A Sturgeon Bay consulting engineer told members of the Forestville Village Board Thursday that a giant septic system might be what's needed to solve issues at the community's wastewater treatment plant.

William Baudhuin, president of the Sturgeon Bay engineering firm that bears his name, said he was offering a second opinion on solutions for the community's sewer plant.

Forestville's sewer system dates back to the 1940s, and the Wisconsin Department of Natural Resources oversees what is discharged from the treatment plant.

In recent years, the DNR has lowered the amount of ammonia the plant can discharge into the Ahnapee River because it depletes oxygen for aquatic life in the river and in Lake Michigan.

Forestville's existing plant can't meet the DNR limits during winter months when settling ponds are ice-covered. Village officials expect even lower limits when a new permit is issued for the period beginning in 2012.

Engineers from Ayres Associates of De Pere have been working on potential solutions to the problem, and on locating places in the 60-year-old sewer lines where storm water and other runoff is getting into the system. Some of the potential solutions include additional lagoons and possibly piping the wastewater to Algoma for treatment there.

Ayres Consulting Engineer Peter Kolaszewski said during dry months, the treatment plant handles around 30,000 gallons of water a day. Wet weather results in higher flow through the plant, averaging around 77,000 gallons. However, in April 2008, Kolaszewski said more than 400,000 gallons went through the plant in 24 hours.

The village is in the process of seeking a U.S. Department of Agriculture grant for the project estimated to be more than $2 million.

Baudhuin said once the flow problems are solved, the village might be able to use a large septic system, similar to what many rural homes use, for waste disposal. His firm is currently working on a 75,000 gallon-per-day septic system for a private development in central Wisconsin and has done a 45,000-gallon system for Rhinelander.

By disposing of the treatment plant's output on land, the ammonia issue would go away, Baudhuin said. In looking at a soils map of the Forestville area, he said, "There are soils around that could support it."

Such a system would have a building cost of about $20 per gallon of waste treated. However, the septic system would eliminate an estimated $85,000 to $100,000 in annual maintenance and chemical costs at the present treatment plant, village officials said.