The City of Everett’s first sewers were constructed in 1890, three years before Everett was incorporated. In 1897, the construction of the citywide system began in north Everett. This north portion of the system is combined, carrying stormwater and sanitary sewage to the Everett Water Pollution Control Facility (EWPCF). With population growth, the system expanded to the south. The south portion of the system is sanitary sewage only.
Today, the wastewater system serves more than 136,000 people, conveying sewage through approximately 345 miles of sewer mains, interceptors, laterals, and 29 lift stations to the EWPCF. Everett also treats a portion of the sewage from three neighboring sewer systems: Mukilteo Water and Wastewater District, Alderwood Water and Wastewater District and Silver Lake Water and Sewer District. The system plays a vital role in protecting public health. It also protects rivers, lakes and streams from pollutants and minimizes harmful impacts to the natural environment.
The EWPCF is located on Smith Island in north Everett. It has two parallel wastewater treatment systems, which provide secondary (biological) treatment with disinfection. The trickling filter/solids contact (TF/SC) system is a mechanical plant, which treats up to 21 million gallons per day (MGD). The aeration/oxidation ponds, or lagoon system, treats the wastewater flows not treated and discharged by the TF/SC plant and provides storage capacity for storm flows from the combined sewage system. Discharge of effluent from the two treatment systems is through two separate outfalls.
In the past, all EWPCF discharge was to the Snohomish River. Since 2005, TF/SC discharges to a marine deep-water outfall in Port Gardner Bay shared with the City of Marysville. A plant expansion completed in 2007 increased the EWPCF total hydraulic capacity to 36.3 MGD.
Each person contributes about 50 to 100 gallons of used water each day to the wastewater flow. Sewer lines carry wastewater from sinks, showers, washing machines, streets and gutters and industries. Since 2007, there has been an increase in organic loading to the EWPCF, which will require adding treatment capacity in the near future to remain in compliance with environmental regulations.