Mica Landfill

The 161-acre site is a municipal solid waste landfill approximately 11 miles southeast of Spokane and 1.5 miles north of the Town of Mica.

Spokane County operated the landfill from 1972 until 1990, and Spokane County and the City of Spokane jointly operated it from 1990 through 1991. The landfill stopped receiving waste in late 1991.

The landfill received about 65,000 tons of waste per year in the form of residential and municipal solid waste, dewatered sewage treatment plant sludge, demolition debris, and industrial wastes. Demolition debris was generally mixed with municipal waste or used as base material for landfill roads. Industrial wastes included pesticides, fungicides, herbicides, fertilizers, electronics industry chemicals, petroleum products, degreaser solvents, dyes and paints, industrial sludges, baghouse dust wastes, and other miscellaneous chemicals. About 24,000 tons of black dross, which is a byproduct of the aluminum production industry, was disposed in a designated area of the landfill between 1974 and 1987.

The landfill was added to the Superfund: National Priorities List in 1985 after an evaluation by the U.S. Environmental Protection Agency, and Ecology became the lead cleanup agency for the site.

Several cleanup actions protect human health and the environment, including:

• An engineered cap over the landfill
• A leachate collection system
• A gas collection and treatment system
• Property deed restrictions

The deed restrictions limit or prohibit any activity that will damage the cap or may cause a release, require the maintenance of fences and locked gates, restrict land use for industrial purposes only, and require future owners to comply with these restrictions. In addition, state law prevents groundwater supply wells within 1,000 feet of the permitted landfill boundary. 

The cleanup at Mica Landfill continues to protect human health and the environment. Compliance monitoring ensures remaining soil and groundwater contamination does not migrate off-site. The deed restrictions ensure site uses will not expose remaining contamination. 

You can learn more in the periodic review reports:

• 2020
• 2013
• 2007