 0.51 0.45 0.473 0.068 785 0.12 0.121 0.51 0.45 0.482 -0.361 785 0.43 0.543 0.51 0.45 0.482 0.061 800 0.12 0.121 0.51 0.45 0.491 -0.370 800 0.42 0.545 0.51 0.45 0.491 0.055 815 0.12 0.122 0.51 0.45 0.500 -0.378 815 0.41 0.548 0.51 0.45 0.500 0.048 830 0.12 0.122 0.51 0.45 0.509 -0.387 830 0.41 0.550 0.51 0.45 0.509 0.041 845 0.12 0.123 0.51 0.45 0.518 -0.395 845 0.40 0.552 0.51 0.45 0.518 0.034 860 0.11 0.123 0.51 0.45 0.527 -0.404 860 0.40 0.554 0.51 0.45 0.527 0.027 875 0.11 0.124 0.51 0.44 0.536 -0.413 875 0.39 0.556 0.51 0.44 0.536 0.020 890 0.11 0.124 0.51 0.44 0.545 -0.421 890 0.39 0.559 0.51 0.44 0.545 0.013 905 0.11 0.125 0.51 0.44 0.554 -0.430 905 0.38 0.561 0.51 0.44 0.554 0.006 Mod. FAA Minor Storage Volume (cubic ft.) = 1,060 Mod. FAA Major Storage Volume (cubic ft.) = 11,743 Mod. FAA Minor Storage Volume (acre-ft.) = 0.0243 Mod. FAA Major Storage Volume (acre-ft.) = 0.2696 Determination of MAJOR Detention Volume Using Modified FAA Method (For catchments less than 160 acres only. For larger catchments, use hydrograph routing method) (NOTE: for catchments larger than 90 acres, CUHP hydrograph and routing are recommended) UDFCD DETENTION BASIN VOLUME ESTIMATING WORKBOOK Version 2.34, Released November 2013 Determination of MINOR Detention Volume Using Modified FAA Method DETENTION VOLUME BY THE MODIFIED FAA METHOD Petersen Toyota D1 1180-027-00 Basin D1 Detention Volume - Existing Release Rate.xls, Modified FAA 5/27/2014, 8:20 PM Existing Release Rate Required Detention Volume Point Sub-basin Area (acres) tc (min) 2-yr Peak Runoff 5-yr Peak Runoff Q n = C n I n A n 0.786 1 (10 ) 28 . 5 t c P I + = 0 . 395 1 . 1 5 S C L ti − = t c = t i + t t 0 . 5 V = C v S w 10 180 = + L tc V L tt 60 = 0% Pavers 40% Walk 90% Sub-basin Area (acres) tc (min) 2-yr Peak Runoff 10-yr Peak Runoff Q n = C n I n A n 0.786 1 (10 ) 28 . 5 t c P I + = 0 . 395 1 . 1 5 S C L ti − = t c = t i + t t 0 . 5 V = C v S w 10 180 = + L tc V L tt 60 = Impervious COMPOSITE 38 1.11 1.89 3.87 1.11 0.00 1.90 0.01 3.88 0.01 39 1.09 1.86 3.80 1.09 0.00 1.87 0.01 3.82 0.02 40 1.07 1.83 3.74 1.08 0.01 1.84 0.01 3.76 0.02 41 1.05 1.80 3.68 1.06 0.01 1.81 0.01 3.70 0.02 42 1.04 1.77 3.62 1.04 0.00 1.78 0.01 3.64 0.02 43 1.02 1.74 3.56 1.03 0.01 1.76 0.02 3.59 0.03 44 1.01 1.72 3.51 1.01 0.00 1.73 0.01 3.54 0.03 45 0.99 1.69 3.46 1.00 0.01 1.71 0.02 3.48 0.02 46 0.98 1.67 3.41 0.99 0.01 1.68 0.01 3.44 0.03 47 0.96 1.64 3.36 0.97 0.01 1.66 0.02 3.39 0.03 48 0.95 1.62 3.31 0.96 0.01 1.64 0.02 3.34 0.03 49 0.94 1.60 3.27 0.95 0.01 1.61 0.01 3.30 0.03 50 0.92 1.58 3.23 0.93 0.01 1.59 0.01 3.25 0.02 51 0.91 1.56 3.18 0.92 0.01 1.57 0.01 3.21 0.03 52 0.90 1.54 3.14 0.91 0.01 1.55 0.01 3.17 0.03 53 0.89 1.52 3.10 0.90 0.01 1.53 0.01 3.13 0.03 54 0.88 1.50 3.07 0.89 0.01 1.51 0.01 3.09 0.02 55 0.87 1.48 3.03 0.88 0.01 1.50 0.02 3.06 0.03 56 0.86 1.47 2.99 0.87 0.01 1.48 0.01 3.02 0.03 57 0.85 1.45 2.96 0.86 0.01 1.46 0.01 2.98 0.02 58 0.84 1.43 2.92 0.85 0.01 1.44 0.01 2.95 0.03 59 0.83 1.42 2.89 0.84 0.01 1.43 0.01 2.92 0.03 60 0.82 1.40 2.86 0.83 0.01 1.41 0.01 2.88 0.02 0.00 -0.02 0.00 C 3 2 1 1 ( c ) C t C P I + = Survey Area Data: Version 8, Dec 23, 2013 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—Nov 18, 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 (Pedersen Toyota) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 3/27/2014 Page 2 of 4