URBAN STORMWATER POLLUTANT REMOVAL EFFICIENCY OF CATCH BASIN INSERTS

In a storm sewer system, the catch basin is the interface between surface runoff and the sewer. Responding to the need to improve the quality of stormwater from urban areas and transportation facilities, and the Phase I and II Stormwater Rules from the EPA, several companies market catch basin inserts as Best Management Practices (BMPs) for urban water quality management. However, little data have been collected under controlled tests that indicate the pollutant removal efficiency of these inserts when the inflow is near what can be expected to occur in the field. A stormwater simulator was constructed to test inserts under controlled and replicable conditions. The inserts were tested for removal efficiency of total suspended solids (TSS), and total petroleum hydrocarbons (TPH) at an inflow rate of 757 to 814 liters per minute (lpm) with influent pollutant concentrations of 225 milligrams per liter (mg/l) TSS and 30 mg/l TPH. These conditions are similar to stormwater runoff from small commercial sites in the Southeastern United States. Results from the testing indicate that at the test flow rate and pollutant concentration, average TSS removal efficiencies ranged from 11 to 42% and for TPH, the removal efficiency ranged from 10 to 19%.