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HomeMy WebLinkAboutFile Documents.1265 Mountain View Dr.0031-2021-BCHO (6)1265 MOUNTAIN VIEW DRIVE LOT 7, WEST MEADOWS CITY OF ASPEN, COLORADO DRAINAGE REPORT July 6, 2021 Prepared by 3C GROUP, LLC 4530 Running W DR Gillette, WY 82718 970.875.4411 08/02/2021 Lot 7, West Meadows July 2021 Drainage Report ii “I hereby affirm that this report and the accompanying plans for the drainage improvements at Lot 7, West Meadows were prepared by me or under my direct supervision for the owners thereof in accordance with the provisions of the City of Aspen URMP” Scott P. Gregory, PE License No. 41690 Licensed Professional Engineer, State of Colorado 08/02/2021 Lot 7, West Meadows July 2021 Drainage Report iii TABLE OF CONTENTS 1.0 Introduction 1-1 1.1 Project Background and Location 1-1 2.0 Proposed Drainage 2-2 Offsite Drainage 2-2 On-Site Drainage 2-2 3.0 Conclusions 3-3 LIST OF APPENDICES Appendix A Existing and Proposed improvement drawings Appendix B Proposed Basin Calculations 08/02/2021 Lot 7, West Meadows July 2021 1-1 Drainage Report 1.0 Introduction 1.1 Project Background and Location The proposed project is located at 1265 Mountain View Dr in this City of Aspen, Pitkin County Colorado. Currently there is an existing Single-Family Residence, driveway and landscaping. This project proposes to remove and replace the existing concrete driveway and parking area, along with the walkway to the front door and replace them in like kind. There is also additional landscaping area and xeriscape gravel areas proposed as part of the overall landscaping plan for the lot. The total affected impervious area is 3,360 square feet. 08/02/2021 Read drainage report requirements in Appendix A of URMP. Lot 7, West Meadows July 2021 2-2 Drainage Report 2.0 Proposed Drainage The overall development of Lot 7 consists of a single-family home consisting of one overall drainage basin. The proposed drainage patterns as part of the original design are consistent with historic drainage patterns and represent the existing conditions. Offsite Drainage The surrounding lots and cemetery area to the south are not proposed to change, and do not adversely affect this parcel with respect to offsite runoff. These areas have not been accounted for in this report due their unchanged status. On-Site Drainage Runoff from the developed area was designed to be released at a rate consistent with historic flows. Runoff from the developed areas, which includes the xeriscape gravel areas, driveway, and parking area, are conveyed via a series of drainage swales and downspout piping to onsite landscaped areas for bio retention of WQCV. A summary of the drainage basin and peak runoff for the 5-year and 100-year design storms are summarized in the appendix of this report 08/02/2021 Show how all affected impervious area is directed to the bioretention area. Detention requirements are for 100year storm. No snowmelt is allowed to drain to the street. Snowmelt must be captured and detained on site. Lot 7, West Meadows July 2021 3-3 Drainage Report 3.0 Conclusions As previously stated, the intent of any proposed improvements to the driveway and landscape areas is to maintain the drainage runoff conditions as are currently operating and to incorporate water quality storage to offset the proposed improvements. The grass lined swales and planting areas accomplish this goal with still keeping the as-is natural feel of the subject lot. 08/02/2021 Lot 7, West Meadows July 2021 D Drainage Report Appendix A Existing and Proposed improvement drawings 08/02/2021 08/02/2021 Survey must be provided and stamped by a certified surveyor. 