The Massachusetts Department of Environmental Protection (“MassDEP”) has been updating its policy and guidance to address improvements in scientific understanding as well as its experience in addressing site contaminants.  As we previously reported, significant changes to the Massachusetts site cleanup regulations, known locally as the Massachusetts Contingency Plan (“MCP”), became effective June 20, 2014.  These changes substantially revised numeric standards and closure requirements and modified the assessment and remediation of sites with vapor intrusion, historic fill, and light nonaqueous phase liquid (“LNAPL”).  Today, we provide an update on recent activities.

TCE Sites

Trichloroethylene or TCE is a volatile organic compound that at some sites seeps from soil or groundwater into the air of overlying buildings.  This is referred to as vapor intrusion.  The 2014 changes to the MCP made the site closure standard more strict for sites with TCE in groundwater to address concerns regarding vapor intrusion.  In addition, the MCP amendments substantially changed the approach to vapor intrusion sites placing greater emphasis on indoor air testing, among other things.  Guidance regarding these changes is still being drafted by MassDEP. 

But what of the sites with TCE in groundwater that were closed prior to the recent changes to the MCP?  MassDEP discussed this question at the October 22, 2015 Waste Site Cleanup Advisory Committee meeting.  MassDEP indicated that a fairly large number of sites (at least 700) have been closed out under previous versions of the MCP that allowed site closure under a less strict standard.  Further, MassDEP indicated that some of these sites may pose an “imminent hazard” because the existing science on the toxicology of TCE indicates that TCE can cause harm to a fetus in utero over a fairly short time frame and at low concentrations in indoor air.

While it is not clear today how MassDEP is going to evaluate these sites and on what timeframe, it is clear that MassDEP believes that some number of these sites must be reopened to address a current public health risk, and MassDEP will be evaluating closed TCE sites to identify which must be reopened.  

LNAPL Guidance

On November 1, 2015, MassDEP issued a second public review draft of its proposed LNAPL guidance entitled:  “Light Nonaqueous Phase Liquid and the MCP:  Guidance for Site Assessment and Closure.”  The first public review draft was issued in July 2014 and its informal public comment period ended October 20, 2014.  Over 100 pages of comments from seven individuals or organizations were submitted to MassDEP.

Based on our review of the revised draft, the essential elements have not changed, but the guidance has been rewritten to provide a clearer and more developed description of the underlying science, how specific lines of evidence can be utilized to develop a site-specific conceptual site model, and how to use these lines of evidence to comply with the MCP.  The guidance continues to provide as an option for petroleum sites a simplified approach that is presumptively compliant with the MCP.

MassDEP has opened an informal public comment period on the revised LNAPL guidance that ends on December 18, 2015. 

Other MCP Guidance

Since the MCP was revised in June 2014, MassDEP has been developing guidance materials to assist with implementation.  These include the Greener Cleanups Guidance, which has been finalized, and the LNAPL guidance, discussed above.  In addition, MassDEP hopes to finalize policies on notices of activity and use limitations and vapor intrusion during the fall of 2015 and plans to issue draft guidance on historic fill for informal public comment during the fall of 2015.