VASSALBORO — Sanitary District Trustees are trying to find a way to avoid having ratepayers bear the entire burden of a proposed $5.1 million replacement of the town’s aging and potentially hazardous sewage treatment system.

Trustees have been presented with a range of options for replacing the possibly unsound system but are leaning toward connecting to the Kennebec Sanitary Treatment District in Waterville through Winslow’s sewer district as the most viable and cost-effective solution.

The board will hold a public hearing on the proposed project 6 p.m. Monday in the Town Office.

Officials hope to get as much as 80 percent of the funding through grants and other sources, but they acknowledge that with a project of this scope, there will likely be some local costs.

The project’s effect on customer rates won’t be known until trustees pull together a complete financing package, said Chuck Applebee, who manages Vassalboro’s sewer operations.

“Anyone that would make an exact rate projection now wouldn’t know what they were talking about,” Applebee said Friday.

The town maintains two open-pit sand-filter treatment sites in North Vassalboro and another in East Vassalboro, but the system is more than three decades old and beyond its useful life.

An engineering report released in December notes that parts in treatment systems sometimes need emergency equipment replacement, and the sand filters are not treating sewage as effectively as they should. In an emergency, the system could deteriorate rapidly and might create a public health problem, the report warns.

Richard Green, an engineer from Hoyle, Tanner and Associates, which evaluated the system, previously said that the plants are living on borrowed time.

On Friday, Applebee said the engineer’s assessment of the system is accurate and the sanitary district has to look into alternatives.

“There isn’t an option. Something has to be done,” Applebee said.

People also have complained about the smell and appearance of the open pits, especially the one near residences and offices in North Vassalboro, said Board of Trustees Chairman Ray Breton.

The district serves 193 customers, with the equivalent of about 250 users, according to Green’s report. District customers pay 6 cents per cubic foot, with the average household paying an annual sewer bill of about $480.

With its small user base, the district will have to get significant financing to pursue the project. Trustees already have submitted paperwork for financing from the U.S. Department of Agriculture’s Rural Development program that could cover up to 75 percent of the cost.

Considering the system’s deteriorated condition, the best option presented to the sanitary district is connecting to Winslow, Breton said.

Treating sewage at the KSTD plant in Waterville will be less expensive than in Vassalboro, and new customers could hook onto the extension to Winslow, which might help to bring down user rates and position the town for further growth, he added.

“In the long run, we’ll be way ahead of the game” if the line is in place, Breton said.

The engineering report notes that the Maine Department of Environmental Protection considers a project affordable if it will not increase the annual user rate more than 2 percent of the median household income. Using that criterion, the district would need to find at least $4 million in grants and cover the remaining amount with a traditional 20-to-30-year loan to finance construction, according to estimates in the report.

A survey of district customers showed that their median income was $31,000, Applebee said.

“Usually USDA acts as an anchor agency. That’s why we started with them,” Applebee said. The district also is considering loan and grant opportunities from Maine DEP, funding from a town TIF district, and pursuing Community Development Block Grants, Applebee added.

If trustees approve the proposal, construction of the new system might not begin for another two years, he said.

Meanwhile, the district is considering fixes to its current system to limit storm water and melting snow that the system is treating accidentally.

Trustees plan to remove storm and cellar drains and gutters this year to cut back on infiltrating water, Applebee said.

Peter McGuire — 861-9239

pmcguire@centralmaine.com

Twitter: @PeteL_McGuire