Wednesday, June 28, 2017

SR 900 to close July 28-31 between Issaquah and Renton for culvert work

By Tom Pearce

It's not on most maps, but it's as important as a highway – at least for fish.

We're a month out from another big fish passage project this summer. Starting at 7 p.m. Friday, July 28, we'll close SR 900/Renton Issaquah Road Southeast for the weekend so we can dig up the highway and replace the culvert for Green Creek, west of 164th Avenue Southeast. The highway will reopen by 5 a.m. Monday, July 31.

Yeah, I couldn't find it on the map either, but after a field trip, I can assure you it's there. Our graphic artists even created our own map that shows the creek's location.

Restoring fish passage
Crews that built the original road about 100 years ago put in the culvert. It's only four feet wide and three feet tall; the upstream side of the creek is more than 11 feet wide. That means when the water level is up, the creek runs through the culvert with so much force that fish can't continue upstream – their highway is pretty much shutdown.
This culvert below SR 900 in Renton is about 100 years old and needs to be replaced with a larger culvert.

Through the years the creek has worn away at the downstream side of the creek bed, to the point where it's now created a tough jump for fish in a shallow creek, especially if there's a heavy flow coming out of the culvert. All that makes the creek a barrier to fish passage.

A 2013 U.S. District Court injunction requires us to replace those sorts of culverts under state highways. The Green Creek culvert is one of 475 that need to be fixed by 2030.

Dig it
SR 900 is two lanes wide with almost no shoulder at Green Creek, and carries about 9,500 vehicles a day. However, the culvert is more than 25 feet beneath the road, so it will take our contractor crews an entire weekend to dig out the old culvert and replace it with a 16-foot wide, 10-foot tall culvert that is 55 feet long. Once that's in place, they'll fill in the gap, repave SR 900, replace the guardrail and reopen the highway.

With the new culvert in place, the crews will be able to create a natural creek bed in it, making it much easier for salmon, trout and other species to travel upstream.

The scenic route
Drivers will need to use a detour around SR 900 in late July when the
highway closes to allow crews to replace a fish culvert.

Even though the highway will be closed all weekend, you'll still be able to use it between Issaquah and Renton. We'll have a signed detour set up via 164th Avenue Southeast, Southeast 128th Street/Northeast 4th Street and Duvall Avenue Northeast. Folks who live between 164th Avenue Southeast and Duvall Avenue Northeast will have access on SR 900 up the work zone, but they won't be able to cross it during construction.

It's a lot of work for a little creek, but by closing our highway for a weekend, we're reopening a highway for fish that's been closed to salmon and other native species for a very long time.

1 comment:

MikeNorthwest said...

Excellent project! Thank you for accomplishing so many projects that make life better for everyone!

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