A 48-foot long by 8-foot wide trailer became home to the Pilot Plant for the Green River Filtration Facility in May 2009. Equipment inside tests the ozonation, chemical addition, rapid mixing, flocculation, sedimentation and filtration processes. Additional equipment provides data monitoring and collection in support of regulatory approval for high-rate filtration (greater than 6 gallons per minute per square foot).

We also use the Pilot Plant to evaluate alternative treatment options, such as chemical strategies, filter media configurations and to optimize parameters for the design of the full-scale Green River Filtration Facility. Optimizing design parameters occurs through replication of water treatment processes on a small scale. We will eventually use those processes in the Green River Filtration Facility.

Pilot plant operations are basically complete, barring any additional testing requested by the Washington state Department of Health or a major water quality event occurs and we want to capture more treatment experience.

During the three years the pilot was in operation, Tacoma Water gathered a significant amount of useful information including 10 different filter media configurations, 20 different chemical treatment combinations, five different source water blends and collection of 20 million data points.