The Massachusetts Department of Environmental Protection plans to begin contacting some owners of properties with closed trichloroethylene (TCE) remediation sites and requiring them to conduct testing, following a review of approximately 1,000 sites with TCE in groundwater closed prior to the 2014 changes to the TCE standards. We reported in our last edition that MassDEP has been considering reopening such sites contaminated with TCE that had been assessed and closed under older, more lenient regulations.

At the January 28, 2016 Waste Site Cleanup Advisory Committee meeting, MassDEP stated that approximately 200 sites of the 1,000 it reviewed may present a significant indoor air issue. If initial testing of groundwater, soil vapor, or indoor air suggests that further investigation or other action is necessary to address an indoor air issue, MassDEP will require the owner to take that action.

We understand that MassDEP is concerned about the potential health risks of TCE at these sites for several reasons:

  • First, TCE is volatile, and therefore TCE in soil or groundwater under or near a building may seep into the air of that building. If this occurs, there is a potential exposure pathway for humans occupying or residing at that location.
  • Second, the scientific understanding of the potential health risks of TCE has evolved significantly, with the result that the standard in Massachusetts has become more strict. For example, the reportable concentration for TCE in groundwater near buildings has changed from 300 ug/L before 2006 to 5 ug/L today. As a result, MassDEP has indicated that it is possible that sites closed properly under the prior standard could pose an imminent hazard under current standards.
  • Finally, as MassDEP has described in its fact sheet on TCE Toxicity Information: Implications for Chronic and Shorter-Term Exposure (August 15, 2014; revised 3/27/2014), a potential risk posed by TCE exposure is developmental heart defects, which can occur after only short-term exposure during a critical phase of gestation. As a result, MassDEP has emphasized that the possibility that TCE concentrations in indoor air are significant should be considered fairly early in the site assessment process to ensure any imminent hazard is addressed promptly.