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The 5-acre MGM Brakes site is a former aluminum brake manufacturing and casting facility in Cloverdale, California. Facility activities contaminated groundwater and soil with volatile organic compounds (VOCs), including benzene, chlorobenzene, trichloroethylene (TCE) and vinyl chloride. Following construction of the remedy, monitoring is ongoing.
What Has Been Done to Clean Up the Site?
The site is being addressed through federal, state and potentially responsible party (PRP) actions.
EPA has conducted several five-year reviews of the site’s remedy. These reviews ensure that the remedies put in place protect public health and the environment, and function as intended by site decision documents. The most recent review concluded that response actions at the site are in accordance with the remedy selected by EPA and that the remedy continues to be protective of human health and the environment.
What Is the Current Site Status?
The site’s long-term remedy for groundwater included excavation and off-site disposal of polychlorinated biphenyl (PCB)-contaminated soils, demolition of the casting plant, decontamination of PCB-contaminated equipment, source identification, and installation of wells to identify the extent of contamination. EPA later updated the remedy to include monitored natural attenuation and allow deeper contaminated soils to remain in place; previous excavations found removal to be difficult and impractical. Natural attenuation describes a variety of in-place processes that, under favorable conditions, act without human intervention to reduce the mass, toxicity, mobility, volume or concentration of contaminants in groundwater.
Demolition of the casting plant finished in 1992. A temporary cap covered the concrete building floor slab until its demolition in 1993. A well system dewatered the area to allow for subsurface soil excavation by transferring groundwater to an on-site treatment plant. Dewatering took place in 1993. Excavation of contaminated soils finished in 1994. EPA could not identify the source of groundwater contamination. The California Regional Water Quality Control Board (RWQCB) has reduced groundwater monitoring requirements as contamination at the site decreases. Monitoring of the natural attenuation remedy is ongoing.