The Muskego Sanitary Landfill is a 56-acre site that was the location of a former landfill, animal-rendering plant and gravel quarry in Muskego, Wis. EPA has been overseeing a cleanup done by site operator Waste Management of Wisconsin, Inc. and several other companies that sent industrial waste to the landfill or used hazardous substances on site. They are all considered to be responsible for environmental problems at the site. Under four EPA legal orders, the companies investigated contamination, removed buried drums, upgraded the landfill cover and leachate and gas collection systems, and installed a collection system to address ground water contaminated with volatile organic compounds such as vinyl chloride and heavy metals including lead and chromium from landfill waste.
Although construction of the primary elements of the cleanup (landfill capping, ground water pumping and treating, and air and ground-water monitoring) was finished in 1997, the cleanup has been reviewed often. In addition, two comprehensive, formal reviews have been done to ensure that the cleanup is still protecting people and the environment. Such reviews are required by law and are done every five years. In 1999, the formal review recommended various follow-up activities including hooking up nearby residences to the municipal water system and abandoning several drinking-water wells. In 2004, another formal review showed that the cleanup might not be working as expected because ground-water contamination had been moving off site. That review recommended further ground-water investigation.