Leaking Thompson Park reservoir should be repaired soon

May 16—WATERTOWN — A leak in one of the reservoirs in Thompson Park that loses 400,000 gallons of water a day should finally be fixed.

A contractor, North Country Contractors, Calcium, has started excavating outside the 5-million-gallon water tank.

City officials believe that the leak is occurring in a pipe that leads to the "East" reservoir. Officials have said they have known about the leak for decades.

They hope to pinpoint the leak in a 50-foot section between a valve box and the water tank's wall, city engineer Tom Compo said. The pipe is encased in 27 feet of concrete.

In March, water department employees "isolated" the leak, he said.

If it does end up being a pipe that leads into the reservoir, the pipe will be removed and replaced by another one, Compo said. "We'll cut the pipe out and sleeve the new one in," he said.

If that's it, the repairs will cost $325,000. However, the leak could still be within the tank's wall and that would cost substantially more, he said.

Earlier this week, about half of the excavation work was completed. Compo thinks the repairs could be "completed within three weeks."

In the past several months, water department employees and consultant DN Tanks, a Massachusetts company that specializes in reservoirs and tanks, have worked on the issue.

The 5-million-gallon tank was drained in December and a diver went inside to examine it. Nothing was found, leading to the suspicion that the piping was the source of the leak.

In August 2021, Watertown City Council members earmarked $500,000 in American Rescue Plan Act funding to find the leak.

The drinkable, leaking water can normally be seen near the Franklin Street entrance to Thompson Park — close to a paved trail — and flows out of the park and into a drainage ditch.

While it looks like a natural stream, there's usually a faint smell of chlorine from the treated drinking water — and it flows year-round without freezing.

The second, smaller reservoir holds 3 million gallons of water.

On a related note. Water Superintendent Vicky L. Murphy confirmed that she is not recommending to install liners in the two reservoirs anytime soon.

The capital projects program in the proposed $56.4 million city budget for 2024-25 includes spending $5 million to install liners in both reservoirs.

But Murphy stressed that she's not recommending them to be installed now because "the water department doesn't have the money to do that."

They should be installed at some point, but they're "on hold for now," she said.

During this spring's budget deliberations, the liners were briefly discussed. The public wants to know why the liners were needed when the reservoirs have never had liners.