Watershed-Based Optimal Stormwater Management: Part 2—Hydrologic Modeling of LID/BMP Sites on Little Crum Creek in Suburban Philadelphia

A dynamic rainfall-runoff computer simulation model of the impaired Little Crum Creek (LCC) watershed in southeastern Pennsylvania was created using EPA's hydrologic simulation SWMM. The model was calibrated and verified using storm event data taken from three monitoring stations in the LCC watershed. The model was used in the second phase of a multiyear project to develop an action plan to promote installation of stormwater BMPs and green space preservation to restore water quality in the stream. Guidelines for selecting potential sites for projects were obtained in the first phase of the project using the optimization screening model StormWISE. The second phase involves detailed simulation studies of candidate sites in each of the four municipalities to better characterize the benefits to the watershed and to refine the cost estimates. Final recommendations for locations and types of BMP and LID projects are developed to maximize the reduction in volume and sediment loads at the least cost within the LCC watershed.