Concord Monitor – Webster,  Hopkinton to share $4.1 million cost for septic sludge cleanup

The Hopkinton transfer station is facing a $3.6 million cleanup effort after sludge that has built up in septic tanks over the years was found to contain harmful “forever” chemicals.

Containing the contaminated site to prevent further environmental damage is now a costly but necessary project for the city.

Since both Hopkinton and Webster use the transfer station, the two cities split the cost, with Hopkinton covering 75% and Webster covering 25%. David Hemenway, Webster's chairman-elect, expressed concern about Webster's share of the project's financing.

“Obviously you want to make it easier for Hopkinton residents to do this rather than having to send it away,” Hemenway said.

At the same time, Hemenway said Webster residents don't want to end up paying the additional costs of this project just because they use the transfer station.

Over the years, the 52,000 tons of sludge containing “forever” chemicals have accumulated in the transfer station lagoons from municipal and commercial waste pumped from septic tanks, primarily from Hopkinton and Webster.

Hopkinton City Manager Neal Cass said sludge removal would normally involve preparation and application to fields, but the presence of forever chemicals (PFAS) has changed that approach.

A 10 percent rebate was added to the total cost of the project, bringing the total bond amount to $4.15 million, which will be voted on at the upcoming town meeting. Additionally, the city received a grant that will allow it to borrow that amount from the state's Clean Water Revolving Fund.

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Instead of transporting the waste elsewhere, which would cost about $13 million, a plan submitted to the New Hampshire Department of Environmental Services focuses on a more economical approach.

This plan calls for moving the contaminated material from a lagoon for on-site storage. The excavated area will be filled with rocks, sand and a barrier to ensure the mud remains six feet above the water table. The excavated mud is then placed back into the lagoon, covered and finally covered with another separating layer and a few centimeters of topsoil.

“The plan is really designed to protect cities well into the future,” Cass said. “It complies with all waste regulations.”

Sruthi Gopalakrishnan can be reached at [email protected].