Washington Water Power Central Steam Plant

The site was built in 1915 to burn coal and produce steam and electric power. In the mid-1960s, the boilers were converted to use petroleum (Bunker C). Seven underground storage tanks were constructed to store fuel.

Petroleum for the boilers spilled in 1982. Investigations found petroleum in soil and shallow groundwater. The contaminated groundwater is not a source of drinking water and is not connected to the Spokane-Valley Rathdrum-Prairie Aquifer.

Cleanup included excavating contaminated soil near the ground surface and replacing it with clean soil, capping the area with asphalt, and removing the underground storage tanks. A restrictive covenant is on the property, prohibiting the use of groundwater and any activities that would expose remaining contaminated soil.

Quarterly groundwater monitoring began in 1997. Gasoline- and diesel-range petroleum concentrations have met state standards since February 2005. However, petroleum continues to be removed from extraction wells. Bunker C continues to be detected at low concentrations in some groundwater monitoring wells. The site is now retail stores, restaurants, hotels, and commercial parking lots.

Periodic reviews

During the periodic reviews in 2023 and 2014, Ecology decided the cleanup continues to protect people and the environment. No repair, maintenance, or further cleanup were required.

During the periodic review in 2008, Ecology found a monitoring well on the eastern side of the intersection of South Lincoln Street and West First Avenue was missing the monument lid and well casing cap. The well was properly closed in 2010 to prevent potential groundwater contamination.