A poorly-designed culvert has hastened the erosion of a bluff canyon between Sequim and Port Angeles, forcing a temporary road closure and an unplanned culvert replacement project, Clallam County officials said.
The 1960s culvert near the corner of West Bluff Drive and Juan De Fuca Way had a “Niagara Falls effect” on the upper slopes of the bluff, causing it to undercut the surrounding area, Assistant County engineer Joe Donisi said.
The leading edge of the 180-foot-deep ravine was about 40 feet from Bluff Drive in February and had moved to within 12 feet of the residential road when it was closed to traffic May 1.
“It kind of comes in spurts,” Donisi said of the erosion.
Crews have dumped truck loads of rock and gravel in the area west of Siebert Creek, installing a temporary water bypass system to protect Bluff Drive and an adjacent yard from further erosion of the bluff.
No homes or other structures have been threatened, Donisi said.
“We’ll get a contractor in there to get the old culvert out that’s causing problems and get a new one in that will be water tight,” County Engineer Ross Tyler said on May 11.
“We should be able to stop the erosion.”
Clallam County commissioners were scheduled to discuss a call for bids for the West Bluff Drive culvert replacement project this week.
County officials hope to reopen West Bluff Drive from Juan De Fuca Way and Island Vista Way by the end of the summer.
Donisi estimated the cost of the culvert replacement project would be about $300,000. That includes the erosion control that has occurred since West Bluff Drive was closed.
“The neighborhood is very happy that we’re there,” Donisi said.
“We’ve been on a first-name basis with many, many people in the neighborhood that are very positive about us working there.”
Donisi said the erosion was accelerated by the design of the old culvert.
The outflow of the new 12-inch pipe will be lower on the hill to reduce the Niagara Falls effect, he said.
“We’re going to get it down the slope so we’re not pouring water on top of the ravine,” Donisi said.
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Rob Ollikainen is a reporter with the Olympic Peninsula News Group, which is composed of Sound Publishing newspapers Peninsula Daily News, Sequim Gazette and Forks Forum. He can be reached at 360-452-2345, ext. 56450, or at rollikainen@peninsuladailynews.com.
In an attempt to hold back further erosion, fill rock and gravel were placed at the bottom of a drainage gully after a failed culvert eroded a section of bluff in The Bluffs neighborhood east of Port Angeles. (Keith Thorpe/Peninsula Daily News)
