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The Massachusetts Department of Environmental Protection (MassDEP) finalized their Vapor Intrusion Guidance: Site Assessment, Mitigation, and Closure document on October 14, 2016.  As stated from the guidance, “This document provides guidance on investigating, assessing, understanding, and mitigating vapor intrusion at disposal sites regulated under Massachusetts General Law, chapter 21E and the Massachusetts Contingency Plan.”

The vapor intrusion guidance was in draft form since October 2014 and went through a lengthy public review process prior to it being finalized.  For the most part, there were no substantial changes from the public comment draft version of 2014 to the final guidance; however, there were numerous changes in terminology and clarifications on various items throughout each section.

Wondering how this might affect your site or your remediation plans? Land Science® can assist with providing some of the insight into the new guidance document. Contact Land Science, we have a team dedicated to vapor intrusion and mitigation solutions.

Have other vapor intrusion or mitigation questions? Land Science’s team is always available to assist. In addition, you can visit the Land Science’s Resource Page for industry resource links to each state agency, vapor intrusion guidance, as well as national and federal guidance documents.

Pennsylvania’s Department of Environmental Protection (PADEP) issued the “Land Recycling Program Technical Guidance Manual for Vapor Intrusion into Buildings from Groundwater and Soil under Act 2” this summer and the document will become final in November 2016.  This 103-page Technical Guidance Manual outlines significant changes and replaces the original Technical Guidance Manual dated January 24, 2004.

As this is the first substantial change to the guidance in over twelve years, it is important to understand changes and how they might affect your site or remediation plan. Some of the key changes to the guidance include VOC mitigation requirements, soil and groundwater screening levels and methods, and vapor intrusion modeling guidance.

A full version of PADEP’s guidance document can be found at the Land Science’s Resource Page, as well as other national and federal guidance documents and other state guidances.  Have additional questions? Contact Land Science, we have a team dedicated to vapor intrusion and mitigation solutions.

California has issued revised screening levels (SL) for vapor-phase tetrachloroethylene (PCE). On September 8, 2016, California’s Office of Environmental Health Hazard Assessment (OEHHA) adopted an updated inhalation {Cancer} unit risk (IUR) factor for tetrachloroethylene (PCE). Updating the IUR also created revised recommended residential and commercial/industrial ambient air and soil gas screening levels (SL) for PCE. The Department of Toxic Substances Control’s (DTSC’s) revised PCE SLs are slightly more conservative than previous and remain below the United States Environmental Protection Agency (USEPA) SL for PCE. The USEPA’s SL are higher due to the use of a less conservative IUR (2.6E-07) than DTSC’s (6.1E-06) to derive its current SL; however, the USEPA acknowledges that the general IUR should not be used in all cases for evaluations and that “A number of uncertainties underlie the cancer unit risk for PCE…” Learn more by downloading the US EPA’s Chemical Assessment Summary of PCE here.

Below is a table of the former and revised DTSC SL’s.

On October 17, 2016, California’s DTSC Human and Ecological Risk Office (HERO) issued a response to inquiries associated with the PCE revised IUR and SL. Refer to this memorandum for further details associated with the updated IUR and SL’s. These SLs should be used in conjunction with the June 2016 Human Health Risk Assessment (HHRA) Note 3. DTSC indicates that a subsequent update to the HHRA Note 3 will be issued December 2016/January 2017, which will include the changes to the PCE toxicity criteria.

The exposure and risk factors for PCE and other chlorinated constituents, within the vapor phase, continue to be at the forefront of many regulatory agency mandated updates and often generate several topics of discussion. The overall trend continues to be conservative when evaluating the risk of these constituents. Ultimately, directing many site evaluations towards pre-emptive mitigation approaches, such as vapor intrusion are highly recommended to comply with increasing regulatory guidelines. Have further questions? Contact Land Science as our team of scientists and engineers are dedicated to vapor intrusion and mitigation related issues and developing solutions for sites across the US.