08/02/2021 All affected impervious area drainage must be captured. Show on civil plans how this is routed to detention.Stamped Civil plans required. Read requirements on Civil plan submittals in URMP. Show in Civil plans how this retention is accomplished. Provide plans to show how retention is accommodated. Show how driveway is routed to retention areas. No snowmelt is allowed to be discharged to the street. Lot 7, West Meadows July 2021 E Drainage Report Appendix B Proposed Basin Calculations 08/02/2021 Report Created: 7/7/2021 11:37:23 AM Parcel ID: 273501309017Pitkin County Parcel Report Woody Creek-Roaring Fork River Not within a Historic District No Zoning Overlay on this parcel AACP Not within a Caucus Area Watershed Drainage Historic District Zone District Overlays Master Plan Area Caucus Boundaries Pitkin County Library Aspen School District No. 1 (RE) Aspen Fire Protection District City of Aspen Water Service Area Aspen Consolidated Sanitation District Library District School District Fire District Water District Sewer System Services Land Use Category 5603 Sq. FeetImprovements Assessor's Information Township, Range, Section 15333.12 Sq. Feet 1265 MOUNTAIN VIEW DR Aspen GIS Parcel Size Address (Assessor's Records) Jurisdiction Property Information 1112: Residential-Single Family Residence 1265 MOU NTAI Address (GIS Points)1265 MTN VIEW DR 6615 RUTGERS AVE HOUSTON, TX 77005 R005467 MH MOUNTAIN VIEW LLCOwner Account Owner Address T:10, R:85, S:1 Subdivision: WEST MEADOW Block: 2 Lot: 7Legal Description No Zoning District on this parcelZone District 08/02/2021 2 4 U.S. House of Representatives District Board of County Commissioners District(s) State Senate District State House District Voting Precinct Voting Information 3 5 61 Meadows Lot 4, Pitkin Reserve, Red Butte, North Ranch, Maroon Creek Wetlands, Red Butte Ranch Racetrack, Meadows, Rio Grande Single Track, Red Butte, Chatfield, McLain Flats Rd, Cemetery Lane, Meadows Rd, Rio Grande, Rio Grande - RF Gorge, Aspen Institute, Music Tent Tot Lot Park, Henry Stein Park, Aspen Golf Open Spaces Nearby (1/2 Mile) Trails Nearby (1/2 Mile) Parks Nearby (1/2 Mile) Public Amenities Woody Creek-Roaring Fork River Watershed Subbasin Watershed Drainage Historic District Tax Information Address Retired Parcel Documents Parcel 273501309017 1265 MTN VIEW DR Brush Creek-Roaring Fork River COUNTY TV/FM TRANSLATOR COUNTY HUMAN SERVICES ASPEN CONSOLIDATED SANITA ASPEN VALLEY HOSPITAL COLORADO MTN COLLEGE Total COUNTY ROAD & BRIDGE ASPEN HISTORIC PARK & REC COLORADO RIVER WATER CONS PITKIN COUNTY LIBRARY OPEN SPACE & TRAILS HEALTHY COMMUNITY FUND ROARING FORK TRANSP AUTH ASPEN FIRE PROTECTION ASPEN AMBULANCE DISTRICT ASPEN SCHOOL DISTRICT PITKIN COUNTY GENERAL FND CITY OF ASPEN 2.297 0.3 