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HomeMy WebLinkAboutWPO200302301 Calculations Stormwater Management Plan 2004-01-15HYDROLOGIC/HYDRAULIC CALCULATIONS FOR HOLLYMEAD TOWNCENTER RERGIONAL SERVICE AREA C SEDIMENT BASIN 1 January 15, 2004 LOCATION: Tax Map 32 Parcel 4 1 D Albemarle County, Virginia PREPARED BY: Rivanna Engineering & Surveying, PLC P.O. Box 7603 Charlottesville, VA 22906 P: 434.984.1599 F: 434.984.8863 NOTES: The composite curve number used for these calculations allows for the construction of Anchor A on Regional Service Area B, Block C1 on Regional Service Area C, and Timberwood Boulevard. When these areas are constructed the sediment basin will have to be converted to a Stormwater management facility and the cap removed from the 18 -inch outlet to Forest Lakes. Z3/ 2miG Hollymead Towncenter 1/19/2004 Regional Service Area C Sediment Basin 1 FLOOD HYDROGRAPH REPORT Hydrograph Number: 2 Name: DA -Z, 10 year Type: Computed Flood [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 180.83 (cfs) Time to Peak (Tp) = 720.00 (min) Time of Base (Tb) = 1472.39 (min) Volume = 10.3260 (ac -ft) Time Step = 2.00 (min) Flow Multiplier = 1.00 [UNIT HYDROGRAPH INFORMATION] Number = 1 Type = SCS Curvilinear Peak Flow (Qp) = 190.58 (cfs) Time to Peak (Tp) = 6.67 (min) Time of Base (Tb) = 33.33 (min) Volume = 2.3423 (ac -ft) Shape Factor = 484.00 Time Step: = 2.00 (min) Excess Rain = 1.00 (in) Lag Time = 6.00 (min) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] ------------------------------------------------------ Description Area CN ------------------------------------------------------ <None> ------------------------------------------------------ Overall Approximation 28.0000 86 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 10.00 (min) [RAINFALL DESCRIPTION] Distribution Type = SCS II Total Precipitation = 6.00 (in) Return Period = 2 (yr) Storm Duration = 24.00 (hr) 2 Hydrograph Number: Name: Type: [HYDROGRAPH INFORMATION] Hollymead Towncenter 1/19/2004 Regional Service Area C Sediment Basin 1 FLOOD HYDROGRAPH REPORT 3 DA -Z, 100 year Computed Flood Peak Flow (Qp) = 253.98 Ws) Time to Peak (Tp) = 720.00 (min) Time of Base (Tb) = 1472.39 (min) Volume = 14.8278 (ac -ft) Time Step = 2.00 (min) Flow Multiplier = 1.00 [UNIT HYDROGRAPH INFORMATION] Number = 1 Type = SCS Curvilinear Peak Flow (Qp) = 190.58 (cfs) Time to Peak (Tp) = 6.67 (min) Time of Base (Tb) = 33.33 (min) Volume = 2.3423 (ac -ft) Shape Factor = 484.00 Time Step: = 2.00 (min) Excess Rain = 1.00 (in) Lag Time = 6.00 (min) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] ------------------------------------------------------ Description Area CN ------------------------------------------------------ <None> ------------------------------------------------------ Overall Approximation 28.0000 86 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 10.00 (min) [RAINFALL DESCRIPTION] Distribution Type = SCS II Total Precipitation = 8.00 (in) Return Period = 2 (yr) Storm Duration = 24.00 (hr) 3 Structure Number Type Name [RATING CURVE LIMIT] Minimum Elevation Maximum Elevation Elevation Increment [STAND PIPE INFORMATION] [ORIFICE INFORMATION] Hollymead Towncenter 1/19/2004 Regional Service Area C Sediment Basin 1 OUTLET STRUCTURE REPORT : 1 : Stand Pipe : SWM1- Sed. Basin Structure 511.0000 (ft) 529.0000 (ft) 0.5000 (ft) Diameter = 5.00 (ft) Crest Length = 15.71 (ft) Effective Crest Length = 11.71 (ft) Orifice Coefficient = 0.60 Fractional Open Area = 1.00 [ORIFICE EQUATION] Q = Co*A ( (2gh) /k) ^0. 