Sludge in septic lagoons accumulated over the years at Hopkinton’s transfer station has been identified as containing “forever” chemicals, and the town is working on a plan to resolve the issue. 

The movement comes after the Department of Environmental Services issued a notice after a site visit in 2021, urging the town to take action.

The accumulation of sludge in these lagoons comes from residential and commercial waste pumped from septic tanks, primarily within Hopkinton and Webster, said Neal Cass, Hopkinton’s town administrator.

“It has been determined, like everywhere, there is PFAS present in the sludge so we decided to close those lagoons and begin the cleanup process,” said Cass.

Since the notice was issued, the once-active lagoons have stopped accepting septic waste and town officials are now working with the Concord-based engineering firm NOBIS to develop a cleanup plan, expected to be ready by early September.

Any septic waste from the two towns is now diverted to wastewater plants in Concord and Allenstown.

After the Hazardous Waste Management Bureau detected elevated levels of PFAS in groundwater monitoring wells around the transfer station where the septic lagoons are located, the Department of Environmental Services was notified.

Anthony Drouin, the residuals management supervisor at the state agency, responded by visiting the site and discovering extensive stockpiles of septic solids rising up to 20-foot-tall berms that encircled each septic pit at the facility.

“If they actually had managed it over the course of time, it wouldn’t have accumulated,” said Drouin, stressing the importance of consistent management. “Every other year or every five years if they will look at the pile and said okay, let’s bring it here or there, get approval, they might be able to manage it more on a scheduled basis than waiting for this complete end of the term or doomsday.”

Now the town is left with 20,000 cubic yards of solid septic waste that could prove expensive to manage. But Hopkinton will share the expenses with the town of Webster as the two towns share the transfer station located at 491 East Penacook Road in Hopkinton.

It is expected the plan from the engineering firm will recommend capping the lagoons with an impermeable liner.

Septic collection facilities, like the one in Hopkinton, operating for decades, would require closure at some point.

Drouin said that these facilities should be prepared for eventual closure and recommended having funds set aside.

“I always say if you have a septic facility in your community, you should be taking the money you’re receiving from those haulers and putting it aside for closure, because there’s going to be a day when you’re going to either need to close the facility or further manage it,” said Drouin.

Usually, septic sludge is managed through landfill disposal, finding farms willing to accept treated and certified sludge or through incineration. However, Hopkinton did not undertake any of these methods.

The main concern with the PFAS-laden sludge, according to Drouin is its potential impact on the public water supply located northwest of the transfer station, as well as the drinking wells in the vicinity.

“Protecting those wells is very important; we don’t want to see anybody’s well becoming impacted,” said Drouin.

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