A proposed overhaul of Middleborough’s aging waste-water treatment plant faces its first key hurdle Monday night, when Town Meeting voters weigh a funding request that would set the estimated $30 million project in motion.
The annual session is slated to consider whether to appropriate $2 million to $2.5 million to design the project, which would be the first major update to the plant since it opened in 1977. The exact design cost is still being finalized.
Officials said the project is needed for Middleborough to comply with new treatment standards required by the US Environmental Protection Agency .
“We are about to get a new permit from the federal EPA, and they are raising the bar for nitrogen and phosphorous removal. And to meet that new permit, we have to upgrade the plant,” said Town Manager Charles J. Cristello. “We have to redesign it, and install a new process that will allow us to get to a lower level of those nutrients.”
Cristello said the project will also address deficiencies related to the plant’s age.
“We’ve gone more than 30 years since a major upgrade to the plant,” he said. “So the plant is old and tired . . . and a certain amount of work needs to be done to just upgrade the existing equipment.”
The treatment plant on Joe Ciaglo Way sits on an approximately 5.5-acre site off Route 44 and adjacent to the Nemasket River, which flows into the Taunton River. Designed to treat 2.1 million gallons of effluent a day, the system on average moves about 1.1 million gallons a day, said Todd Goldman, the plant’s superintendent.
The municipal sewer system, which entails 23 miles of mains and six pumping stations linked to the treatment plant, serves about a quarter of the town’s approximately 23,000 residents. Its 7,000 customers also include some businesses, the largest of which — Ocean Spray Cranberries Inc. — sends 230,000 gallons of pretreated waste water from its Bridge Street location into the system each day.
The project would be funded entirely through sewer fee revenues, so no tax funds are involved. To generate the funds needed to pay for the plant upgrade, the town two years ago began increasing sewer charges to its customers by 15 percent annually, a policy that will continue for three more years.
“EPA commends the proactive efforts of Middleborough to upgrade its plant to meet the stringent nutrient reduction requirements of the upcoming permit . . . and we look forward to working with the community as it moves forward with this important project,” Paula Haschig, a spokeswoman for the agency’s New England region, said by e-mail.
Excess nutrient levels can cause significant algae growth in water bodies, resulting in depleted oxygen levels that in turn can cause illness and death in fish. High algae levels also cause elevated toxins and bacterial growth that can be harmful people who drink or come into contact with the water or consume tainted fish, according to the EPA.
The higher standard for removing phosphorus and nitrogen is invoked when the waterways receiving treated effluent from a plant already have high nutrient levels, according to Haschig’s e-mail. “The need for more stringent permit limits for phosphorus and nitrogen is assessed on a site-specific basis,’’ she wrote, “but has been recognized as a pressing problem nationwide.”
The EPA is in the midst of issuing new permits to all of the waste-water plants in the Taunton River basin, “and upgraded nutrient treatment is being assessed in each” case, Haschig said. The permits are in the draft phase for the plants in Bridgewater, Brockton, Mansfield, Somerset, and Taunton, as well as Middleborough.
At least two of the other communities — Mansfield and Taunton — are also planning plant upgrades, Haschig said, noting that Middleborough may be the furthest along in the process.
Goldman said that if Middleborough does not move to upgrade the plant, the EPA would probably order the town to carry out the improvements under threat of a fine.
Middleborough is negotiating a contract with a firm selected to undertake the design, according to Cristello. Should Town Meeting approve the funds, the town would proceed with preliminary design work and to finalize its EPA permit, a process likely to take six to eight months.
The design would then take another year to complete, after which Town Meeting would be asked to OK the improvements. Construction would take about two years.
The bulk of the project’s costs would involve converting the plant to handle the more advanced system for removing phosphorous and nitrogen, Goldman said.
The plant currently uses “activated sludge treatment,” a process in which microorganisms and air are introduced into partially treated wastewater in a series of tanks. The microorganisms feed on the organic matter in the water, making it cleaner. The plan calls for switching to a “five-stage Bardenpho” process, a more extensive treatment using other types of microorganisms and a different array of tanks.
The project’s other renovations, many of which would be needed to bring the plant up to code, include replacing the electrical system; adding new valves, pipes, and pumps; taking measures to make the plant more handicapped accessible; and installing fire sprinklers.
Goldman said the most difficult aspect of the project would be keeping the plant in operation during construction.
“You are basically going to be building a new plant around an old one while it’s running,” he said. “It’s going to be a major challenge.”