PITTSFIELD -- Think outside the box. Or, in this case, the lagoon.

That's what town officials may need to do in order to accomplish the overdue task of removing solid waste without passing on huge rate increases to the town's water and sewer customers.

Acheron Engineering recently studied the town's options for removing sludge from one of its two wastewater lagoons. Company officials explained their findings to the Town Council on Tuesday night.

Most removal options are too expensive for Pittsfield to consider, the company says, and so it is recommending the town study further an uncommon method that, if it worked, could save the town millions of dollars.

Such a study would gather "sound science" the town could then use to convince the Maine Department of Environmental Protection, which needs to give its approval.

Essentially, the idea involves draining water from the wastewater lagoon and allowing the remaining sludge to bake in the sun so it's lighter and there's less of it to remove.

"This is out of the box," said Kirk Ball, vice president of Acheron Engineering. "It's not what everyone is used to, especially in the Northeast."

Pittsfield faces a unique challenge in removing the solid sludge: It's been building up for at least twice as long as it should have, and at 35 acres, the lagoon containing the sludge is probably the biggest in the state of Maine. Sludge, which is the solid byproduct from wastewater, blankets the bottom of the lagoon, Ball explained.

The town's wastewater-treatment facility began operating in 1978 and it was designed so that sludge should be removed every 10 to 15 years. But sludge has never been removed.

Ball listed three possible ways to get rid of the sludge: composting, landfill and spreading it on a field.

It's unlikely Pittsfield could spread the sludge on land, Ball said, because the town would need to succeed in a complicated state permit process and then find the 4,000 acres of land to spread it on.

More likely options are disposing of the sludge at composting sites or landfills, which would cost the town between $50-$60 a ton.

The town's options are also limited when it comes to removing the sludge from the lagoon and drying it out so that the substance loses much of its volume and is less expensive to transport.

One option is amassing a fleet of floating vehicles called dredges, which plant large pumps into the lagoon and suck the sludge out. That could be done in one summer season at a cost of $5.3 million, or accomplished incrementally over 15 years at a cost of $9.9 million.

Although "technically feasible," those and other options are not likely because of the high cost, Ball said.

"We dug in as deep and as hard as we could," Ball said of his company's study.

That's why Ball and his company have recommended the town spend another $15,000 to study further an option called solar drying. The water from the first lagoon would be drained and poured into the second lagoon, and then the only the sludge would remain so it can dry out in the sun, from June to September.

That would cost between $617,000-$1.4 million, depending on how much water is leftover in the dried sludge.

The main risk involved with solar drying, Ball explained, is that it's weather-dependent. If it rains a lot in central Maine during the summer months, it could be years before the sludge is dried and ready to be removed.

The Maine Department of Environmental Protection also has concerns. The agency reviewed Acheron's sludge study and sent a letter to the town government this week with observations and concerns.

Jim Pollock, of the solid waste division, says solar drying seems "quite risky" with a "50/50 chance of failure." Likewise, Dick Darling, of the water quality management division, says solar drying "is probably not feasible" given weather conditions in recent years.

Even so, given the potential of savings for the town government, and ultimately ratepayers, Acheron officials think the solar drying option should be studied this summer.

"If the town invested in a pilot program, and gathered science, the potential cost savings are enormous," Ball said. "We may find it is a viable option."

Councilor Michael R. Gray said the town should schedule a meeting with state officials soon and attempt to get the solar-drying study ready in time for the summer.

"June is right around the corner," Gray said.

Scott Monroe -- 487-3288, 861-9253

smonroe@centralmaine.com