Learn about Earthquakes and Sewers

January 21, 2013

When city dwellers suddenly lose their flushing toilets to an earthquake,  they are further distressed and their capacity to survive and recover is deeply compromised.  By understanding how infrastructure will fail and experimenting with alternative, decentralized and waterless systems we can strengthen community resilience before a seismic event and speed recovery after it.

The Oregon Resilience Plan brings new understanding of the impact of earthquakes on sewer systems.  Mark Knudson’s November 2, 2012 presentation at the five-day Resilience NW Conference was an eye opener:  “Water Supplies – What You Should Know: The Oregon Resilience Plan For Water & Wastewater Systems”   Tualatin Valley Water District’s head engineer co-chaired the water and sanitation committee of Oregon Seismic Safety Policy Advocacy Commission, or OSSPAC.  Presented to the Oregon Legislature in 2013, the draft plan was announced by The Oregonian in early February.  See Executive Summary and complete version of The Oregon Resilience Plan: Reducing Risk and Improving Recovery for the Next Cascadia Earthquake and Tsunami.

Impact zones for the magnitude 9.0 Cascadia earthquake scenario. Damage will be extreme in the tsunami zone, heavy in the Coastal zone, moderate in the Valley zone, and light in the Eastern zone.

Impact zones for the magnitude 9.0 Cascadia earthquake scenario. Damage will be extreme in the tsunami zone, heavy in the Coastal zone, moderate in the Valley zone, and light in the Eastern zone.

Life without Sewers – Conclusions of The Oregon Resilience Plan

  • Much longer recovery time for sewer and wastewater than for water.
  • For Portland, controlling threats to public health and routing sewage away from population will take an estimated 6 to 12 months.
  • Repairing collection systems that convey sewage to wastewater treatment plans will take 1-3 years.
  • Restoring operation of pump stations and wastewater treatment to current levels will take 3+ years.
  • Recovery times are much longer for the Coastal zone, where it will take 1 to 3 years just to control threats to public health and route sewage away from population. The rest will take more than 3 years.

The impact of a Cascadia Subduction Zone quake of 1700 is known.      In the mid 1990s, USGS geologists started to work with colleagues in Japan to understand the impact of the 0.9 magnitude quake that occurred on January 26, 1700 off the Oregon coast and generated a well-documented tsunami in Japan.   The Orphan Tsunami reads like an adventure story.  Authored by Brian F. Atwater in collaboration with Japanese experts, the beautifully illustrated, 144 page book is downloadable free.

The M 9.03 Tohoku earthquake and tsunami in Northern Japan will leave the city of Sendai  without wastewater treatment for three to five years.   With earthquakes every 10 to 20 years, Japan has upgraded its piped systems periodically and was considered prepared.  Yet the earthquake  left 19,000 dead and 325,000 people were still displaced at the end of 2012.  Destruction of pipes in areas built on fill was enormous. Sendai was prepared with portables in parks and a temporary system that was up and running in 2-3 months.“Fully restoring water and sewer services to the town will take three to five years,”  however, noted the Washington Association of Water and Sewer Districts in  “Powerful Japanese Earthquake Provides Lessons for Northwest Water, Sewer Districts Before the Big One Hits.”

Sanitation failure is immediate and long term.  The diagram below from an illustrated Japanese study grasps complex systems interdependency when seismic activity destroys pipes, brings down structures, and disrupts transportation.

With collapsed bridges and destroyed transportation infrastructure, authorities will be unable to respond.  We need to prepare at the household and neighborhood level. Says James RoddeyUltimately, preparedness is a personal responsibility. When we get the big one, nobody is riding in on a white horse to save you (think Katrina); in fact 80% of all rescues in an earthquake are done by your neighbors.  The place to start is talking with our neighbors, imagining scenarios in ways that stimulate not fear but creativity and ultimately inspire an sense of community resilience.

Citizens to the rescue!  When the centralized systems of Christchurch failed, activists of  New Zealand Permaculture Emergency Response Network introduced residents to a simple toilet design appropriate anywhere for emergencies and lang term use.  See Compost Toilets: Their Use as an Emergency Response in Christchurch.

Learn More

 Earthquake and Hazards Program of the Association of Bay Area Governments.   Iinformation specific to water and wastewater treatment plants on liquefaction, landslides, location of active faults and details of infrastructure in hazard areas.

Seismic Assessment and Design of Sewers   Webinar on earthquake hazards and their impact on wastewater collection systems by Donald Ballantyne, an engineer who has worked on systems in Vancouver BC, Seattle, Portland and SanFrancisco.

Sewers Float and other aspects of Sewer Performance in Earthquakes has illustrations of damaged sewer lines and wastewater treatment plans in a number of US and Japanese cities. Since water pipes must be able to withstand both pressure and soil loading, they are much stronger than sewer pipes which only need to withstand soil loading.  While water plants are generally built on competent soils, wastewater treatment plans are often built on fill where there is greater risk of liquefaction.

Learn More

The Oregon Resilience Plan: Reducing Risk and Improving Recovery for the Next Cascadia Earthquake and Tsunami. 2013.  Executive Summary and complete version 

“Calif. quake model looks for ‘big one’ in NW”  Keely Chalmers January 10, 2013  Short (2:20) video. Good for training awareness.

 The Earthquake Engineering Research Institute.  A place to follow the latest research.

Billions needed to upgrade America’s leaky water infrastructure.” Washington Post. January 2, 2012.  In the United States, sewer infrastructure is already vulnerable and problems are exacerbated by customer ignorance.

“Saving U.S. Water and Sewer Systems Would Be Costly”  By Charles Duhigg New York Times: March 14, 2010

“Low-Cost Sanitation Solutions A report on progress in Post-Earthquake Haiti” Andrew Larsen & Fontes Foundation.” FSM 2 Conference Durban, South Africa October 30, 2012. Project funded by a grant from the Bill & Melinda Gates Foundation


Our Mission Through education and advocacy, PHLUSH helps local governments and citizen groups to provide equitable public restroom availability and to prepare for a pipe-breaking seismic event with appropriate ecological toilet systems.

Our Vision Toilet availability is a human right and well-designed sanitation systems restore health to our cities, our waters and our soils.

Public Hygiene Lets Us Stay Human (PHLUSH) was founded in Portland, Oregon and today collaborates with groups across North America.

PHLUSH is a member of the World Toilet Organization and a partner in the Sustainable Sanitation Alliance.

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