The W.R. Grace & Co. Acton Plant is a former industrial facility in Acton and Concord, Massachusetts, that produced sealants, latex products, and battery and concrete materials. The site has been on the National Priorities List (NPL), the federal roster of priority Superfund sites, since September 1983. Physical construction of the cleanup is complete, and the site reached ready-for-reuse status in October 2016. Groundwater treatment and monitoring continue, and the site remains on the NPL pending final deletion.
From 1954 until 1980, chemical wastes were disposed of in unlined lagoons and an on-site landfill. That contaminated soil, sediment, and groundwater across the property. EPA identified 41 contaminants of concern, including metals such as arsenic, cadmium, chromium, and lead, and volatile organic compounds (VOCs) such as benzene, trichloroethene, vinyl chloride, and 1,1-dichloroethene. Groundwater contamination spread offsite, and in 1978 two municipal water supply wells tested positive for 1,1-dichloroethene, prompting temporary closure. The Acton Water District installed air stripper units to remove contaminants from the water supply and continues operating them today.
Cleanup actions have included excavating about 10,140 cubic yards of contaminated sediments from Sinking Pond and North Lagoon Wetland, followed by replanting of the affected wetlands. Source control work was finished by 1997. A groundwater extraction and treatment system installed in 1983 was replaced in 2012 with a Landfill Area Treatment System that continues to pull and treat contaminated groundwater near the former landfill. Remaining groundwater contamination is also being addressed through monitored natural attenuation, a process that relies on natural breakdown of contaminants over time, combined with ongoing extraction and treatment. EPA's performance measures confirm that human exposure is currently under control across the entire site and that groundwater migration has been stabilized with no unacceptable discharge to surface water.
EPA completed its sixth Five-Year Review in June 2024. That review confirmed the remedy protects human health and the environment in the short term. An updated fact sheet was released in October 2024. Nine businesses now operate on-site, employing 35 people and generating about $8.6 million in annual sales. The Concord portion of the property has been redeveloped into a solar array and bus maintenance facility owned by the town. W.R. Grace owns most of the remaining land and continues planning for further redevelopment.
Community members can review site documents at the Acton Public Library at 486 Main Street or at the EPA Region 1 Records and Information Center in Boston. EPA held an open house on November 12, 2024, at Acton Town Hall, and posters from that meeting are available for review. For questions, residents can contact EPA's Community Involvement Coordinator Darriel Swatts or Remedial Project Manager Kara Nierenberg using the contact information below.
