Site runoff storage, also known as stormwater detention, is required for developments with a net new impervious area of 25,000 square feet or greater. Site runoff storage facilities consist of site runoff storage and a control structure with an emergency overflow.
The maximum allowable release rate is equal to 0.10 cfs multiplied by the number of acres disturbed by the development. The design rainfall depth and duration is the 100-year, 24-hour duration ISWS Bulletin 75 rainfall depth. Details and exceptions to site runoff storage requirements are in Article IX of the Ordinance.