During the glacier outburst that caused flooding in Juneau a week and a half ago, Sterling Shearer watched as 40 to 50 trees — some as tall as 80 feet — were swept down the Mendenhall River and got tangled under the temporary work platform next to the historic Brotherhood Bridge his company is replacing.
Orion Marine Contractors Inc. has been removing debris since then, said Shearer, the firm’s project manager.
“We just finished yesterday,” Shearer said in a phone interview Monday. “We were able to get all the trees out and put them on the bank, saw them up and remove them from the site.”
The deadfall of trees actually created a log dam under the temporary work trestle (which Shearer says everyone mistakenly thinks is the new bridge), diverting the flow of water around the dam instead of under the bridge like usual. That eroded the riverbanks around the existing bridge.
Shearer said they tried to mitigate that by placing “emergency rock” — rip-rap blasted from Stabler’s Point Quarry near the Auke Bay ferry terminal — on the embankments to protect them from further erosion. That measure was a written directive by the Department of Transportation, he said. A cost estimate was not immediately available.
As for the trees, crews removed them from the water with cranes that were already on site. They finished by Monday and moved the debris to a disposal site off Sherwood Lane.
The clean up only delayed the $21.5 million bridge replacement project by a few days. The project was awarded to Orion Marine Contractors in January, Shearer said it’s still slated to be completed by October 2015.
“It delayed us, but not too bad, just a day or two,” he said. “We had to change up our production to remove the logs and debris, so it was probably two days of production time where we had to use our cranes ... to remove all that stuff, and take all our equipment off the temporary work trestle.”
The company was well informed of the potential for flooding before the outburst since agencies were monitoring Suicide Basin water levels before it erupted and dumped billions of gallons of water into Mendenhall Lake, which flows into the Mendenhall River. They didn’t lose any equipment in the flooding.
Shearer prepared for the flooding by taking staff on a helicopter ride to see potential hazards up the river so they could plan ahead. They took the trip about a week before the flood.
During the jökulhlaup, as the glacial outburst is called, Shearer said he wasn’t really concerned because it never got to the point where safety was an issue.
“I was more concerned that there was going to be ice, but we only got two or three icebergs that came down,” he said. “It wasn’t like a rage of waves ... or anything like that. It just slowly increased and increased.”
It ended up being a pretty cool show.
“I was on site, standing on the trestle watching the trees come down,” he said. “I got some pretty good photos.”