New Lake Oswego wastewater treatment plant continues to take shape
Sustainability was at the forefront of the Lake Oswego City Council's most recent discussion around the Tryon Creek Wastewater Treatment Plant project.
While no decisions were made and no significant updates were discussed during the Oct. 5 meeting, the council learned more detail about the site, technology and timeline.
The current Tryon Creek Wastewater Treatment Plant, which is owned by the city of Portland, was built in 1964 and needs to either be rebuilt or upgraded to meet regulatory requirements. At this point, the city intends to build a new plant that would be owned by Lake Oswego, operated by an outside firm and provide service for Lake Oswego and parts of the greater Portland area.
This past May, the council selected EPCOR Foothills Water Partners to design, build, finance, operate and maintain the new plant.
While the current plant sits on about 13 acres of land, there are about six acres of buildable land to construct the new plant. The old facility cannot be demolished until the new plant is up and running. Deputy City Manager Anthony Hooper said the new plant will look more like a commercial building and will include odor control.
"This project is looking like it's going to be less costly," said Hooper of building a new plant versus upgrading the old site, though he acknowledged that it's still early in the process.
Lee Ward, an EPCOR project manager, said staff is investigating and confirming that the preferred AquaNereda technology for the plant is the right choice.
"We feel very confident in the choice," said Ward.
While there are many technologies that could be used, the Lake Oswego site has a small footprint with many limitations — including the type of technology that's used.
But Ward said AquaNereda has many benefits, aside from meeting the small footprint requirement. This technology is more financially feasible and adaptable to high flows caused by rain infiltration into the wastewater system. Ward said the new technology would likely result in capital cost savings in terms of the plant's life cycle, as well as operational and electricity costs.
"It only takes about 40-50% of the energy that would be used (with a) membrane bioreactor," Ward said of the comparison between AquaNereda and the other technology option.
Hooper added that conversations with the Oregon Department of Environmental Quality have continued to go well, and he is confident they will permit this type of technology.
"At previous Council meetings, the Council gave direction to make sustainability a priority," read the Oct. 5 staff report. "The project team is committed to making the new treatment facility as sustainable as possible within the constraints of land area and technological limits. There are many sustainability-related questions that have been examined by our project team."
The project team discussed energy efficiency, net-zero energy, reclaiming water and residual waste.
City Councilor Massene Mboup was curious why the Gresham wastewater treatment plant reached net-zero energy uses, whereas it seemed that wasn't possible for Lake Oswego.
"It's very important in every decision we are making that we are making sure we are catering to the environment," Mboup said.
Ward said the Gresham plant has a much larger footprint and flow than Lake Oswego. He said the plant also has a collection system for fats, oils and greases, which enables it to create energy, along with the use of solar panels.
Ward said Portland's Columbia Plant is in the process of building a renewable natural gas system.
"Currently, the Tryon Creek Wastewater Treatment Plant uses about 3 to 4 trucks per day to transport the residuals to the Columbia Plant, which currently run on Compressed Natural Gas (CNG)," the staff report read. "Once the biogas upgrading system at Columbia Blvd. is operational in spring 2022, these trucks will be fueled with Renewable Natural Gas (RNG), lowering GHG emissions and improving air quality. The same amount of trucking is anticipated for the new plant."
Residuals could not be treated on site in Lake Oswego because of space constraints. Although, after the existing plant is demolished and remediated there could be an opportunity to build a residual facility on about two acres where the current plant sits.
"We're not precluding ourselves from taking steps if that's the decision that's made," Ward said.
While solar panels are proposed to be used on the roof at Lake Oswego's new site, there isn't enough space to have as many as the Gresham plant utilizes.
Hooper said there was potential for a water reclamation project, which would allow the city to reuse water from the plant to irrigate Foothills Park and George Rogers Park.
This smaller-scale approach to reuse water, compared to a city-wide model, is preferred due to noise, traffic impacts and cost, along with many other reasons.
Councilor Jackie Manz asked if the plant could capture microplastics.
Ward said this is an emerging issue and that the solution isn't fully developed, but with the way the plant will be built "there will be an opportunity in the future to retrofit without tearing down and replacing entire processes," he said. "I do think that's going to come out — something that's going to be emerging in the future."
The project team will return before the council in January with updated renderings and a site plan with 30% of the design completed.
"At that point we'll have a lot more information," said Hooper, adding that there is a community meeting next week that he encourages folks to attend.
The information session will be held on Zoom from 6-8 p.m. Wednesday, Oct. 13.
During the information session, people can tune in to learn more about the project, ask questions and provide feedback.
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