You are here:
VERTICAL PROFILING OF VOCS IN GROUNDWATER AND SOIL VAPORS TO EVALUATE THE RISK OF VAPOR INTRUSION
Citation:
PAUL, C. J. AND D. C. DIGIULIO. VERTICAL PROFILING OF VOCS IN GROUNDWATER AND SOIL VAPORS TO EVALUATE THE RISK OF VAPOR INTRUSION. Presented at Groundwater Resources Association of California High Resolution Site Characterization and Monitoring, Long Beach, CA, November 14, 2006.
Impact/Purpose:
To inform the public.
Description:
The Draft EPA Subsurface Vapor Intrusion Guidance Document was established to address the incremental increases in exposures and risks from subsurface contaminants that may be intruding into indoor air@. The document utilizes attenuation factors based on indoor air/soil gas or indoor air/groundwater concentration ratios in order to calculate vapor intrusion action levels. This study compared both soil gas and groundwater concentrations of VOCs from three locations at the Raymark Superfund site in Stratford, CT. Groundwater samples were obtained using traditional sampling methods including a bladder pump, a peristaltic pump, and a Grundfos® submersible pump. Vertical profile devices (polyethylene passive diffusion bags and a discrete multi-level sampler) were used in monitoring wells to compare discrete interval concentrations with the pumped values. Soil gas and groundwater water samples were obtained using direct push technology (Geoprobe®) adjacent to monitoring wells for comparison purposes. Samples were analyzed for 1,1,1-TCA, TCE, and 1,1-DCE. Results of this study indicate that using groundwater concentrations may not provide adequate information to assess risk from vapor intrusion. Location, depth, and method of samples collection and spatial variability must be considered if groundwater data are used in the risk assessment process.