USACE again says lake tap is frontrunner for long-term flood mitigation, denies it abandoned that stance
- Mark Sabbatini
- 1 day ago
- 5 min read
Head of US Army Corps of Engineers, during visit to Juneau this week, expands on flood-control efforts planned in the months and years ahead
By Mark Sabbatini
Juneau Independent
A "lake tap" drainage tunnel is back as the most viable long-term glacial flooding solution for the Mendenhall Valley — and the head of the U.S. Army Corps of Engineers said while visiting Juneau on Tuesday it’s never been otherwise since it was declared a preferred solution in December.
A coalition of federal and local officials announced in December they were aligned on a drainage tunnel to control flooding from Suicide Basin as the most cost-effective and safest of five long-term options. However, local leaders were dismayed a month ago when City Manager Katie Koester told the Juneau Assembly the USACE was rescinding plans to study a lake tap as a preferred solution, saying "it was a really disheartening pivot that left us a little bit speechless."
Another shift in perceptions occurred Tuesday when Assistant Army Secretary for Civil Works Adam Telle said at a press conference in Juneau the agency he heads isn’t rescinding long-term plans, but shifting its focus to short- and medium-term actions.
"So just because I've shifted my attention to really look at what's in front of us right now doesn't mean that anything has changed in terms of long term," he said.
Telle and other USACE officials are visiting Alaska this week to review projects in several communities. The group arrived in Juneau on Monday and spent their time leading up to their Tuesday afternoon departure touring the Mendenhall River areas where flooding is occurring, flying over Mendenhall Glacier to examine Suicide Basin, and meeting with local officials about project updates.
Local leaders participating in Tuesday’s press conference characterized the USACE's backtrack of a long-term solution as a misunderstanding.
"That's one of the reasons we appreciate the secretary, and the generals and the colonel, for coming here face-to-face," Mayor Beth Weldon said. "There's not going to be a miscommunication problem at all. So we appreciate that. We appreciate their enthusiasm and dedication to a short-, medium- and long-term solution."
The dispute was raised at a Senate committee hearing in late February, where U.S. Sen. Dan Sullivan, R-Alaska, told Telle, "the concern in Juneau is the Corps pulled back without clearly communicating the change in direction to the community." That led to further meetings in Washington, D.C. with the Alaska delegation and local officials prior to meetings this week in Juneau.
USACE officials reiterated and expanded on flood-control efforts planned in the months and years ahead.
Short-term measures before this year’s flood season include raising some HESCO barriers now forming a semipermanent levee along one side of the Mendenhall River since last year’s record flood resulted in water levels a few inches below the tops, Telle said.
"What we do know is that raising the HESCO barriers even by a few inches may result in (five times) the protection for the community," he said.
Short-term work may also include trying to change some flow areas of the Mendenhall River, Telle said.
"This can be done relatively quickly and for low cost," he said. "The question is does that straightening actually just move the risk to a different part of the community? And so we want to be very careful about that. We've got extensive modeling underway right now."
Officials are beginning work this spring on a second phase of HESCO barriers that will extend the wall in both directions, as well as provide protection on both sides of the river, said Col. Jeff Palazzini, USACE’s Alaska district commander. More riverbank armoring and pumps to assist where flooding occurs are also planned.
"In the medium term we're looking at more permanent and more survivable barriers that can be implemented, as well as continuing to look at channel modifications," Telle said. Additional work during that time will include technical analysis and engineering involving a long-term solution.
Five long-term options were evaluated by federal and local officials late last year, which were labeled lake tap, dam, floodwall/levee, hybrid (dam and floodwall/levee) and relocation. The agreement on a lake tap as the preferred solution was announced jointly by the City and Borough of Juneau, Central Council of Tlingit and Haida Indian Tribes of Alaska, and the U.S. Forest Service following a three-day charrette hosted by USACE in December.
Telle, reiterating comments made by officials in December, said assessing a lake tap as the seemingly most viable option doesn’t mean the other four are being excluded from further consideration.
However, among four display boards set up for the press conference, the lake tap alternative was highlighted on two, while the other two boards focused on shorter-term efforts. One of the boards, headlined "Alaska Mining Industry Support For A Lake Tap," was a copy of a March 20 letter sent to Alaska’s congressional delegation by the Alaska Miners Association, Hecla Greens Creek Mining Co. and Coeur Alaska Inc.
In the letter, the mining entities expressed their support for a lake tap as the long-term flooding solution, and stated the two mining companies have the experience to perform tunneling work.
"Based on our companies’ collective expertise in tunneling in formations similar to Bullard Mountain, we think there are significant opportunities to reduce cost, schedule risk, and construction complexity while simultaneously improving the long-term resilience and adaptability of the Lake Tap," the letter states.
When asked why the letter from the mining entities was highlighted and what role their input played in USACE declaring a lake tap the most feasible option, Telle said, "We're taking advice from experts across the board," and he wasn’t involved with seeking their input.
CBJ Public Works Director Denise Koch, in an interview after the press conference, said she reached out to local mining officials in February because "I was looking to them as people who have expertise in tunneling."
"I thought, ‘Who has the most experience?’" she said. "Lake tap is functionally a tunnel and who has the most experience with that is the mining community."
• Contact Mark Sabbatini at editor@juneauindependent.com or (907) 957-2306.
