The overall objective of the study was to develop a deeper understanding of UST residuals at closure: their quantities, origins, physical/chemical properties, ease of removal by various cleaning methods, and their environmental mobility and persistence. The investigation covered underground storage tanks containing: gasoline, diesel oil, and fuel oil. It obtained information in two phases. Phase I elicited data via telephone contacts with knowledgeable individuals including tank cleaning companies, from literature cited by these experts, on-site visits and from questionnaires completed by state representatives. Phase II monitored selected tank cleaning cases and made quantitative measurements of the amounts of residuals left in USTs before and after cleaning, characterizing the nature of the residuals and any rinses generated during the cleaning process. To support the objectives of the study, the following information was collected for each UST site included in the study: estimates of volumes of tank residuals and secondary wastes, hazardous characteristics and chemical composition of the residuals and secondary wastes, detailed descriptions of the cleaning methods used, and background information on the UST/site that relates to the nature of the residuals. The report documents the study findings in order to aid regulators and to assist those implementing/overseeing closure activities.

"Office of Research and Development." "EPA project officer: Anthony N. Tafuri"--T.p. "EPA/600/R-92/057." "EPA contract no.: 68-03-3409"--T.p. "April 1992." Includes bibliographical references.