standing Mystic water treatment plant

Mystic Wastewater Treatment Plant. Sun file photo

STONINGTON — The Water Pollution Control Authority on Tuesday imposed a moratorium on new connections to the Mystic Wastewater Treatment Plant.

The moratorium is designed to give officials time to address an increase in flow at the plant, the result of wet fall and spring seasons that have taxed the system, WPCA Director Doug Nettleton said Thursday.

“Basically, this means no new flows to the Mystic treatment plant for the time being,” he said.

The state permit, he said, only allows for 800,000 gallons of flow a day, but the wet weather has resulted in an average of 822,000 gallons a day.

“One day, the average flow for the day was 1.2 million gallons,” he said. “There are a lot of catchalls in the permit.” 

A “90 percent of design” rule states that if the plant exceeds 720,000 gallons a day for six months in a row, the town must submit a plan to the Department of Environmental Protection to handle the additional flow.

The Perkins Farm project off Jerry Brown road will not be affected by the moratorium because it already has approval for sewer connection, which will create a 40,000 gallon per day increase at the Mystic plant. Other big projects such as Smiler's Wharf in Mystic can still plan ahead, Nettleton said, but there will be no new flows allowed right now.

“This is unprecedented building we have going on, so it’s put a lot of pressure on the WPCA to keep things moving,” Nettleton said. “It would be irresponsible to allow people to tap into the line and increase the flow."

“The plant has been running well, and the operators are doing a good job, but technically we’re in violation,” he said. “With the kind of flows we’ve been getting, we can’t predict if this wet weather is the new norm.”

The Stonington Borough plant is running below capacity, which will give Mystic an option to connect to a transmission line to the Borough plant. The Borough transmission line is rated for 300,000 gallons a day, Netteton said.

“We really have to covet that capacity because solutions aren’t cheap,” he said.

The town has received approval in the capital improvement budget for $2 million to connect to the Borough transmission line and for an “I and I” or “inflow and infiltration” study. Suez Water Technologies and Solutions of Paramus, N.J., runs Stonington’s three sewer plants.

“We’re doing the study to find out how clean water is getting into the system,” Nettleton said. “Inflow is the flow getting into the system by sump pumps in basements. Infiltration is flow getting in through cracks in the pipes and leaking manholes.”

Nettleton noted that sump pumps, which are illegal in the town, are a “big problem” in Mystic. The problem is commonplace in many communities, officials said.

“Sump pumps go into the sewer lines,” Nettleton said. “We have to get our hands around this problem.

“It’s so easy to connect a sump pump to the sewer system. You can’t dump (water) into the street because the water will freeze, and you can’t dump it into the ground because it will come right back into the house,” he said.

While the fine for a sump pump connected to a sewer line is $100 a day, Nettleton said he would prefer that people notified the department to work on a possible solution.

“We want to work to get this flow out of the system,” he said, “We may be forced into getting heavy, but the first step is finding out how big a problem it is. We’ll find out by doing the inflow and infiltration study. We can tell where it comes from because it’s clear water.”

Nettleton said the problem isn't just in Mystic. Sump pumps have been an issue in Stonington and Pawcatuck as well, he said, but those systems "have plenty of capacity." He said the study will allow the community to get a better grasp of just how serious the problem is — and how exactly to address it. 

“The study will open up manholes so we can narrow down where the excess water is coming from,” Nettleton said.

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