20.5 BMP F140 - Parking Lots for Additional Detention

Private parking lots may be used to provide additional detention volume for runoff events greater than the 2-year runoff event provided all of the following are met:

The depth of water detained does not exceed 0.5 feet (6 inches) at any location in the parking lot for runoff events up to and including the 100-year event.

The gradient of the parking lot area subject to ponding is 1 percent or greater.

The emergency overflow path is identified and noted on the engineering plan. The overflow must not create a significant adverse impact to downhill properties or the downstream stormwater system.

Fire lanes be used for emergency equipment are free of ponding water for all runoff events up to and including the 100-year event.

A signed letter from the property owner is provided stating they understand that the Parking Lot is being proposed for detention and a covenant and easement agreement is signed and recorded and includes the parking lot as part of the detention facility.

Comply with all criteria and standards in Modeling Your Best Management Practices, Design Criteria for All Stormwater Treatment and Flow Control BMPs, Constructing Your Best Management Practices and Accessing and Maintaining Your Best Management Practices as applicable to the project in addition to criteria within each BMP. Where criteria or standards conflict, utilize the criteria and standards contained within the specific BMP.