5.093 1.436 0.501 8.844 0.956 2.422 3.75 0.177 2.638 0.094 0.287 4.013 2.65 0.065 0.502 $1,200.79 $160.43 $735.52 $96.06 $30.10 $844.71 $91.90 $306.12 $775.55 $459.82 $56.68 $20.81 $1,285.00 $1,630.83 $2,831.93 $160.75 $848.56 AmountAuthorityMill Levy 36.025 $11,535.56 No Retired 08/02/2021 Soil Map—Aspen-Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 7/4/2021 Page 1 of 3 43 4 1 0 1 0 43 4 1 0 3 0 43 4 1 0 5 0 43 4 1 0 7 0 43 4 1 0 9 0 43 4 1 1 1 0 43 4 1 1 3 0 43 4 1 1 5 0 43 4 1 0 1 0 43 4 1 0 3 0 43 4 1 0 5 0 43 4 1 0 7 0 43 4 1 0 9 0 43 4 1 1 1 0 43 4 1 1 3 0 341330 341350 341370 341390 341410 341430 341450 341470 341490 341510 341530 341550 341330 341350 341370 341390 341410 341430 341450 341470 341490 341510 341530 341550 39° 12' 18'' N 10 6 ° 5 0 ' 1 5 ' ' W 39° 12' 18'' N 10 6 ° 5 0 ' 5 ' ' W 39° 12' 13'' N 10 6 ° 5 0 ' 1 5 ' ' W 39° 12' 13'' N 10 6 ° 5 0 ' 5 ' ' 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: 1:1,070 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. 08/02/2021 MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features 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 of the version date(s) listed below. Soil Survey Area: Aspen-Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties Survey Area Data: Version 11, Jun 5, 2020 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Data not available. 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. Soil Map—Aspen-Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 7/4/2021 Page 2 of 3 08/02/2021 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 107 Uracca, moist-Mergel complex, 1 to 6 percent slopes, extremely s 4.1 100.0% Totals for Area of Interest 4.1 100.0% Soil Map—Aspen-Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 7/4/2021 Page 3 of 308/02/2021 Aspen-Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties 107—Uracca, moist-Mergel complex, 1 to 6 percent slopes, extremely s Map Unit Setting National map unit symbol: jq4g Elevation: 6,800 to 8,400 feet Mean annual precipitation: 16 to 19 inches Mean annual air temperature: 40 to 43 degrees F Frost-free period: 75 to 95 days Farmland classification: Not prime farmland Map Unit Composition Uracca, moist, and similar soils:50 percent Mergel and similar soils:40 percent Minor components:10 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Uracca, Moist Setting Landform:Structural benches, valley sides, alluvial fans Down-slope shape:Linear Across-slope shape:Linear Parent material:Mixed alluvium derived from igneous and metamorphic rock Typical profile H1 - 0 to 8 inches: cobbly sandy loam H2 - 8 to 15 inches: very cobbly sandy clay loam H3 - 15 to 60 inches: extremely cobbly loamy sand Properties and qualities Slope:1 to 6 percent Depth to restrictive feature:More than 80 inches Drainage class:Well drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat):Moderately high to high (0.20 to 2.00 in/hr) Depth to water table:More than 80 inches Frequency of flooding:None Frequency of ponding:None Calcium carbonate, maximum content:10 percent Available water capacity:Very low (about 2.6 inches) Interpretive groups Land capability classification (irrigated): 6s Land capability classification (nonirrigated): 