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County gives $125,000 to study Silverdale flooding

At least once a year the rains come down, Clear Creek’s water levels go up and businesses on the north end of Silverdale get wet.

To buck that all too common trend, the Kitsap County Commissioners approved at their May 6 meeting to spend $125,000 to create a flood hazard management plan.

According to county stormwater manager David Dickson, the Public Works Department evaluated flooding problems throughout the county in 1999 after a major rainstorm.

“We ranked them and Silverdale came out No. 1 because there was significant impact on vehicles as well as the businesses there,” Dickson said. “Most of the other flooding areas were nuisance problems that could be easily fixed.”

Why the problem exists isn’t a big secret. Back when Silverdale was a farming village famous for its chickens, flooding was uncommon as fields, woodlands and wetlands absorbed most of the moisture.

But in the 1970’s and ’80s as pavement, homes and businesses moved in, the Clear Creek floodplain, detailed in a 1979 Public Works study, was often ignored to make way for progress.

“This has been a meander plain where Clear Creek has moved back and forth for thousands of years,” Dickson said. “We’ve tried to pen it in this spot and it’s bucking a bit. We didn’t do as good of job respecting the flood zone as we should have when development went in.”

When flooding was considered, Dickson said a 25-year rainstorm was the standard. The current standard is now a 100-year rainstorm of five or six inches “which happens two or three times a year,” he said.

Assistant Public Works Director Jon Brand said a number of businesses, including All Star Lanes (a frequent flooding victim) knew what they were getting into.

“They knew they were in a flood plain and they were designed to provide parking lot ponding,” Brand said. “But the flood plain elevations they established in there don’t necessarily represent what is always going to be such as if there’s additional development or how hard it’s going to rain.”

Knowing there were problems, Public Works officials wanted to know if anything could be done to possibly restore the flood plain north of the bowling alley on county property.

“We hired a geotechnical engineering firm (Meyers Biodynamics Inc. of Bainbridge Island) to figure out what’s happened down there over time to see what’s been filled and what was original grade,” Dickson said. “They came in and mapped where the historic flood plain is and where there is fill.”

Ryan Meyers of Meyers Biodynamics Inc. said the survey showed areas of indiscriminate fill in various spots and different types of fill for road embankments.

Now the county is poised to make some changes which should not only help Clear Creek flow at two chokepoints, but restore some of the flood plain habitat over the next few years.

The first is the creation of a comprehensive flood hazard management plan to identify if the county’s flood plain ordinance is adequate and if there is need for more controls.

“It’s great if you could just go out and tinker with the plumbing and fix it, but that’s not always the full solution,” Dickson said.

The next step is to remove two blocking areas. A $1 million bridge would replace a culvert north of Waaga Way on Silverdale Way and a new wider, longer $2 million bridge would replace the current span on Myhre Road. Both bridges would be designed to be expanded easily if needed.

The county property near All Star Lanes would have several thousand tons of fill removed to allow some open space for flood control.

“Nobody likes it when Silverdale Way gets choked down to one lane,” Dickson said. “We hope this will significantly reduce the amount and frequency that we’ll see water in the streets down there.”

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