AYER -- Transforming organic waste into energy at the town's plant is feasible, but would come with significant risk, residents learned at a public-input forum last week.

The project to reduce the town's cost of sludge disposal would involve treating Ayer's wastewater sludge and commercial food waste with anaerobic bacteria. The result would be power that could fuel the wastewater plant or be used toward renewable-energy credits.

But a major obstacle would be the cost.

The Department of Public Works received a state-funded grant to study potential financing options for the idea.

DPW Superintendent Mark Wetzel estimated Ayer spends about $150,000 every year in energy for wastewater treatment and about $200,000 to manage biosolids -- which means trucking sludge to Millbury or Rhode Island to an incinerator.

"We're running probably eight loads a week at least; sometimes we might be doing as many as 12 loads a week," he said. "So there's a lot of operation costs and disposal costs related to that."

Need for such a treatment plant could grow even more with the state's recent ban on commercial and industrial food in landfills.

The facility would be set up around the town's current wastewater-treatment plant, with an area to receive the organics. The waste would be sent through anaerobic digesters, transformed into methane and then into energy.

One of the big challenges, Wetzel said, would be figuring out how to collect enough commercial food waste to break even. He identified potential waste sources within a 30-mile radius of the town, many within the Route 128 belt.


"Would that be economical for them to bring the waste out to Ayer? I would probably guess not, but there may be some other choices being developed," he said.

Benjamin Mosher, a principal engineer at CDM Smith, who worked on the study, presented three size options for the proposed plant.

Alternative A sought only 1 percent of the available industrial waste within the 30-mile radius, while Alternatives B and C, respectively, sought 5 percent and 10 percent.

Mosher said 10 percent of the waste in that area is a lot of waste to capture.

Annual operating and maintenance costs for the smallest facility could cost $600,000, although the town could get credits for renewable energy and for using its own power to generate its own heat.

If the town created its own pre-processing system, Mosher said, annual costs would be more than if it brought in waste that was pre-processed.

For the smallest facility to break even with a pre-processing plant, the town would have to charge $650 per ton for disposal. Without pre-processing, the cost would be $350 per ton.

Mosher said the average solid-waste disposal rate now is about $70 per ton.

"People would have to pay a decent amount more than they do now, just to put it in the landfill," he said.

Those costs would be lowered as the facility accepts a higher percentage of trash, but Mosher noted that a bigger size comes with a higher financial risk.

The town could apply for a number of different grants from the state and National Grid for financial opportunities.

Wetzel also presented a range of ownership options -- the plant could be owned by the town, a mixture of public-private partnership or completely private.

Wetzel said the best solution would be to consider privatizing the operation.

"I think from my point of view, Ayer's not a big enough community with enough expertise for us to build, own and operate this type of facility," he said. "The private ownership is something that I think we could manage pretty easily."

The state is looking into how to get older anaerobic-digestion systems back up and running, Wetzel said.

"I think we also need to see where the smoke is clearing around what the state's going to do," Wetzel said, adding that the state needs to deal with both food and biosolid-waste management.

"We're not the only town in Massachusetts that trucks our sludge out of town to an incinerator where it gets burned," he said.

Wetzel said he has talked to a couple of energy developers interested in talking with the town about the project. He said he would determine different options for the community to be presented later. 

"I think it's still a really good idea, really good concept," he said. "It's just that we don't have enough free money to do it."

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