By Meredith Kendrick
The U.S. Environmental Protection Agency (EPA) is proposing a permanent public water line extension for neighborhoods affected by groundwater contamination linked to the former Tinkham Garage, a 375-acre Superfund site on Londonderry’s east side.
The site has a long and complex history. Originally agricultural land, it was later used by John Tinkham for hauling and washing industrial and septic waste, some of which was disposed of in trenches and leach fields. The site was added to the National Priorities List in 1983 after reports of “foamy, smelly” stream water and contaminated wells.
EPA officials said the contaminants of concern, including 1,4-dioxane and PFAS, can travel through fractured bedrock and reach private wells. “We know we have 1,4-dioxane and we know we have PFAS compounds, primarily PFOA and PFOS,” said Cheryl Sprague, the EPA’s remedial project manager. “Over 90% of households had detections of PFOA.”
The EPA released the plan on July 11 following years of sampling and monitoring that revealed elevated levels of 1,4-dioxane and PFAS in residential wells located downgradient from the site. At a public meeting on July 10, EPA officials said their proposed action is based on a determination that “groundwater used as drinking water downgradient of the site in these neighborhoods presents an unacceptable risk” to human health.
1,4-dioxane is a synthetic industrial chemical commonly used as a solvent stabilizer and found in products such as adhesives, paint strippers, and some personal care items. It is highly water-soluble and does not easily break down in the environment, which allows it to travel quickly through soil and groundwater. According to the EPA, 1,4-dioxane is classified as a likely human carcinogen based on evidence of cancer in animal studies. Exposure may occur through inhalation, ingestion of contaminated water, or skin contact, with potential health effects including liver and kidney damage and an increased risk of cancer over long-term exposure. Due to its mobility and persistence, 1,4-dioxane is difficult to remove from drinking water and is not effectively treated by standard filtration methods.
PFAS, or per- and polyfluoroalkyl substances, also referred to as “forever chemicals,” are a group of synthetic chemicals used in products such as nonstick cookware, waterproof clothing, firefighting foam, and food packaging. They do not break down easily in the environment or the human body. According to the U.S. Centers for Disease Control and Prevention and the EPA, exposure to certain PFAS has been linked to increased cholesterol levels, liver damage, thyroid disease, decreased vaccine response in children, developmental delays, and increased risk of kidney and testicular cancer. The National Academies of Sciences have also recommended blood testing for individuals with high exposure due to the chemicals’ persistence and potential long-term health effects.
The EPA’s preferred remedy includes connecting 89 homes that currently rely on private wells to municipal water and disconnecting those wells to reduce what officials called “stresses on the aquifer.” Sprague explained, “We would extend the water line and connect the households in these two neighborhoods to the water line. The design and the installation would be coordinated with your local supplier. Pennichuck Corporation is the local water supplier. They are the experts. This is considered a permanent provision of alternative water. It would stay there and it will immediately mitigate risk.” The targeted neighborhoods include the Boston, Charleston, and Albany streets, which are southeast of the Tinkham Garage site, as well as residential properties along Ross and Tokenol.
Since 2018, residents whose well water exceeded state or federal drinking water standards have been offered bottled water. According to the proposed plan, 66 homes are currently receiving bottled water while the long-term remedy is finalized.
The proposed fix is estimated to cost $6.8 million and would be implemented by responsible parties identified by the EPA under the Superfund program. The EPA may issue an order or carry out the work directly if necessary.
One resident asked about the cost to homeowners and the requirement to disconnect wells. Sprague replied, “Once you are connected and water is flowing into your house, you are responsible for the payment of your water.” The average monthly cost, according to Pennichuck Water, is expected to be about $60 per month over five years.
Home owners are not legally required to connect to the new public water line, but the EPA strongly encourages it to reduce health risks and environmental impacts. EPA officials confirmed that connection to the water system and disconnection of private wells require the homeowner’s permission through an access agreement. While some residents in previous Superfund projects have refused connection, the EPA typically installs a curb stop at the property line and may request permission to continue sampling private wells. Active private wells could continue to draw contaminated groundwater, increasing the risk of exposure and affecting nearby properties.
EPA officials encouraged residents to submit comments online at www.regulations.gov, by email, or by mail. “We want to hear from you,” Sprague said. “Yours is the final criteria we need to hear from.”
A formal public hearing is set for July 29 at 6 p.m. at Town Hall.
More information, including the proposed plan and meeting materials, is available on the town’s website under the Tinkham Garage Superfund Site section.