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2020 Volatilization To Indoor Air Pathway Screening Levels
The Department of Environmental, Great Lakes, and Energy Remediation and Redevelopment Division (RRD) developed the 2013 Guidance Document for the Vapor Intrusion Pathway (2013 VI Guidance) to provide information to department staff and their contractors conducting investigations and remedial or corrective actions at sites with potential vapor intrusion issues. The document is available as a technical reference to assist any party conducting activities to address the volatilization to indoor air pathway.
In June 2017, the department rescinded the vapor intrusion screening levels that were included in Appendix D of the 2013 VI Guidance. On June 2, 2020 RRD announced proposed modifications to Appendix D and accepted comments through July 2, 2020. RRD has reviewed the comments received and revised to clarify areas noted by the comments. A summary of the comments received and RRD’s response is available.
Effective today RRD makes the following modifications to the 2013 VI Guidance:
Replacement of rescinded Appendix D.1 – Volatilization to Indoor Air Pathway (VIAP) Screening Levels with Residential and Nonresidential VIAP Screening Level Tables
The VIAP screening levels are provided as a voluntary tool that may be used to determine that site conditions do not present a risk and allow a quick regulatory closure or that site conditions warrant a more site-specific evaluation, at common residential and nonresidential sites. The residential scenario represents a home with a basement and the nonresidential scenario represents an average-sized commercial building with slab-on-grade construction (e.g., gas station convenience store).
The availability of the VIAP screening levels do not affect the ability of a person to use the Part 201 generic cleanup criteria or Part 213 risk-based screening levels when appropriate and applicable, or to develop Part 201 site-specific volatilization to indoor air criteria (SSVIAC) or Part 213 site-specific target levels (SSTLs) under Section 20120b for the department’s review and approval. The availability of the screening levels will not change the validity of any SSVIAC or SSTLs that have been previously provided or approved by RRD. These remain valid for the conditions their development was based on and can still be used.
When site conditions are appropriate, these screening levels may be voluntarily proposed for use as Part 201 SSVIAC or Part 213 SSTLs. The use of the screening levels as Part 201 SSVIAC or Part 213 SSTLs requires documentation that the site conditions are appropriate for use. Therefore:
- Any document submitted under Part 201 that relies on the screening levels as SSVIAC including a Baseline Environmental Assessment, Documentation of Due Care Compliance, a Response Activity Plan, No Further Action Report, or any other document that is submitted for department review and approval must include the documentation.
- Any document submitted under Part 213 that relies on the screening levels as SSTLs including a Baseline Environmental Assessment, Documentation of Due Care Compliance, Final Assessment Report, or Closure Report submitted for department review and approval must include the documentation.
The addition of Appendix C.7 – Checklist for Determining if the Volatilization to Indoor Air Pathway Screening Levels Apply
A checklist for conditions that are not consistent with the development of the VIAP screening levels has been drafted to evaluate when Part 201 site-specific criteria or Part 213 SSTLs may need to be developed. This checklist will also be available to use to document site conditions are appropriate to voluntarily use of the screening levels as Part 201 SSVIAC or Part 213 SSTLs and may be included with submittals to the department to receive approval.
RRD continues to pursue the development of an on-line calculator that can assist in developing Part 201 SSVIAC or Part 213 SSTLs for scenarios where the screening levels do not apply, or where site conditions can be modified to produce more representative SSVIAC or SSTLs. Until the calculator is available, the department will continue to assist in developing SSVIAC and SSTLs for this pathway. Requests for assistance in their development may be made using the questionnaire available on the RRD Resource Materials web page. Alternatively, a person may develop SSVIAC or SSTLs using any of the options available in Section 20120b and submit the necessary information to the department for review and approval.
For questions regarding the development and/or use of the VIAP screening levels, please contact Dr. Shane Morrison, RRD Toxicologist, at morrisons5@michigan.gov, or the VI Technical Assistance and Program Support (TAPS) Points of Contact (POC) for the district where a site is located. Please do not reply to this email.
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