MERIDEN — A more than $38 million project to upgrade the city’s wastewater treatment plant on Evansville Avenue is about three-quarters complete, city officials said.
The project began in 2019. Its scope is two-fold: to reduce the levels of phosphorus in treated wastewater pumped into the Quinnipiac River and to reduce the overflow of untreated sewage that gets discharged into the river following significant weather events.
In 2018, the city received a U.S. Environmental Protection Agency administrative order that found the city non-compliant with its wastewater discharge permit because of overflows.
According to the order, the EPA found that on eight separate occasions over a more than four-year span — between February 1, 2013, and October 31, 2017 — the city discharged untreated sewage from the Harbor Brook Pump Station at levels that exceeded the amount the city was allowed to discharge under its federal and state-issued permit.
Under the permit, the National Pollutant Discharge Elimination System, the city is authorized to discharge a maximum daily limit of 50 milligrams per liter of untreated wastewater. The EPA order cited one occasion in February 2016 when the city’s discharge had reached 202 milligrams per liter — more than four times the allowable limit.
Meriden officials said such discharges occurred during significant storms when the plant is inundated with stormwater, thus causing the untreated wastewater to overflow into the Quinnipiac.
The city did not receive a financial penalty under the EPA’s order. The order required Meriden officials to develop and submit an inflow and infiltration control plan to both EPA and the state, detailing how the city would address the violations.
Richard Meskill, the city’s public utilities director, anticipates the entire project will be completed by May 2022. The phosphorus reduction component of the project is scheduled to be completed by this December.
Meskill explained officials from both EPA and the state Department of Energy and Environmental Protection approached the city about developing a plan to address the overflow issue.
The city’s plan involves diverting that untreated sewage into two concrete digesters located at the Evansville Avenue facility. Meskill explained those digesters, which have the capacity to hold up to 2.5 million gallons of sewage, currently sit empty.
“They haven’t been active for a number of years. They’re not needed at this point,” Meskill said. “We found an alternate use for it, basically.”
Officials plan to divert the flow of untreated sewage into those digesters during a storm. The untreated sewage, instead of flowing into the river, would be stored in those digesters.
“After the storm event subsides, we would begin reversing the flow,” Meskill explained. “… That would help alleviate any potential overflow.”
Other municipalities in the Meriden area have recently undertaken steps to upgrade their water…