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HomeMy WebLinkAboutWPO201400067 Calculations WPO VSMP 2015-03-05 New NNW' WPO 201400067 STORM WATER MANAGEMENT VOLUME CALCULATIONS FOR MINOR SITE PLAN AMENDMENT COVENANT CHURCH DATED: March 5, 2015 LOCATION: Tax Map 61, Parcel 156 Albemarle County, Virginia OWNER: Church of God 1025 East Rio Road Charlottesville, VA 22901 PREPARED BY: Meridian Planning Group, LLC 1413 Sachem Place, Ste 1 Charlottesville, VA 22901 434.882.0121 ' I/'l�7fY rte-r •s'� ��/ Z 'fir k�, ,'S •t4 PRE-DEVELOPMENT 1-YEAR RUN-OFF DA-A Pre-Development: 1-Year 24-Hour Runoff Hvdrooraph TR-55 Tabular Hydrograph Method Input Data: Rainfall Distribution Type . Type II Rainfall Depth 3.50 in Base Flow 0.00 cfs la/P Interpolation Off Subarea Downstream Area CN Tc Tt Name Subareas (acre) (hr) (hr) DA-A none 0.34 87 0.10 0.10 Computed Results: Peak Discharge ((gyp) 1.17 cfs Time to Peak 12.10 hrs Runoff Volume 0.04 acre-ft PRE-DEVELOPMENT 10-YEAR RUN-OFF DA-A Pre-Development: 10-Year 24-Hour Runoff Hydroaraph TR-55 Tabular Hydrograph Method Input Data: Rainfall Distribution Type ..Type II Rainfall Depth 5.60 in Base Flow 0.00 cfs la/P Interpolation Off Subarea Downstream Area CN Tc Tt Name Subareas (acre) (hr) (hr) DA-A none 0.34 87 0.10 0.10 Computed Results: Peak Discharge (Qp) 2.22 cfs Time to Peak 12.10 hrs Runoff Volume 0.07 acre-ft BASIN AND OUTLET PARAMETERS PRIMARY OUTLET DESIGN Outflow Total Discharge 44.90 cfs Water Surface Elevation 455.00 ft Tailwater Elevation 0.00 ft Detention Base Elevation 0.00 ft Outlet#1:Weir Shape Rectangular w/o Contracted End Crest Length 0.50 ft Invert Elevation 453.50 ft Coefficient 3.33 Number of Openings 1 Outlet#2: Riser Riser Top Elev 454.00 ft Riser Base Elev 445.00 ft Riser Diameter 48.00 in Orifice Coefficient 0.60 Weir Coefficient 3.33 Culvert Length 318.85 ft Culvert Diameter 36.00 in Culvert Invert In 425.36 ft Culvert Friction Coefficient .. 0.01 Culvert Entrance Loss Coefficient .. 0.10 Stage (ft) Discharge (cfs) 453.50 0.00 453.75 0.21 454.00 0.59 454.25 6.31 454.50 16.46 454.75 29.51 455.00 44.90 STAGE-STORAGE REPORT Elev(Ft) Area (SF) Storage(CF) 453.00 2329 0.00 454.00 3254 2908 455.00 4169 6619 POST-DEVELOPMENT 1-YEAR RUN-OFF DA-A: 1-Year 24-Hour Runoff Hydrograph TR-55 Tabular Hydrograph Method Input Data: Rainfall Distribution Type ..Type II Rainfall Depth 3.50 in Base Flow 0.00 cfs la/P Interpolation Off Subarea Downstream Area CN Tc Tt Name Subareas (acre) (hr) (hr) DA-A none 0.34 82 0.10 0.10 Computed Results: Peak Discharge (Qp) 0.96 cfs Time to Peak 12.10 hrs Runoff Volume 0.03 acre-ft DA-A: 1-Year 24-Hour Routed Hydrograph Storage Indication Method Results: Inflow Peak Flow 0.96 cfs Inflow Peak Time 12.10 hr Routed Peak Flow 0.02 cfs Routed Peak Time 15.95 hr Maximum Pond Storage 0.0374 acre-feet Maximum Pond Elevation 453.54 ft POST-DEVELOPMENT 10-YEAR RUN-OFF DA-A: 10-Year 24-Hour Runoff Hvdrodraph TR-55 Tabular Hydrograph Method Input Data: Rainfall Distribution Type ..Type II Rainfall Depth 5.60 in Base Flow 0.00 cfs la/P Interpolation Off Subarea Downstream Area CN Tc Tt Name Subareas (acre) (hr) (hr) DA-A none 0.34 83 0.10 0.10 Computed Results: Peak Discharge (Qp) 2.00 cfs Time to Peak 12.10 hrs Runoff Volume 0.07 acre-ft DA-A: 10-Year 24-Hour Routed Hvdrodraph Storage Indication Method Results: Inflow Peak Flow 2.00 cfs Inflow Peak Time 12.10 hr Routed Peak Flow 0.27 cfs Routed Peak Time 12.45 hr Maximum Pond Storage 0.0535 acre-feet Maximum Pond Elevation .. 453.79 ft