Windham is on the verge of opening a new sewer system, the culmination of a project that has been in development for five years.

Development of the project began in 2021, when the town entered into an agreement with the Portland Water District to put a sewer site together and voting in favor of a Clean Water State Revolving Loan the following year. The main impetus for the project was to clean up the nitrogen and phosphorus in Windham’s groundwater, which was over EPA limits in many parts of town and polluting the nearby Presumpscot River.

The centerpiece of the new sewer system is the North Windham Wastewater Treatment Plant, a membrane bioreactor that is under construction in the vicinity of Manchester Elementary School. The plant is due to begin operations in June, after a delay caused by the need to replace the piping, which had failed a sludge removal test. The plant is designed to handle 160,000 gallons per day of flow, with the potential to expand to 320,000 gallons per day, and is currently permitted by the Maine Department of Environmental Protection to discharge 154,000 gallons per day of treated effluent. The plant will operate largely unattended, with operators at the plant for a couple of hours on weekdays.

The plant is largely structurally complete and is fully connected to the power grid, with mechanical and electrical work still underway inside the plant. The plant’s membranes are ready for installation. That will take place in May in order to prevent the membranes from being damaged on-site. A ribbon cutting ceremony is expected to take place sometime after the “first flush,” currently set for Tuesday, June 23, said Town Manager Robert Burns.

The town has started connecting North Windham businesses to the new sewer system, particularly in the vicinity of the North Windham Mall. According to the town newsletter, a number of businesses have completed the necessary sewer connection documents, and preliminary construction work has begun to connect them to the gravity sewer system beneath Route 302. This is the second of three phases of the sewer project. The first phase was the installation of the sewage collection systems, and completed last year.

Once North Windham is fully connected to the new system, attention will turn toward a connection between the treatment plant and the new RSU 14 middle school, currently under construction and expected to open by 2027. Burns said Shaw Brothers, the same contractors who worked on the treatment plant and sewer system in North Windham, were awarded a contract from the Portland Water District to start construction on a sewer main connecting the plant to a pump station next to the school. A separate project from the main sewer system, work on this connection is expected to start later this month, and continue through to autumn.