MULTI-PHASE APPROACH FOR CHARACTERIZING RESIDUAL CVOCS IN COASTAL PLAIN SEDIMENTS AT THE SAVANNAH RIVER SITE, SOUTH CAROLINA

Shallow vadose zone sediments beneath the TNX facility at the Savannah River Site are contaminated with residual chlorinated volatile organic compounds (CVOCs). A multi-phase approach was initiated to characterize the vertical and lateral extent of the residual CVOCs in the vadose zone, characterize the stratigraphy, and determine the best remediation technology. Each phase included the use of different tools that were best suited for the desired results. The different tools included continuous splitspoon soil sampling with an auger rig, soil vapor sampling with Cone Pentrometer Technology (CPT), and the installation of Soil Vapor Extraction (SVE) wells. The final phase will consist of performing SVE tests to characterize the extent and concentration of contaminants.

A multi-phase approach was taken to accurately characterize the stratigraphy and residual CVOCs because of the heterogeneous sediments underlying the TNX facility. The sediments are unconsolidated and semiconsolidated and made up of mainly shallow-marine quartz sands with clay and silt layers. The heterogeneity of these sediments required dense coverage of data to accurately map the geology and contaminant concentrations in order to design and install an effective remediation system.