The Resource Conservation and Recovery Act (RCRA) requires EPA to identify which wastes should be regulated as hazardous waste under subtitle C and establish regulations to manage them. For example, hazardous waste landfills, such as those used for disposing ash from hazardous waste incinerators, generally must comply with certain technological requirements. These requirements include having double liners to prevent groundwater contamination as well as groundwater monitoring and leachate collection systems. In 1980 the Congress amended RCRA to, among other things, generally exempt cement kiln dust from regulation under subtitle C, pending EPA’s completion of a report to the Congress and subsequent determination on whether regulations under subtitle C were warranted. The Congress required that EPA’s report on cement kiln dust include an analysis of (1) the sources and the amounts of cement kiln dust generated annually, (2) the present disposal practices, (3) the potential danger the disposal of this dust poses to human health and the environment, (4) the documented cases of damage caused by this dust, (5) the alternatives to current disposal methods, (6) the costs of alternative disposal methods, (7) the impact these alternatives have on the use of natural resources, and (8) the current and potential uses of cement kiln dust. As of May 1994, there were about 115 cement kiln facilities operating in 37 states and Puerto Rico. Of these, 24 were authorized to burn hazardous waste to supplement their normal fuel. Even with the 1980 exemption, certain aspects of cement kilns’ operations must comply with some environmental controls. Under the Clean Air Act, EPA requires cement kiln facilities to comply with ambient air quality standards for particulate matter. Under the Clean Water Act, EPA regulates the discharge of wastewater and storm water runoff from cement kiln facilities. Under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA or Superfund), EPA can require cement kiln facilities to clean up contamination resulting from cement kiln dust. In August 1991, EPA’s regulations for boilers and industrial furnaces that burn hazardous waste took effect. While every cement kiln that burns hazardous waste is subject to these regulations, its dust is not classified as hazardous waste if at least 50 percent (by weight) of the materials the kiln processes is normal cement-production raw materials and the kiln’s owner or operator demonstrates that burning hazardous waste does not significantly affect the toxicity of the dust. According to EPA Office of Solid Waste officials, of the 24 cement kilns authorized to burn hazardous waste, they are not aware of any that are required to manage the dust as a hazardous waste. Despite these existing controls, in making its regulatory determination in February 1995, EPA stated that additional controls over cement kiln dust are warranted under RCRA because of its potential to harm human health and the environment. EPA also determined that existing regulations, such as those under the Clean Air Act, may also need to be improved because they are not tailored to cement kiln dust or because their implementation is inconsistent among the states. As partial justification, EPA cited 14 cases in which cement kiln dust has damaged groundwater and/or surface water and 36 cases in which cement kiln dust has damaged the air. EPA also cited the general lack of groundwater monitoring systems around dust management units at cement kiln facilities and the current lack of federal regulations to protect groundwater from the risks posed by cement kiln dust. Furthermore, after collecting and analyzing site-specific information, EPA concluded that potential risks did exist at some facilities. Although in 1980 the Congress directed EPA to complete its report on cement kiln dust by 1983 and to determine within 6 months thereafter whether regulations were warranted, EPA did not do so. It completed its report in December 1993 and issued its determination in February 1995.EPA officials said that the agency did not meet these statutory deadlines because, at that time, EPA viewed completing its report on cement kiln dust as a lower priority than other work. According to EPA’s Acting Chief of the Special Wastes Branch, the agency ranked completing its report and determination on cement kiln dust a low priority because cement facilities were considered to pose minimal risk because of the very small proportion of them on EPA’s National Priorities List. In addition, cement kiln dust exists in smaller volumes in comparison to other high-volume wastes that EPA was required to study, such as wastes from mining for ores and minerals and exploring for oil and gas. EPA wanted to complete studies of these high-volume, temporarily exempt wastes prior to completing its study on cement kiln dust. For example, EPA estimated that the mining industry generated 1.3 billion metric tons of waste in 1982, and it completed its study on these wastes in 1985. EPA officials said that they also needed to meet other statutory time frames for completing standards for other wastes that the agency placed a higher priority on, such as treatment standards for land disposal of hazardous waste. In settlement of a 1989 lawsuit filed against EPA because of its failure to comply with the statutory time frames, EPA entered into a consent