5 [DEFINITIONS] Co = Orifice Coefficient A = Wetted Area, (sq ft) [WEIR INFORMATION] Crest Elevation = 525.5000 (ft) Weir Coefficient = 3.33 Exponential = 1.50 [WEIR EQUATION] Q = Cw * L * H^exp [DEFINITIONS] Cw = Weir Coefficient H = Headwater depth above inlet control section invert ft L = Crest lenght ft [OPTIONAL WEIR INFORMATION] Structure Number 1 Type Rectangular Weir Suppressed [WEIR INFORMATION] Crest Length = 4.00 (ft) Crest Elevation = 523.7500 (ft) Weir Coefficient = 3.33 Exponential = 1.50 IV. Hollymead Towncenter 1/19/2004 Regional Service Area C Sediment Basin 1 [RECTANGULAR SUPRESSED EQUATION] Q = Cw * L * H^exp [DEFINITIONS] Cw = Weir Coefficient H = Headwater depth above inlet control section invert L = Crest lenght [CULVERT INFORMATION] Type Circular Concrete - Square Edge with Headwall [OUTLET STRUCTURE INFORMATION] Diameter = 36.00 (in) Invert Elevation = 519.0000 (ft) Pipe Length = 120.00 (ft) Slope = 0.01 Manning's n Value = 0.01 Orifice Coefficient = 0.60 Tailwater Elevation = 517.8000 (ft) Number of Barrels = 1 [UNSUBMERGED EQUATION] H/Diam = Hc/Diam+K*(Q/(A*Diam^0.5))^M-0.5*S Coefficient K = 0.01 Coefficient M = 2.00 Q Maximum = 42.85 [SUBMERGED EQUATION] H/Diam = c*(Q/(A*Diam^0.5))^2+Y-0.5*S Coefficient c = 0.04 Coefficient Y = 0.67 Q Minimum = 48.97 [DEFINITIONS] H = Headwater depth above inlet control section invert, (ft) Diam = Interior height of culvert barrel, (ft) He = Specific head at critical depth (dc+Vc^2/2g), (ft) Q = Discharge, (cfs) A = Full cross sectional area of culvert barrel, (sq ft) S = Culvert barrel slope, (ft/ft) Hollymead Towncenter 1/19/2004 Regional Service Area C Sediment Basin 1 [STAND PIPE STAGE VS. DISCHARGE] OUTLET STRUCTURE REPORT -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Elevation Stage Weirs Orifices Stand Pipe Culvert Total (ft) (ft) (cfs) (cfs) (cfs) (cfs) (cfs) 519.0000 4.0000 0.00 0.00 0.00 0.00 0.00 519.5000 4.5000 0.00 0.00 0.00 0.00 0.00 520.0000 5.0000 0.00 0.00 0.00 5.57 0.00 520.5000 5.5000 0.00 0.00 0.00 11.63 0.00 521.0000 6.0000 0.00 0.00 0.00 19.00 0.00 521.5000 6.5000 0.00 0.00 0.00 27.03 0.00 522.0000 7.0000 0.00 0.00 0.00 35.15 0.00 522.5000 7.5000 0.00 0.00 0.00 42.85 0.00 523.0000 8.0000 0.00 0.00 0.00 50.08 0.00 523.5000 8.5000 0.00 0.00 0.00 55.99 0.00 524.0000 9.0000 1.67 0.00 0.00 61.04 1.67 524.5000 9.5000 8.65 0.00 0.00 65.68 8.65 525.0000 10.0000 18.62 0.00 0.00 70.16 18.62 525.5000 10.5000 30.84 0.00 0.00 74.45 30.84 526.0000 11.0000 44.95 0.00 13.78 78.53 58.74 526.5000 11.5000 60.74 0.00 38.99 82.44 82.44 527.0000 12.0000 78.04 0.00 71.63 86.21 86.21 527.5000 12.5000 96.73 0.00 108.68 89.82 89.82 528.0000 13.0000 116.70 0.00 137.71 93.32 93.32 528.5000 13.5000 137.89 0.00 163.69 96.70 96.70 529.0000 14.0000 160.23 0.00 176.80 99.97 99.97 0 Hollymead Towncenter 1/19/2004 Regional Service Area C Sediment Basin 1 RESERVOIR REPORT Reservoir Number: 1 Name: SWM1 - SED BASIN [RATING CURVE LIMIT] Minimum Elevation = 511.0000 (ft) Maximum Elevation = 529.0000 (ft) Elevation Increment = 0.5000 (ft) [STAGE STORAGE INFORMATION] [DISCHARGE INFORMATION] Structure Number: 1 Type: Name: SWM1- Sed. Basin Structure [RESERVOIR STAGE STORAGE/DISCHARGE] -------------------------------------------------------------------------------- Elevation Stage Area Storage Discharge (ft) (ft) (sq ft) (cu ft) (cfs) 519.5000 8.5000 0.0000 