King County Bellevue Pump Station - Upgrade & Force Main Installation


A new 5,300-foot-long, 24-inch-diameter pipeline was installed from the Bellevue Pump Station directly to the Eastside Interceptor, a large regional pipe near Interstate 405.  The force main project was completed in March 2008.  Phase Two began shortly after in the fall, and was completed in 2010.  The above grade pump station was demolished and replaced with a facility featuring more powerful pumps, a new generator building, improved odor control equipment, and updated architecture.


SSA provided acoustical evaluation of pump station and force main construction.  Services included evaluation of all new major equipment for environmental noise control to the neighboring properties and noise levels within the pump station.


The Bellevue Pump Station Force Main utilized Horizontal Directional Drilling (HDD).  HDD applications in urban settings have inherent challenges with a built-out environment, and require sufficient drill side and pipe side construction areas.  The two main segments of the force main were installed under several residences, Bellevue High School, a condominium complex, and a courthouse building, with only 650 feet of pipe laydown area.  The second HDD segment is 1000 feet long, crossing under State Route 405 with a 70 foot elevation difference that required a lane closure of a major arterial in Bellevue, WA.


We conducted site measurements to determine the existing noise levels at the site, and provided details and specifications where required for noise mitigation to receiving properties and interior areas.