Evaluation of purging methods when sampling for volatile organic compounds from low-yield monitoring Wells
The purpose of this laboratory study was to determine the effects various purging procedures have on chlorobenzene and 1,1,1-Trichloroethane concentrations in a simulated monitoring well and how effective purging procedures were in providing representative samples. The experimental apparatus consisted of a teflon monitoring well complete with filter pack and bentonite seal constructed in a 10.2 cm diameter stainless steel screen and casing which acted as a "borehole" for the monitoring well. Low-permeability soil in a 25.4 cm diameter stainless screen surrounded the borehole and simulated an aquitard or low-permeability aquifer. This apparatus was placed in a tank filled with chlorobenzene and 1,1,1-Tricholorethane-spiked water. The experiments included the purging procedures mentioned above. Samples were collected before purging, during water-level recovery and 24 hours after purging. Contaminant concentrations within the tank were monitored before and after each experiment to establish a baseline in which to compare the sampling results of each purging experiment. (Abstract shortened with permission of author.).
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