6s Hydrologic Soil Group: B Map Unit Description: Uracca, moist-Mergel complex, 1 to 6 percent slopes, extremely s--- Aspen-Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 7/4/2021 Page 1 of 208/02/2021 Ecological site: R048AY237CO - Stony Loam Other vegetative classification: Stony Loam (null_82) Hydric soil rating: No Description of Mergel Setting Landform:Valley sides, alluvial fans, structural benches Down-slope shape:Linear Across-slope shape:Linear Parent material:Glacial outwash Typical profile H1 - 0 to 8 inches: cobbly loam H2 - 8 to 20 inches: very cobbly sandy loam H3 - 20 to 60 inches: extremely stony sandy loam Properties and qualities Slope:1 to 6 percent Depth to restrictive feature:More than 80 inches Drainage class:Well drained Runoff class: Very low Capacity of the most limiting layer to transmit water (Ksat):Moderately high to high (0.60 to 6.00 in/hr) Depth to water table:More than 80 inches Frequency of flooding:None Frequency of ponding:None Calcium carbonate, maximum content:10 percent Available water capacity:Low (about 3.3 inches) Interpretive groups Land capability classification (irrigated): 4s Land capability classification (nonirrigated): 4s Hydrologic Soil Group: A Ecological site: R048AY237CO - Stony Loam Other vegetative classification: Stony Loam (null_82) Hydric soil rating: No Minor Components Other soils Percent of map unit:10 percent Hydric soil rating: No Data Source Information Soil Survey Area: Aspen-Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties Survey Area Data: Version 11, Jun 5, 2020 Map Unit Description: Uracca, moist-Mergel complex, 1 to 6 percent slopes, extremely s--- Aspen-Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 7/4/2021 Page 2 of 208/02/2021 Project Title: Catchment ID: Illustration Instructions: For each catchment subarea, enter values for A and C. Subarea Area Runoff Product ID acres Coeff. A C*CA input input input output E1 0.08 0.02 0.00 Sum:0.08 Sum:0.00 Area-Weighted Runoff Coefficient (sum CA/sum A) =0.02 *See sheet "Design Info" for inperviousness-based runoff coefficient values. Area-Weighting for Runoff Coefficient Calculation 1265 Mountain View Dr E1 - 5yr UD-Rational v1.02a, Weighted C 7/7/2021, 10:30 AM08/02/2021 Project Title: Catchment ID: I.Catchment Hydrologic Data Catchment ID =E1 Area =0.08 Acres Percent Imperviousness =5.00 % NRCS Soil Type =A A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =5 years (input return period for design storm) C1 =28.50 (input the value of C1) C2=10.00 (input the value of C2) C3=0.786 (input the value of C3) P1=0.64 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.02 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.02 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Type Meadow Field Pasture/Bare Swales/ Lawns Ground Waterways Conveyance 2.5 5 7 10 15 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.0200 25 0.02 N/A 0.05 7.76 1 0.0100 30 10.00 1.00 0.50 2 3 4 5 55 Computed Tc =8.26 Regional Tc =10.31 User-Entered Tc =8.26 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =1.86 inch/hr Peak Flowrate, Qp =0.00 cfs Rainfall Intensity at Regional Tc, I =1.71 inch/hr Peak Flowrate, Qp =0.00 cfs Rainfall Intensity at