Floodwaters sweep across the Interstate 5 corridor between Chamber Way and state Route 6, scattering concrete Jersey barriers in the process, on Dec. 4, 2007. The state Department of Transportation is considering placing flood walls along the stretch of freeway as a means of prtecting the roadway. Local flood officials oppose the idea.
A potential proposal to build flood barriers along a portion of Interstate 5 has drawn ire from several members of the Chehalis River Basin Flood Authority.
As part of the 2011 legislation that allocated the Flood Authority $1,320,000 to mitigate flooding in the river basin, legislators required the Office of Financial Management to evaluate projects alternative to water retention, specifically those that could protect the Interstate, airport and medical facilities.
The flood wall is one of the projects being considered.
J. Vander Stoep, who represents Pe Ell on the Flood Authority, said a barrier that only protects I-5 won't necessarily reduce flooding, and there's a risk that it could actually make flooding worse.
"If your goal is a basinwide solution for flooding, a wall that just protects I-5 is not a good idea," he said.
Bart Gernhart, the assistant regional administrator for engineering for WSDOT, said calling it a "flood wall" is a misnomer.
"Some people want to believe we're putting in 8-foot-high walls," he said. "That's not necessary. We're not doing that."
The barriers, he said, are actually 42-inch high cast-in-place concrete barriers, the same type of high-impact barrier that can stop large freight trucks going 70 miles an hour.
Abbi Russell, a spokesperson for WSDOT, said the barriers, when used in the median, stopped water from flowing all the way across I-5 in the 1996 and 2007 floods. This would be the same concept, but used on the outside of the interstate.
However, there could be a taller wall on the east side of the Chamber Way exit.
Gernhart said if the airport dike, which is located on the west side of the exit, is raised, WSDOT won't have to put flood walls on the freeway.
But there is still a risk of flooding from the east side, and because I-5 dips down, a portion of the wall could be built as high as 8 or 9 feet.
The wall would extend from the 13th Street exit north to around Mellen Street. But, Gernhart stressed, the flood barriers are only one idea being considered by the WSDOT, which was required by the Legislature to evaluate project alternatives.
Raising portions of the Interstate or using levees, bridges or berms are other proposed projects being evaluated.
Gernhart said the Legislature didn't ask for an actual project design, but rather basic information regarding the alternatives.
"This is different than when we're given $5 million to go build a bridge," he said. "Right now we're getting an understanding at the local level of how the flood works, and we're identifying different possible solutions."
Gernhart said engineers are still in the early stages of scoping. They'll have to identify the benefits and downsides of each proposed solution and come up with options to mitigate any potential negative impacts.
The final Office of Financial Management report is due to the Legislature in July. Gernhart said the WSDOT will have just a couple of months to complete its work, so the project evaluation will not be that detailed, unless the Legislature funds a second study phase that allows the WSDOT to go into more detail.
That is exactly what concerns Julie Balmelli-Powe, the outgoing Chehalis representative on the Flood Authority.
"Unfortunately, the DOT has been tasked to do this in a very short period of time, and they don't have the time to look at it thoroughly," she said. "When the Legislature looks at the projects, this is going to look good on paper, and it will be compared to other solutions that will have been thoroughly studied."
Balmelli-Powe said so far the WSDOT proposal shows flood walls as being relatively low in cost and having very little impact to the surrounding area, which may encourage Legislators to support the project.
"I just think it's the wrong approach if they're trying to help the people in the basin," she said. "It's a tunnel-minded look at solving flooding."
Another concern is that proposal to widen the portion of I-5 that runs through Centralia.
"Once they expand I-5, they'll have to build the wall again," Vander Stoep said. "So whatever the cost is, double it."
Balmelli-Powe said Flood Authority members are particularly worried about the flood barriers because the reason the state and federal government are concerned about flooding in the Chehalis River Basin is the potential threat to I-5.
"The fear is that they'll protect I-5, and then there won't be any federal dollars to help protect the citizens," she said. "I hate to think that they're rushing into this, and the citizens will suffer the consequences."
The Legislature also requires the OFM report to include alternatives to water retention. The Flood Authority is working on a list of 138 flood mitigation projects. The list served as source material for the 2012 legislative jobs package, and will be consulted if the Flood Authority is allocated additional funding in the future. The final version of the list will be completed next month.
Members of the Flood Authority agree that several different types of projects will be needed to truly mitigate flooding.
“We know other things are necessary,” Chair Vickie Raines said. “It won’t just be, ‘Slap down a dam and walk away.’”
