Abstract
A method is presented to estimate the sediment volume and associated frequency of sediment dredging for sedimentation basins (SBs) by applying the Revised Universal Soil Loss Equation Version 2 (RUSLE2) with additional site-specific information. Sedimentation basins in Pennsylvania are currently designed according to the standards of allocating 2000 cubic feet (57 m3) of sediment storage volume per acre of drainage basin as suggested by Pennsylvania Department of Environmental Protection. A procedure for calculating sediment storage volume and sediment dredging frequency concomitant with soil loss from the drainage basin is currently not available. Inadequate provisions for sediment volume lead to accumulation of sediment in the basin, decreasing particle removal and increasing outlet total suspended solids concentration. RUSLE2 was applied to estimate sediment delivery into four SBs at a Pennsylvania Department of Transportation I-99 construction site. RUSLE2 estimate was higher than the field-measured value by roughly 30%. Field observations indicated that the basins were filled with sediment beyond the sediment zone, and basin effluent sampling showed peaks in sediment concentration. Hence, the RUSLE2 estimate appears reasonable, accounting for soil loss from the basin. Furthermore, RUSLE2 analysis explained that the basis for observed high turbidities in one of the basins was a result of increased sediment delivery to the basin, due to physical configurations and the types of grassy areas associated with that basin. Results show that to control sediment resuspension and sediment loss in the basin, the design for sediment volume of a basin must be calculated individually, accounting for sediment delivery, soil particle size, and precipitation events. RUSLE2 has been used here to show how a soil loss calculation tool can be used in organizing these data for design purposes.
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