MWH Constructors and Slayden Constructors Inc. were awarded a $125 million contract by the city of Spokane to provide general contractor and construction manager services for an upgraded tertiary filtration system for the Riverside Park Water Reclamation Facility. As designed, the system is the most effective phosphate removal process of its kind in the U.S., according to the project team.
The filtration system upgrade will increase the removal of phosphorus from the effluent to more than 99 percent. The current system removes 90 percent of phosphorus, which has been associated with low oxygen levels and algae blooms that can harm aquatic life in the Spokane River and Long Lake. With additional disinfection, the new filtration system could bring the effluent in compliance with Washington State Department of Ecology “Class A” standards, allowing the water to be safely reused for irrigation, industrial processes, dust control, wetland enhancements and recharging groundwater supplies.