Eastside water tank leaks 26 million gallons a year. Now city will pay $2.94m to fix it
Great Falls faces a significant problem with its drinking water. It’s not an issue of contamination – the city falls well within all state and federal guidelines for clean water. The issue is a matter of storage capacity.
On a hot summer’s day in August as people water their lawns, take relief in the public swimming pools, shower, wash, and flush their toilets, Great Falls’ 60,000 residents typically use as much as 30 million gallons of treated, sanitary water each day – enough to fill more than 60 Olympic-sized swimming pools. That demand is filled by only two major above ground storage tanks: one at the top of Hill 57 on the northwest corner of town, the other at Dudley Anderson Park, atop a hill off 33rd Street at the city’s east end.
Combined these two giant tanks have a storage capacity of just 9.5 million gallons, less than a third the amount of water used on any give 4th of July, and under half what is recommended for a city the size of Great Falls. Now, one of these two indispensable tanks is in trouble, leaking water at a rate of approximately 26 million gallons a year. That’s nearly enough to completely drain the 4.75-million-gallon tank every two months.
The lost water isn’t readily seen and isn’t flowing onto the ground. Instead, it is trapped by what is know as a “ring drain” which captures the lost water and redirects it into the city’s sanitary sewer system which ultimately returns it to the Missouri River. The biggest concern isn’t cost, it’s the potential for a sanitary water crisis if the city’s water treatment plant were to go offline unexpectedly.
“The reason why we are not simply replacing this tank is we require about 20 million gallons of storage for the city,” Great Falls Public Works Director Chris Gaub told city commissioners on Tuesday. “We are 10.5 million gallons short of that. We currently only have about 9.5 million gallons of storage, so if the water treatment plant were to go offline for any reason during the summer season – which includes power outages – we’d only have about four hours to bring the plant back online before our customers would start seeing the effects.”
“This 80-year-old tank is critical to our overall water system,” Gaub continued. “It holds almost five million gallons of water, which is 50% of our city’s storage capacity. It’s also the primary supply to the elevated water tower on the east side of town.”
Problems at the 33rd tank were confirmed during a routine inspection in October 2022 when underwater divers were sent into the blackness of the enormous tank to inspect and clean it. It’s a process few are likely aware of but is standard operating procedure for municipal water tanks all across the country.
“We actually hire dive crews to come in every four to five years for a couple of different reasons,” explained Water Treatment Branch Manager Jason Fladland. “One, there’s always a little bit of sediment in the bottom of that tank. As much as we try to remove everything, there’s reactions with iron and manganese that will precipitate down and end up in the bottom of that tank.”
“What we hire these guys to do is come in, and they get sprayed down with a bleach solution on top of their dive suits, so they get disinfected before they get into the tank,” he added. “Then they will go in and actually clean that tank.”
“It’s standard procedure to have divers come in because then we don’t have to take the tank offline,” Fladland continued. “If we take a tank down and then have somebody go inside, then the tank has to be completely disinfected. It then takes up to 48-hours to confirm that the tank is ready to go back online.”
“They’re expensive, but they’re worth it,” Fladland said of the highly trained divers.
Information from Potable Divers, the municipal water tank cleaning company hired by the City of Great Falls, shows specially trained crews descending into the inky blackness with underwater lighting and what looks like a large household vacuum cleaner wand to suck out any sediment at the bottom. In addition to cleaning out any debris, the divers also look for cracks or coating failures, anything that could indicate a structural problem within the tank.
What Potable Divers found at 33rd Street was cracking along the tank’s inner lining, but its underlying structure appeared to be sound. The engineering consultant hired by the City of Great Falls recommended the city attempt to repair the 33rd Street tank with a liner system rather than immediately replace it. The cost to make the repair was estimated at $2.75 million.
“We estimate this will extend the life of the tank by around 20 years or so,” Gaub told the commissioners. “This liner can also be spot repaired which could further extend the life of this tank.”
Only one bid was submitted for the project by the April 3, deadline. That came from DN Tanks, a specialty company headquartered in Wakefield, Massachusetts, for $2.94 million. At Tuesday’s regular meeting of the Great Falls City Commission unanimously approved the nearly $3 million contract without batting an eye. The alternatives were few, and the option to repair rather than replace a five-million-gallon water tank – a project estimated to cost around $12 million – saved the city more than $9 million, at least temporarily.
In a twist of irony, DN Tanks, then under a different name, is the same company which originally built the 33rd Street water tank back in the 1940s.
“It’s kind of a niche area of the market,” Fladland said of DN Tanks’ area of specialization. “It was really neat to hook up with the original builder of the tank. They had all the plans from the original construction – granted they’re on microfiche.”
Work on the repair project is expected to begin this October when municipal water usage is at a low, and is expected to be completed sometime in January 2025. Fladland said the city’s water treatment plant has already conducted a successful test that predicts Great Falls customers will not experience any sudden drop-off in their household water service while the project is underway.
“They shouldn’t see a difference,” he said. “We did a trial run with it in February, and we did not incur any phone calls. There was nothing out there. What we’re relying on also is the Hill 57 tank on the north end of town. We’re relying heavily on that volume of water as well.
Still, the city cannot afford to ignore its sanitary water storage capacity indefinitely. If Great Falls expects to grow and expand its population in the decade ahead its water storage problem will only become more acute with the passing years. Attracting families to the city depends in no small part on the ability to ensure that when they turn on their taps clean, fresh drinking water will be readily available.
This article originally appeared on Great Falls Tribune: City approves $2.94 million to repair leaky drinking water tank
