Phase 2/BNR Tertiary WWTP Project

This project included construction of a new 12.7 MGD Tertiary Treatment Process suitable for river discharge. This new facility was the second phase of major improvements implemented to maintain discharge permit compliance and to improve the plant’s operational ability as urban growth continues. It is the largest water project in the City’s history and constructed an outfall to the river. The process included primary effluent pump station, internally fed rotary drum fine screens, biological nutrient removal (BNR) aeration system, Evoqua membrane bioreactor tanks, UV disinfection, and a tertiary effluent (TE) pump station. Additional structures included a dilution pump station, primary effluent pump station, electrical building, distribution box, aeration blower building, mixed liquor screening, membrane blower building, RAS pump station, WAS pump station, main electrical building, standby generator, operations center, and a tertiary maintenance shop. A two-mile-long, 3-inch carbon steel TE pipeline was installed between the pump station and existing plant discharge piping. Additionally, the project removed and relocated 70,000 CY of compost waste and constructed a new compost shop building, office facility, grinding facility, and truck scale. The relocation of the compost facility required coordination with a third party and maintenance of operations the entire time. There was a significant dewatering operation of 2 million gallons/day. At the time this was the largest MBR in the Western U.S. 

While the majority of the project did not directly impact operations, several key components of work required a closely coordinated effort with the operations and maintenance staff. GSE constructed a below grade influent pump station within the existing facility. This pump station tied into the plant’s main influent pipeline. This work involved a deep and complex shoring plan with a dewatering system and a large diameter hot tap on a critical influent pipeline. These activities were coordinated with plant staff to ensure that the existing facility was not impacted and that operations could perform their tasks safety without access impeded by construction activities.

This project received the 2016 CMAA Project Achievement Award.