Brownfields are abandoned or underutilized lands and/or buildings for which redevelopment or reuse is complicated due to the perception or presence of environmental contamination. Estimates of the number of brownfield sites in the United States range from just tens of thousands to more than 450,000. The number of acres of impacted land is uncertain. The industrial heritage of many cities has left them with acres of properties deemed valueless because of the potential environmental liability associated with former industrial practices. These sites are largely the unintended consequence of federal and state legislation that was aimed at cleaning up contaminated industrial sites. Federal and state laws have often required significant cleanup and mitigation efforts to be undertaken before these properties could be reused to their fullest potential. Rather than assume the expense and environmental risks, would-be buyers have walked away from these suspect properties within once-thriving industrial centers. The consequences have been far reaching: deeply eroded tax bases, pockmarks within urban development projects, lost employment opportunities, underutilization of existing infrastructure, and the sprawl of industrial development into suburban and exurban greenfields. The resulting spreading out of industrial and commercial sites has had its own consequences from increased use of automobiles, reduced environmental quality in outlying areas, and increased pressure on the limited resources of suburban and rural communities.

At the heart of the issue is the liability and uncertainty created by the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA ) passed in 1980, widely known as the Superfund. CERCLA...