User-Defined Tc, I =1.86 inch/hr Peak Flowrate, Qp =0.00 cfs (Sheet Flow) 20 Shallow Paved Swales Sum CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD 1265 Montain View Dr E1 - 5yr Paved Areas & UD-Rational v1.02a, Tc and PeakQ 7/7/2021, 10:30 AM08/02/2021 Project Title: Catchment ID: Illustration Instructions: For each catchment subarea, enter values for A and C. Subarea Area Runoff Product ID acres Coeff. A C*CA input input input output E1 0.08 0.24 0.02 Sum:0.08 Sum:0.02 Area-Weighted Runoff Coefficient (sum CA/sum A) =0.24 *See sheet "Design Info" for inperviousness-based runoff coefficient values. Area-Weighting for Runoff Coefficient Calculation 1265 Mountain View Dr E1 - 100yr UD-Rational v1.02a, Weighted C 7/7/2021, 10:29 AM08/02/2021 Project Title: Catchment ID: I.Catchment Hydrologic Data Catchment ID =E1 Area =0.08 Acres Percent Imperviousness =5.00 % NRCS Soil Type =A A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =100 years (input return period for design storm) C1 =28.50 (input the value of C1) C2=10.00 (input the value of C2) C3=0.786 (input the value of C3) P1=1.23 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.24 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.02 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Type Meadow Field Pasture/Bare Swales/ Lawns Ground Waterways Conveyance 2.5 5 7 10 15 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.0200 25 0.02 N/A 0.05 7.76 1 0.0100 30 10.00 1.00 0.50 2 3 4 5 55 Computed Tc =8.26 Regional Tc =10.31 User-Entered Tc =8.26 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =3.57 inch/hr Peak Flowrate, Qp =0.07 cfs Rainfall Intensity at Regional Tc, I =3.29 inch/hr Peak Flowrate, Qp =0.06 cfs Rainfall Intensity at User-Defined Tc, I =3.57 inch/hr Peak Flowrate, Qp =0.07 cfs (Sheet Flow) 20 Shallow Paved Swales Sum CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD 1265 Montain View Dr E1 - 100yr Paved Areas & UD-Rational v1.02a, Tc and PeakQ 7/7/2021, 10:29 AM08/02/2021 Project Title: Catchment ID: Illustration Instructions: For each catchment subarea, enter values for A and C. Subarea Area Runoff Product ID acres Coeff. A C*CA input input input output P1 0.08 0.80 0.06 Sum:0.08 Sum:0.06 Area-Weighted Runoff Coefficient (sum CA/sum A) =0.80 *See sheet "Design Info" for inperviousness-based runoff coefficient values. Area-Weighting for Runoff Coefficient Calculation 1265 Mountain View Dr P1 - 5yr UD-Rational v1.02a, Weighted C 7/7/2021, 10:24 AM08/02/2021 Project Title: Catchment ID: I.Catchment Hydrologic Data Catchment ID =P1 Area =0.08 Acres Percent Imperviousness =95.00 % NRCS Soil Type =A A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =5 years (input return period for design storm) C1 =28.50 (input the value of C1) C2=10.00 (input the value of C2) C3=0.786 (input the value of C3) P1=0.64 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.80 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.80 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Type Meadow Field Pasture/Bare Swales/ Lawns Ground Waterways Conveyance 2.5 5 7 10 15 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.0200 25 0.80 N/A 0.19 2.18 1 0.0100 30 10.00 1.00 0.50 2 3 4 5 55 Computed