Considerable attention has been focused on regulatory classification of ash from municipal solid waste (MSW) incinerators. Such attention has raised several issues, which range from the applicability of current federal regulations, to the manner of sampling, and the type of test to apply to characterize the ash. When lab tested under the provisions of the 1976 Resource Conservation and Recovery Act (RCRA) and its subsequent amendments, municipal waste combustion (MWC) residues sometimes exceeded heavy metal limitations. Lacking evidence to the contrary, the public and the media have viewed MWC residue as ""toxic."" Elected officials, similarly, have relied on such laboratory data to shape their perspective. Reliance on just laboratory leachate data has led to state regulations imposing economic burdens on resource recovery projects. On September 18, 1992, Mr. William Reilly, Administrator of the United States Environmental Protection Agency, issued a policy statement declaring that MWC ash should be regulated as a non-hazardous solid waste. The author hopes that the Clinton administration will continue the current policy. This book would serve to defend the current policy. The engineering approach, emphasizing a rational evaluation of peer-reviewed field data, could defuse environmentalists' claims. Should federal policy remain, due to USEPA's recognition of their problems with field data and lab procedures, this book provides a guideline to implement combustion residue beneficial use. The described engineering methodology, advocating end-product performance and reliance on field data, provides a more rational approach than worst-case, risk-assessment models. This book provides a technical assessment of combustion residues' environmentally benign characteristics and a blueprint to achieve their utilization. Readers, representing both sides of the combustion residue controversy, should appreciate the application of the rational, engineering approach aimed at demonstrating environmental compatibility of heavy industrial energy projects. This engineering approach will enable us to achieve a true balance between industrial growth and environmental compatibility.