Two months after installation of a new permeable reactive barrier (PRB) wall at the Peterborough South Municipal Water Supply Well Superfund site began, New Hampshire Ball Bearings (NHBB) Marketing Manager Robyn Nattila said the project is on schedule for its expected completion in October.

Peterborough’s South Municipal Water Supply Well was installed in 1952, and the NHBB facility opened just over 1,000 feet away in 1957. In 1982, the New Hampshire Department of Environmental Services (NHDES) determined the well was contaminated with volatile organic compounds. Investigations by NHBB and the state determined that NHBB was the source of the contamination. In 1984, the area was designated as a Superfund site by the EPA. Since then, NHBB has cooperated with the EPA and NHDES to help remediate the issue. Installing a new PRB, which will help clean contaminated groundwater as it flows through the barrier wall and away from the NHBB facility. is the most-recent project in the ongoing cleanup effort.

“The PRB is an example of technologies that NHBB has invested in toward the ultimate goal of reopening the South Well,” Nattila said, but added that decisions regarding the use of the South Well as a water supply for Peterborough will come after an evaluation from the state and the EPA.

A PRB is a vertical structure, installed underground in locations of natural groundwater flow, that allows the water to pass through it for treatment. The barrier is treated with a material that causes a chemical reaction which neutralizes the contamination before it flows out into the environment. While a PRB was previously installed at the site in 2014, an evaluation of the groundwater determined that it was not performing effectively enough, and it was necessary to install a new PRB using a different construction method in order to more effectively clean the groundwater.

According to Nattila, the primary contaminants found in the South Well are perchloroethylene (PCE) and trichloroethylene (TCE), which were common commercial and industrial cleaning solvents used in the 1950s through the early 1970s. 

“Prior to the development of modern waste-management practices, it was not uncommon for manufacturers in the ’50s and ’60s to dispose of liquid wastes ‘down the drain,’” said Nattila. “This did occur occasionally at NHBB, resulting in discharge of liquid wastes on NHBB property.”

Since the beginning of the cleanup, the NHBB has treated billions of  gallons of groundwater, Nattila said.