M E M O R A N D U M

To: Voluntary Response Action Program (VRAP) Users

From: Nicholas Hodgkins, VRAP Coordinator

Date: February 18, 2009

Re: Consideration of vapor issues at Maine Voluntary Response Action Program (VRAP) petroleum sites

For non-Stringent classified sites that have petroleum contamination, the guidance in the January 1, 2009, “Procedural Guidelines for Establishing and Implementing Action Levels and Remediation Goals for the Remediation of Oil Contaminated Soil and Ground Water in Maine” (hereinafter referred to as the “Petroleum Cleanup Guidelines”) will need to be followed to determine if the site is classified as a “Baseline 2” or “Intermediate” site. You may follow the standard operating procedure (SOP) for soil gas sampling referenced in the Petroleum Cleanup Guidelines, or provide VRAP with an alternative method for our review and approval. Both onsite and offsite vapor issues must be considered. The Petroleum Cleanup Guidelines and the Soil Gas Sampling SOP can be found on the petroleum program web page at:
http://www.maine.gov/dep/spills/petroleum/index.html .

In lieu of soil-gas sampling, a site may be classified as Baseline 2 if 1) new construction is planned for the site that will include engineered vapor mitigation systems, or 2) current onsite structures will have engineered vapor systems installed, and 3) there are no offsite impacts.

If a petroleum site is classified as an Intermediate site, measures will need to be taken to eliminate the hazard. This can be accomplished through soil removal to the Intermediate standard, or by installation of engineered vapor mitigation systems (i.e. vapor barriers, depressurization systems, sub-slab venting systems, etc.). Engineered mitigation systems submitted to VRAP must be stamped by a Maine Professional Engineer. The mitigation system must also be certified as “working” as designed (i.e. achieving the task it was designed for) after installation by a Maine Professional Engineer. This can most easily be demonstrated through sampling.

For other, non-petroleum VRAP sites, the soil gas sampling SOP may be followed to collect vapor samples if volatile organic compounds (VOCs) are present or suspected to be present at a site.