Wastewater Collection & Treatment

Wastewater Collection 

Wastewater collection responsibilities cover operation and maintenance of city-owned wastewater collection systems, including the Winslow and South Island Sewer Systems. The Winslow Sewer System serves the historic downtown Winslow area and the South Island Sewer System serves the Lynnwood Center, Point White, Pleasant Beach, Emerald Heights, Blakely School, and Rockaway Beach neighborhoods. The collection systems have a combined infrastructure that includes:

Infrastructure Component
Emergency Generators
Miles of Force Main
Miles of Gravity Collection System
Residential Grinder Pumps
Sewage Pump Stations


Wastewater collection activities are performed to safely convey sewage from individual residences and buildings to the Wastewater Treatment Plant. At each building, sewage flows by gravity or is pumped by an on-site pump station to a gravity sewer main located in the city right-of-way. At the right-of-way, sewage flows by gravity until it enters a city pump station. The pump station pumps the sewage along to another pump station or to the Wastewater Treatment Plant.

Pump Stations

The pump stations are monitored by telemetry 24/7/365, and include redundant backup systems, as well as an emergency power source to keep the systems operating under all conditions.

Routine wastewater collection activities include pump station and main line inspection, testing, and maintenance.

Wastewater Treatment

The City’s South Island Wastewater Collection system flows to the Fort Ward Wastewater Treatment Plant that is owned and operated by Sewer District Number 7. The sewage is treated under contractual agreement between the City and Sewer District Number 7.

Winslow Wastewater Collection System

The City’s Winslow wastewater collection system flows to the Winslow Wastewater Treatment Plant that is owned and operated by the City. The plant is a Class 3 secondary-activated sludge plant that employs dissolved oxygen for solids treatment and ultraviolet light for disinfection.

Each year the plant treats 150-million gallons of wastewater with typical conventional pollutant removals above 97%. The treated wastewater is discharged east of Wing Point into the Puget Sound. Plant activities are regulated by the State of Washington Department of Ecology, and the Plant maintains an accredited water quality laboratory.

Routine activities include:

  • Biosolids dewatering
  • Laboratory sample collection, testing and analysis
  • Process control
  • Regulatory reporting