Site evaluation activities at the Site were performed by the Maryland Department of the Environment (MDE) per agreement with EPA Region 3’s Site Assessment Branch beginning in March 2014. A Site Inspection report was prepared by MDE in April 2015 followed by more extensive vapor intrusion investigatory work by MDE at three homes in August, November and December 2015. In February 2016, based on elevated subslab and indoor air analytical results for PCE found in two of the three homes sampled, MDE began plans to install VI mitigation systems at the two homes.
Based on geologic factors, it appeared to MDE that VI systems may be unusually costly. MDE had the ability to install a system at one home but officially requested EPA to install a system at the other home as well as take the lead for further investigatory and mitigation activities. EPA agreed to do so.
EPA collected indoor air samples at the second home and confirmed that PCE readings exceed acceptable levels particularly in light of the inhabitant demographics and living arrangement. This led to the preparation of a Special Bulletin and installation of a sub slab depressurization system at one home.
Beginning in October 2021, a Subsurface Vapor Extraction (SVE) system was installed adjacent to the dry cleaners as a pilot project. EPA is evaluating the system effectiveness by frequent monitoring and occasional sample collection. We are also conducting additional sampling of soil gas and groundwater to gauge the effect of the SVE system. If granted access, we plan to conduct further investigatory work in additional homes.
