Work continues on the Kummer Bridge on State Route 169 after its emergency closure in November due to concerns about the stability of its foundation.

The bridge crosses the Green River and connects SR-169 from Black Diamond to Enumclaw.

In mid-November, state Department of Transportation geotechnical engineers reported the soil supporting the bridge was showing unusual movement that could be aggravated by heavy rain. This created concern that the southernmost bridge pier couldn’t be supported by the soil if it slid, and the pier would slide with it.

The bridge has been closed since Nov. 18 and isn’t expected to reopen until July.

State Sen. Pam Roach, R-31st Legislative District, said she had seen photos of the work being done and wanted to see it for herself.

“I was absolutely amazed and wanted to take a closer look at it,” Roach said. “This is a point in history. Hopefully, people will be able to understand the scope of the work and why this is taking so long. You’re just talking about a ton of dirt here.”

During a tour of the bridge Tuesday morning with Roach, Russ East, who serves as assistant regional administrator for DOT, explained the project.

“What normally happens on a slide is that it slides, then the slide kind of buttresses the base of the slope and stabilizes,” East said. “But with the river, it goes in the river and the river hauls it away. The focus now is on protecting the bridge.”

Over the years, the soil has moved, but in November, East said, it slid a half-inch in a week. That rang alarm bells for transportation officials.

“We noticed more activity down on (the south) end, so we put instrumentation in this fall and began monitoring,” he said. “We were trying to do some low-cost, low-impact work to stabilize it. As we were in the middle of that work and we had that instrumentation, we found that the ground actually under the foundation and end pier had moved.”

A hillside near the bridge was the subject of extensive work to reinforce it, beginning last summer and ending in October. Drain pipes, soil “nails” and concrete were used by DOT to stabilize the slope near the southeast end of the span.

When they realized that work hadn’t been enough to stabilize the slope, DOT officials said, “Time out. These efforts aren’t working,” East related.

Crews have excavated 20,000 yards of material, and workers are now 30 feet down from the south end of the bridge, which right now leads nowhere. Excavation has gone so far that a portion of the road is gone and has been disconnected from the bridge.

“The primary reason for doing the excavation here was first to relieve the pressure that was pushing on the foundation,” East said. “We didn’t want to endanger the bridge any more.”

Another thing crews had to tackle was unplugging 250 feet of drain line under the road.

During the next six months, repairs will be made to the Kummer (also known as Green River) Bridge in two phases:

• Crews are working to remove excess water by clearing trenches, unplugging manholes and installing pumps to help drain water from the unstable hillside.

• Then the soil that is putting pressure on the bridge pier will excavated. Crews will dig out a section of roadbed 30 feet deep and 300 feet long just south of the bridge and replace it with lighter-weight material.

“There’s two things that we wanted to do,” East said. “Get rid of the water because the water is one of the primary elements that causes the slide, and relieve the pressure.”

As the 30-day emergency contract work wraps up, the state will put the next phase of the work to fix the bridge out for bid, with the plan to start work in March and reopen the road by mid-July at the latest.

“We’re going to push hard for the Fourth of July,” East said. “That’s going to be an aggressive schedule. We know it’s been tough for a lot of people.”

The project is estimated to cost $15.5 million, which is coming from emergency funds provided by the federal government, according to Bill Vlcek, deputy regional administrator for DOT.

“That’s a current estimate,” Vlcek said. “If the final estimate comes in a little higher, then we’ll go back to the feds and ask them for the additional funding at that point. We hope to be underneath that.”

The bridge handles about 9,000 vehicle trips daily, according to DOT.

Staff writer Kris Hill can be reached at (425) 432-1209 (extension 5054) and khill@reporternewspapers.com