Title: Comparison of Geoprobe(R) PRT and AMS GVP Soil-Gas Sampling Systems with Dedicated Vapor Probes in Sandy Soils at the Raymark Superfund Site 
Resource Type: document --> case study 
Country: USA 
Year: 2007 
Availability: EPA 600-R-06-111 
Author 1/Producer: US EPA 
Author / Producer Type: Agency, regulator or other governmental or inter-governmental body 
Report / download web link (=direct link): http://www.epa.gov/ada/download/reports/600R06111/600R06111. ...  
Format (e.g. PDF): PDF 
Size: (e.g. 20mb) 4.67 
EUGRIS Keyword(s): Contaminated land-->Site investigation-->Methods
 
Short description: A study was conducted near the Raymark Superfund Site in Stratford, Connecticut to compare results of soil-gas sampling using dedicated vapor probes, a truck-mounted direct-push technique - the Geoprobe Post-Run-Tubing (PRT) system, and a hand-held rotary hammer technique - the AMS Gas Vapor Probe (GVP) kit. A comparison of VOC concentrations using dedicated vapor probes and the GVP sampling kit indicated that the two methods provided similar results. However, at one location, VOC concentrations were significantly higher for dedicated vapor probes indicating potential leakage with the GVP system. VOC concentrations using the PRT system were higher than VOC concentrations using dedicated vapor probes by an average factor of 1.2. This is the same magnitude observed for spatial variability on a scale of 1 m (median of 1.2 and average of 1.3 for 90 sample pairs). However, this effect did not appear to be due to spatial variability which would result in random scatter not a consistent bias as observed. It is also unlikely that extraction volume or sampling sequence caused the observed bias given the results of extraction volume and sample sequence testing. VOC concentrations using the PRT system were also higher than VOC concentrations using the GVP kit by an average factor of 2.4. Similar to the comparison between probe and PRT sampling systems, the effect did not appear to be due to spatial variability, extraction volume, or sequence of sampling. Thus, utilization of the PRT system resulted in observation of higher concentrations of VOCs compared to the GVP kit and dedicated vapor probes. However, variation in concentration was relatively minor when compared to spatial variability on the scale used for comparison testing. Hence for practical purposes, all three sample systems can be considered approximately equivalent. 
Link to Organisation(s): EPA Environmental Protection Agency
 
Submitted By: Professor Paul Bardos WhoDoesWhat?      Last update: 16/04/2007

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