Performance Monitoring of Temporary Sediment Control Basins

Earthmoving activities during construction cause disruption of stabilized land, leaving sites susceptible to soil erosion. To minimize water quality implications downstream of active construction sites, regulations require stormwater pollution prevention plans, which encompass the design, installation, and maintenance plan of erosion and sediment control practices used during construction. One common sediment control practice used on construction sites is a sediment basin. This research evaluated the performance efficiency of temporary sediment control basins through in-field monitoring of two basin systems on the U.S. 30 expansion project in Tama County, Iowa. Monitoring was conducted on a single basin over a period of four weeks in the fall of 2018 and captured seven rain events. Turbidity and total solids concentrations were used to determine performance efficiency of the basins. The basin provided an average turbidity reduction of -92 NTU, indicating higher turbidity at discharge than inflow, and total solids reduction of 15.5 mg/L. A five-week monitoring period of two basins in series captured fifteen rain events. The two basins provided average turbidity reductions of 24 and 107 NTU, respectively, and a collective turbidity reduction of 43 NTU. Design modifications to the standard sediment basin were suggested to enhance performance including: use of an upstream rock check dam, geotextile lining, coir baffles, and surface dewatering system.