Watertown will spend up to $750,000 to fix reservoir leak

Mar. 31—WATERTOWN — City officials finally know exactly what has been causing a leak in one of the reservoirs in Thompson Park that loses 400,000 gallons of water a day.

And it could cost as much $750,000 to fix.

On Monday night, the City Council will be asked to approve $750,000 in bonding to pay for repairs to a pipe that leads into the 5-million gallon water tank at the park.

According to a memo, City Manager Eric Wagenaar expects the cost will be in the range of $500,000 to $750,000 to fix.

City officials have known about the leak for decades.

City Councilman Benjamin J. Shoen brought the leak up when he was a candidate last fall.

“I’m just happy this is finally going to fix it,” he said Saturday.

About a month ago, the 5-million gallon reservoir — the larger of the two water tanks — was drained so the piping going into it could be inspected to see if that’s the source of the leak.

The leak was found in that pipe going through the reservoir wall and encased in 30 feet of concrete, Shoen said.

Bids will go out soon to find out how much exactly it will cost to fix, Shoen said. But he added that the repairs will eventually pay for themselves because the treatable water will no longer be lost from the leak.

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

The leak has been a problem that spans decades, according to city officials who have noticed a stream flowing out of the park for many years.

Councilwoman Lisa A. Ruggiero said council members have been blamed for allowing the leak to continue when previous councils knew that it had been happening for many years.

“I’m just glad it’s getting fixed,” she said.

The 5-million gallon tank also was drained last 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.

The reservoir continues to leak 400,000 gallons of treated water a day.

In August 2021, council members earmarked $500,000 in American Rescue Plan Act funding to find the leak. The drinkable 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.