Environmental Services, Wilmington, MA
By utilizing a 2014 revision to the regulations, Tata & Howard achieved permanent closure for a commercial developer on a Site in Wilmington, Massachusetts. The contaminants of concern at the Site are chlorinated volatile organic compounds (CVOCs). The CVOCs were detected in June 1994 as part of a due diligence assessment for bank financing, and the sources of the CVOCs are from prior operations at the Site that utilized chlorinated solvents to clean electronic parts. These compounds were released to the environment through improper disposal and leakage from the equipment that was used onsite.
Remedial activities were performed at the Site to reduce the concentrations of CVOCs in soil and groundwater, and in August 2000, a Class C Response Action Outcome (RAO) was filed with the Massachusetts Department of Environmental Protection (MassDEP) as a Temporary Solution. The Class C RAO concludes that there was “No Substantial Hazard” to human health, safety, public welfare, or the environment caused by the contamination at the premises. However, the ultimate goal was to achieve a condition of “No Significant Risk” and file a Permanent Solution. Because this was just a Temporary Solution, groundwater monitoring of selected wells continued through 2015 to demonstrate that conditions at the Site continued to support the No Substantial Hazard conclusion.
The hurdle to achieving No Significant Risk was overcome in 2014 when MassDEP revised the regulations to allow the use of active vapor intrusion mitigation systems to achieve a Permanent Solution. In May 2015, T&H filed a Release Abatement Measure (RAM) Plan for the installation of a sub-slab depressurization system (SSDS) at the Site. Based on more recent data, six points and radon type fans were installed to develop a negative pressure field beneath the western portion of the building that would mitigate the intrusion of CVOC vapors into the building. T&H also installed a remote telemetry system equipped with an alarm that will notify MassDEP and the owner of the building if the SSDS fails due to loss of power, mechanical issues, or other disruption of the system.
The building is primarily comprised of office and commercial warehouse space, and an Activity and Use Limitation was implemented as part of the Permanent Solution to prohibit more sensitive uses in the future, such as daycare or residential.