b'STORMWATERCATALOG STORM WATER QUALITY MANAGEMENT PLAN CALCULATIONS Provide detailed design calculations for all structural controls used on the site.Example:Dry Detention Basin1.Determine the drainage area that contributes storm water runoff to the basin. ExampleThe drainage area served only accounts for the storm water runoff from inlet 1.Inlet 2 drains the backslope swale and is not included in the calculations.The inlets are identified inExhibits 5.A \x1e 20 acres2.Compute the water quality treatment volume. The water quality treatment volume is 0.5 inches of runoff from the drainage area. V wq \x1e 0.5 in\x1d 1 ft \x1d 20 acres \x1e 0.83 acre \x1f feet12 in3.Design the basin layout with approximate length to width ratio of at least 3:1. The basin width is 140 ft wide.The length of the basin is 440 ft and the side slopes are 3:1.The storm water quality depth was calculated based on an average storm water quality basin acreage of 0.36 acres. A b \x1e 0.36 acred wq \x1eV wq / A b \x1e 0.83 acre \x1f feet /0.36 acre \x1e 2.30 feet4.Calculate the orifice area require to drain 50 percent of the water quality volume within 24-hours. UsingEq. 2from theStorm Water Quality Management Guidance Manual , page 4-38, the orifice area required would be: A p \x1e V120.3 \x1ct \x1cHWhere:A p \x1e perforation area, square inches V \x1e the design volume, cubic feet V \x1e 50% V wq\x1ct \x1e the draw down time, hours C - 1 322 INFO@PARKUSA.COM|888-611-7275|WWW.PARKUSA.COM'