Construction at the Washington Park Reservoirs started in 2016 and will continue until 2025. Read on for the most recent update.
The Water Bureau is replacing its original 1894 reservoirs with a new 12.4-million-gallon, seismically reinforced underground reservoir. This reservoir will supply water to Portland’s west side and serve more than 360,000 people, including all downtown businesses and residents, 20 schools, 5 hospital complexes, and more than 60 parks.
When you subscribe, select the checkbox next to "Washington Park Reservoir Improvement Project."
We began the first fill of the reservoir in mid-December to begin testing the reservoir. The reservoir is divided into two chambers, known as cells, and as of mid-January, both cells were filled.
Take video tours of the unfilled reservoir
Due to precautions we are taking during the pandemic, we couldn’t offer public tours of the finished reservoirs. We were, however, able to capture some video—two videos, in fact, each with a different look and feel. We hope you enjoy!
Madison Trail reopens for public use
As of March 1st, a fallen tree has been cleared from the path and Madison Trail has reopened. Our contractors may need to make temporary closures of the trail to move equipment and supplies around the site from time to time. However, these closures will take place during construction hours, and the trail will remain open during non-working hours.
Filling the reservoir
We have begun the process of filling the reservoir with water. Because this is the first time the reservoir structure has had to withstand the weight and pressure of water, we are only filling one of the two cells at a time, and only bringing the water level up four feet per day. This allows the weight of the water to “settle in.”
You might be surprised to learn that it is common to find small leaks and cracks the first time a brand-new reservoir is filled. Even though it’s the best building material to use for all kinds of projects, concrete cracks. Just look at your own driveway or sidewalk to observe the properties of concrete. Because we expect this, concrete crack repair is a step in our process and written into our contract.
Some of these cracks may repair on their own during the filling process through a process called autogenous healing. In this process, cement from within the reservoir hydrates and cures, sealing these hairline cracks.
Crack repair is an anticipated step with the construction of any large concrete infrastructure project.
For the fractures that don’t heal on their own, we hire specialized divers to swim through the filled reservoir with video cameras and canisters of a milk-based substance. If they see an area that looks like it might be prone to leaking, they spray the milk sealer into the water. If there is a crack, the movement of the water pulls the milk into the crack and the diver marks the area to be repaired. The video documents the process to make it easier for us to return to the spot and make repairs. When divers recently tested the first half of the reservoir for leaks, no cracks were significant enough to attract the milk substance—a good sign!
To make sure the reservoir starts its long life water tight, we are repairing areas that show the potential for leakage. We inject grout deep into the hairline cracks to seal them, testing a second time to make sure filled every little space.
Park openings and closures
Visit the Explore Washington Park COVID-19 resource page for updated maps and information about Washington Park openings, closures, and safety.