Brightwater safety plan gets OK

Published 6:47 am Monday, March 3, 2008

King County can safely build its Brightwater sewage treatment plant in south Snohomish County despite the fact that at least one active earthquake fault line runs under the site, according to a supplemental environmental review released April 11.

Last fall, a King County hearing examiner ordered the county to do a second environmental impact statement to make sure the treatment plant would survive a major earthquake on the fault.

King County has made several changes since environmentalists forced it to take another look at the earthquake danger, said Christie True, Brightwater project director. The changes would limit the amount of damage that would occur if there was a large quake on the fault, she said.

“We’ve really changed our thinking as to how we look at earthquakes,” True said. “We are in a seismically active area, so we should design the facilities that way.”

Those changes include rearranging the site plan to get key structures away from a known fault at the north end of the site, as well as another that may exist at the south end of the site.

King County has decided to use flexible connections on all the pipelines at the facility, which would allow the pipes to move instead of break during a quake.

It also decided to keep chemicals used to treat sewage in separate locations to reduce the chance they could mix and explode.

True thanked the Sno-King Environmental Alliance “for taking us down that path. I think we have a better project for it.”

Members of that group are suing King County in hopes of using the discovery of the fault line to force Brightwater to be built somewhere else.

“They’ve had several months now to paint a pretty picture of how earthquakes are not a problem,” said Corinne Hensley, a spokeswoman for the alliance.

King County knew the chances were high there would be a fault at the Highway 9 location well before the fault was discovered last fall, she said.

“They eliminated all the other sites that were within a half-kilometer of a fault, but they wouldn’t eliminate this one,” she said. “Why? These faults are on the site, not a half-kilometer away.”

True said it’s too late for King County to find another site, and the danger of an earthquake is extremely low, especially compared to what would happen if construction on Brightwater doesn’t start on time.

“By being late in starting Brightwater, we know we will have overflows into fresh water and Puget Sound,” True said.

King County is expected to outgrow its sewage treatment capacity about the time Brightwater opens in 2010, she said.

Lukas Velush is a reporter with The Herald in Everett.