Stormwater must be pretreated before discharging to infiltration areas to maintain the long-term viability of the infiltration area. Developments and redevelopments must incorporate effective non-point source pollution reduction BMPs to achieve 90% total suspended solid removal. Findings 1. A hydrograph method based on sound hydrologic theory is used to analyze runoff for the design or analysis of flows and water levels. 2. Runoff rates for the proposed activity do not exceed existing runoff rates for the 2-, 10-, and 100-year critical storm events. Stormwater leaving the project area is discharged into a well-defined receiving channel or pipe and routed to a public drainage system. 3. Stormwater runoff volume retention is achieved onsite in the amount equivalent to the runoff generated from one inch of rainfall over the impervious surfaces of the development. a. The amount of proposed impervious onsite is 32,647 square feet. b. Volume retention: Volume Retention Required (cu. ft.) Volume Retention Provided (cu. ft.) 2,449 2,779 c. Banking of excess volume retention is not proposed. d. Infiltration volume and facility size has been calculated using the appropriate hydrological soil group classification and design infiltration rate. e. The infiltration areas are capable of infiltrating the required volume within 48 hours. f. Stormwater runoff is not pretreated to remove solids before discharging to infiltration areas. 4. Best management practices achieve 90% total suspended solids removal from the runoff generated on an annual basis. 5. A recordable executed maintenance agreement has not been submitted.
RULE D: FLOOD CONTROL Standards Compensatory storage shall be provided for fill placed within the 100-year floodplain. All habitable buildings, roads, and parking structures on or adjacent to a project site shall comply with District freeboard requirements. Findings 1. There is no floodplain on the property according to FEMA. 2. All habitable buildings, roads, and parking structures on or adjacent to the project site comply with CRWD freeboard requirements.
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