The Columbia Boulevard Wastewater Treatment Plant is constructing two new clarifiers as part of its Secondary Treatment Expansion Program. A $5.35 million construction permit was recently issued for the clarifiers.

The Secondary Treatment Expansion Program is the largest improvement project to the treatment plant at 5001 N. Columbia Boulevard in Portland since the 1970s, according to the City of Portland, the project owner. The improvements, designed by architect Jacobs Engineering Group and constructed by Kiewit Infrastructure, will increase the treatment plant’s resiliency, protect water quality and provide healthier work environments for workers.

“It is also linked to our ‘Big Pipes’ program in that it addresses how we treat all that combined sanitary and stormwater conveyed to the plant,” Project Manager Muriel Gueissaz-Teufel said.

The two main features of the project are the two new clarifiers that will increase the plant’s secondary treatment capacity and new solids processing facilities to replace old assets and increase capacity to the year 2045. The clarifiers will replace old composters and work buildings along the Columbia Slough.

Clarifiers are large tanks in which aerated wastewater slows down and solids from this process separate from the water.

“We have a regulatory mandate to add these clarifiers,” Gueissaz-Teufel said. “The treatment plant, when it rains hard, we have two basic processes: One is biological; the other one is chemical.”

The two clarifiers will increase the biological side of things. It will also improve resiliency of operations.

“This will add a lot of resiliencies from an operational standpoint but also from a seismic standpoint because they will be built to the structural code,” Gueissaz-Teufel said.

Construction began in November 2020 for the first phase of construction with site preparation, ground improvements and the installation of temporary facilities and systems to allow deconstruction of existing facilities and systems without service interruption. The ongoing work is approximately $100 million.

Since November 2020, the team finalized the design and engineering of the permanent facilities, Gueissaz-Teufel added.

“We’re going to council next week for that second phase,” Gueissaz-Teufel said. “That should be all complete by December 2025.”

The clarifiers will be complete by 2024 and the rest of the construction will be done by 2025. Other work includes cleaning and restoring the eight aeration basins, deconstructing aging work areas, renovating storage facilities, constructing a new multi-use building, replacing the solids facility and process, adding new pipes underground, and replacing old electrical equipment located in the tunnels with new equipment above ground.

Public Information Officer Diane Dulken said they will lock in a maximum price for the project at the council meeting on Wednesday, Aug. 24. The total project cost will be $515 million, including what has been spent so far.

The project team is also excited to be implementing a Community Benefits Agreement to address historic inequities in construction workforce and contracting, Gueissaz-Teufel said. The project will continue to provide millions of subcontracting work to people of color, women and disadvantaged businesses, while providing workforce training and development opportunities to women and people of color. Gueissaz-Teufel said this is the first project implementing that agreement. Approximately $80 million will go to minority certified firms for their work on the project, she said.

Even while deconstructing, the treatment plant has continued to be operational.

“This is really a plant that operates continuously that we all rely on to protect public health and the environment,” Dulken said.

The team has been recycling the dirt during excavation so it can be repurposed.

“We have worked with DEQ to see if there can be a beneficial use for the soil,” Gueissaz-Teufel said. “We reached out to local agencies to see if maybe there is a mutual agreement we can figure out.”

The Port of Portland has entered into an agreement with the project to take the soil to their own site.

“It diverts the landfill, it reduces carbon emissions, and it saves us at least $5 million,” Gueissaz-Teufel said. “It’s been a good partnership for us.”

The plant is a resource recovery facility that harvests the resources considered waste. A huge part of this is the water.

“We’re recovering water and putting it back into the river in a clean form,” Gueissaz-Teufel said.

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