Portland’s water mains that cross the Willamette River are more than 50 years old and will probably not survive a major earthquake. The Willamette River Crossing Project, which will build an earthquake-resilient water line under the Willamette River, is part of the Water Bureau’s investment in preparedness. The improvements we’re making will enhance our water system’s resilience and reduce future risks, ensuring safe and abundant water for generations to come.
The Water Bureau has worked for the past several decades to increase the number of water supply facilities that can withstand earthquakes. Reservoirs at Kelly Butte, Powell Butte, and Washington Park all meet seismic standards. The Willamette River Crossing is the next step in strengthening our system to make it more resistant to earthquakes. The new pipe is critical for bringing water to the west side of town.
As part of the Water Bureau’s Capital Improvement Program, this project is funded by revenue bond proceeds paid back with the utility ratepayers’ fund. This means current and future ratepayers contribute to the project.
Construction work hours are expected to be 7 a.m. to 5 p.m., Monday through Friday. However, some future work will take place overnight, between 5 p.m. and 7 a.m. We will coordinate any overnight hours with affected property owners, businesses, tenants, and transportation agencies.
Work schedules can change for many reasons, including weather, traffic, and problems with tools, machines, or supplies. Sometimes we need to stop between different types of work and start again later.
Work on this project will take place on both the east and west sides of the river in locations where we will have to connect to the existing water system as well as in locations where we will build shafts to send a tunneling machine underground.
Project timeline and phases
The project has two distinct but overlapping phases: exploration/design and construction. For example, during the design phase, we may use construction equipment to gather information to inform the design of the pipeline.
The project is currently in the design phase. Along with utility locates, site exploration, and soil testing, this phase includes conducting a geotechnical probe. The probe provided essential information on how the geology beneath the river will impact construction. Conducting the geotechnical probe helped us determine the best tools to use to build the pipeline and the best path across the river.
Design phase 1: Pre-construction activities (2019 to 2020)
- Soil sampling: On the east and west sides of the river, crews dug in the street, sidewalk, and public right-of-way to find the exact locations of underground utilities and assess conditions at the site.
- Geotechnical investigation: We needed to know what’s underground before going “full bore.” Drilling a geotechnical probe helped us identify the types of soil and rock deep underground. A 12-inch-diameter probe drilled a pilot hole from the parking lot on the west side toward the east. The computerized drill bit sent information to the surface about what it encountered. This process helped us understand the next steps we need to take.
- West-side connection: Several years ago, the Water Bureau installed a large water pipe called the “Westside Header” on the west side of the Willamette River. This 5,000-foot-long water pipe received water from the east side of the river, then carried that water to the pipe system along the west side of the river. During winter 2020/2021, crews added a connection to the Westside Header to get it ready for the new Willamette River Crossing.
Design phase 1A: More investigation (January 2021 to September 2021)
Through the geotechnical probe, we discovered that the soil along our proposed route couldn’t be drilled with the technology we were hoping to use. We did more vertical borings in the area to better understand the soil conditions underground. This additional geotechnical exploration and analysis took about six months and led to changes in our construction plan.
Design phase 1B: Fine-tuning our design (October 2021 to February 2022)
Based on information gathered from the geotechnical probe in 2020 and additional testing in the spring of 2021, we learned that we needed to change the path the pipe takes across the river and use direct steerable pipe instead of horizontal directional drilling. Over the next four months, our contractor will fine-tune the design so that we can begin construction in summer 2022.
Construction plan changes between Phase 1A and Phase 1B
Between the river and Southeast 10th Avenue, we will replace the pipes close to the road surface instead of tunneling. We will cut a trench into the road surface and install pipe in the trench (this is much like the standard work we do replacing water mains across the city). There are a couple of benefits to making this change:
- We’re using this opportunity to replace about 1,000 feet of existing cast-iron pipe with new earthquake-resilient pipe. This strengthens a part of our system that is more likely to be damaged in an earthquake or leak due to age.
- This will save us a significant amount of money, because building a tunnel of this length is much more expensive than installing a pipe close to the road surface.
- Compared to the previous plan, this plan will have much less impact on intersections, delivery bays, and business entrances on Southeast Stephens Street.
We’re moving the planned pipe about 200 feet to the south and will microtunnel under South Montgomery Street. There are benefits to this change as well:
- Moving the pipe one block south allows us to install the pipe under a nearby park and road instead of under a privately owned building.
- The new plan helps us avoid the environmental risk and cost of our drill encountering marine pilings in the river.
- Going under the road helps us maintain business and residential access for multiple properties in the area and avoid unintentionally disrupting utilities (such as sewer pipe and electric and gas lines) that serve the area.