Deconstructing the Eklutna dam: multiple agencies come together to remove obsolete structure.

AuthorRohloff, Jessica
PositionCONSTRUCTION

Decades after it became obsolete and was abandoned, the lower Eklutna dam is finally being removed. Construction is ahead of schedule, under budget, and expected to be complete this fall. But it may only be the first step of a two-part process, and part two could prove to be more difficult. "The project is moving faster and going better than anyone expected," says Brad Meiklejohn, Alaska state director for The Conservation Fund. "Because it's gone faster, we've been able to stay under budget."

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One of the ingredients that has contributed to the success of the Eklutna dam removal project was careful planning. The planning stage alone took fifteen months, according to Sam Barber, construction manager for Eklutna Construction and Maintenance, the company contracted to remove the dam. That time was spent evaluating different scenarios for tearing down the dam in a way that is both safe and cost-effective. "There have been a lot of challenges, but it [has] gone way faster and better than we expected, and, because it [has] gone faster, it's been able to stay under budget," says Meiklejohn. "We had a limited amount of money, and we said, 'Hey, let's see if we can pull this off with the time and money that we have.'"

So far, so good.

Eklutna Construction and Maintenance

Planning began in January 2015 and was finalized by February 2016, allowing pre-construction to begin. The Conservation Fund raised $7.5 million for the project and contracted with Eklutna Construction and Maintenance for the work.

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Because Eklutna Construction and Maintenance is a wholly-owned subsidiary of Eklutna, Inc., the Alaska Native Corporation that owns the land on which the dam resides, "They're motivated [and] have a lot of skin in the game," Meiklejohn says. "They're being very creative and responsible, finding the most cost efficient ways to do the work."

This is not a typical worksite. Workers must descend 300 feet down into the canyon to reach the work site. To accommodate this, a 400-step aluminum staircase was constructed to allow workers to get in and out of the canyon. During pre-construction, the crew removed trees from the canyon and put structures in place for emergencies. A helicopter pad was built, as well as a floodplain in the event workers need to get to high ground in a hurry.

There are additional factors complicating the deconstruction: the dam is constructed of seventy feet of century-old concrete, and because concrete continues to harden after it cures--even underwater--this particular concrete presents even more difficulties for those removing it.

By late July, workers had removed the top six feet of the dam. This part of the job was especially slow-going because the top ten feet of the dam are reinforced with rebar.

The original plan was to use hydraulic chippers to break apart the concrete dam, but that wasn't going as quickly as planned. So workers began drilling holes in the dam and filling them with a substance that expands overnight to crack the concrete. The material is similar to spray foam insulation used in residential homes, but it's strong enough to break 100-year-old concrete and is completely inert (so it does not impact water quality).

The next step for the workers is...

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