Tc =2.68 Regional Tc =10.31 User-Entered Tc =5.00 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =2.48 inch/hr Peak Flowrate, Qp =0.15 cfs Rainfall Intensity at Regional Tc, I =1.71 inch/hr Peak Flowrate, Qp =0.10 cfs Rainfall Intensity at User-Defined Tc, I =2.17 inch/hr Peak Flowrate, Qp =0.13 cfs (Sheet Flow) 20 Shallow Paved Swales Sum CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD 1265 Montain View Dr P1 - 5yr Paved Areas & UD-Rational v1.02a, Tc and PeakQ 7/7/2021, 10:24 AM08/02/2021 Project Title: Catchment ID: Illustration Instructions: For each catchment subarea, enter values for A and C. Subarea Area Runoff Product ID acres Coeff. A C*CA input input input output P1 0.08 0.86 0.07 Sum:0.08 Sum:0.07 Area-Weighted Runoff Coefficient (sum CA/sum A) =0.86 *See sheet "Design Info" for inperviousness-based runoff coefficient values. Area-Weighting for Runoff Coefficient Calculation 1265 Mountain View Dr P1 - 100yr UD-Rational v1.02a, Weighted C 7/7/2021, 10:26 AM08/02/2021 Project Title: Catchment ID: I.Catchment Hydrologic Data Catchment ID =P1 Area =0.08 Acres Percent Imperviousness =95.00 % NRCS Soil Type =A A, B, C, or D II.Rainfall Information I (inch/hr) = C1 * P1 /(C2 + Td)^C3 Design Storm Return Period, Tr =100 years (input return period for design storm) C1 =28.50 (input the value of C1) C2=10.00 (input the value of C2) C3=0.786 (input the value of C3) P1=1.23 inches (input one-hr precipitation--see Sheet "Design Info") III.Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficient, C =0.86 Overide Runoff Coefficient, C =(enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 =0.80 Overide 5-yr. Runoff Coefficient, C =(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration NRCS Land Heavy Tillage/Short Nearly Grassed Type Meadow Field Pasture/Bare Swales/ Lawns Ground Waterways Conveyance 2.5 5 7 10 15 Calculations:Reach Slope Length 5-yr NRCS Flow Flow ID S L Runoff Convey-Velocity Time Coeff ance V Tf ft/ft ft C-5 fps minutes input input output input output output Overland 0.0200 25 0.80 N/A 0.19 2.18 1 0.0100 30 10.00 1.00 0.50 2 3 4 5 55 Computed Tc =2.68 Regional Tc =10.31 User-Entered Tc =5.00 IV.Peak Runoff Prediction Rainfall Intensity at Computed Tc, I =4.76 inch/hr Peak Flowrate, Qp =0.32 cfs Rainfall Intensity at Regional Tc, I =3.29 inch/hr Peak Flowrate, Qp =0.22 cfs Rainfall Intensity at User-Defined Tc, I =4.17 inch/hr Peak Flowrate, Qp =0.28 cfs (Sheet Flow) 20 Shallow Paved Swales Sum CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD 1265 Montain View Dr P1 - 100yr Paved Areas & UD-Rational v1.02a, Tc and PeakQ 7/7/2021, 10:26 AM08/02/2021 Project: Basin ID: Design Information (Input):Design Information (Input): Catchment Drainage Imperviousness Ia =95.00 percent Catchment Drainage Imperviousness Ia =95.00 percent Catchment Drainage Area A =0.077 acres Catchment Drainage Area A =0.077 acres Predevelopment NRCS Soil Group Type =A A, B, C, or D Predevelopment NRCS Soil Group Type =A A, B, C, or D Return Period for Detention Control T =5 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 =5 minutes Time of Concentration of Watershed Tc =5 minutes Allowable Unit Release Rate q =0.26 cfs/acre Allowable Unit Release