The City of Colville operates and maintains 125,500 liner feet of underground sewer pipe with 5
sewage lift stations. This extensive piping system serves over 4,700 residential customers by
managing wastewater flows from sinks, showers and bathing, dish and clothes washers, toilets,
and industrial processes. Wastewater flows from homes and businesses through sewer pipes
that lead to the Wastewater Treatment Plant. The Wastewater Treatment Plant processes an
average of 1.01 million gallons of wastewater each day, but the plant can treat up to 2.83 million
gallons a day during the months when maximum flows are occurring.
The City finished construction of the class III treatment plant upgrade in 2006. This upgrade
included an all new activated sludge/extended aeration system with anoxic selector tanks, two
clarifiers, and Ultra violet disinfection. The 38-acre decommissioned lagoon system was
reworked to facilitate 2 aerated bio-solid holding cells, flow equalization cell and a seasonal
storage cell for treated effluent when river flows are low.