decree to publish a report to the Congress on cement kiln dust on or before December 31, 1993. This decree also called for EPA to make a regulatory determination on cement kiln dust by January 31, 1995. RCRA specifically authorizes EPA to modify several requirements that apply to hazardous waste in regulating cement kiln dust. EPA is authorized to modify those requirements that would impose minimum technological standards on new landfills or expansions of existing landfills as well as those that impose corrective action to clean up releases of wastes from units used to dispose of cement kiln dust. EPA is authorized to modify these requirements to accommodate practical difficulties associated with implementing them when disposing of cement kiln dust as well as such site-specific characteristics as the area’s climate, geology, hydrology, and soil chemistry. However, any modifications must ensure the protection of human health and the environment. Although RCRA allows EPA to modify several requirements and thus propose different standards for cement kiln dust than those for hazardous waste, EPA has not yet determined which standards might differ and how they might differ. For example, according to Office of Solid Waste officials, it is not clear whether EPA will include a corrective action requirement to clean up releases from cement kiln dust disposal units that is similar to its corrective action requirement to clean up hazardous waste disposal units. These officials said that EPA will likely focus its management standards on dust generated in the future, as opposed to dust that already exists at cement kiln facilities, because RCRA allows EPA to consider several factors in developing standards for cement kiln dust management, including the impact or cost any management standard may have on the cement kiln industry. Furthermore, these officials said that EPA has to be sensitive to the Congress’s regulatory reform efforts as well as the agency’s goal of taking a more common sense approach to regulating industry. Even though EPA has determined that additional controls are warranted over dust from cement kilns burning hazardous waste as well as dust from those kilns that do not, it has not determined if it will impose the same standards or controls over dust from both types of kilns. EPA’s analysis found that concentrations of 12 metals in dust from both types of cement kilns were at higher than normally occurring levels. Dust from cement kilns burning hazardous waste had concentrations of nine of these metals that were the same or lower than dust from cement kilns that did not burn hazardous waste. Conversely, EPA found that concentrations of three metals—cadmium, chromium, and lead—were higher in dust from cement kilns that burn hazardous waste. (See app. I.) Even though the concentrations of these three metals were higher, EPA found that these increases did not result in discernible differences in risk estimates between dust generated by cement kilns that burn hazardous waste and those that do not. EPA also analyzed the extent to which these metals leached, or washed, out of the dust and found no significant difference between cement kilns that burn hazardous waste and those that do not burn this waste. Although EPA has not yet determined what management standards it will impose on cement kiln dust, Office of Solid Waste officials said that the agency may regulate air emissions from cement kilns burning hazardous waste differently from those that do not burn hazardous waste. According to these officials, because dioxins and furans were found in dust from cement kilns burning hazardous waste, EPA is considering revising its regulations for boilers and industrial furnaces to control their emissions. Even though the levels of these hazardous wastes were generally low, EPA believes their presence warrants concern. Even though EPA did not conclude that cement kiln dust should be classified as a hazardous waste, EPA did conclude that some facilities (in addition to those where damage to surface and/or groundwater and the air has been found) do have the potential to pose a threat to human health and the environment. While EPA plans to propose a program to control cement kiln dust within 2 years, if the agency proceeds with developing federal regulations, it could be several more years after that until cement kilns are required to implement these controls. Interim and possible final actions to reduce the current threat that cement kiln dust may pose at some facilities include requiring the cement kiln industry to adopt dust control standards without EPA’s first having to proceed through a lengthy regulatory development process and making greater use of existing regulatory authority to control cement kiln dust. One action EPA is considering to control this dust is the use of a cement kiln industry proposal called an enforceable agreement. After drafting the general terms of the agreement, the cement kiln industry has been working with EPA and other interested parties to negotiate what controls would be needed to protect human health and the environment. Some possible industry controls are to require landfills used to dispose of cement kiln dust to have such site-specific features as hydrogeological assessments, groundwater monitoring, surface water management, and measures to control emissions of cement kiln dust.