If a major earthquake were to hit Portland tomorrow, city analysts predict the disaster would cause up to 3,000 pipe breaks across the region’s water system.
The number raised eyebrows in the audience Monday afternoon as Michael Stuhr, the director of the Portland Water Bureau, outlined how the city could ensure residents have access to clean water in the event of a devastating earthquake caused by a rupture along the Cascadia subduction zone.
In a presentation on emergency preparedness hosted by the Columbia Corridor Association, Stuhr said the water bureau had analyzed the more than 2,200 miles of pipe snaking through the system to assess the likelihood of infrastructure breaking during a massive tremor. The results show between 1,500 and 3,000 pipe breaks could occur.
The bureau’s service area covers 225 square miles, providing water to Portland along with 20 suburban cities and water districts.
To avert disaster, Stuhr said the city is working on a “backbone plan,” which focuses on fixing pipes that transport water to the region’s “critical infrastructure facilities,” such as hospitals and fire stations.
“There isn’t enough money on this planet to replace every pipe in this system,” Stuhr told the audience. “But the truth is some pipes are more important than others.”
Some of the most critical pipes? Those running across the Willamette River and transporting water from Portland’s east side to its west.
Stuhr said the decades-old pipe crossings are vulnerable, as they lay in shallow trenches at the bottom of the river. But the city is currently in the design phase of a multi-million dollar project to lay new earthquake-safe pipe 80 feet beneath the bottom of the Willamette River. Construction is expected to start in the spring and wrap up in 2022.
Until then, Stuhr told the audience, the city’s water supply is in a precarious position.
“If the big earthquake happened tomorrow, would there be no water available whatsoever? Without meaning to be flip, the answer … is yes,” he said.
Stuhr said the city’s modeling shows three out of the five pipes that currently cross the Willamette River will break in the event of an earthquake, making it impossible to guarantee all residents will have a water supply post-disaster.