MERIDEN — Officials reported an estimated 1.37 million gallons of combined rain and untreated wastewater was discharged into the Quinnipiac River as a result of the heavy rainfall that inundated the area on July 9.
The overflow spilled from the city’s sewer treatment plant on Evansville Avenue into the Quinnipiac. Officials did not provide an estimate for how much untreated sewage flowed into the river, but said it had been highly diluted by the rainwater, which accounted for most of the overflow.
The city was one of several municipalities across Connecticut to report overflows of wastewater into local waterways as a result of the storm, according to the state Department of Energy and Environmental Protection.
DEEP officials reported the overflows that occurred during that storm were among the highest the agency had seen over a short period of time.
In Meriden, Frank Russo, the water pollution control facility’s manager and chief engineer, said the volume of sewage that flowed into the Quinnipiac River July 9 was equivalent to an “eyedropper” amount having been dropped into an Olympic-sized swimming pool.
“It was a really minute amount of waste that gets into the environment,” Russo said.
The Quinnipiac River rises in from Dead Wood Swamp near New Britain and flows roughly southward to Plainville, Southington and Cheshire, west of Meriden, through Wallingford, Yalesville and North Haven, and flows into New Haven Harbor.
The overflow itself represented about 0.07 percent of the total volume of water that flowed through the river on July 9. About 80 percent of the 1.37 million gallons that had flowed from the Meriden plant into the river was rainwater, Russo said.
Officials reported a significantly high volume of water — more than 47 million gallons — had flowed through the treatment plant on the day of the storm.
Officials so far have not reported water contamination, including elevated bacteria levels, as a result of the event.
Still, the volume of overflow was enough to trigger its reporting to DEEP. In the future, reporting would become more widespread.
Under a revision to the state’s Sewage Spill Right-to-Know Statute, which became law this year, a similar spill would require notifications to not only state authorities, but elected and health officials in municipalities downstream. The change goes into effect October 1.
If it had been in effect, Wallingford and North Haven municipal and health leaders also would have been notified.
Another component of that law’s revision requires DEEP to develop a system for notifying local residents by December 1.
State Rep. Mary Mushinsky, D-Wallingford, described discharges such as the one that had occurred in Meriden as “a common problem in the urban rivers of Connecticut.”
Local officials had previously acknowledged a need to reduce wastewater overflows.
The latest incident occurred with the city in the midst of a project aimed at tackling the issue. That $38 million project aims to complete upgrades to the Evansville Avenue plant by early next year.
One of its goals is reducing the overflow of untreated sewage from the facility into the Quinnipiac during significant weather events like the recent storm. Another goal is reducing the levels of phosphorus present in treated wastewater that is pumped into the river.
According to officials, the overflows would be reduced because instead of spilling over into the river they would be diverted into two large concrete digester tanks already located at the facility.
Those digesters can hold up to 2.5 million gallons of sewage but currently sit empty.
Under the city’s plan, sewage would be stored during a storm event. After stormwaters subside engineers would reverse the water flow, treating the stored water, before it gets pumped into the river.
Richard Meskill, the city’s public utilities director, said the project is in its design and initial construction phases.
“We think it will help prevent what occurred last Friday,” Meskill said.
Still he said, the larger issue is within the city’s network of aging sewer pipes. Engineers and contractors will assess the network to determine where improvements can be made.
“Ultimately, the real solution is trying to identify where all this water is coming from in our collection system,” Meskill said.