Utilities in Maine Seek Solutions Amidst Biosolids Disposal Crisis

First a ban on land application. Then severe limits on landfilling. Fears about PFAS contamination cause clean-water utilities to scramble.

Utilities in Maine Seek Solutions Amidst Biosolids Disposal Crisis

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Imagine you own a business that produces a beneficial product. Suddenly the government says you can no longer sell it. You can’t give it away to customers. You might not even be able to dispose of it. And yet you can’t stop making more of it.

That’s basically the situation Maine clean-water utilities are in with biosolids. Public perceptions and state officials’ concerns about PFAS contamination have put biosolids programs in limbo, according to Scott Firmin, director of operations for wastewater with the Portland Water District.

First came a moratorium on land application, with limited exceptions. Next came an outright ban. And finally, earlier this year, severe restrictions emerged on taking biosolids to the state‘s few landfills. At present, the Portland district and a number of other agencies are sending their biosolids by way of a contractor to landfills in the Canadian province of New Brunswick, at considerable cost.

Firmin notes that in 2018 when his district’s land application program was operating, biosolids handling cost about $71 per wet ton. That has risen to $133 per wet ton. “Our biosolids costs have gone from about $1.5 million per year to about $3.2 million,” Firmin says. “It’s not uncommon now for Maine utilities to pay $190 to $240 per wet ton to haul and landfill biosolids.”

The Portland district is looking at near-term alternatives such as centrifuge dewatering, and longer-term possibilities like variations on thermal drying, and even emerging thermal technologies that may reduce PFAS. These would require capital investments in the tens or hundreds of millions of dollars, plus long lead times for facility design, permitting and construction.

Rising concern

Maine was the first state in the U.S. to impose severe PFAS-related limits on biosolids land application. It started four years ago with a moratorium, which left some flexibility for case-by-case evaluation. “For example, you could land-apply provided the background soil PFAS concentration didn’t exceed the screening criteria the Maine Department of Environmental Protection created,” Firmin recalls.

“It also allowed for composting, because utilities could establish site-specific loading rates. If the PFAS concentration was higher than the screening standards, you still could demonstrate that you were applying less compost than if applying biosolids in agronomic quantities.”

Then in 2022, the state legislature began work on a bill that would turn the DEP screening standards into ceiling concentrations: 2.5 ppb for PFOS and 5.2 ppb for PFOA. 

“But during the legislative activity, the bill went from ceiling concentrations to an outright ban on distribution of biosolids-based compost and land application of biosolids, even if the PFAS concentrations were under the limits,” says Firmin.

“That went into effect on Aug. 8 last year, and it took everybody off the land, with very little notice. It took all the material that was being beneficially reused and essentially created landfilling as the sole outlet for Maine utilities such as ours.”

Seeking alternatives

One possible alternative was to haul the material across the state border. But neighboring New Hampshire has a law prohibiting land application of material that can’t be applied in the state where it is produced. “A couple of utilities partnered with the RMI biosolids management firm to send material to Quebec,” Firmin says. “But Quebec recently passed a moratorium on land application of biosolids brought in from another country.”

That left landfilling, but for most utilities it wasn’t an easy or inexpensive alternative. The landfills had contracts with some municipalities that composted their biosolids. In those cases they continued accepting the material but raised their prices. In other cases, landfills simply turned utilities away.

Maine has only about half a dozen landfills, and only two of them are large – one operated by Waste Management and the other by Casella Organics, about two hours north of Portland. Another complication arose last February when the legislature passed a law limiting the indirect import of construction and demolition debris for landfilling from out of state.

That kind of material had been ideal for mixing with biosolids and compost for landfilling, as it lent more structural stability to the landfill cells as they were being filled. “It was kind of a perfect storm,” says Firmin. “More biosolids were being sent to landfill, while the amount of material needed to mix with it was reduced.”

Doors closing

About a month ago, unable to deal with the spike in biosolids, the Casella landfill on which most Maine utilities relied stopped accepting the material. “Now utilities couldn’t compost it, and they couldn’t land-apply it,” says Firmin. “And no other landfills could take a large influx of biosolids. So suddenly there was no place for the material to go.”

As an alternative, Casella arranged to truck the biosolids to a landfill in New Brunswick, four to five hours away for most utilities. The longer drive meant utilities needed to have more containers on standby, and at first there was a shortage of containers. As of mid-March the logistics of supplying containers improved, but the high hauling costs remained. “Canada is not a sustainable outlet for the majority of Maine biosolids,” Firmin says.

Meanwhile, discussions are underway involving state legislators, the state Department of Environmental Protection, the Maine Water Environment Association, and landfill operators with the aim of addressing the short-term issues and longer-term solutions.

Master planning

Looking to the future, the Portland Water District has completed a biosolids master plan. Says Firmin, “The premise of it is that if you have something you need to get rid of, have as little of it as possible. We’re looking at a $9 million upgrade next year that will probably involve replacing our dewatering equipment with centrifuges, which might get us from 20% solids to 26%. That will reduce the amount of material to dispose of, and as handling costs go up, there may be a payback. 

“As part of master planning, we will also look at possible collaboration or regional solutions to maximize the efficiency of projects,” Firmin says. For farther out in time, the district is looking at biosolids dryers that could achieve up to 90% solids, greatly reducing the volume and making the material better suited for landfilling, if that should remain necessary. “The problem is that the emissions are not well understood. Regulators who got burned by biosolids and PFAS are a little concerned about PFAS emissions. So if we wanted to put a dryer in today, I’m not sure the DEP would permit it.”

A dryer likely would cost $45-55 million. Another option would be a thermal process like pyrolysis that can yield a product called biochar, which has carbon sequestration benefits and can be used as a soil amendment or as an ingredient in building materials and products such as inks and dyes. “There’s a developing market for biochar, and it is considered to be close to PFAs-free,” says Firmin. “But again, there is no reliable way to test the air streams.”

For now the district plans to develop siting criteria for drying and other thermal processes, and to work with an engineering consultant to evaluate the available thermal technologies. “We hope to be able to share that information with our regulators and say, ‘Here’s where we’re at. Is this enough for you to be comfortable permitting something? And if not, what do you need?’

“We’re trying to build a technical dialog with our regulators and our policymakers and environmental groups to say, ‘We need a future. And what we have today isn’t it.’”


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