The Freeport Sewer District is preparing to launch a $20 million upgrade to its wastewater treatment plant.

The overhaul of the plant at 43 South Freeport Road is funded through the U.S. Department of Agriculture’s Rural Development Program with a combination of a $12.6 million low-interest loan and a $7.5 million grant, according to Sewer District General Manager Sara Randall.

“It is something we have been planning for the last four years, and so this summer we are going out to bid on various elements of the upgrades,” Randall said.

The project is expected to take two to three years to complete, according to Randall.

The project includes the construction of a new building to house dewatering equipment and store sludge cake, a byproduct of the sewage treatment process. The building will also increase sludge storage capacity, with two tanks to enhance efficiency; improve thickening and digestion; and allow for upgrades to the power distribution equipment. Randall said the new process building will help reduce costs for storage and transportation of waste.

“All this work is going to allow us to process the flow a little bit better and a little bit quicker,” said Leonard Blanchette, Freeport Sewer District construction manager.

A new filter building will be designed to remove solids and enhance the performance of the new ultraviolet treatment system. Randall said the UV disinfection system is a more eco-friendly method of disinfection, improving the water quality before it’s discharged into the Harraseeket River.

Other updates will include upgrades to the pumps in the control building to improve safety. The Headworks Building will have improved management of corrosive gases, screenings and grit, along with UV disinfection, replacing the use of chemicals for disinfection.

Blanchette said a bid for construction will go out on July 15. Randall said the district will be seeking three separate bids to complete the overall project. The other two bids will be for an administrative and laboratory building.

Randall said construction will likely begin by fall, or sooner, with work commencing on the updates for the treatment unit in the Freeport Sewer District, which consists of the three domed buildings behind the district’s office. The contract will be for 270 days to complete the replacement, cleaning and painting of the various parts of the treatment units.

“A lot of the wastewater treatment plants in the state are in this critical time period because it all went in after the Clean Water Act was enacted,” Randall said. “It has been 50 years, and the systems are in need of rehab at this point because they do have an end of their useful life, and the problem with wastewater treatment is that it is so expensive.”

The Freeport Sewer District was established in 1948 and operates as a separate entity from the town’s municipal office, acting as a quasi-municipal entity. The money generated for the Freeport Sewer District is paid for by ratepayers to cover the treatment facility’s operating expenses.

“We are moving ahead because that is what we need to do,” Randall said.