Efforts to improve sewage discharge are underway, Meriden officials say

MERIDEN — Utility officials say the city’s ongoing efforts to reduce phosphorus levels in treated sewage before it’s pumped into the Quinnipiac River has already shown promising results.

Frank Russo, manager and chief operator of the Meriden water pollution control facility on Evansville Avenue, and utility manager Richard Meskill showed the Record-Journal on Thursday the system currently in place to filter the phosphorus and nitrogen from the wastewater before it is treated and discharged into the river. This system has been operational since fall 2021.

It has already reduced the amount of phosphorus in treated wastewater from previous levels of around 0.7 micrograms per litre, to 0.094 micrograms.

The computerized system, which pushes water through a series of filters, pipes and pumps, is housed in a brick building and a large rectangular concrete structure next to it. This concrete structure consists of 128 individual sand filter bowls, all of which use sand to filter out phosphorus that had been solidified with chemicals from the water during the overall treatment process before it was released into River.

Russo, when explaining the process of phosphorus removal, often called the mineral “phos”.

“And the dirty water with the phos comes from the bottom,” Russo said. “And that water comes up and filters through the sand. As it rises in the sand, because we added this chemical that turns phosphorus into solids, those particles get trapped in the sand. So the clean water comes out the top and transports.

This clean water is backwashed to get rid of phosphorus particles and returned to the head of the plant for further processing, Russo explained.

Russo said Meriden’s sand filtration system is likely one of the largest in operation in New England.

Russo said Meriden has one of the strictest phosphorus limits in the state. And wastewater is not the only source of phosphorus, which is also found in rainwater and fertilizers.

Russo said one of the main problems with phosphorus is that it helps algae grow very quickly.

“One pound of phosphorus will help support the growth of 16 pounds of algae. It’s a problem in a river like the Quinnipiac,” Russo said.

When this algae begins to decompose, this decomposition draws oxygen from the water, which Russo says can kill large populations of fish.

“That’s why you want to keep it out of there so you don’t grow all that algae and harm the river or the wildlife,” Russo said.

Untreated

The sewage phosphorus reduction project was linked to another project aimed at preventing the discharge of untreated sewage into the Quinnipiac River during major weather events and heavy rains.

Officials said such storms could occur once or twice a year.

In 2018, the city received an administrative order issued by the United States Environmental Protection Agency, after the federal agency found the city non-compliant with its sewage discharge permit. The EPA found that over a four-year period, there were eight instances where untreated sewage discharges from the Harbor Brook pumping station exceeded the limits the city is allowed to discharge by the agency. and by the State Department of Energy and Environmental Protection.

City officials have therefore embarked on a bond-funded project, which is also partially covered by public funds from the Clean Water Fund. The city issued a $50 million bond for the project. Now officials are requesting a change order for $5.65 million to allow for the completion of this project. The cost of the project has increased due to ongoing supply chain issues caused by the COVID-19 pandemic, officials said. The requested change order must be reviewed by the council’s finance committee.

To prevent sewage releases into Quinnipiac, officials devised a plan to divert water into two large concrete digesters located at the Evansville Avenue facility. They are capable of holding over two million gallons of water.

Meskill, the utility manager, said the plan is to try to capture water that accumulates during major rain events.

“The plant can’t necessarily handle all of that flow, which is mostly rainwater,” Meskill said. But officials need to be careful because rainwater mixes with sewage in its collection system.

The design of the plant is to put a discharge point in the piping allowing water that cannot flow through the plant to be directed to the digester. The plan also calls for the relining of pipes to reduce leaks inside and outside the system.

This project is still about 18 months from completion.

“We’re dealing with a very old system, which was first launched in the 1800s,” Meskill said. “And because of his age, there are leaks. It’s not necessarily leaks out of the pipes, but water seeping into the pipes — groundwater and surface water. So during these large storm events, you see very high flows that exceed the processing capacity of the plant.

“So there have been leaks there that are allowing that water to flow out,” Meskill said. “The whole plan of this change order is to try to capture that water in on-site storage tanks. The capacity of these tanks can hold quite a lot of water.

[email protected]:@MikeGagneRJ

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