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Volume 4: Investigative approach for petroleum VIAP

C.2.0 Structure adjacent to the vapor source

Near-slab soil gas or soil gas samples outside of a structure is the primary way to evaluate the VIAP when the vapor source is adjacent to and not beneath a structure. For petroleum, soil gas samples are collected for the evaluation of O2 and chemical analysis as described in Appendix B in the March 2016, Application of Target Detection Limits and Designated Analytical Methods.

If the O2 in the soil gas is greater than 2%, then there is sufficient O2 to support rapid aerobic degradation and a reduction in the LIZ may be established. Chemical analysis collected should affirm this. The number of sampling events required for a petroleum release for a structure that is adjacent to a vapor source is found in Table C-3.

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