U.S. Army Corps: Albeni Falls Dam gate replacement may span 4-10 years

By Zach Hagadone
Reader Staff

Officials from the U.S. Army Corps of Engineers and Bonneville Power Administration spoke to a group of in-person attendees and online participants at an informational session Oct. 7 at the Ponderay Events Center, focused on the ongoing project to replace as many as 11 spillway gates at the Albeni Falls Dam. Analysis in the spring revealed serious defects in the 70-plus-year-old steel used to fabricate them, and the replacement effort could take no fewer than four years and up to seven or even 10 years to conclude the entire project. 

U.S. Army Corps Col. Kathryn Sanborn — who is district commander based in Seattle — was guarded in her assessment of when the work could be completed, noting that the timeline is being directed by the ability of the steel industry to fabricate the gates and the difficulty of installing them.

“When it comes to actually installing these new gates, we’re going to be effectively merging two different eras of engineering,” she said, referring to the changes in steel manufacturing as well as safety standards since the 1950s, when the dam was constructed.

USACE Col. Kate Sanborn visits Albeni Falls Dam near Oldtown to address the gate defects with stakeholders in May 2024. Photo by Ben Olson.

There are a limited number of contractors in the country who can handle such a job, she said, and the U.S. steel industry is much less robust than it was in the 1940s and ’50s. That said, Sanborn referred to using regional expertise from hydraulic steel engineers in Walla Walla, Wash., and design from specialists in Vicksburg, Va.

“I don’t want to promise you something I can’t deliver,” Sanborn said, while outlining the process for replacing Gate 3 — which was the first to be found defective — and will take upward of four years to fully rehabilitate.

The remaining gates, which are likely to suffer from the same faults, would be replaced in six-month intervals thereafter. The central problem with the gates stems from the delamination of the steel over the decades, resulting in holes and cracks that have created a “rolling flaw in the metal,” according to Sanborn. That has meant the steel in the gates has thinned during their service lives, and become less strong and more bendable — liable to “crumple” under the immense pressure exerted by the force of the drainage of Lake Pend Oreille westward into the Pend Oreille River.

Putting some numbers to the equation, Sanborn said that 11.5 feet of Lake Pend Oreille’s water surface is usable for power generation. That amounts to about 1 million acre feet, or 735,000 football fields covered with water.

“That’s a lot of water,” she said. 

“We’re more just shaping and shaving off” that portion as it moves through the dam, Sanborn added.

If the steel in the gates were to fail — a worst-case scenario that the Corps is working to avoid — it would occur “at the speed of sound,” Sanborn said. It would “buckle, collapse downstream; it would collapse like a sheet of paper.”

That would result in water rushing at 20,000 cubic feet per second, which Sanborn said “sounds horrific,” but wouldn’t be “a wall of water.” The shorelines are capable of handling flows of up to 95,000 cfs; but, if such a failure were to occur in the summer, residents would notice a significant change in the lake level — dropping to around the winter pool level of 2,051-2,051.5 feet.

That’s not going to happen, Sanborn said, because Gate 3 will be patched with a fiber-reinforced polymer substance that will function as a kind of “Band-Aid” to reinforce the weakened steel while a replacement is made.

“We don’t really have a choice in terms of what we’re doing going forward,” she said, adding that there’s no “do-nothing” option.

Meanwhile, the dam will continue on reduced operations, with a goal to get the lake back to the 2,062-foot summer pool level even with the restrictions imposed by the gate replacement project next year. Again, however, Corps officials didn’t want to “overpromise” any outcomes. 

Attendees at the meeting were critical of the timeline for the fix — calling it “arbitrary” and unnecessarily long.

One participant, who did not disclose his name, testified that as an area dock owner, “Five or six inches [of water] might not sound like a lot, but to some of us, it is. … Some of us live on shallow water.”

Others, like Lake Pend Oreille Commission Executive Director Molly McCahon, questioned whether there is a cost figure associated with a spillway gate failure and reduction to winter pool level. To that, Sanborn and other officials had no direct answer.

However, Sanborn said, the short-term fix for Gate 3 is expected to be in place by spring 2025 and it’s a case of crossing fingers that the upcoming post-winter snowmelt isn’t too high and residents notice little difference in the lake level fluctuation. 

Leon Basdekas, who serves as Upper Columbia Senior Water Manager for the Corps, told meeting attendees the most recent runoff season had been the sixth-lowest since 1948, with just more than 8 million acre feet of water, but, “Chances are, we’ll get more than that next year,” he said. 

Snowmelt from as far afield as Missoula, Mont. to lower British Columbia flows into the Lake Pend Oreille Basin and through Albeni Falls, with particularly high flows from April to June.

“In the meantime, if a gate fails tomorrow, I don’t have any spares,” Sanborn said. “I don’t have any tools to use to put in that slot.”

Idaho Gov. Brad Little has weighed in on the situation, voicing in an Oct. 3 letter to the Corps his “serious concerns for public safety and utmost expectation for your expediency in replacing all the faulty spillway gates at the Albeni Falls Dam project.”

“I understand your team is exploring creative ways to get new gates built and installed, and they were very clear in expressing the challenges related to engineering, construction, logistics and installation of new gates,” he wrote. “Frankly, a process to replace these faulty gates that stretches out years, approaching a decade, is flat unacceptable. 

“The U.S. government, the largest contractor in the world, and especially the Corps of Engineers, is surely capable of reducing the prolonged elevated risk to life and property by finding a contractor with the ability and capacity to replace all these outdated and compromised spill gates in short order,” he added, referring to the Corps’ plan as “unnecessarily conservative lake level management” that results in “significant economic impact, including loss of recreation, tourism and property damage.”

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