Bull Run Filtration Fact Sheet: Enhancing Seismic Resilience

The Bull Run Treatment Projects will enhance our water system’s resilience, reduce future risks, and better protect customers.  The projects include building a new filtration facility and associated pipelines that will be key components of a more resilient water system.

Much of our existing Bull Run supply infrastructure is located along the Bull Run River which includes areas of unstable geology, areas at greater risk of landslides, and conduit in shared alignments. Infrastructure in shared alignments is at greater risk of being damaged by the same seismic event, generally increasing the consequence of an outage or repair response. 

Earthquake Hazard in Oregon

• There is a growing recognition of earthquake hazard in Oregon. The most significant hazard to Portland is from a major earthquake on the Cascadia Subduction Zone. Recent studies show a 16 to 22 percent probability of an earthquake with magnitude greater than 8.5 on the Cascadia Subduction Zone in the next 50 years (Goldfinger et al., 2016).
• An earthquake has the potential to cause permanent ground deformation and trigger landslides. This can lead to infrastructure damage. Damage to critical infrastructure such as the Bull Run supply, groundwater, and water distribution system could mean Portland has reduced supply or a supply outage.

Oregon Resilience Plan 

• Recognizing the potential earthquake risk, the Oregon House of Representatives passed House Resolution 3 (April 2011), which directed the Oregon Seismic Safety Policy Advisory Commission (Advisory Commission) to prepare the Oregon Resilience Plan.
• The purpose of the Oregon Resilience Plan is to help agencies set internal policy direction that will protect lives and maintain economic and commercial activity following a Moment Magnitude (Mw) 9.0 Cascadia Subduction Zone earthquake and tsunami.
• Re-establishing water service is a crucial element in the overall recovery of communities after a Cascadia Subduction Zone earthquake and is considered a top priority by the Advisory Commission, which set goals, referred to as target states of recovery, for the time required to achieve different levels of service for the water system.
• The target states of recovery identified in the Oregon Resilience Plan require a high degree of reliability from the backbone water system (a backbone system consists of key supply, treatment, transmission, distribution, and collection elements). According to the Oregon Resilience Plan, the backbone should be 80 to 90 percent operational within 24 hours following an earthquake.
• The WSSS shows that the existing system’s projected performance and damage estimates for a Mw 9.0 Cascadia Subduction Zone scenario earthquake (which is expected to produce strong ground shaking and long duration ground motions from 60 to 180 seconds) are such that the system cannot be restored within the time frame identified in the Oregon Resilience Plan.

Resilience Strategy

• We are prioritizing improvements to our water system backbone to address high-risk infrastructure and increase overall system resilience.
• We monitor ground movement occurring along our conduits and have undertaken efforts to reduce these risks.
• Redundancy is a strategy to provide resilience for critical pipe systems. We use this strategy for the conduit system and the Willamette River pipeline crossings that provide water to the west side of the river.
• There have been numerous occasions when unplanned outages have occurred on our supply and transmission piping. The following is a short sample. In these cases, pipeline redundancy allowed us to continue supplying water to customers without interruption:
  • Clay Street Willamette River Crossing – pipeline failure under the Willamette River (2014-2015)
  • Conduits 2 and 4 – Bridge Crossing destroyed by landslide near Headworks (1995)
  • Conduits 2 and 4 – Damaged by flooding at Dam 2 Spillway (1964)
  • Conduit 3 – Failure due to pipeline corrosion (2014)
• Ground movement due to saturated soils has occurred near the Lusted Hill facility close to where Conduits 2 and 4 cross over the top of Lusted Hill. Redundancy facilitated restoration of the area without interrupting supply.
• Ground movement can occur from seismic, flooding, heavy rainfall, and landslide events.
• A combination of pre-event hardening of assets and post-event repair is recommended to meet the desired performance goals in the Oregon Resilience Plan and close the gap between the existing performance and the desired performance goals of the Oregon Resilience Plan.

How Filtration Can Reduce Seismic Risk

• The new filtration facility and pipelines will be designed and constructed to withstand an earthquake and will help us meet Oregon Resilience Plan goals, such as the ability to restore service within 24 hours of a major event.
• The Bull Run Filtration Project includes building new pipelines to carry water to and from the filtration facility. Having two pipes will increase our overall system resilience/reliability and allow for future maintenance to occur without disrupting service.
• The new pipelines will be built to modern seismic standards to better withstand an earthquake or other emergency and will allow segments of nearby existing pipelines that are in poor condition to be retired. 

Bull Run Treatment Projects

We are making two important improvements to our water supply from Bull Run to help keep our water safe and abundant for generations to come. Improved Corrosion Control Treatment will be in place in 2022 and will further adjust the chemistry of our water, reducing potential levels of lead at the tap. Filtration will be in operation in 2027 and will remove the microorganism Cryptosporidium and other potential contaminants from our water. Both projects are required under state and federal law.