City of Walla Walla to launch $10 million wastewater treatment plant overhaul
By Dan Thesman on Wednesday, March 4th, 2026 in Columbia Basin News More Top Stories
WALLA WALLA – The city of Walla Walla is moving forward on an estimated $10 million overhaul of the wastewater treatment plant to replace aging infrastructure nearing the end of its functional life.
The project focuses on rehabilitating two primary digesters, which are large, enclosed tanks that process solids to reduce waste volume and odors. Exposed to corrosive environments for over two decades, these units will receive new mixing and heating systems, along with advanced protective coatings.
A key efficiency upgrade includes replacing the facility’s boilers. The new system will allow the city to use captured biogas as a primary fuel source, with a new waste burner installed to manage excess gas.
Funding is secured through a $7 million loan from the Washington State Department of Ecology and additional support from the Washington Public Works Board. Currently 90 percent through the design phase, construction is scheduled to run from July 2026 to July 2027.
Photo via city of Walla Walla
