15-04-2025
Watertown considering spray-on lining to fix leaking reservoir
Apr. 14—WATERTOWN — The city has found a potentially less expensive way to fix its leaking 5-million-gallon reservoir in Thompson Park — installing spray-on lining rather than replacing the tank.
During a Monday night work session, City Council members learned that City Engineer Tom Compo and Water Superintendent Aaron Harvill have talked with a company that could use a polyurea lining to stop the leak on the larger of two tanks in the park.
"It would be at a fraction of its cost," Compo said.
The city is otherwise faced with replacing the reservoir at a projected cost of $4.3 million, instead of possibly around $1.75 million to $2.25 million for the lining.
For years, the reservoir lost 400,000 gallons of water a day.
City officials thought it was fixed when the reservoir underwent major repairs last spring, but city officials found out in December that the larger of the two reservoirs was leaking once again.
Compo and Harvill met with the company after it had heard the city was having additional issues with the 153-year-old tank leaking, Compo said.
"So we're pretty intrigued," he said.
The city would drain the tank, allowing the company to inspect it and see if the lining would work. The company has used the polyurea material on fixing leaking manhole covers and in some other manners for the city.
The large reservoir would be the largest project using the material.
Council members took no action Monday. City staff will continue to look at the city's options, Compo said. Staff hopes to come up with a recommendation in about a month, City Manager Eric F. Wagenaar said.
Councilman Robert O. Kimball wasn't thrilled with the idea of installing the new type of lining, equating the situation to "buying a new car rather than putting a transmission in my 12-year-old car."
But Councilmen Benjamin P. Shoen and Cliff G. Olney III said they were happy to hear about another option besides replacing the reservoir.
"It's definitely nice to have an option," Shoen said. "Why not?"
The state Department of Health is strongly urging the city to finally fix the problem. If the city proceeds with replacing the reservoir, the new tank would be designed this year, demolition would be completed next spring and construction of the new one would start next June and take about nine months to complete.
The smaller 3-million-gallon reservoir at the park is not likely leaking, but it was built at roughly the same time as the larger one, Compo said, adding that he cannot guarantee that it won't start to have issues.
Last spring, North Country Contractors, Calcium, made major repairs to stop the leak from a pipe going out of the reservoir, costing the city $356,192.
That large leak occurred in a pipe that leads to the "East" reservoir.
The city pinpointed the leak in a 50-foot section between a valve box and the water tank's wall. The pipe was encased in 30 feet of concrete.
In August 2021, City Council members earmarked $500,000 in American Rescue Plan Act funding to find the leak.
Officials have known about the leak for decades.
The treated, leaking water was typically seen near the Franklin Street entrance to Thompson Park — close to a paved trail — and flowing out of the park and into a drainage ditch.
