Operated by the Wastewater Department, the sewer system includes a vast collection system and full-scale, state-of-the-art Wastewater Treatment Plant (WWTP) with capacity of 4.0 million gallons per day, complete with a biosolids dewatering and handling facility, large capacity interceptor sewers ranging up to 27 inches in diameter, and twelve wastewater pumping stations located at strategic points in the system.  The collection system consists of over 113 miles of interceptor and collector lines ranging in size from 6 inches to 27 inches.

Constructed in 2008, the WWTP uses a four-cell vertical loop reactor process with two 90-foot settling clarifiers, a sludge pump station, an effluent pumping station, and an ultraviolet effluent disinfection process. Piping connects the “new” plant to the sludge dewatering and handling facilities, “old plant,” via a 48-inch diameter boring under the high-speed railroad. The WWTP is designed to treat only domestic waste; however, the City’s State Wastewater Operating Permit allows the discharge of pretreated industrial wastewater.

The sewer system currently serves a population of over 15,000 people with approximately 7,000 user accounts and has the capability to serve additional customers in the surrounding area.  The City of Washington provides the full-service operations and maintenance of the wastewater collection along with pumping and treatment systems utilizing our duly State licensed operating personnel.