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Story Published: Oct 22, 2009 at 7:39 PM PDT
Story Updated: Oct 22, 2009 at 7:39 PM PDT
But if the huge rubber and fabric barriers work as advertised and keep flood water out of the county's South Treatment Plant this winter, it's money well spent, said Don Wickens, assistant manager of the wastewater treatment facility.
"We're treating this as very real," Wickens said Thursday about the flood danger from the nearby Green River. "I don't have a billion dollars lying around to replace this plant."
The plant, on 94 acres just south of Seattle, treats the sewage and wastewater from all of south King County and the populous suburbs east of Lake Washington - more than 1.4 million people in all. If the plant is swamped by a flood, it could be knocked out for weeks or even months, said Annie Kolb-Nelson, spokeswoman for the county's Wastewater Treatment Division.
Among its precautions, the county has bought Floodwalls, giant rubber and fabric tubes that can be filled with water and work like huge sandbags. At a demonstration Thursday, crews using fire hoses were able to fill two 15-foot-long tubes to a 3-foot height in about 15 minutes.
Earlier this year, land next to the Howard Hanson Dam on the upper reaches of the Green River was found to be weakened after record January rains. The Army Corps of Engineers, which operates the flood control dam, said it couldn't risk filling its reservoir as usual during the winter rainy season. Corps officials have said there is a 1-in-4 chance they might have to release enough water this winter to cause flooding in the heavily developed Green River Valley south of Seattle.
A flood in the valley could displace thousands of people and cause billions of dollars in damage. But Wickens said losing the treatment plant would be a disaster in itself.
Normally, the plant handles about 110 million gallons of wastewater a day. In a flood, it might have to handle three times that amount as the 16-mile long valley drains.
The Floodwall barriers are being used at a plant entrance and two other below-grade spots, Wickens said. If water pours through those gaps, it could wipe out much of the plant's treatment equipment, which is at ground level or below.
"Most of the plant is all underground or in tunnels, so if it floods here, we lose the plant," he said.
The county also is buying regular sandbags and barricades, acquiring large backup generators, and stocking provisions to staff the plant 24 hours a day should a flood occur. In all, it is budgeting up to $7.5 million to protect the facility.