Chemical and Biological Contamination of Stormwater Detention Pond Sediments in Coastal South Carolina

Acknowledgements This project was jointly funded by South Carolina Department of Health and Environmental Control – Office of Ocean and Coastal Resource Management and the South Carolina Sea Grant Consortium. The toxicology portion of this project was funded by The Citadel Foundation. We would like to acknowledge the following individuals for their valuable assistance in this project. Sadie Drescher was involved in pond selection and field sampling, and she also conducted the survey of pond maintenance histories. Mark Messersmith delineated drainage areas, determined impervious cover, and produced maps. Denise Sanger was also involved in the pond selection process and provided critical insight to the overall study design. Ron Hemingway analyzed several sediment samples on the GC. Numerous students assisted us with field sampling and laboratory analytical work. They are as follows: facilitating the analysis of total organic carbon and sediment fecal coliforms, respectively, for this project. 3 Executive Summary Stormwater ponds are a common management practice to protect the water quantity and quality of runoff entering natural receiving waters. Ponds are popular among developers for a number of reasons including the fact that they provide open space and wildlife habitat, provide fill material, can be aesthetically pleasing, and require little maintenance. However, the sediment which accumulates in the ponds must periodically be removed in order to maintain pond efficiency. Currently, in South Carolina, there are no requirements that stormwater pond sediments be tested for chemical or biological contaminants prior to sediment removal. Recent reports from elsewhere have characterized stormwater pond sediments, and suggest that contaminant levels can vary widely from background levels to enrichment that is several orders of magnitude greater than background. The purpose of the current project was to characterize the chemical and biological contaminants in stormwater pond sediments here in coastal South Carolina. Stormwater ponds (16 individual ponds) were selected from the suburban areas of Charleston, Beaufort, Georgetown and Myrtle Beach. These ponds represented a subset of stormwater ponds sampled in 2006 as part of a SCDHEC-OCRM water quality survey. Based upon information provided in the original SCDHEC permit, all stormwater ponds were classified into one of four land use classes: golf course, low density residential, high density residential, and commercial. In addition, two manmade ponds not known to be receiving any stormwater runoff were selected as reference ponds. Personnel from SCDHEC-OCRM provided us with information concerning permit age, drainage area, impervious cover, pond surface area, maintenance …