King County commits $70,000 to repair city’s retaining wall

September 6, 2011

By Warren Kagarise

King County recently agreed to fund repairs to a decade-old retaining wall along Southeast Black Nugget Road as city planners seek to shore up the structure against landslides.

The city closed the sidewalk along the wall in March after soggy conditions caused a small landslide on the slope behind Fred Meyer and The Home Depot. The shifting earth did not pose a risk to motorists or residences atop the hill, but the incident refocused attention on plans to strengthen the wall.

County officials committed $70,000 for upgrades. The project could cost up to $640,000 for substantial renovations. The city is setting aside funds to complete the project in the years ahead.

“If we were designing it today, it would probably be better to not build the wall than to have this kind of an interim state and have to go back and do more later,” city Public Works Engineering Director Bob Brock said. “Unfortunately, that’s not the way it ended up.”

Issaquah annexed the slope and the surrounding area in February 2000. The annexation occurred after development already started in the area, so city and county officials agreed to allow the county Department of Development and Environmental Services to continue conduct inspections on projects already under construction.

“The county coming to the plate to provide funding is appropriate, given the fact that the city inherited the structure and it was built under King County standards,” said Councilman Joshua Schaer, Council Transportation Committee chairman. “We sort of inherited some of the design flaws or problems with the structure.”

Concerns about safety, complaints about aesthetics

The wall — a collection of dislodged and rotting timbers, distorted pilings and a face darkened from seeping moisture — stretches for about 1,000 feet along Southeast Black Nugget Road.

The problems mean the expected lifespan for the structure is decades shorter than a typical retaining wall built to last 50 or 75 years.

The city hired consultants last year to evaluate structural deficiencies. The report, submitted to the city in March 2010, detailed structural shortcomings and listed needed improvements to shore up the wall.

“Repair should be performed as soon as possible to reduce or eliminate the hazards to pedestrians on the sidewalk,” the report states.

Crews added crossbars in recent months to strengthen the structure. Plans call for completing long-term structural improvements and adding a concrete face to the wall.

“There’s probably enough immediate work that’s been done that we’re not in any kind of a dangerous situation,” Brock said. “We certainly don’t want to keep putting off the remedial work for too long.”

City Council members approved the city-county agreement Aug. 15.

Mayor Ava Frisinger said city leaders receive occasional calls from passers-by about the structure’s moisture-marred surface.

“The comments that we have heard from citizens about the wall have been related to the aesthetics,” she said.

Issaquah, King County forge agreement

King County negotiators recognized the hardship such repairs could place on the city, and offered funds to help offset costs, city officials said. City staffers, and representatives from the county Department of Development and Environmental Services and County Executive Dow Constantine’s office negotiated the agreement.

“I think they basically understood and agreed that there were enough areas that were in question that they would feel comfortable being a partner in the agreement,” Brock said.

Construction on the upgrades could start as early as next year. The project received substantial attention from council members after the March sidewalk closure, but the upgrades did not rank as a top priority on the Capital Improvement Plan — a long-term guide to planned updates of municipal facilities, equipment and roads.

“It’s been on our CIP now for awhile, going back beyond even this year,” Schaer said. “It’s just something that needs to get fixed, because we don’t want the wall to deteriorate or cause safety issues. In my mind, it’s a pretty important project.”

In the meantime, the wall is in OK shape — at least until autumn and winter rains saturate the adjacent hillside. Instability on the slope is common after heavy rain.

“We just have to keep an eye on the seepage and make sure there aren’t any issues during the winter,” Brock said.

Schaer said the problem could worsen if construction is not completed on the wall as soon as possible.

“We’ve been fortunate so far that there hasn’t been a significant problem,” he said. “We’re playing on borrowed time, so to speak. We need to get this fixed.”

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