| 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
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| Resource Type: |
document --> case study
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| Country: |
USA
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| Year: |
2007 |
| Availability: |
EPA 600-R-06-111
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| Author 1/Producer: |
US EPA
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| Author / Producer Type: |
Agency, regulator or other governmental or inter-governmental body
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| Format (e.g. PDF): |
PDF
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| Size: (e.g. 20mb) |
4.67
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EUGRIS Keyword(s): |
Contaminated land-->Site investigation-->Methods
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| 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.
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Submitted By:
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Professor Paul Bardos WhoDoesWhat?
Last update: 16/04/2007
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