SOUTH CAROLINA STORMWATER DETENTION PONDS: SEDIMENT ACCUMULATION AND NUTRIENT SEQUESTRATION

Wet detention ponds are commonly used as a means of managing stormwater runoff in South Carolina’s Low country. As sediments accumulate in these ponds, water volume is reduced leading to a decrease in runoff retention. Periodic dredging is required to maintain pond function, but dredging is costly and there is little data available to support how often pond dredging is required. This study aims to determine the rate at which sediments are accumulating in ponds, the sources of sediments, and the role sedimentation plays in nutrient retention within ponds. It is hypothesized that the answers to these questions will be dependent on a host of characteristics including size, influent sources, watershed development density, trophic status, and treatment regime.

Core samples will be collected from sample ponds and radiometrically dated using lead-210 to determine the rate of sediment accumulation. Biomarker analysis of n-alkanes in core samples will give insight into the origins, terrestrial or aquatic, of organic carbon in sediments. Total carbon, nitrogen, and phosphorus will also be determined to assess the carbon and nutrient sequestration capacity of these ponds. This information can help inform future pond management decisions as well as increase understanding of how coastal stormwater ponds collectively alter material transport and transformations along the land-sea interface.