Council discusses Hollywood Hill flood plan
by Jeff Switzer
WOODINVILLE--With the memory of February's floods fresh on their minds, the City Council discussed on Monday the county's proposed $500,000 drainage improvement project, one which should prevent water coming off Hollywood Hill from causing damage by flooding the streets below.
King County has determined that three factors contribute to the flooding (which has occurred four times in the past 10 years): Sediment from the ravine plugs downstream culverts; the stream is forced into a 90-degree bend; and culverts along 148th Avenue NE are undersized even without sediment problems.
The county will begin its stream stabilization project Aug. 5, closing off 146th Place NE between 148th Avenue NE and 155th Avenue NE while a crane places logs, stumps, and boulders along 1,000 feet of the ravine to stabilize the bottom of the channel. According to the county, this will help keep sediment from filling downstream culverts.
The City of Woodinville will smooth the 90-degree bend and replace the culverts along 148th Avenue NE--which average 12 inches in diamete--with "substantially larger culverts," some 42 inches in diameter.
The final step of the current program includes regular maintenance of the culverts and cleaning the storm channel of any sediment which does accumulate.
Woodinville is negotiating its share of the $210,000 project with the county (the stream stabilization portion is outside of the city). Other more expensive alternatives were abandoned, including relocating the stream to a "more historic course," a $1.2 million proposition which would bypass the ballfields but would go through private property.
The relocation project has popular support because the stream, which is a Class II stream with 100-foot setbacks to protect the salmonid trout populations, hinders the use of the properties in Hollywood Highlands.
Another option, called a high-flow bypass system, was abandoned because of its possible effects on the Sammamish River and previous opposition to such systems from the Muckleshoot Tribes.