WILTON — Mix, cook, set. The simple recipe produces a Class A compost at the town’s wastewater treatment plant and provides a cost-effective solution to handling sludge.

Since 1996, the plant has composted sludge and offered it free. It even provides free delivery of larger loads in some areas at lower cost than what the department would pay to have it hauled away.

Prior to composting, sludge was hauled to fields in Wilton and Jay where farmers spread it like manure.

“The writing was on the wall,” said Clayton Putnam, waste water plant superintendent. Calcium added to the sludge to stabilize it was too much for the soil, he explained.

Instead of footing the cost of the very expensive soil testing necessary to continue, the department, under the leadership of the late Russ Mathers, looked for alternatives. With Department of Environmental Protection permission, “the recipe,” as Mathers called it, was developed.

The result is what “DEP and the Environmental Protection Agency call Class A compost good to use on plants whose produce is consumed or ornamental, flowering plants,” Putnam said.

An initial investment of $70,000 included construction of a pole barn. The department has a composting budget of $18,700 to handle the production of approximately 400 cubic yards of compost produced each year.

The budget divided by just 380 yards realizes a cost of $49 per cubic yard, he said.  Sometimes that cost has dropped to as low as $30 per yard.

The amount includes materials and renting trucks from the town’s road department. Other towns are paying about $80 per cubic yard to have sludge hauled off, he said.

When the Rumford-Mexico Sewerage District started composting it also saw an initial investment of nearly $80,000, Superintendent Greg Trundy said.

At a cost of $100,000 a year to deal with sludge, it didn’t take long to recover the expense, he said.

That department cooks nearly 4,000 yards a year and charges $2 per yard for compost.

“The charge doesn’t cover costs but it’s cost avoidance and we get rid of it all,” he said.

In Livermore Falls, sludge is hauled to New England Organics in Unity, Superintendent Greg Given said. It’s an expensive option so he said he’s also considered composting.

Word has spread about the quality of the compost in Wilton. In the early days, a gardening club in Wilton tried it and granted their “seal of approval,” Putnam said.

“It’s a good supplement for the soil,” he added. “It’s a soil aerator. Mixed with soil it provides a place for water to run down into the soil.”

One man from Rangeley comes twice in the spring and fall to load pails with compost. A Wilton man shovels about 25 pails full for his daffodil bed while others boast of its ability to rejuvenate a lawn, he said.

The department delivers loads of 12-cubic yards to about 20 people,  usually once in the spring before Memorial Day and once in the fall.

Composting is done 365 days. It’s been available on a first come, first served basis but now if quantities are limited, Wilton residents get first-preference.

“Our goal is none on site,” he said. “Today there are about 107 cubic yards ready.”

People can go the plant anytime and shovel into pails or trailers. If it’s during work hours, the crew will load a truck for them.

Putnam’s fond of the cooking analogy.

The recipe calls for sawdust and shavings mixed with de-watered sludge.

“After so many years, we know when it’s ready to cook by what it looks like,” he said.

Stored in bins, the piles of mixed ingredients cook for 21 days and rise to temperatures of 120-130 degrees, he said, pointing to small thermometers lodged in the middle of the pile. Then it sets for 21 days.

Pipes provide the opportunity to add cooling air.

“We don’t want it too hot too fast. It would be like putting a cake into a 450-degree oven,” he said.

Over the winter the process is slowed due to icy sawdust.

As the plant anticipates the second phase of renovation, another pad with a roof to store and mix the compost materials is under consideration.

For more information, contact the plant is 645-3682.

 [email protected]

Plant phone number added to article Aug. 31.