Rate q =0.91 cfs/acre One-hour Precipitation P1 =0.64 inches One-hour Precipitation P1 =1.63 inches Design Rainfall IDF Formula i = C1* P1/(C2+Tc)^C3 Design Rainfall IDF Formula i = C1* P1/(C2+Tc)^C3 Coefficient One C1 =28.50 Coefficient One C1 =28.50 Coefficient Two C2 =10 Coefficient Two C2 =10 Coefficient Three C3 =0.789 Coefficient Three C3 =0.789 Determination of Average Outflow from the Basin (Calculated):Determination of Average Outflow from the Basin (Calculated): Runoff Coefficient C =0.80 Runoff Coefficient C =0.86 Inflow Peak Runoff Qp-in =0.13 cfs Inflow Peak Runoff Qp-in =0.36 cfs Allowable Peak Outflow Rate Qp-out =0.02 cfs Allowable Peak Outflow Rate Qp-out =0.07 cfs Mod. FAA Minor Storage Volume = 104 cubic feet Mod. FAA Major Storage Volume = 252 cubic feet Mod. FAA Minor Storage Volume = 0.002 acre-ft Mod. FAA Major Storage Volume = 0.006 acre-ft 5 <- 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) 0 0.00 0.000 0.00 0.00 0.000 0.000 0 0.00 0.000 0.00 0.00 0.000 0.000 5 2.15 0.001 1.00 0.02 0.000 0.001 5 5.48 0.003 1.00 0.07 0.000 0.002 10 1.72 0.001 0.75 0.01 0.000 0.001 10 4.37 0.004 0.75 0.05 0.001 0.003 15 1.44 0.002 0.67 0.01 0.000 0.002 15 3.66 0.005 0.67 0.05 0.001 0.004 20 1.25 0.002 0.63 0.01 0.000 0.002 20 3.17 0.006 0.63 0.04 0.001 0.005 25 1.10 0.002 0.60 0.01 0.000 0.002 25 2.81 0.006 0.60 0.04 0.001 0.005 30 0.99 0.003 0.58 0.01 0.000 0.002 30 2.53 0.007 0.58 0.04 0.002 0.005 35 0.90 0.003 0.57 0.01 0.001 0.002 35 2.30 0.007 0.57 0.04 0.002 0.005 40 0.83 0.003 0.56 0.01 0.001 0.002 40 2.12 0.008 0.56 0.04 0.002 0.006 45 0.77 0.003 0.56 0.01 0.001 0.002 45 1.97 0.008 0.56 0.04 0.002 0.006 50 0.72 0.003 0.55 0.01 0.001 0.002 50 1.84 0.008 0.55 0.04 0.003 0.006 55 0.68 0.003 0.55 0.01 0.001 0.002 55 1.72 0.009 0.55 0.04 0.003 0.006 60 0.64 0.003 0.54 0.01 0.001 0.002 60 1.63 0.009 0.54 0.04 0.003 0.006 65 0.60 0.003 0.54 0.01 0.001 0.002 65 1.54 0.009 0.54 0.04 0.003 0.006 70 0.57 0.003 0.54 0.01 0.001 0.002 70 1.46 0.009 0.54 0.04 0.004 0.006 75 0.55 0.003 0.53 0.01 0.001 0.002 75 1.40 0.010 0.53 0.04 0.004 0.006 80 0.52 0.004 0.53 0.01 0.001 0.002 80 1.33 0.010 0.53 0.04 0.004 0.006 85 0.50 0.004 0.53 0.01 0.001 0.002 85 1.28 0.010 0.53 0.04 0.004 0.006 90 0.48 0.004 0.53 0.01 0.001 0.002 90 1.23 0.010 0.53 0.04 0.005 0.006 95 0.46 0.004 0.53 0.01 0.001 0.002 95 1.18 0.010 0.53 0.04 0.005 0.005 100 0.45 0.004 0.53 0.01 0.001 0.002 100 1.14 0.010 0.53 0.04 0.005 0.005 105 0.43 0.004 0.52 0.01 0.002 0.002 105 1.10 0.011 0.52 0.04 0.005 0.005 110 0.42 0.004 0.52 0.01 0.002 0.002 110 1.06 0.011 0.52 0.04 0.006 0.005 115 0.40 0.004 0.52 0.01 0.002 0.002 115 1.03 0.011 0.52 0.04 0.006 0.005 120 0.39 0.004 0.52 0.01 0.002 0.002 120 1.00 0.011 0.52 0.04 0.006 0.005 125 0.38 0.004 0.52 0.01 0.002 0.002 125 0.97 0.011 0.52 0.04 0.006 0.005 130 0.37 0.004 0.52 0.01 0.002 0.002 130 0.94 0.011 0.52 0.04 0.007 0.005 135 0.36 0.004 0.52 0.01 0.002 0.002 135 0.92 0.011 0.52 0.04 0.007 0.005 140 0.35 0.004 0.52 0.01 0.002 0.002 140 0.89 0.011 0.52 0.04 0.007 0.004 145 0.34 0.004 0.52 0.01 0.002 0.002 145 0.87 0.012 0.52 0.04 0.007 0.004 150 0.33 0.004 0.52 0.01 0.002 0.002 150 0.85 0.012 0.52 0.04 0.007 0.004 155 0.32 0.004 0.52 0.01 0.002 0.002 155 