HomeMy WebLinkAboutWPO201900067 Calculations 2021-04-01CARTERENGINEERINGCONSULTANTSW4 DEVELOPMENT CAR WASHSTORMWATER MANAGEMENTDESIGN CALCULATIONSWP0201900067Date: January 21, 2020PREPARED BY:CARTER ENGINEERING CONSULTANTS, INC.4/i/^t3651 Mars Hill Rd Ste 2000 Watkinsville, GA 30677 www.cartereneineerine.net Phone: 770.725.1200 Fax: 770.725.1204APPROVEDby the Albemarle CountyCommunity Development DepartmentDate____________________________File_____________________________04/01/2021WPO201900067
W4 Development Car Wash SWMP
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Table of Contents
Page Title
3 Project Narrative
4 Virginia Runoff Reduction Method Worksheet Summary
5 LD-204 Inlet Calculations
6 LD-229 Pipe Calculations
7 LD-347 Hydraulic Grade Line Analysis
Hydrologic Report for Jefferson Square
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Project Narrative:
This site is a redevelopment project that includes the construction of a car
wash with associated parking and utilities. The site is currently a multi-
tenant office facility. The limits of disturbance is 0.99 acres.
Water Quality:
The current site includes a multi-tenant office building and parking lot. 0.99
acres of disturbed area was analyzed for water quality. The site will require
0.45 lb/year to be treated. The required 0.45 lb/year will be satisfied by
purchasing nutrient credits from a DEQ approved credit bank in accordance
with LIS code of Virginia 62.1-44.15:35
Water Quantity:
The site drains to an existing stormwater management pond constructed to
provide detention for the subject property as well as the surrounding
shopping center. The pond was designed utilizing a runoff coefficient of
0.80. The calculated runoff coefficient after construction of the car wash is
complete will be 0.72 therefore in compliance with the original study. The
hydrologic report for Jefferson Square Shopping Center is attached. This
project fulfills the requirements of section 9VAC25-970-66 Section D.
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LD-204SHEETRTEPROJDATEOF(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)A-2DI-1300+52.750.200.900.180.686.644.530.004.530.021.504.531.42A-3DI-1301+44.000.300.850.260.506.643.330.003.330.021.503.332.25A-4DI-1302+10.250.290.850.250.526.643.470.003.470.021.503.472.12A-5DI-3,4602+62.750.290.950.280.286.641.830.001.830.020.054.271.500.350.081.660.711.090.060.0917.626.000.340.480.880.001.000.462.184.27sum CANUMBERCOMPUTED LENGTHLT, (FT) (App. 9c-17)T, SPREAD (FT)W (FT)W/TSW (FT/FT)SW/SXEO (APP. 9C-8)a = 12W (SW - SX) + Loc. Depr.S1W = a/(12W)SG = SX + S1W (EO), (FT/FT)US 29ARB-2019-8517-Jan-20I (IN/HR)Q INCR (CFS)Qb, CARRYOVER (CFS)QT, GUTTER FLOW (CFS)S, GUTTER SLOPE (FT/FT)SX, CROSS SLOPE (FT/FT)VDOT Drainage ManuaL, SPECIFIED LENGTH (FT)L/LTQi, INTERCEPTOR (CFS)1 of 1Rev. May 2016TYPEDRAINAGE AREA (AC)LENGTH(FT)STATIONSag Inlets OnlyDepth at InletE (APP. 9C-18)Appendix 9B-1 LD-204 Stormwater Inlet Computations11STORMWATER INLET COMPUTATION SHEET INLETCCAQC, CARRYOVER (CFS)d (FT)h (FT)d/hT, SPREAD @ SAG (FT)
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LD-347ROUTE:PROJ:July 2000COUNTY:DISTRICT:SHEET1OF1AREARUN-INLETRAINRUN-CAPA-FLOWFROMTODRAINOFFTIMEFALLOFFLENGTHSLOPEDIA.CITYVEL.TIMEPOINTPOINT"A"COEF.QMINUTESINCRE-ACCUM-MIN-IN./HR.C.F.S.UPPERLOWERFT.FT./FT.IN.C.F.S.F.P.S.ACRESCMENTULATEDUTESENDEND(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(17)(17)(18)A-0A-10.000.000.000.715.06.644.71480.65480.267.750.0518.004.712.67 0.05 10.11A-1A-20.200.900.180.715.06.644.71482.90480.6545.000.0518.004.712.67 0.28 10.06A-2A-30.300.850.260.535.06.643.52483.81482.9091.250.0118.003.521.99 0.76 9.78A-3A-40.290.850.250.285.06.641.83484.48483.8166.250.0118.001.831.03 1.07 9.02A-4A-50.030.950.030.035.06.640.19485.00484.4852.500.0118.000.190.11 7.95VDOT Drainage ManualSTORM SEWER DESIGNCOMPUTATIONSCAINVERTELEVATIONSINCREMENT ACCUMULATEDREMARKS1 of 1ALBERMARLE4Appendix 9B-2 LD-229 Storm Drain Design ComputaionsARB-2019-85CAR WASHDESCRIPTION:
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LD-347Rev 5/18/16PROJECT :SHEET: ofOutletInletINLET WaterDOQOLOSfOHf1.30.5FinalWaterRimSTATIONSurface%VOHOQiViQiViVi2HiAngleH∆HtHtHtHSurfaceElev.Elev.2gElev.(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)A-1481.461.504.717.750.050.392.670.02772.452.676.540.11070.03320°0.00000.06090.07910.03040.4484481.91489.50A-2484.101.504.7145.000.052.252.670.02771.651.993.280.06150.018480°0.04300.08920.11590.04462.3392486.44490.50A-3485.011.503.5291.250.010.911.990.01541.041.031.070.01650.004945°0.00770.02810.03650.01400.9406485.95491.00A-4485.681.501.8366.250.010.661.030.00410.000.110.000.00020.000180°0.00010.00430.00560.00210.6668486.35491.00A-5486.201.500.1952.500.010.530.110.00000.000.000.000.00000.00000°0.00000.00000.00010.00000.5250486.73490.70FINAL H = Hf + HtHt = Ho + Hi + H∆1 of 1VDOT Drainage Manual20° K = 0.2515° K = 0.1910° K = 0.135° K = 0.06Hi = 0.35 V2i / 2g; Ho = 0.25 V2o / 2g; H∆ = K V2i / 2g; 90° K = 0.7080° K = 0.6670° K = 0.6160° K = 0.5650° K = 0.5040° K = 0.4330° K = 0.3525° K = 0.301Appendix 9B-3 LD-347 Hydraullic Grade Line Computations116-0020JUNCTION LOSSHYDRAULIC GRADE LINE (HGL)