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City of Ramsey <br /> Project B1700969 <br /> March XX,2017 <br /> Page 10 <br /> DRAFT <br /> ■ DRO was detected at concentrations of 240µg/L,300µg/L,and 310µg/L in groundwater <br /> samples S-6W,S-8W,and S-9W, respectively.These concentrations exceed the provisional <br /> MDH HBV of 200µg/L for total petroleum hydrocarbons. <br /> F.S. Soil Vapor Analytical Results <br /> A summary of the soil vapor analytical results is provided in Table 3.The complete laboratory reports <br /> with chain-of-custody forms are included in Appendix D. <br /> For comparison purposes,Table 3 includes Intrusion Screening Values(ISVs). ISVs were developed by the <br /> Minnesota Pollution Control Agency(MPCA)in coordination with the Minnesota Department of Health <br /> (MDH)as screening values for evaluating vapor intrusion risks from VOCs identified in indoor air.The <br /> potential for indoor air to be impacted by soil vapor intrusion can also be assessed using ISVs. <br /> Concentrations of VOCs in air or soil vapor and ISVs are expressed in units of micrograms per cubic meter <br /> (µg/rn ). <br /> Per 2016 MPCA guidance,soil vapor results are compared to 33X ISVs to assess vapor intrusion risk. <br /> According to the guidance,soil vapor concentrations greater than 33X ISVs indicate a vapor source with <br /> potential vapor intrusion risk is present. A Site with contaminant concentrations greater than 33X ISVs <br /> would typically require either mitigation or additional assessment of potential pathways and receptors to <br /> better quantify risks,which might include collection of sub-slab or indoor air samples. <br /> The following provides a summary of the soil vapor analytical results. <br /> ■ Tetrachloroethene (PCE or PERC)was detected at a concentration between its Residential <br /> and Industrial ISV. <br /> ■ No other VOCs were detected at concentrations greater than Residential ISVs. <br /> BRAUN <br /> INTERT€C <br />