
DE National Guard
Location | New Castle, DE |
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Project Owner | Delaware Army National Guard |
Ten Bears performed a Limited Phase II Investigation on behalf of the Delaware Army National Guard. The Delaware Army National Guard plans to renovate the current on-site building and install a parking lot. The Limited Phase II Investigation was to evaluate the recognized environmental conditions identified in a previous Phase I Environmental Site Assessment. Recognized environmental conditions included impacts from on- and off-site underground storage tanks, and impacts from off-site fuel releases. It was also noted that the Site is adjacent to another site with known PFAS groundwater contamination. The Limited Phase II Investigation included the collection of soil, indoor air, and soil gas samples. Ten Bears collected the soil samples via hand auger, and installed vapor points to collect soil gas samples. Soil samples were submitted to Eurofins Lancaster Laboratories Environmental Testing for analysis of PFAS. Soil gas and indoor air samples were submitted to EMSL Analytical, Inc for analysis of volatile organic compounds. The soil laboratory results indicated that there were no PFAS compounds at concentrations exceeding regulatory levels for the proposed use.
As a precautionary measure, a Human Health Risk Assessment was done using the maximum detected concentrations. The risk assessment indicated no risk to a residential use scenario. The soil gas and indoor air laboratory results indicated no volatile organic compounds at concentrations exceeding regulatory screening levels. As such, neither petroleum vapor intrusion nor petroleum vapor within indoor air pose unacceptable risk to building users. Based on the findings, Ten Bears recommended no further evaluation of volatile organic compound-based vapor intrusion risk in and around the on-site building or indoor air conditions.
For PFAS in soil, Ten Bears recommended establishing a Contaminated Materials Management Plan and a Site specific Health and Safety Plan for use during earth-moving work, due to the potential for soil movement to inadvertently impact more sensitive receptors, if soils are relocated off site during construction. Ten Bears later expanded these plans to incorporate other Delaware Army National Guard facilities and assisted the client and their legal counsel with navigating the purchase of the Site within an EPA Superfund Site, as well as seeking regulatory agency approvals.