EGLE RRD specifies soil gas sampling requirements for Final Assessment Reports
The Department of Environment, Great Lakes, and Energy (EGLE), Remediation and Redevelopment Division (RRD), is publishing the following policy to clarify the number of soil gas sampling events required for a Final Assessment Report (FAR). This policy was developed based on RRD's current knowledge of biodegradation of petroleum vapors and developed to be protective of human health and the environment while allowing corrective actions to move forward at petroleum releases regulated under Part 213, Leaking Underground Storage Tanks, of the Natural Resources and Environmental Protection Act, 1994 PA 451, as amended. The policy will reduce the number of unnecessary FAR extension requests related to obtaining multiple rounds of soil gas samples prior to FAR submission. It will also allow FARs to be submitted with ongoing soil gas sampling proposed in corrective action plans, as appropriate.
If an owner or operator is using soil gas samples to evaluate the volatilization to indoor air pathway (VIAP) as part of a risk-based corrective action site assessment, RRD has decided that it is often not practicable to conduct multiple soil gas sampling events prior to the due date for a FAR, as required by Section 324.21311a. Thus, multiple rounds of soil gas sampling is not required for the purposes of a FAR. This is consistent with the approach for delineating the extent of groundwater contamination, which is often based on a single groundwater sampling event in the FAR and followed up with multiple sampling events prior to closure to demonstrate groundwater plume stability. As appropriate, a corrective action plan to address the VIAP would include additional soil gas sampling with a contingency plan to address unacceptable risks.
RRD is developing guidance for evaluating the VIAP for petroleum releases regulated by Part 213. Until such guidance is finalized, the following recommendations from Table 4‑1 and 5-3 in the 2013 Guidance Document for the Vapor Intrusion Pathway are offered to evaluate the VIAP prior to closure. Generally, when evaluating VIAP risks from petroleum, use row 1 when evaluating the VIAP risk from soil/groundwater, use row 2 when evaluating from non-aqueous phase liquid (NAPL) that is stable (residual or mobile NAPL), and use row 3 when evaluating from NAPL that is not stable (migrating NAPL).
For questions regarding the Soil Gas Sampling Requirements for Final Assessment Reports, please contact Steve Beukema, Part 213 Program Specialist, EGLE, RRD, at 269-547-0125, or BeukemaS@Michigan.gov.
|
