One of Tempe Town Lake’s dams leaking air

One of the rubber dams forming Tempe Town Lake is leaking air and the company that made it says it won’t make it again. Even more, as of yet there is no set cost for a replacement, but that’s somewhat moot because the city doesn’t have the money for a replacement anyway.

Replacing Tempe Town Lake dams may cost $22M

“Annoying is a good word for it,” Tempe City Manager Charlie Meyer said Tuesday.

Tempe Town Lake is the centerpiece of a massive project that, seemingly overnight, transformed an empty, ugly scar of a riverbed into a 2-mile-long hub of recreation and private development.

The manufacturer of the dams, rubber conglomerate Bridgestone, told the city its products should last 25 to 30 years — although the guarantee expires after 10. The lake was filled in 1999.

But two years ago, Tempe officials learned the dams at the lake’s western end were aging faster than promised.

To blame was Arizona’s harsh climate, especially the baking afternoon sun.

The dam is still covered under the warranty, but when that expires and what happens afterward are up for debate.

“Bridgestone has stated, publicly, they intend to support their customers and honor their warranty,” Meyer said. “What we’re trying to find out is exactly what does all of that mean.”

Mayor Hugh Hallman said he was asking questions about the dams’ longevity 10 years ago.

“This is an example of questions that weren’t fully answered at the time and politics allowed that to occur,” Hallman said. “We now have to attend to the consequences of not full vetting all of the issues — but we will do that.”

It isn’t known when the dams might fail, Meyer said. But he added: “We’re operating under the premise we try to replace them as quickly as we can.”

But replace them with what?

Much of the city’s problem stems from the fact these dams are specialized, as they have to handle the ebbs and flows of the Salt River.

In the Valley’s recorded history, the Salt’s greatest recorded flow was 200,000 cubic feet per second, reached in 1905. Meyer used the analogy of a cubic foot being represented by a basketball – meaning, that’s a lot of roundball in the river.

“We’ve got to pretty much allow a full flood to run through Tempe Town Lake, and when it’s over put the dams back up,” Meyer said. “That is a much, much more complicated engineering task than simply holding back water.”

Don’t look to Bridgestone for a solution; the company has let Tempe know it no longer makes dams, which Hallman said was disappointing.

“But there are other suppliers,” Hallman said.

At the moment, Meyer said, city staffers are soliciting bids on possible fixes, as well as speaking with Bridgestone and another company.

Hallman added he has a hunch Bridgestone could, in fact, make a replacement.

As for the cost, recently an estimate of $22 million was kicked around, up from last year’s approximation of $16.6 million.

But Meyer said the $22 million was just a placeholder in lieu of a firm answer.

“I’m not even sure what the $22 million was based on,” Meyer said.

“That’s the number we have plugged into the capital budget.”

Money for maintaining the lake is raised through a special tax assessment of nearby properties. With this deflating development, the city has been caught short on funding.

“So, we don’t have, yet, stored up the amount of money that you would have planned for as a replacement,” Meyer said. “If we could go out 20 years, we wouldn’t have a funding source problem.”