We’re rebuilding the Washington Park reservoirs. The Portland Water Bureau is replacing reservoirs that have served the city since 1894 with a new 12.4-million gallon, seismically reinforced underground reservoir.
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The Portland Water Bureau is replacing reservoirs that have served the city since 1894 with a new 12.4-million gallon, seismically reinforced underground reservoir. When completed, this project will supply water to Portland's west side and serve more than 360,000 people, including all downtown businesses and residents, 20 schools, five hospital complexes, and more than 60 parks.
The new reservoir will be built within the footprint of the existing Reservoir 3 (upper) with a reflection pool on top. The new reservoir keeps the historic look and feel of the original reservoir and is being engineered to withstand future seismic activity, as well as movement from an ancient landslide on site. The existing Reservoir 4 (lower) is being developed into a lowland wildlife habitat area, bioswale, and reflecting pool. View an artist's rendering of an aerial view of the completed project:
The project is part of the Water Bureau's Capital Improvement Program and is funded by revenue bond proceeds paid back with the utility ratepayers' fund.
Project Location and Background
In order to comply with federal and state mandates and ensure a healthy, resilient, and secure water system, the Portland Water Bureau and Oregon general contractor Hoffman Construction Company began an eight-year capital improvement project to update the Washington Park reservoir site at 2403 SW Jefferson Street.
Washington Park's previously open Reservoirs 3 (upper) and 4 (lower) occupied the site, along with two gate houses, a weir building, three pump houses, a generator house, and associated underground piping. The reservoirs were part of an ingenious gravity‐fed drinking water system constructed more than 120 years ago in the 1890's. The system was active for more than a hundred years before the current construction project began.
Construction began in June 2016 and will continue through 2020. A pause in major construction is scheduled to begin in 2021 to allow the soil that was placed around the reservoir to settle. During this time, we will continue work on some smaller projects on the site, such as upgrading the hypochlorite building near the base of Reservoir 4. We currently expect the soil to have settled approximately nine inches by 2023. Once we determine that the soil has settled into place, we will begin construction of the elements that sit on top of it: the reflecting pool, interpretive features, railings, benches, and landscaping. The project is expected to conclude in fiscal year 2025.
Fall 2020: Reservoir construction completed.
The reservoir structure will be completed. Crews begin the process of connecting the reservoir to the rest of the water system.
Early 2021: Reservoir operational.
The reservoir will be tested, sanitized, and filled. The reservoir begins serving water to the surrounding area.
Spring/Summer 2021: Soil placement.
Soil will be placed over the reservoir and around the site in preparation for future construction of reflecting pools, walkways, and landscaping.
Summer/Fall 2021: Settlement monitoring begins.
Soils need to settle before the final construction phase can begin and will be monitored throughout the site.
2021 to 2023: Earthworks and monitoring phases.
Work that's not dependent on the soil settlement may continue, such as restoring historic building features and upgrading the Hypochlorite Building.
2023 to 2025: Final construction phase begins.
The timing of this phase depends on how much and how quickly the soil settles. Watch for another schedule update as we near the final construction phase.
Building with Earthquakes in Mind
Even though the new reservoir will keep the historic look and feel of the original reservoir, it is being engineered with modern technology and building standards to withstand seismic activity. The Portland Water Bureau has worked for the past several decades to increase the number of water supply facilities that can withstand earthquakes. These include the reservoirs at Kelly Butte and Powell Butte that store water on the east side and the future Willamette River Crossing, which will bring water under the river from the east to the west side of Portland. The Washington Park Reservoirs Project is yet another key to our region's ability to provide water and recover economically after an earthquake.
In 1894, heavy equipment like tower cranes, backhoes, and forklifts were practically nonexistent. Materials were delivered by wagon and pulled by horses or mules. Workers moved supplies and materials around the site using wheelbarrows and brute strength.