The Town Garage/Radio Beacon site sits in Londonderry, New Hampshire, on High Range Road. The U.S. Department of Defense ran a radio beacon there from the early 1940s until 1968. Contamination was found in residential and commercial wells in 1984, and the town garage was identified as the likely source. EPA added the site to the National Priorities List (NPL) in 1989 and completed a full investigation by 1992.
Six contaminants were found in groundwater across the entire site. They are 1,1,1-trichloroethane, 1,1-dichloroethene, antimony, barium, beryllium, and chromium. EPA determined all six pose an unacceptable risk to human health or the environment based on the amounts found and their potential health effects.
Rather than digging up contaminated soil, EPA chose a practical remedy. Affected homes and businesses were connected to the public water supply, cutting off any exposure route through private wells. An open floor drain at the town garage was removed in 1996. EPA also relied on natural attenuation, meaning contaminants break down on their own over time while groundwater stays monitored. A residential development of about 45 homes was built over part of the groundwater plume from 1997 to 1998 and was connected to public water. Monitoring wells stayed in place, and contaminant levels dropped significantly over time.
Human exposure is under control, and groundwater migration has been stabilized with no unacceptable discharge to nearby surface water. Physical construction of the cleanup is complete across the entire site. EPA and the State of New Hampshire confirmed that all required cleanup under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) has been finished and no further cleanup by responsible parties is needed. The site was deleted from the NPL in July 2014. Five-year reviews confirmed the remedy continues to protect human health and the environment. The site now hosts two residential neighborhoods, Holton Circle with about 25 homes and Saddlebrook with about 20 homes, along with a wetland area.
Community members who have questions or concerns can contact EPA directly. Site records are available at Leach Library in Londonderry or at the EPA Region 1 Records and Information Center in Boston, Massachusetts. Anyone with concerns about a specific property should conduct a title search and review site files for details on cleanup standards and remedy components.
