Mystic Sewer Amnesty Yields Modest Returns

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STONINGTON — Under the town’s announced sump pump amnesty, sixty-five property owners in Mystic admitted to having a sump pump discharging into the municipal sewer system, an illegal practice. The amnesty is part of a broader effort by Stonington to address sewer capacity issues.

Stonington Water Pollution Control Authority Director Douglas Nettleton sent a letter in early August to 1,400 property owners in Mystic offering amnesty from August 15 to September 30 to any violators.

“If you (responded) within that time period, you would be exempt from any penalties later on down the road. If you didn’t take advantage of that and have a sump pump connection and we found out later, then of course we wouldn’t give you any leeway,” said Nettleton by phone Thursday.

Nettleton said he’d hoped for a better response, and was aware of violators who had not responded.

The amnesty is in preparation for a $300,000 Inflow and Infiltration study planned for this fall to identify water entering and exiting the town’s sewer system.

“The whole idea behind this is to develop a spreadsheet that basically tells us how bad the problem is,” Nettleton said, referring to increased flows to the Mystic sewage treatment plant that exceed its 800,000-gallons-per-day capacity. These flows usually coincide with heavy rains.

Information on the locations of the sump pumps will expedite the I&I study. The study will likely take 12 to 18 months to complete, but will depend on the weather, he said.

“I’d like to have a wet season and also a dry season to do the work because you want a comparison,” he said. “We need to see if we have major leaks and check if the groundwater is higher — narrow it down and go into different sections and do a lot of flow monitoring.”

According to Nettleton, the problem tends to disappear during dry weather, and reappears during periods of heavy rain.

Unbillable water flows

Stonington’s three sewage systems — the other two are in Stonington Borough and Pawcatuck — all have problems that require I & I studies, Nettleton said, but for the time being the focus is on Mystic.

“Because of costs and everything, we’re just we’re just concentrating on Mystic, because that’s the biggest problem right now,” he said.

Stonington is also planning to reactivate diversion pipes connecting Mystic and the borough, which can reduce the overcapacity issue.

“We kind of have a two prong attack going to see if we can reduce flows but also provide a solution to the flow that we have coming in,” he said.

Nettleton explained that in addition to overtaxing the Mystic treatment plant, water flowing from sump pumps into the sewage system is not billable by the town, creating a financial problem.

“It costs us money and it doesn’t generate any revenue,” he said. “That flow is flowing through the sewer lines, quite possibly is going through a pump station, maybe two pump stations, so we’re paying to treat it at a treatment plant and it all costs money. But yet, none of that flow is generating revenue and that’s a real problem for us.”

With the tourist season winding down and less rainfall, Nettleton said he’s hoping the Mystic plant’s September volumes will be reduced. The tourist season may also have generated extra revenue from water usage.

Billing for sump pumps

Some communities bill property owners who discharge sump pumps into a municipal sewer system, Nettleson said, but determining a fair billing for the flow is a problem.

“It’s not measured, it’s kind of hard to meter as as opposed to a water meter. There probably are ways to do that, very complicated ways,” he said. “I’ve talked to a lot of these people and most of them say that their sump pump doesn’t run very often — that may or may not be the case. But say you have somebody whose sump pump is running daily and it’s pumping almost all the time — should they pay the same as someone who tells me it only runs when we have a super heavy rainfall?”

Nettleton said the town’s Water Pollution Control Authority is considering a base charge for sump pumps.

“With our financial situation, we can no longer just absorb costs like this so we’re looking at all different ways that we might do this,” he said. “Part of hiring consultants doing I & I is calling upon their expertise and asking how do we achieve this?”

Mystic’s excessive sewage levels are a mystery Nettleton intends to solve.

“You really always hope that you’re going to find a real big, like a smoking gun type of thing and maybe we will, but a lot of times it’s just it’s just hard work and a lot of little stuff that you have to take care of,” he said.

In the meantime, some of Mystic’s flows will travel through 6-inch and 12-inch pipes to the borough’s plant, he said.

“Those pipes are fine. You don’t need to patch them up or whatever. They’re working,” he said.

When the diversion pipes were last used about two years ago, odor was a concern, but it won’t be a problem this time around, he said.

“We’re building odor control into it and in my opinion, as long as we keep it moving and keep it fresh, there won’t be the issues that we had before, but we are preparing for the worst case scenario. If we do need to use odor control, it will be in place,” he said.

The plan to reactivate the diversion pipes is under review and may go into effect in September 2020, subject to a construction schedule for work at both the Borough and the Mystic plants.

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