Poor soils bedevil Highway 16 near Sedgwick

The in basket: Two readers have suggested that the condition of Highway 16 in both directions just north of the Sedgwick interchange needs work.

Nelson Lanchester wrote some weeks ago, “When is the state going to admit and fix Highway 16 westbound north of Sedgwick interchange where the highway starts to go up the hill.

“When they constructed the additional two lanes back when, they used sawdust as a fill instead of earth/rock,” Nelson said. “After this many years the sawdust has deteriorated and the highway is sinking.”

Then this month, Vivian Henderson had this to say about a spot on the other side of the highway.

“There is a huge patch of asphalt that appears to have been put down hastily long ago and never improved.  It has been there for years, covers both lanes extensively as well as the highway shoulders.  It is breaking down and is getting rougher and rougher to drive over. I’m wondering if it poses a hazard to drivers not expecting the surface of the road to change so abruptly; especially at night. Why doesn’t the state fix it?”

The out basket: Well, the state does fix it, intermittently and temporarily, with what local Maintenance Superintendent Duke Stryker calls a “grader patch.”

A grader spreads a layer of asphalt over the surface to compensate for whatever subsidence has occurred. I recall it last being done two years ago, when the patch got noticeably wider. Dke said “the Integrity of the structure of the road wasn’t compromised,” so the grader patch was sufficient..

That entire area suffers from poor soils and both problems stem from subsidence that results.

That spot Vivian mentions is fairly obvious, but the dip in the lanes heading toward Gorst is more subtle. I’d never noticed it until Nelson mentioned it. It’s just past the end of the on-ramp from Sedgwick.

Frankly, neither problem seems to me to be a hazard to motorists.

The state does have some repaving planned this summer in the lanes bound for Gorst, Duke says, but not on the highway heading the other way.

Duke was surprised by Nelson’s description of the construction of those lanes with sawdust, saying that just isn’t a material acceptable to the state. But it has been used.

Mel Holgerson, state project engineer when the Gorst-bound lanes were built, said they used sawdust to minimize the weight of the roadway. The alternative would have been to dig  out and replace marshy soil to a depth of about 35 feet and they feared that the other two lanes, built years before, might give way because of the digging that close to them, Mel said.

When Kitsap County extended Sedgwick Road west from Sidney Road years later, it did dig out a lot of the bad soil but still needed a membrane fabric to support the roadway, former assistant public works director Ron Yingling tells me.

And I recall reporting on the use of wood chips years ago as the base for the repair of Highway 166 just west of Ross Point when it was called Highway 160. The roadway had simply dropped away toward Sinclair Inlet. It was a variation on the problems along that highway that usually involved slides from above covering the asphalt.

The idea was to use a lightweight fill material to keep the base below the asphalt from giving way again. And so far, it hasn’t, though I’ve been watching a subsidence that Duke’s crews patched last year around the point on the Port Orchard side.

That’s not where the wood chips went, though.

 

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