Summary: The Environmental Protection Agency (EPA) has come up with remedies to clean up 275 of the nation's most hazardous waste sites. Although construction has been completed at these sites, additional activities, known as operations and maintenance, may be necessary to ensure that remedies continue to function effectively and that the cleanup protects human health and the environment. The federal government, states, and responsible parties must perform long-term operations and maintenance at nearly two-thirds of the 275 sites GAO reviewed. These activities, which include controlling the erosion of landfill covers, treating contaminated groundwater, or enforcing restrictions on land or water use on sites, will continue for decades and in some cases, indefinetly. For cleanup remedies that EPA or the responsible parties have already undertaken or will undertake, GAO estimates that about $32 billion will be needed for operations and maintenance costs nationwide through fiscal year 2040. The states and responsible parties will bear most of these costs. At least every five years EPA is required to review conditions at many sites that need operations and maintenance, and these reviews have often uncovered problems that the state or responsible parties have had to correct. However, EPA has a large backlog of overdue reviews and consequently may be unaware of deteriorating conditions at some site.
