Dam removal ahead of schedule: Glines gone in a year
A plume of sediment can be seen widening out from the mouth of the Elwha River on Sunday.
By Paul Gottlieb
Peninsula Daily News
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PORT ANGELES — The Glines Canyon Dam, the upper dam on the Elwha River, will be completely removed ahead of schedule between spring and summer 2013, federal officials said this week.
The last remnants of the lower dam, the 108-foot Elwha Dam, which formed Lake Aldwell 5 miles upstream from the river's mouth, were removed in March.
“Dam removal continues to be ahead of schedule,” Tim Randle, a sedimentation and river hydraulics expert with the Bureau of Reclamation, told the Port Angeles City Council on Tuesday.
“We should be done around the spring of 2013,” Randle said.
Randle also told the council that the movement of up to 24 million cubic yards of sediment behind the two dams is proceeding according to models devised for the project.
“Within three to five years from now is the general expectation that the reservoirs will no longer contribute sediment in significant quantities,” he said.
Meanwhile, the National Park Service, which is overseeing the project, and Barnard Construction of Bozeman, Mont., which is tearing down the dams, said Wednesday the dams will be completely dismantled by summer 2013.
The new project window puts complete teardown well before the original September 2014 deadline set in the National Park Service's $26.9 million dam-removal contract with Barnard Construction.
Removal of the 99-year-old Elwha and 85-year-old Glines Canyon dams west of Port Angeles is the cornerstone of the $325 million Elwha River restoration project to restore the river's fish runs by unblocking the river.
Barnard began the project in September.
Blasting will continue on the 210-foot Glines Canyon Dam, which forms Lake Mills 9 miles upstream, this afternoon, Barnard Construction project manager Brian Krohmer said Wednesday.
Krohmer said it is the third of 25 blasts that will be conducted to tear down the edifice, the tallest dam to be removed in the nation's history.
Seeding and bank-strengthening straw placement will continue at the Elwha Dam site, with Barnard's work there “absolutely done” by June or July 2013, Krohmer said.
“There are still a lot of unknowns, with river flows and a lot of fish windows left,” he said, adding that the project may not be completed until summer 2013.
“We've got a long ways to go,” he said.
Olympic National Park spokeswoman Barb Maynes said Wednesday that weather could change the schedule.
“We're being fairly open about the summer timeline,” Maynes said.
“The construction schedule is constantly under adjustment,” she said.
“We now anticipate the project to be complete by 2013.”
Fine sediment from the project has flowered into a plume often visible at the mouth of the Elwha River, where the storied waterway meets the Strait of Juan de Fuca.
“Not much sand and gravel has been released past the dams, but fine sediments have made it to the river mouth,” Randle said in his presentation.
Sand and gravel are now being released past the former Elwha Dam site, where the dam has been completely torn down, and will be released past the Glines Canyon Dam site beginning this fall, when the reservoir will low enough to allow for significant sediment transport, Randle said.
Gravel that stays behind where the newly free river meanders will provide vital habitat for salmon, Randle said.
Major revegetation of the exposed reservoirs and their banks will continue once the dams are gone, he said.
“Within three or five years after the dams are gone, we are pretty much back to a natural condition,” Randle said.
The city and National Park Service will still need to meet to determine “when NPS and when we determine, together, when the project is complete” under the Elwha Act of 1992, city Public Works Director Glenn Cutler said at the council meeting.
An industrial pretreatment plant for Elwha River water that comes into the city's municipal plant is removing solids and reducing turbidity, he said.
“The water-treatment plant is working as anticipated,” Cutler said, adding that the water quality meets or exceeds state Department of Health standards.
After every 15 feet of reservoir drawdown, the reservoir is held constant for 14 days, Randle said in his presentation.
Water is being treated by the Elwha, Port Angeles and Nippon Paper Industries USA treatment plants, he said.
“Reservoir drawdown increments of 15 feet, followed by a two-week hold period, has resulted in vertical and lateral sediment erosion matching the pace of dam removal,” Randle said in his presentation.
About half the sediment will remain in the former Mills reservoir site behind Glines, Randle said in his presentation.
The Elwha water-treatment plant eventually will be shut down, “but not until we are sure the turbidity entering what was left in Lake Mills is essentially the same turbidity that is getting downstream,” he added Wednesday.
Senior Staff Writer Paul Gottlieb can be reached at 360-452-2345, ext. 5060, or at firstname.lastname@example.org.
Last modified: May 21. 2012 9:07AM