The last 30-ft-tall stub of Glines Canyon Dam didn’t go out quietly last week, but the detonated concrete offered up plenty of opportunity for people to nosily celebrate the virtual completion of the Elwha River dam removal project in Washington State.
In what was the nation’s largest dam removal project, Bernard Construction Inc. crews from Bozeman, Montana, removed the 210-ft-tall Glines Canyon Dam and the 108-ft-tall Elwha Dam, opening up the Elwha River in the Olympic National Park for the first time in 100 years.
The dismantling started in September 2011, with the methodical removal of Elwha Dam, which wrapped up in March 2012 well ahead of the contractor’s schedule. The Glines Canyon project, 13 miles from the mouth of the Elwah River and about eight miles upstream of the Elwha Dam, took longer, but finished last week when the last 30 ft of the dam was blasted away.
Crews drilled an extensive pattern of holes into the remaining concrete, then packed those holes with explosives to dislodge and fracture the remaining concrete and rebar. Now gone, crews will continue cleaning up the debris from the blast, a process that will finish this fall.
The release of water behind the dams and the 78 million cubic yards of sediment that came with it necessitated the slow dismantling of the dams. As the two dams dropped in height, the river began to meander sediment downstream and restore natural processes. Over 70 acres of new beach and riverside habitat has already been created.
Scientists also believe that all five native species of salmon will return to the 45-mile river that once teemed with the fish.
The Elwha Dam, located about five miles from the river’s mouth, was built in 1913 and the larger Glines Canyon Dam took shape in the 1920s, opening in 1927. The dams lacked fish ladders and the power generated from them was negligible.
The $325 million project won’t officially wrap until 2016, as a host of scientists and agencies will continue monitoring of all things natural—a natural environment with no concrete dams to get in the way.
Tim Newcomb is Engineering News-Record’s Pacific Northwest contributor. He also writes for Popular Mechanics, Sports Illustrated and more. You can follow him on Twitter at @tdnewcomb or visit his website here.