0.83 0.012 0.52 0.04 0.008 0.004 160 0.32 0.004 0.52 0.01 0.002 0.002 160 0.81 0.012 0.52 0.04 0.008 0.004 165 0.31 0.004 0.52 0.01 0.002 0.002 165 0.79 0.012 0.52 0.04 0.008 0.004 170 0.30 0.004 0.51 0.01 0.002 0.002 170 0.77 0.012 0.51 0.04 0.008 0.004 175 0.30 0.004 0.51 0.01 0.002 0.002 175 0.76 0.012 0.51 0.04 0.009 0.003 180 0.29 0.004 0.51 0.01 0.003 0.002 180 0.74 0.012 0.51 0.04 0.009 0.003 185 0.28 0.004 0.51 0.01 0.003 0.002 185 0.72 0.012 0.51 0.04 0.009 0.003 190 0.28 0.005 0.51 0.01 0.003 0.002 190 0.71 0.012 0.51 0.04 0.009 0.003 195 0.27 0.005 0.51 0.01 0.003 0.002 195 0.70 0.012 0.51 0.04 0.010 0.003 200 0.27 0.005 0.51 0.01 0.003 0.002 200 0.68 0.012 0.51 0.04 0.010 0.003 205 0.26 0.005 0.51 0.01 0.003 0.002 205 0.67 0.013 0.51 0.04 0.010 0.002 210 0.26 0.005 0.51 0.01 0.003 0.002 210 0.66 0.013 0.51 0.04 0.010 0.002 215 0.25 0.005 0.51 0.01 0.003 0.002 215 0.65 0.013 0.51 0.04 0.011 0.002 220 0.25 0.005 0.51 0.01 0.003 0.002 220 0.64 0.013 0.51 0.04 0.011 0.002 225 0.25 0.005 0.51 0.01 0.003 0.002 225 0.63 0.013 0.51 0.04 0.011 0.002 230 0.24 0.005 0.51 0.01 0.003 0.001 230 0.62 0.013 0.51 0.04 0.011 0.002 235 0.24 0.005 0.51 0.01 0.003 0.001 235 0.61 0.013 0.51 0.04 0.012 0.001 240 0.23 0.005 0.51 0.01 0.003 0.001 240 0.60 0.013 0.51 0.04 0.012 0.001 245 0.23 0.005 0.51 0.01 0.003 0.001 245 0.59 0.013 0.51 0.04 0.012 0.001 250 0.23 0.005 0.51 0.01 0.004 0.001 250 0.58 0.013 0.51 0.04 0.012 0.001 255 0.22 0.005 0.51 0.01 0.004 0.001 255 0.57 0.013 0.51 0.04 0.013 0.001 260 0.22 0.005 0.51 0.01 0.004 0.001 260 0.56 0.013 0.51 0.04 0.013 0.001 265 0.22 0.005 0.51 0.01 0.004 0.001 265 0.55 0.013 0.51 0.04 0.013 0.000 270 0.21 0.005 0.51 0.01 0.004 0.001 270 0.54 0.013 0.51 0.04 0.013 0.000 275 0.21 0.005 0.51 0.01 0.004 0.001 275 0.54 0.013 0.51 0.04 0.013 0.000 280 0.21 0.005 0.51 0.01 0.004 0.001 280 0.53 0.014 0.51 0.04 0.014 0.000 285 0.21 0.005 0.51 0.01 0.004 0.001 285 0.52 0.014 0.51 0.04 0.014 0.000 290 0.20 0.005 0.51 0.01 0.004 0.001 290 0.52 0.014 0.51 0.04 0.014 -0.001 295 0.20 0.005 0.51 0.01 0.004 0.001 295 0.51 0.014 0.51 0.04 0.014 -0.001 300 0.20 0.005 0.51 0.01 0.004 0.001 300 0.50 0.014 0.51 0.04 0.015 -0.001 Mod. FAA Minor Storage Volume (cubic ft.) =104 Mod. FAA Major Storage Volume (cubic ft.) =252 Mod. FAA Minor Storage Volume (acre-ft.) =0.0024 Mod. FAA Major Storage Volume (acre-ft.) =0.0058 DETENTION VOLUME BY THE MODIFIED FAA METHOD 1265 Moutain View Dr 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 2.35, Released January 2015 Determination of MINOR Detention Volume Using Modified FAA Method FAA Detention Volumes, Modified FAA 7/7/2021, 10:34 AM 08/02/2021 Project: Basin ID: DETENTION VOLUME BY THE MODIFIED FAA METHOD 1265 Moutain View Dr UDFCD DETENTION BASIN VOLUME ESTIMATING WORKBOOK Version 2.35, Released January 2015 0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 0 50 100 150 200 250 300 350 Vo l u m e ( a c r e -fe e t ) Duration (Minutes) Inflow and Outflow Volumes vs. Rainfall Duration Minor Storm Inflow Volume Minor Storm Outflow Volume Minor Storm Storage Volume Major Storm Inflow Volume Major Storm Outflow Volume Major Storm Storage Volume FAA Detention Volumes, Modified FAA 7/7/2021, 10:34 AM 08/02/2021