A new seismic analysis shows Seattle area residents could be without water for one to two months after a big quake, but SPU is keeping the entire report secret and releasing only a 13-page summary due to security concerns.
By Daniel Beekman and Sandi Doughton
The ground would stop shaking. Then the water in the pipes would drain away.
As Anchorage grapples with the aftermath of Friday’s powerful earthquake, a new study says Seattle would lose all water pressure within 24 hours of a catastrophic quake and would need at least two months to entirely restore water service in the city. Suburbs served by Seattle Public Utilities (SPU), which commissioned the study, would also lose service – including Bothell, Woodinville, Kirkland, Redmond and Bellevue.
With Seattle facing 15 to 20 percent odds of a severe earthquake in the next 50 years, the study says the city should spend $850 million through 2075 to mitigate water-system risks posed by the “Big One,” playing catch-up to California cities that already have taken dramatic steps.
“For this very catastrophic earthquake, we’re looking at very significant impacts,” said Alex Chen, SPU’s water-planning director. The utility provides drinking water to 1.4 million people.
The study says a disaster on par with the 2011 quakes in Christchurch, New Zealand, and Tohoku, Japan, would cripple the regional system operated by SPU. Restoring the water system to pre-earthquake conditions would take years.
The magnitude 7 quake that struck near Anchorage on Friday morning was a less-damaging type than Seattle’s worst-case scenarios because it originated 25 miles underground. Even so, it buckled roads, cut off electric power, ruptured hundreds of gas lines and broke water pipes across the city. Train service was shut down after burst pipes flooded the Alaska Railroad Operations Center, and the Anchorage water utility advised all residents to boil water in case of contamination.
Scott Miles, a University of Washington disaster risk-reduction expert, hailed the SPU report but warned the cost estimate could be low. Miles said City Hall leaders will need to show backbone. While the projects may inconvenience the public, “the real disruption” would be water service getting knocked out by a quake, he said.
“Like in Christchurch, this means using portable toilets not just for days, weeks or months, but in some cases years,” Miles said. “Imagine having to pee at 3 a.m. and having to walk out your front door to use the honey bucket on the sidewalk … That’s how important it is to deal with this problem now.”
SPU paid five consultants $900,000 for the 722-page study, which took more than three years to complete. But the only information the utility is releasing to the public is a 13-page summary, raising questions about transparency.
“It’s very disappointing to hear that SPU is not being forthcoming,” Miles said. “The majority of the analysis is not sensitive enough to keep hidden.”
Chen said the secrecy is necessary because some portions of the report contain information about vulnerable points in the water system.
The analysis examines the impacts of a magnitude 7 earthquake on the Seattle Fault and a magnitude 9 quake on the offshore Cascadia Subduction Zone. Between 1,400 and 2,000 pipeline breaks are likely, the summary says, particularly in areas like Sodo and Interbay where loose soils can liquefy and shift.
Those breaches, combined with potential problems at SPU pump stations, reservoirs and elevated tanks, likely would result in SPU’s direct-service water system losing pressure in 16 to 24 hours.