Willamette Water Supply Treatment Plant

Sherwood, Oregon

Alliant Systems is proud to serve as the mechanical contractor for the Willamette Water Supply Program’s Water Treatment Plant, a state-of-the-art, seismically resilient facility located in Sherwood, Oregon. This landmark project forms a vital component of the region’s new water infrastructure—part of a 30-mile pipeline system stretching from an intake facility along the Willamette River in Wilsonville. Once complete, the system will be capable of delivering up to 60 million gallons of clean drinking water per day, with future capacity for as much as 120 million gallons daily, serving residents of Hillsboro, Beaverton, and the Tualatin Valley Water District.

Designed to provide clean, safe, and reliable drinking water to more than 350,000 residents across Washington County, the Willamette Water Treatment Plant represents an essential investment in the region’s long-term water security and climate resilience.

Alliant’s scope includes plumbing, HVAC (wet and dry systems), process piping, and building controls—a comprehensive effort central to the functionality and efficiency of the plant’s operations. The project incorporates advanced hydronic HVAC systems with integrated DDC controls that utilize river water for heat rejection. Multiple piping and sheet metal materials are being implemented to withstand the unique environmental conditions across the site’s multiple buildings. The plumbing systems serve both domestic and process non-potable water, and Alliant’s teams are employing Lean construction practices to maintain precision and efficiency throughout this large, multi-building campus.

The treatment process itself showcases a sophisticated sequence of purification technologies:
• Coagulation and sedimentation: Uses polymers and micro-sand to help particles settle.
• Ozonation: Introduces ozone to eliminate microorganisms.
• Filtration: Passes water through granular activated carbon and sand for fine impurity removal.
• UV light: Destroys any remaining microorganisms.
• Disinfection: Adds chlorine to ensure the water remains clean and safe as it reaches homes.

Through expert coordination, innovative mechanical design, and a steadfast commitment to quality, Alliant Systems is helping deliver one of Oregon’s most critical infrastructure projects—ensuring a reliable, resilient water supply for generations to come.