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Tri-City Service District working to solve wastewater digestion issues

System shared by Tri-City and Clackamas County Service District No. 1 is at capacity


Through much of 2015, members of the Tri-City Service District — which treats wastewater for West Linn, Oregon City and Gladstone — were embroiled in a debate over future governance of the body.

While the district had been managed for decades by Clackamas County, representatives from Oregon City and Gladstone argued that governance should instead come from the three cities themselves. Ultimately, the district arrived at a compromise to consolidate various advisory boards for both the Tri-City Service District and Clackamas County Service District No. 1 (CCSD 1) — which handles wastewater for Happy Valley, Damascus, Milwaukie and unincorporated Clackamas County — to allow for more cohesive dialogue and a potential change in governance at a later date.

But the heavy lifting wasn’t over when West Linn passed its resolution in support of that plan in January 2016 — not by a long shot.

Settling the governance issue — for now — allowed both Tri-City and CCSD 1 to turn their attention to a larger and more expensive problem: what to do with solid wastewater digesters that are at capacity, and thus require significant investment going forward.

At a West Linn City Council meeting Monday, June 27, Clackamas County Water Environment Services (WES) — which operates solid digesters for both districts — Director Greg Geist was on hand to discuss the matter. In the end, the council expressed its general support for WES to move forward with plans to add as many as two additional solid wastewater digesters to its system — most likely using the same “anaerobic digestion” machines that are currently in place at the treatment plant in Oregon City.

“The digesters are running out of capacity, and if they fail they could discharge untreated waste in the river,” Geist said. “Those digesters, they’re a biological process. They are like a stomach, and we’re a stomach that’s eating really rich food and probably too much.”

According to Geist, WES projections show that the two digesters currently in place have about three more years before more must be added. The project cost is estimated at about $55 million, and would be funded through utility rate increases.

Geist estimated that the bump in utility rates would likely be between four and six dollars a month, depending on if customers are located within Tri-City or CCSD 1. At the June 27 meeting, several West Linn councilors argued that rate increases should be higher in areas that are experiencing more growth and thus contributing more to the capacity issue.

West Linn, of course, is not experiencing growth at the rate of nearby cities like Happy Valley.

“When you have CCSD 1 having growth out there in Happy Valley and beyond, they do need to pay their fair share,” City Councilor Thomas Frank said.

“We’re going to be having conversations at the (Regional Wastewater Treatment Capacity Advisory Committee) on how to apportion costs,” Geist said. “I understand you folks see your boundaries. I don’t. I see district boundaries. We’re in this together.”

Though nothing is final yet, WES will most likely move forward with the “tried and true” anaerobic digestion machines as opposed to a newer technology called “OmniProcessor.” The OmniProcessor — endorsed by none other than Bill Gates —transforms waste into clean water, but is thought to be too young and unproven as a technology to be used in Tri-City and CCSD 1.

“You don’t want to be the guy on the bleeding edge of wastewater technology,” West Linn Public Works Director Lance Calvert said. “’Tried and true’ in this case shows it’s robust, and there’s a reason a lot of plants use (anaerobic) technology.”

Moving forward, according to Geist, the goal is to prepare a conceptual design for the new digesters in August, and submit a final report with a cost estimate and technology choice in September.

The West Linn City Council also stated its intention to pass a resolution supporting the anaerobic digesters at a later date.

See related

Discussions continue over Tri-City governance, capital investment

West Linn, Oregon City at odds on Tri-City Service District Governance

Patrick Malee can be reached at 503-636-1281 Ext. 106 or This email address is being protected from spambots. You need JavaScript enabled to view it..