CORDOVA -- The Alaska Department of Transportation and Public Facilities is proceeding with plans to replace the Mile-36 Bridge on the Copper River Highway, known informally as Bridge 339.
Engineers were in Cordova recently for a community forum that laid out plans for the project. Elmer Marx, a bridge design engineer in the Department of Transportation, gave a power point presentation at Mt. Eccles Elementary School.
“This bridge is just the most recent episode with the Copper River,” Marx said. “Can we tame the river like the Columbia or the Mississippi? Well, perhaps with enough money. But I don’t see that happening.”
Complicating the project is the fact that the Copper River is ever-changing, and the Cordova/Copper River area remains “earthquake central for Alaska.”
Surging Copper River
Since 2009, the amount of water flowing under Bridge 339 has surged. It is one of 11 bridges spanning various portions of the Copper River Delta.
Last summer, the flow was measured at 89,000 cubic feet per second (665,800 gallons per second), four times the flow that the bridge was designed to withstand during a flood.
At one point, scour beneath the bridge was advancing at a rate of five feet per day, reaching a depth of 75 feet.
“Mother Nature is always working against us and our luck ran out,” Marx said. “In August it was evident the bridge had failed. This situation is very atypical. We never foresaw 50 feet or more of scour. It became clear that we are pretty much going to have to dispose of the bridge.”
Consequently, Bridge 339 has been closed since last summer. Current estimates have construction of a new bridge starting in the spring of 2015, with the bridge reopening in 2017 if all goes well.
While engineers have already begun preliminary planning, they will work this year gathering engineering field data and developing hydraulic river models.
Permitting is the lengthiest part of the project, engineers told the Mt. Eccles audience.
Plenty of issues
Engineers described a fascinating array of issues they face – from seismic concerns to equipment issues to scour. One unresolved problem is what construction trestle or platform will be used. The existing bridge is unsafe and cannot be used as a construction platform. While the Department of Transportation has funding for the engineering and design phase, no money has been allocated to construction. Preliminary estimates put the cost at about $25 million.
Steve Titus, regional DOT director, said, “AKDOT is aware of the importance of this project to the community, and it is going to get done.”
Exactly when -- and who will pay – is unclear.
“The community can support the project by contacting their legislators and congressmen to share with them the importance of the bridge,” Marx said. “In the meantime AKDOT will continue moving forward.”
The Department of Transportation is also currently working with the U.S. Forest Service, Eyak Corporation and the Native Village of Eyak regarding lands access issues for the upcoming season. The Childs Glacier recreation area is closed until further notice and Titus cautions residents that Bridge 339 is closed to all pedestrian and vehicular traffic.
This article originally appeared in The Cordova Times and is republished here with permission.