The refinement of an effective institutional framework for regulating the cleanup of hazardous wastes is greatly enhanced through the collection of reliable information on cleanup costs. This information is critical in order develop environmental policy that is sensitive to the economic tradeoffs between environmental restoration and the allocation of funds to social programs and future economic growth. Unfortunately, a dearth of cost data is evident for biologically-based waste treatment methodologies, which recently have gained widespread acceptance as effective means of remediating wastes under appropriate environmental conditions. Costs of remediating petroleum underground storage tank sites in Tennessee were studied in order to compare resources allocated to the cleanup of sites which used soil bioremediation versus other “conventional” types of soil remediation. An analysis of various site characteristics was undertaken in order to gain an understanding of cost variations between biological and non-biological cleanup methodologies.