Optimizing Sediment Basin Configuration: Insights from SWMM Analysis for Improved Design Efficiency

Marketing Paragraph: Statement of Purpose: This project aims to enhance the performance of sediment basins by providing insight into the volumetric sizing of the live storage component. Through a long-term SWMM analysis across many locations in the U.S., recommendations will be made for future sizing guidance in the construction general permit. Specifically, the analysis will compare the mean percent of live storage volume utilized and the mean percent of inflow volume that overflows through the spillway for the proposed sizing methods to current sizing guidance.

Full Abstract: Complete Proposal for Your Session: This project aims to develop recommendations for future volumetric sizing guidance of the live storage component of sediment basins on construction sites. To do so, a study of the long-term performance of four proposed sizing guidance methods for sediment basins compared to two standard designs was conducted using the USEPA SWMM. Such proposed sizing methods include applying a sizing factor of 1,800 ft3 per acre (125 m3 per ha) of disturbed land and calculating the volume of runoff generated using the local 85th, 90th, and 95th percentile precipitation events. The two standard design sediment basins include calculating the runoff generated from the local 2-yr, 24-h storm event and applying the sizing factor of 3,600 ft3 per acre (250 m3 per ha) of disturbed land.
Stormwater runoff from construction sites is a leading cause of environmental degradation, yet sizing guidance for sediment basins lacks scientific justification and relies on industry rules-of-thumb. This study aims to provide scientific justification for sediment basin sizing regulations by investigating the mean percent of live storage volume utilized and the mean percent of overflow through the auxiliary spillway for each proposed sizing method compared to the standard methods.
Sediment basins were designed and sized in Excel for 25 locations across the United States, each with varying annual precipitation amounts. At each location, sediment basins were designed for each of the 6 sizing methods, including the 2 standard methods. The geometry data, along with several other parameters, were input into SWMM to run long-term simulations using the local historical precipitation and temperature data. This project seeks to provide further understanding of the long-term performance of sediment basins and hopes to both provide future sizing guidance as well as be used as a basis for future testing and analysis of the long-term performance of sediment basins to ensure that a sufficient amount of live storage volume is utilized while ensuring that overflow from the basin is not detrimental to water quality and downstream communities.