■ Previously: Heavy weather, fast currents and the lack of sediment in the river contributed to the degradation of jetties at the mouth of the Columbia River.
■ What’s new: The Corps of Engineers on Wednesday proposed a restoration that would take until 2030 and cost in excess of $400 million.
■ What’s next: The draft environmental assessment is available for review and comment until Feb. 12.
• View the draft environmental assessment online at http://www.nwp.us...>
• For questions or comments on the draft EA or to request a copy, call Barbara Cisneros at 503-808-4784 or e-mail Barbara.G.Cisneros@usace.army.mil.
• Comments also can be submitted by mailing them to: District Engineer, Portland District, U.S. Army Corps of Engineers, Attn: Barbara Cisneros, CENWP-PM-E, P.O. Box 2946, Portland, OR, 97208-2946.
• The draft EA is available for review and comment until Feb. 12.
Federal engineers are proposing an 18-year construction schedule to rehabilitate badly eroding jetties at the mouth of the Columbia River.
Total cost: $400 million to $470 million.
The north and south jetties, originally constructed between 1885 and 1917, enable a multibillion-dollar shipping industry by taming the river’s notoriously rough bar. The jetties tamp down waves from the ocean, while also serving as a barricade against beach sand that would otherwise clog the shipping channel.
The Army Corps of Engineers now is proposing a major rehabilitation project to shore up the north and south jetties, as well as Jetty A just inside the river’s mouth near Cape Disappointment.
Construction would begin in 2012 and continue each year through 2030.
The proposed project calls for the placement of 364,000 tons of rock on the north jetty and nearly 750,000 tons on the south jetty. The project will include massive armor stones capping the tip of each jetty.
Further, contractors will build 11 spur groins to stabilize the jetties’ sandy foundations.
These underwater joints, situated perpendicular to the jetties themselves, are intended to counteract the steady flow of water and waves eroding the sandy shoals on which the jetties sit.
“Water running parallel to the jetty could move the sandy foundation, which could destabilize the toe, which could cause rocks to fall out,” said Matt Rabe, spokesman for the Corps in Portland. “By putting these spur groins at strategic places along the jetty, you’re disrupting that steady flow of water.”
Engineers believe this feature is essential in light of beach erosion occurring north and south of the Columbia’s mouth.
When the jetties were originally constructed a century ago, they created a firehose effect by squeezing the river’s current.
The jetties essentially act as a funnel.
Between 1885 and 1925, according to a report by the corps in 2003, the firehose blasted 500 million to 800 million cubic yards of sand out of the estuary and into the ocean, where waves piled it along the jetties’ back edges. The movement of sand from the estuary to the beach shored up each jetty’s foundation, cleared dangerous sandbars from the shipping channel, and created popular public beaches.
In recent years, however, those beaches have eroded severely.
Sand that would have otherwise replenished the beaches north and south of the river has dwindled with the construction of upriver dams beginning in the 1930s. The dams capture two-thirds of the sediment that would have otherwise flowed to the estuary, according to a recent study of coastal erosion.
“The beaches have eroded so much that the jetties are exposed to increasingly energetic wave conditions,” according to George Kaminsky, a coastal engineer for the Washington Department of Ecology who co-authored the study.
Rabe said the Corps extensively modeled the new environment, and engineers believe the rehabilitated jetties will endure for 50 years.
“In the future, if we face any situations like we have today, we could do spot repairs,” he said.
The corps will open the project to a bidding process.
Each jetty stone would weigh between 30 and 50 tons, and be delivered by barge or truck from quarries in Washington, Oregon and British Columbia.
The lengthy construction schedule means that the overall project will have to compete against other national priorities on a year-by-year basis. A Corps spokesman said the project will be constructed in phases, to minimize the risk that funding setbacks in the future might undermine work already completed.
“We will work this the way we process all construction projects that go beyond one or two years,” Rabe said. “We make sure Congress and the administration understand the work that we’re doing, the priority, and then each year we will submit the incremental costs that we believe we can spend for that year.”
The Pacific Northwest Waterways Association, an industry group based in Portland, noted that the jetties protect a shipping industry that annually hauls more than 40 million tons of cargo valued at $16 billion.
Glenn Vanselow, the group’s executive director, extolled Wednesday’s announcement.
“It is an extremely positive step for the Northwest, as this project will help to maintain the economic viability of our region,” he said.
He said he’s not concerned about the lengthy construction schedule.
Vanselow noted that it took several years for Congress to appropriate the federal share of a $190 million project to deepen the shipping channel from 40 to 43 feet between the mouth of the river and the Vancouver-Portland area. The cost of jetty rehabilitation dwarfs the channel deepening project.
“This seems to be a prudent way of going about attacking the most vulnerable parts first,” he said. “It makes sense to us.”
Erik Robinson: 360-735-4551, or email@example.com.