Performance analysis of constructed urban stormwater detention ponds

The management of stormwater runoff is becoming an increasingly important issue to Tennessee communities as urban development expands. With such development, the amount of stormwater runoff generally increases. Detention ponds are the most common tools used to control excess stormwater caused by increased development. The main components of a detention pond are the storage volume, the dam, and the control outlet. If any of the components are designed or constructed incorrectly there is a possibility of downstream damage and flooding which can result in costly lawsuits.

Twenty ponds in the Knoxville area were analyzed to determine if the ponds were built to the intended design. Constructed detention ponds from five jurisdictions were surveyed and compared to the intended design and design plans.

This study indicated that seventeen of the twenty ponds were not built according to the intended design plans. The ponds have inadequate storage volumes, under-constructed outlets, or a combination of the two. The result is that the ponds are ineffective in reducing the peak runoff to the downstream residents. Recommendations are presented for regulators, designers, and those performing construction. One of the most important recommendations is that the detention ponds should be inspected during and after construction to insure compliance with design plans.