ABSTRACT ENVIRONMENTAL AND ECONOMIC IMPACT OF UNDERGROUND STORAGE TANKS IN THE UNITED STATES AND TERRITORIES By Clete R. Helvey December 1992 The existing population of Underground Storage Tanks (USTs) in the United States is enormous. The three major problems relating to (USTs) which must be addresses by communities and UST owners are: (1) the large number of aged USTs in the United States without adequate leak protection, the risks associated with UST management (2) and (3) the rising costs of UST remediation and regulation requirements. The consequences of using USTs for storage of liquid fuels and chemicals are addresses in this paper. The discussion involves such parameters as age, material, product, corrosion, location and quantity. All of these parameters have a direct influence on the environmental and economic impact of USTs in the United States. It will be seen that while age, material and corrosion play a T257860 2 major role in the number of leaking USTs; product, location and quantity are major factors associated with the impacts of those leaks. This paper discusses the number of existing USTs and the percentage of those that are leaking. It also presents the costs associated with the remediation of those leaks and the separate costs of replacing or updating old USTs to meet the new Environmental Protection Agency (EPA) regulations.