Rains cause localized flooding in Renton; water from clogged catchbasin cuts into I-405 hillside

Leaf-clogged catch basins created localized flooding throughout Renton Monday morning as a major rainstorm rushed through Western Washington.

Some flooding was reported near the Antioch Presbyterian Church near the 44th Street exit on Interstate 405.

A flood watch for rivers was issued early in the day for King County, although the Green River wasn't flooding. The Snoqualmie River was expected to crest at flood stage, but the danger diminished during the day.

Crews for the multimillion-dollar Stage 2 project to add lanes and a half-diamond interchange on Interstate 405 near City Hall were busy Monday dealing with all the extra water from the storm.

The hillsides remained stable throughout, according to Lisa Hodgson, an engineer for the Washington state Department of Transportation.

Small rills, or tiny streams, were carved in the massive excavation along Interstate 405 near the Benson Road bridge after a catch basin at the Berkshire Apartments became clogged with leaves and water flowed over the bank, said Hodgson.

The rills are easily visible from the freeway and nearby areas of downtown Renton.

The small streams cut into the hillside are not a concern and will not destabilize the slope, said Hodgson.

Crews will add material and then reseed the hillside, she said.

Crews using a conveyor system have finished moving about 130,000 cubic yards of material from the area just below the apartment complex to a hillside just below Cedar Avenue a short distance away.

Before the rainstorm, crews working for Gary Merlino Construction had installed temporary erosion control on the hillside, including sheets of plastic, grass seeding and various types of matting.

Also visible are wattles, or round-shaped bundles of hay and other material about six to eight inches in diameter that slow down the water as it sheets off the hillside. The wattles help prevent the creation of rills.

Contact Renton Reporter Editor Dean Radford at editor@rentonreporter.com or 425-255-3484, ext. 5050.

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