The four aeration basins are 28 feet deep and hold 1 million gallons each. Two 140-foot diameter secondary clarifiers follow the activated sludge aeration basins. Effluent is disinfected with chlorine and de-chlorinated with sulfur dioxide before final discharge to the Yakima River. An odor control system was added to the facility in 1992. Geodesic domes were constructed over the trickling filters as part of this project.
Foul air is ducted from certain areas of the plant and treated in two packed tower odor scrubbers.
Sludge settled out in the primary clarifiers and wasted from the activated sludge system is pumped to the anaerobic digesters for stabilization. There are three heated and mechanically mixed primary digesters with a combined capacity of 1.6 million gallons and three secondary digesters with flexible membrane gas holder covers. After stabilization in the anaerobic digesters, sludge is dewatered by centrifuge and recycled on permitted farmland as a soil conditioner and fertilizer. The Pretreatment Program will be fully delegated by the end of the 5-year permit cycle. The wastewater plant currently receives an average monthly flow near 13 mgd.