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Organic Carbon as Inhibitor to SVOC and Metal Migration
Citation:
SCHLOTTER, N., M. BORST, AND D. MCCHESNEY. Organic Carbon as Inhibitor to SVOC and Metal Migration. Presented at NGWA CONFERENCE ON EASTERN REGIONAL GROUND WATER ISSUES, RONKONKOMA, NY, June 23 - 24, 2008.
Impact/Purpose:
to present information
Description:
The Safe Drinking Water Act (SDWA) authorizes the Underground Injection Control (UIC) program to protect underground drinking water (USDW) sources from contamination caused by underground injection wells, including regulation of stormwater drainage drywells for parking lot and roof runoff. Samples of accumulated sediments collected from stormwater drywells during Environmental Site Assessments have exceeded New York State recommended soil clean-up objectives for semi-volatile organic chemicals (SVOCs), especially polycyclic aromatic hydrocarbons, and sometimes metals. Organic carbon accumulated in the sediment layer may limit the mobility and consequent threat from these compounds to the USDW. EPA conducted a limited sampling of stormwater drywells to determine how the concentrations of SVOCs and metals vary with depth and with organic carbon concentration in the sediment and native soil materials. Five stormwater drywells draining similar, highly trafficked paved parking surfaces were sampled. Core samples of accumulated sediment and underlying native soil were collected from each well. Analytical samples were collected from the extracted cores. The first sample was collected about 5 cm below the estimated bottom of the accumulated debris layer (e.g., twigs, trash, etc.). The second was collected about 5 cm above the interface between the sediment layer and the native soil layer. The final sample was collected about 0.5 m below the sediment-native soil transition. Analyses were conducted for soil moisture content, Organic Carbon, SVOCs, and arsenic, cadmium, chromium, copper, lead, mercury, palladium, platinum, and zinc. In wells containing standing water, the water was sampled and analyzed for the targeted metals. Results provided general information on contaminants and levels observed in the organic layer and native soil layer which showed both inter-well and intra-well variability.