Strategies/guidance for managing stormwater: Infiltration vs. surface water discharge

Past studies have identified urban runoff as a major contributor to the degradation of many urban streams and rivers. The management of municipal stormwater runoff necessitates decisions as to whether the "disposal" of runoff should be through infiltration, surface discharge or a combination of the two. Typically, this management is addressed through the use of "best management practices" (BMPs) at the site in question or at a location in the conveyance system prior to discharge to a receiving water body either above or below ground. These BMPs may be selected based on site-specific conditions and discharge requirements, but often they are selected based on past history of what has worked in the municipality, the experience of the planners with specific BMPs, and regulatory requirements on the federal, state and local level. The primary objective of this project is to develop a preliminary guidance document for municipal planners and engineers to use when they are evaluating their various stormwater management options, especially as they balance master planning requirements for their specific localities/regions and regulatory requirements. The preliminary guidance manual will propose a simple decision tree analysis structure to guide planners through the steps needed to determine the requirements for infiltration as well as the water-quality standards and quality of stormwater that may inhibit the use of infiltration. Copyright ASCE 2005.