Welcome to the City of Port Townsend

Treatment System

Basic History
The wastewater treatment facility was upgraded in 1993 and is located in the North Beach neighborhood of Port Townsend. It borders environmentally sensitive areas of Fort Worden State Park and Chinese Garden Lagoon. The facility is designed for a population of 12,000 and currently serves approximately 9,000 residential and commercial users. Customers contribute wastewater flows for treatment averaging 950,000 gallons per day.

Wastewater treatment is the process of removing contaminants, solids, and harmful bacteria from wastewater prior to discharge into the environment.


Three general processes used at the city of Port Townsend’s wastewater treatment facility are preliminary treatment, secondary treatment, and disinfection.

Bar Screen Preliminary treatment has two mechanical devices. The first is a Bar Screen that removes roots, rags, and large debris. The second piece of equipment is a grit classifier which removes inorganic materials like sand and grit. All of these removed items are sent to a landfill.

Secondary treatment mixes bacteria, oxygen, and fresh organic material into a pair of Oxidation Ditches. Bacteria eat the organic material, become heavier, and are sent to the Secondary Clarifiers. The clarifiers allow solids in wastewater to settle out on the bottom for removal. Clarifiers also remove floating scum and grease. Clear wastewater from the clarifiers is disinfected and flows into Chlorine contact basins. Chlorine contact basins provide enough detention time for chlorine to disinfect any remaining pathogenic bacteria. Sodium Bisulfite is used to de-chlorinate treated wastewater prior to the treatment facilities discharge into the Strait of Juan de Fuca.

One of the byproducts of secondary treatment is removal of nutrient rich material, known as biosolids. These solids are removed from wastewater by use of a Belt Press and transported to the city’s compost facility for making Class "A" compost.

Additional information about our city’s wastewater treatment may be found in the brochure, City of Port Townsend Wastewater Treatment Facility. It provides detailed descriptions, design criteria, a flow diagram, and additional facility photos. A copy of the brochure is also available at the wastewater treatment facility on 5300 Kuhn Street, Port Townsend, WA.