Petroleum Release Site Investigation

Biwabik, MN

During the investigation of several petroleum release sites in the City of Biwabik, Perchloroethylene (PCE), a dry cleaning solvent, was discovered. Our staff was retained to conduct an assessment of past property uses in the area to identify potential sources of the contamination. After identifying several possibilities, we developed a three-phase investigation plan.

The initial phase of the investigation consisted of installing passive soil gas samplers to screen the suspected sources for PCE. Two passive soil gas samples identified PCE contamination in one of the areas. The second phase of the investigation consisted of soil and soil gas sampling. This utilized direct push technology to verify the results of the passive soil gas sampling and to characterize contaminant concentrations at the apparent source of the release. The final phase utilized rotosonic drilling to collect discreet groundwater samples to determine the vertical and horizontal extent of groundwater contamination.