WILTON — Residents will be asked at the upcoming annual Town Meeting to approve a $4.8 million project to finish upgrades needed for the aging wastewater treatment system, said Town Manager Rhonda Irish.

Selectmen this week voted to bring the project, the second of two phases to improve the system, to voters at the meeting scheduled for June 18.

If passed, the new project would add to the annual debt payment tied to the initial system upgrades, which residents approved last year. The town’s sewer customers would have to pay an added $177 per year for 30 years on their sewer bills to pay off the debt on the new project, Irish said.

To pay off the debt on the initial $4.7 million project, the town’s 944 sewer customers are already slated to pay an added $213 per year over the next 30 years on their sewer bills. That added sewer bill charge along with a minor adjustment to sewer rates to provide some savings for a majority of residential customers was approved earlier this month by selectmen.

Irish said the state Department of Environmental Protection has put pressure on the town to repair its 32-year-old wastewater treatment system. The new project would make upgrades to the treatment plant, whereas the initial project is primarily improving the pump stations, she said.

Wilton’s last sewer rate increase was in 1987 and state officials have said the aging system is a threat to dump raw sewage into nearby streams and Wilson Lake.

Clayton Putnam, superintendent of the town Water and Sewer Department, has explained at public hearings on the two projects the challenges residents would face if the upgrades are rejected.

If the system failed and caused an environmental hazard, the state government would take over the upgrade project, Putnam told residents. He added this scenario would probably cost the town a lot more money, because it would lose low-interest loans and grants from state and federal agencies that have already been approved to help fund the projects.

The Maine Clean Water Revolving Loan Fund has approved a $438,156 loan to help pay for the new project, with a condition that forgives $81,844 of that amount if certain criteria are followed, a town report states.

The federal agriculture department also approved a $2.48 million loan and a grant of almost $2 million to cover the remaining project costs, the report states. The initial project received similar federal grant and loan packages.

In other action this week, selectmen reviewed the articles they plan to bring before voters at the annual Town Meeting.

Selectmen have proposed a $2.86 million budget that is up about $5,000, or less than 1 percent, from last year, Irish said. She added that this town budget increase would not affect the tax rate, currently at $14.60 per $1,000 of property valuation.

Selectmen are expected to review and approve the article questions at the next regular selectmen’s meeting, which has yet to be scheduled next month.

David F. Robinson — 861-9287

drobinson@centralmaine.com