Hydraulic Challenges of Designing for a High-Capacity and High-Head Pump Station
King County is developing a new wastewater treatment plant to service a growing area of King and Snohomish Counties, Washington. To convey flows to the Brightwater treatment plant, the influent pump station (IPS) and a series of new tunnels and interceptors are being constructed. The plant IPS is located approximately 2.5 miles upstream and connected to the treatment plant via a tunnel containing the influent force main and other pipelines. The new 170-million gallon per day (mgd), 90-foot deep IPS has six centrifugal, two-stage (total dynamic head or TDH of 285 feet) raw sewage pumping systems that utilize two different sized pumps: two 20-mgd pumps, three 45-mgd pumps, and one standby 45-mgd pump.