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adjacent to the disturbed area. The use of vertical retaining structures is <br />specifically prohibited. <br />Velocitdissipation: Velocity dissipation devices shall be placed at discharge <br />locations and along the length of any outfall to provide non-erosive flow velocity <br />from the structure to a water resource so that the natural physical and biological <br />characteristics and functions of the water resource are maintained and protected. <br />C. Stormwater Quality Control: The site shall be designed to direct runoff to one or more <br />SCMs that meet or exceed the criteria in the Construction General Permit. <br />D. Stormwater Quantity Control: The Comprehensive Stormwater Management Plan shall <br />describe how the proposed SCMs are designed to meet the following requirements for <br />stormwater quantity control for each watershed in the development: <br />The peak discharge rate of runoff from the Critical Storm and all more frequent <br />storms occurring under post -development conditions shall not exceed the peak <br />discharge rate of runoff from a I -year, 24-hour storm occurring on the same <br />development drainage area under pre -development conditions. <br />2. Storms of less frequent occurrence (longer return periods) than the Critical Storm, <br />up to the 100 -year, 24-hour storm shall have peak runoff discharge rates no <br />greater than the peak runoff rates from equivalent size storms under pre - <br />development conditions. The 1, 2, 5, 10, 25, 50 and 100 -year storms shall be <br />considered in designing a facility to meet this requirement. <br />The Critical Storm for each specific development drainage area shall be <br />determined as follows: <br />Determine, using a curve number -based hydrologic method or other <br />hydrologic method approved by the City Engineer, the total volume (acre- <br />feet) of runoff from a 1 -year, 24-hour storm occurring on the development <br />drainage area before and after development. These calculations shall meet <br />the following standards: <br />(l) Calculations shall include the lot coverage assumptions used for <br />full build out as proposed. <br />(2) Calculations shall be based on the entire contributing watershed to <br />the development area. <br />(3) Model pervious, directly connected impervious and disconnected <br />impervious areas as separate subwatersheds. <br />(4) Drainage area maps shall include area, curve number, and time of <br />concentrations. Time of concentration shall also show the flow <br />