LAKE STEVENS — Emergency repairs are under way along Grade Road, a key connection between Highway 92 and downtown Lake Stevens.
The road has been closed since October, when the embankment below the pavement showed signs of slipping. Catherine Creek runs to the east of the road and has been eating away at its bank.
On March 25, city officials discovered that the bank is undercut by erosion, in some places up to four feet.
“Basically, you’ve got a bunch of earth that’s hanging by its own cohesiveness with nothing under it, just a cliff that goes out up to four feet,” Lake Stevens Public Works Director Mick Monken said. “It wore away the protective surface and found the soft underbelly of the bank and started eroding at the dirt and the soil there.”
He thinks failure of the road — meaning part of the bank and pavement collapsing entirely — is imminent if repairs aren’t finished soon. That would close the road longer and make for a tricky and expensive rebuild. It also would dump debris and human waste into the creek from a sewer line that parallels the road.
The state Department of Fish and Wildlife granted the city emergency permission for temporary repairs. The city has a contract with Marshbank Construction and workers set up at the site Monday. The plan is to divert the stream from where it’s slicing into the bank and put in large rocks to hold the slope together for the next couple of months. Temporary repairs should take two to three weeks.
Crews can’t start on a permanent fix until July because they have to schedule around fish migrations. The final repair project would involve realigning or replacing the sewer line, building a retaining wall to brace the bank and repaving the road. If work starts in July, it could be done by September, Monken said. The road would reopen nearly a year after it was closed.
In the meantime, an estimated 4,000 people are detouring around the closure, Monken said. The road also is an important route for freight and school buses.
The entire repair project is expected to cost between $300,000 and $500,000. A more detailed breakdown of the price hasn’t been completed because engineers don’t yet know the full extent of the damage to the bank or whether the sewer line needs to be realigned or replaced, Monken said.
Grade Road is closed from 30th to 32nd streets NE. About 120 feet of the road is affected by the sliding slope. Cracks started appearing in the pavement last week.
The city had to gain access to less than an acre of undeveloped private land next to the road in order to start work. They recently reached an agreement with the landowner and gained permission to work on the property while a sale is finalized, Monken said.
“We’re actually ahead of the worst case scenario,” he said. “We fully expected we would do the temporary work this year, but we didn’t have possession of the property, so we were telling the public it could be as long as summer of 2017 before we could really fix it.”
The city has been working with a geotechnical firm since 2014 to monitor Grade Road, which was built in the early 1900s.
The city also is monitoring Callow Road. There’s no erosion there, but the slope under the pavement has been settling for decades and the road is becoming less stable.
A design is in the works now and repairs are expected to cost up to $600,000. However, Callow Road is not at risk of failing right away, Monken said.
The drivers rerouted by the Grade Road closure have been patient with the city, Monken said. He asked them to hang in there a little bit longer.
“We’re not out of the woods yet, but we’re closer than we’ve ever been before to fixing it,” he said.
Kari Bray: 425-339-3439; kbray@heraldnet.com.
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