King County has granted the city of Enumclaw more than $300,000 to combat flooding in the eastern portion of the city.
The announcement was made mid-September in a press release sent out by the King County Flood Control District, a special purpose taxing district tasked with providing funding and overseeing flood protection projects all over the county.
The special purpose tax district was created in 2007, and is comprised of the nine King County councilmembers.
The money Enumclaw received will be used to replace two underground culverts underneath Battersby Avenue, approximately halfway between Garrett Street and Farman Street North.
The culverts help channel Watercress Creek, which flows from the Enumclaw Quarry in the Birch area, northeast of the city, to just south of the U.S. Forest Service Ranger Station on state Route 410.
“By replacing these two aging culverts, we reduce the risk of flooding in Enumclaw while also improving fish migration,” Council member Reagan Dunn, the Flood Control District’s chair, said in the press release.
According to City Administrator Chris Searcy, the area this work will focus on — south of Battersby, but north of state Route 410 — is prone to flooding “due to problems downstream around this culvert,” and added the culverts, which are made of metal, “are ready to fail anytime.”
In fact, according to a June 2018 staff report, one culvert failed in 2009, resulting in an emergency repair by inserting a length of PVC pipe through both culverts. However, the patch job only covered half the length of the pipes, starting on the north side of Battersby Avenue.
“The temporary repair… resulted in the road being secured, but the south half of the culverts left in very poor condition,” the report reads. “The failure of either of these culverts during a storm event could result in severe flooding all the way south to SR410.”
This time around, most of the culverts — 72 out of 88 feet — will be replaced, and instead of replacing the culverts with the same corrugated metal tubing, the city has opted to install what’s called a “bottomless box culvert,” which is a three-sided culvert and a bottom made of natural stream bed material.
“The stream will continue through this box culvert underneath the trail and the road and be much more like a natural stream, so it won’t be any barrier to [fish],” Searcy said.
According to the city and the Department of Fish and Wildlife, fall chum and chinook, winter steelhead, and some coho and resident trouts traverse Watercress Creek.
Work on the culverts will including closing Battersby Avenue, and will start sometime in 2020 at a time when no fish are using the creek.
Searcy couldn’t say how long the work would take, but based on the culvert replacement that happened on Veazie Cumberland Road in 2016, “it was a significant amount of time — it was weeks and weeks and weeks,” he said. “But I don’t know if it has to be that long.”