Linnton’s Tank Farms in a Cascadia Earthquake

By Nancy Hiser

In 2019, the Multnomah County Office of Sustainability and the City of Portland Bureau of Emergency Management partnered to undertake a study of the anticipated damages from the Critical Energy Infrastructure (CEI) Hub in the event of a Cascadia Subduction Zone Earthquake or other seismic event.

In late July they released their report–the most in-depth and expansive assessment to date of the CEI Hub risks, “CEI Hub DRAFT Seismic Risk Analysis.” That was followed by an online presentation on August 4th.  They have requested public input prior to finalizing the report.  

The County, City, and contracted professionals deserve high praise for an exceptional, clearly written document. It provides impressive detail, not previously published.  Graphs and tables are presented in easy-to-understand formats making their findings accessible to the public.

Background

The report begins with reviews of prior studies from 2012 to 2019, the bases of most of our current knowledge until now, including reports from Oregon Department of Geology and Mineral Industries (DOGAMI), Oregon Seismic Safety Policy Advisory Commission (OSSPAC), the Oregon Resilience Plan, and more.  

Study Purpose

The stated purpose of this study is to:

• Estimate the magnitude and extent of physical impacts of potential tank content releases,

• Evaluate the resulting damages, and

• Identify financial responsibility.

Only the initial purpose was addressed; the ongoing study will address damages and fiscal responsibility.

Tank Failure 

The critical tank failure variables are:

Geologic: land characteristics that impact tank failure, including liquefaction settlement and lateral spreading

Location: whether materials will release onto soil or into water (The Willamette River)

Tank Integrity: failure rates depend on age of tanks

• The large majority of petroleum tanks (92%) were constructed before 1993 and are predicted to fail with 50-100% of contents released.

• Tanks constructed between 1993 and 2004 are designed for shaking but not liquefaction settlement or lateral spreading and could fail with up to 10% content released.

• Tanks constructed after 2004 to survive liquefaction and lateral spreading could still develop connection failures or other damages resulting in as much as 10% release.

Tank Contents: amounts of hazardous, flammable, or volatile materials

Expected Release

Of the 630 tanks in the CEI Hub, 415 are active.  The fill level of tanks averages 67% and the expected total release is from 94 to 194 million gallons (57% on ground and 43% into the Willamette River).  In comparison, the worst spill in US history and one of the world’s worst environmental disasters was Deepwater Horizon in 2010.  It spilled between 134 and 206 million gallons into the Gulf of Mexico.

Fire and Toxic Impacts

The report details the likelihood of explosions and power lines acting as ignition sources for fires. Flammable materials will comprise 93% of releases.  Additionally, the catastrophic toxicity of the released materials into the air, water, and land will create enormous clean-up challenges and extensive long-term damage to the environment and wildlife.  Researchers identified variables such as the time of the event (weekday vs. weekend, day vs. night, summer vs. winter) that will affect the loss of life, short and long-term effects on the environment and air quality, effects on navigation, and impacts on cultural resources.

See the presentation slides and read the report at

https://www.multco.us/sustainability/cei-hub-draft-seismic-risk-analysis

You can also leave public comments at this site through August 29. In September or October the data from this study will explain damages and discuss financial responsibility.

Linnton’s Reality

The St Johns Bridge is predicted to fail in a major earthquake. St. Helens Road will be impassable. Forest Park may catch fire.  Collectively, these realities will compromise our evacuation and existence.  Portland Fire & Rescue has repeatedly stated they will not be able to assist us in the immediate aftermath.  The only solutions are 1) to relocate the tank farms — this author is now convinced this is futile — or 2) to make the tanks safer through technological mitigation.  We need to support those who are actively working on reducing the CEI Hub risks.  Let your concerns be heard–please.  With proactive steps, catastrophe may be avoided.

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