Dover Municipal Landfill accepted domestic and industrial waste, including leather-tanning wastes, organic solvents, and wastewater sludge, from 1960 to 1980. The site sits about 1,500 feet north of the Bellamy Reservoir, which supplies drinking water to Portsmouth and nearby communities. EPA added the site to the National Priorities List in September 1983, and investigation work began in March 1984.
Groundwater is the primary concern. It contains chlorinated solvents such as trichloroethene, tetrachloroethene, vinyl chloride, and dichloromethane, along with 1,4-dioxane, benzene, toluene, acetone, and arsenic. Surface water, soil, and sediment also carry contaminants including heavy metals like arsenic, cadmium, lead, and mercury. In total, EPA has identified 39 contaminants of concern across all media at the site.
EPA selected a cleanup plan in September 1991 covering landfill recontouring, a cap to block water infiltration, a groundwater collection system, and long-term monitoring. The plan was updated in 2004 and again in 2009, adding air sparging and multi-level groundwater extraction. In May 2022, EPA finalized an Explanation of Significant Differences that added 1,4-dioxane as a contaminant of concern and updated groundwater cleanup levels. Physical construction wrapped up in September 2012. The Dover Group, representing the responsible parties, is implementing recommendations from EPA's most recent five-year review.
The five-year review completed in September 2022 found that the landfill cap and groundwater extraction system are generally working as intended. However, 1,4-dioxane and PFAS are migrating toward the Bellamy Reservoir in the Southern Plume area. As of 2023, no contaminants have been detected above drinking water standards in reservoir intake samples. Two residential wells were historically affected by site contamination, but a water line installed in 1981 eliminated that exposure pathway. There are currently no human exposures to site contamination. The landfill is capped, the area has public water service, and institutional controls restrict land use and groundwater use at the site. The next five-year review is scheduled between September and November 2027, with sitewide readiness for anticipated reuse expected between December 2027 and February 2028.
Community members can contact EPA's Community Involvement Coordinator or the Remedial Project Manager. Site documents are available at the Dover Public Library at 73 Locust Street or at the EPA Region 1 Records and Information Center in Boston, reachable at (617) 918-1440.
