The MGM Brakes site is a former aluminum brake manufacturing and casting facility in Cloverdale, California. It was added to the National Priorities List (NPL) on September 8, 1983, after an initial assessment in 1981. The NPL is EPA's list of the most contaminated sites in the United States that require long-term cleanup. The site was deleted from the NPL on September 16, 2019, meaning EPA determined cleanup was complete and the site no longer poses a significant threat.
EPA identified 17 contaminants of concern at the site. These include volatile organic compounds (VOCs) such as benzene, trichloroethene, chlorobenzene, vinyl chloride, 1,1-dichloroethene, and 1,2-dichloroethene, as well as polychlorinated biphenyls (PCBs). These contaminants were found in groundwater, soil, surface water, sediment, and buildings on the site. PCBs were the most widespread, detected across all of those media.
Cleanup began in the early 1990s. Workers demolished the casting plant's concrete floor slab in 1993 and finished excavating contaminated soils by 1994. A well system was installed to treat groundwater. The long-term remedy relies on monitored natural attenuation, which means naturally occurring processes gradually reduce contaminant levels over time. EPA later updated the remedy to allow deeper contaminated soils to remain in place, determining that removing them would be impractical. The California Regional Water Quality Control Board reduced groundwater monitoring requirements as contamination levels dropped. Physical construction of the cleanup is complete across the entire site.
EPA completed five-year reviews in 2003, 2008, and 2013 to check that the cleanup continues to protect people and the environment. The most recent review confirmed that response actions match the selected remedy. Human exposure is under control across the whole site, meaning there are no unacceptable ways for people to come into contact with contaminants. Contaminated groundwater migration is also stabilized, with no unacceptable discharge to surface water. The site achieved its cleanup goals for current and expected future land uses, and all required land-use restrictions are in place. Ongoing monitoring continues to track natural attenuation progress.
Community members with questions can contact the Community Involvement Coordinator. For technical questions about the cleanup, contact the Remedial Project Manager.
