S.W. Dash Point reopened after mudslide, damage proving costly

A section of Southwest Dash Point Road that closed, following a mudslide last week, is now open to traffic, but the damage is proving costly to the city.

The roadway reopened Wednesday after the mudslide damaged about 120 feet in the 2800 block of Southwest Dash Point Road, from approximately 26th Place Southwest to 30th Avenue South, March 16.

The mudslide, which started on a privately-owned hillside, occurred at approximately 2 a.m. The mudslide went down the hill, across Dash Point Road and into Lakota Creek. Nobody was injured in the event.

“If anybody was driving through at that time it would have been an unfortunate situation,” Mayor Jim Ferrell said.

The aftermath, however, was significant, and the city could face a price tag of more than $40,000.

Ferrell said the magnitude of the mudslide that covered between 100 and 120 feet of road was astonishing. Several safety barriers lining the road, some of which that were linked, were either moved or damaged. Public Works Director Marwan Salloum told the City Council Tuesday night city staff only found two of the 10 concrete ecology barriers. The rest, he said, are buried in the creek or embankment somewhere. The guard rail was also pushed away from the road.

Ferrell said it was astounding how far those barriers were carried in the slide.

“First of all, you would not believe the force involved,” he said. “Some of those barriers weigh several thousand pounds, and it literally lifted a barrier at least 15 to 20 feet across the road and up an embankment. The amount of force to do that was really staggering.”

In addition to the barriers and guard rail, the road was covered in a small river of mud and debris, and approximately 2 feet of road on the Lakota Creek side was lost. Trees that fell in the slide knocked down a power line, which took out power at the Lakehaven Utility District wastewater treatment plant.

Lakota Creek was not blocked, however, and did not affect the Lakehaven wastewater treatment plant operations, although the facility had to run off of a generator after losing power for a while, Ferrell said. The creek also did not appear to sustain major damage, although mudslide debris that crossed the road destroyed some of the embankment and caused soil to slough into the creek. Salloum said the creek moved about 15 feet closer to the roadway.

City crews removed the mud and debris from the road March 16 and March 17 after a geotechnical engineer determined the area was safe. Lakehaven Utility District provided city staff with trucks to help clear the mud and debris, and Puget Sound Energy’s tree service removed hazardous trees in the area to prevent them from falling into overhead power lines. Lakehaven also allowed the city to store some of the debris and mud on its property.

Ferrell said the road was closed while repair work was completed and the city determined whether the underlying roadway was safe for drivers.

Since the mudslide, 2 feet of roadway was repaired. City staff will meet with someone from the Washington Department of Fish &Wildlife, March 31, to determine if the city has to make any repairs to Lakota Creek.

He said the department may opt for the city to do nothing as long as fish habitat wasn’t damaged.

Salloum said, while it has cost the city $40,000 to repair the roadway, replace the barriers and remove the debris, as of Tuesday, the price tag will likely go up. He said the city does not know if it will have to clean up the creek, nor has city staff disposed of the debris currently at Lakehaven.

The city also hasn’t stabilized the hillside, Salloum said.

While the mudslide started on private property, and it is possible the city may recoup some costs from the homeowner’s insurance company, the city still needs to stabilize the hillside to prevent future incidents.

Salloum told the council a heavy rain may cause more problems.

“I won’t go that far as to say it’s stable,” he said. “The soil is very loose and unstable.”

A contractor visited the site Wednesday and applied hydro sealant to the hillside to help secure it further.

After surveying the mudslide damage, March 16, Ferrell declared a state of emergency for the site to allow staff to expedite cleanup and avoid going through a lengthier public-bidding process. While it is possible the city could receive state or federal funding to recoup its costs, that is unlikely to happen, Salloum said.

He said, for the Federal Emergency Management Agency or state to fund the project, Gov. Jay Inslee would have to declare the event, or a period of time during which the event took place, such as this winter, a disaster. He would then have to recommend to the president a state of disaster be declared, which the president would have to do.

“Unless the governor declares this event a disaster, it’s going to be hard to recover any of the cost,” Salloum said.

Cliff Mass, a professor of atmospheric sciences at the University of Washington, told mynorthwest.com, March 15, between March 7 and March 13, the Pacific Northwest has received 200 to 600 percent of its normal rainfall.

City staff work to clear out trees caused by a mudslide that originated on a hillside on private property off of Southwest Dash Point Road last week. A guard rail was also pushed off the road in the incident. Courtesy city of Federal Way