Gate issue is long-term problem

OLDTOWN — “So what I’m hearing tonight is — the dam’s broken, it’s not safe to operate, and we don’t have the funds to fix it,” a community member said at the Albeni Falls Dam meeting held last Thursday.

The meeting, held by U.S. Army Corps of Engineers, was prompted by the April discovery of defects on spillway Gate 3 at the dam.

During a maintenance inspection in June 2023, the gate was removed to repair cracked welds and repaint it. However, the gate ended up remaining removed when further defects were discovered after a more in-depth inspection.

“When they were doing the in-depth inspection, the kind of inspection you can only do after you’ve removed all the paint, which means you can only do it after you’ve taken it out of the dam … that is the level of inspection that we were doing when these steel defects were found just last month,” Kathryn Sanborn, USACE Seattle district commander, said.

Ultrasonic testing was completed on the gate prior to the paint removal in an attempt to detect any abnormalities, but nothing was discovered until the paint was fully stripped from the gate. Defects — holes in the steel — were found on the two primary girders of the gate and exist throughout the length of each. 

“Essentially, what the flaw is — the steel is delaminating,” she said.

All 11 gates — 10 main gates and one spare — were constructed and put in the same year the dam was completed in 1955. Although the gates had an average expected lifespan of 50 years, they have outlived that expectancy by almost 20 years.

Sanborn said it is likely the defects have been there since the gates were built and have gradually gotten worse over time due to their continued use.

“Until every gate is inspected, we have to presume that the other gates have the same defect,” she said. “They were built at the same time with the same steel, so our current regulation standards guide us to having this presumption.”

Sanborn said it’s unclear at this time whether the discovery of the defects will change the level of scrutiny the gates are inspected annually.

Although Gate 3 has not shown any signs of failure, she said that USACE will not be returning it to the dam until full repairs or replacements have been completed.

“Now that we know the defects are there, now that we know there is a problem, we cannot safely put them back into use,” she said. “We cannot safely put Gate 3 back into use and just say, ‘Well, it was working before, so we’re going to assume that this risk is not there.’”

The type of defects that were found in the steel, she said, would give no warning or response time before complete failure — the gate would simply fully give out almost instantaneously.

This would not only damage the spillway itself, but likely also the crane that sits on top of the spillway. Depending on the extent of gate failure, the crane operator could also be seriously injured or killed. With life, health and safety at the forefront of USACE’s missions, staff will not implement any decisions that could harm individuals working at the dam.

To mitigate the risk of catastrophic failure of any of the gates, USACE will be moving the gates as little as possible until full diagnostics have been completed on each gate. This means the gates will remain either fully open or fully closed as much as possible to lessen the heavy pressure on different portions of the gates.

“We’re only going to move them when absolutely necessary to control the lake refill and to manage quadrants,” Sanborn said. “We’re only going to move one at a time, rather than spreading flow out across many gates. When possible, we’re only going to have the gate move to fully open or fully closed.”

Should another gate break, she added, there are no other spares to put in place of it, not even from other dams. In the 1950s, there was not a lot of communication between different sites on what kind of dams the others were building, Sanborn said. Each dam was built for the specific space and reasons needed for that area. Because of this, there are no dams in the vicinity — or possibly the whole country — that have a gate that would fit in Albeni Falls Dam.

If a gate were to fail in the near future, Sanborn said lake levels would rise quickly and begin plummeting between July and August.

“This is exactly what we’re trying to avoid,” she said.

USACE’s goal right now is to have lake levels to 2,060 by mid June and 2,062 by the end of June. Depending on external factors, such as the weather, those levels could be reached sooner or later.

“Refilling Lake Pend Oreille isn’t a matter of if, it’s a matter of when,” said USACE Upper Columbia Basin senior water manager Leon Basdekas.

These plans, added Sanborn, are only for this summer. As of right now, staff expect drawdown in the fall to look normal. As for next year, there are too many unknowns to make a guess at what things will look like, she said.

Right now, staff are trying to figure out short-term solutions to the issues at hand, but Sanborn told the audience not to expect things to calm down immediately. Getting each gate tested and additionally repaired or replaced, if needed, is going to take much longer than one might expect.

“The reality is – it’s going to be years, not months,” she said.

Sanborn said she understands the frustration that it took nearly a full year for the defects to be fully discovered.

“I know you guys are frustrated,” she said. “I’m frustrated, too. The fact that it took us 10 months to get to the point where we could identify the defects — it shouldn’t have taken us that long.”

However, Sanborn said that even if the defects had been discovered instantly, things would not look much different than they do right now, since there is still little funding available and only one spare gate.

“Nine months ago, let’s say we had identified the defects then,” she said. “We’d still be doing the same thing we’re doing now.”

Regarding long-term plans, staff are hard at work seeking engineering solutions to find the best way for corrective action, analyzing the other gates, and determining effective gate movement for the time being. USACE staff will also be heavily pursuing funding opportunities for permanent corrective action for the dam’s spillway gates.

“Eleven gates is not an insignificant rehab, or replacement; we don’t know yet,” she said. “That’s probably not going to have an insignificant price tag.”

While Sanborn said she wishes they could have already paid for the full replacement of the gate, the country’s infrastructure is old and there are many more needs than there are available funds to pay for those needs, which is why staff are looking at every possible option for a short-term fix.

“We’re working all options to try and make sure we have something that works sooner and then something that’s going to work in an enduring solution for hopefully many decades to come,” she said.

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