The New Hampshire Plating Co. site covers 13 acres in Merrimack, New Hampshire. An electroplating facility ran there from 1962 to 1985. Wastewater carrying metals, solvents, and cyanide flowed into unlined lagoons, contaminating on-site wetlands, soils, and groundwater. The site was added to the National Priorities List in 1992 and has been in active cleanup ever since.
EPA has identified 31 contaminants of concern across groundwater, soil, and soil gas. These include volatile organic compounds such as trichloroethene, tetrachloroethylene, chloroform, and vinyl chloride. Heavy metals found at the site include arsenic, cadmium, chromium, lead, manganese, and nickel. Cyanide was detected in both soil and groundwater. In the area focused on trichloroethylene contamination, 1,4-dioxane and perfluorooctanoic acid (PFOA) were also found in groundwater.
Early cleanup work ran from 1987 through 2007. Workers treated lagoons, removed contaminated sludges and soils, demolished the building, and installed a soil cover system. A 1998 cleanup plan selected natural attenuation to address groundwater, but a 2014 five-year review found that approach was not working as expected. A follow-up investigation from 2015 to 2018 showed higher-than-expected tetrachloroethylene levels, caused by the contaminant seeping back out of less permeable soil layers. In response, EPA issued a modified cleanup plan in August 2023. That plan calls for in-situ activated carbon injections and phytoremediation to treat groundwater in place. Remedial design was completed in July 2025, and remedial action was expected to start in spring 2026, with completion estimated between December 2027 and February 2028. In 2019, EPA installed a vapor intrusion mitigation system at a neighboring property to address contamination concerns there.
Human exposure at the site is currently under control, and contaminated groundwater is stabilized within the original area of contamination. Physical construction is complete across the entire site, but cleanup goals for current and expected future land uses have not yet been fully achieved. Institutional controls remain in place to limit land use and protect cleanup components. The most recent five-year review was completed in February 2025.
Community members who want to stay informed can review site documents at the Merrimack Public Library in Merrimack, NH, or at the EPA Region 1 office in Boston, MA. For questions, community members can contact the EPA's Community Involvement Coordinator or Remedial Project Manager.
(NOTE: This summary was created based on all information available on the EPA's official site profile page as of May 29, 2026. To see the most up-to-date information provided by the EPA, visit the EPA's official profile page for this site. For questions, or to politely encourage the EPA keep their profile pages current, contact the EPA Community Involvement Coordinator or Remedial Project Manager assigned to this site.)
