System Information

Sewer System

The city owns and operates a wastewater treatment plant located on the banks of the South Fork Snoqualmie River by State Route 202. The majority of wastewater produced within the city originates from domestic sources, including single-family residences, multi-family developments, mobile home parks, businesses, and other commercial enterprises.

Identifying Sources of Inflows and Infiltration

Another source of flows in the sewer system is stormwater inflow and groundwater runoff infiltration. In 1974, 1986, and 1997, utilizing TV inspections of the sewer system, the city went through extensive studies to locate and identify the sources of inflow and infiltration.

Expanding the Capacity of the System

As a result of the studies, beginning in 1995 the city aggressively implemented a capital improvement program to improve operations and expand capacity of the system. This program included the construction of a new operations building at the wastewater treatment plant, installation of a secondary clarifier and ultraviolet disinfection system, replacement of leaky collection system pipes in the downtown area, and construction of a biosolids handling / drying facility.

ULID No. 6 Project Completion

As a result of a request of property owners on the east end of town, ULID No. 6 was formed to finance bringing sewer service to the newly annexed Tanner and Truck Town areas. The ULID No. 6 project included installation of sewer pipelines, construction of a new pump station and connection to the existing treatment plant. The project was completed in 2011.