0.0000 0.00 520.0000 9.0000 32269.0000 8067.2500 0.00 520.5000 9.5000 33471.5000 24502.3750 0.00 521.0000 10.0000 34674.0000 41538.7500 0.00 521.5000 10.5000 35876.5000 59176.3750 0.00 522.0000 11.0000 37079.0000 77415.2500 0.00 522.5000 11.5000 38343.0000 96270.7500 0.00 523.0000 12.0000 39607.0000 115758.2500 0.00 523.5000 12.5000 40871.0000 135877.7500 0.00 524.0000 13.0000 42135.0000 156629.2500 1.67 524.5000 13.5000 43441.5000 178023.3750 8.65 525.0000 14.0000 44748.0000 200070.7500 18.62 525.5000 14.5000 45921.2500 222738.0625 30.84 526.0000 15.0000 47094.5000 245992.0000 58.74 526.5000 15.5000 48314.6250 269844.2813 82.44 527.0000 16.0000 49534.7500 294306.6250 86.21 527.5000 16.5000 50754.8750 319379.0313 89.82 528.0000 17.0000 51975.0000 345061.5000 93.32 528.5000 17.5000 52612.5000 371208.3750 96.70 529.0000 18.0000 53250.0000 397674.0000 99.97 Maximum Storage = 397674.0000 (cu ft) Maximum Discharge = 99.97 (cfs) 7 Hollymead Towncenter 1/19/2004 Regional Service Area C Sediment Basin 1 FLOOD HYDROGRAPH REPORT Hydrograph Number: 4 Name: DA -Z Rtd., 2 year Type: Reservoir: Modified Puls [HYDROGRAPH INFORMATION] = 1 Peak Flow (Qp) = 5.15 (cfs) Time to Peak (Tp) = 806.00 (min) Time of Base (Tb) = 2880.00 (min) Volume = 2.8423 (ac -ft) Time Step = 2.00 (min) Peak Elevation = 524.2494 (ft) Detention Time = NA [RESERVOIR STRUCTURE INFORMATION] Number = 1 Name = SWM1 - SED BASIN Storage Type = User -Defined Area Maximum Storage = 397674.0000 (cu ft) Maximum Discharge = 99.97 (cfs) [INFLOW HYDROGRAPH INFORMATION] Number = 1 Name = DA -Z, 2 year Peak Flow (Qp) = 107.33 (cfs) Time to Peak (Tp) = 720.00 (min) Time of Base (Tb) = 1472.39 (min) Volume = 5.9620 (ac -ft) Flow Multiplier = 1.00 8 Hollymead Towncenter 1/19/2004 Regional Service Area C Sediment Basin 1 FLOOD HYDROGRAPH REPORT Hydrograph Number: 5 Name: DA -Z Rtd., 10 year Type: Reservoir: Modified Puls [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 46.25 (cfs) Time to Peak (Tp) = 732.00 (min) Time of Base (Tb) = 2880.00 (min) Volume = 7.2062 (ac -ft) Time Step = 2.00 (min) Peak Elevation = 525.7762 (ft) Detention Time = NA [RESERVOIR STRUCTURE INFORMATION] Number = 1 Name = SWMl - SED BASIN Storage Type = User -Defined Area Maximum Storage = 397674.0000 (cu ft) Maximum Discharge = 99.97 (cfs) [INFLOW HYDROGRAPH INFORMATION] Number = 2 Name = DA -Z, 10 year Peak Flow (Qp) = 180.83 (cfs) Time to Peak (Tp) = 720.00 (min) Time of Base (Tb) = 1472.39 (min) Volume = 10.3260 (ac -ft) Flow Multiplier = 1.00 0' Hollymead Towncenter 1/19/2004 Regional Service Area C Sediment Basin 1 FLOOD HYDROGRAPH REPORT Hydrograph Number: 6 Name: DA -Z Rtd., 100 year Type: Reservoir: Modified Puls [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 88.42 (cfs) Time to Peak (Tp) = 730.00 (min) Time of Base (Tb) = 2880.00 (min) Volume = 11.7080 (ac -ft) Time Step = 2.00 (min) Peak Elevation = 527.3060 (ft) Detention Time = NA [RESERVOIR STRUCTURE INFORMATION] Number = 1 Name = SWMl - SED BASIN Storage Type = User -Defined Area Maximum Storage = 397674.0000 (cu ft) Maximum Discharge = 99.97 (cfs) [INFLOW HYDROGRAPH INFORMATION] Number = 3 Name = DA -Z, 100 year Peak Flow (Qp) = 253.98 (cfs) Time to Peak (Tp) = 720.00 (min) Time of Base (Tb) = 1472.39 (min) Volume = 14.8278 (ac -ft) Flow Multiplier = 1.00 10 'ST 44 \ ` \ o \ 55 Z �� • t � ! f f / �! n \ \ ,moo \\ \ Z r� 57. 5 40 oa�l.�_NLTH o, �9 TIMOTHY R. 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