Which regulation deals with cleaning up inactive hazardous waste sites?

The regulation that deals with cleaning up inactive hazardous waste sites is the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). Enacted in 1980, CERCLA, commonly known as Superfund, was established specifically to address the cleanup of hazardous substances at sites where those substances pose a threat to public health or the environment.

CERCLA provides the federal government with the ability to respond to uncontrolled or abandoned hazardous waste sites and to ensure that responsible parties are held accountable for the cleanup. This act also established a trust fund, often referred to as the Superfund, to provide the necessary resources for these cleanup operations, especially when the responsible parties are unable or unwilling to perform the cleanup themselves.

This focus on hazardous waste sites distinguishes CERCLA from the other regulations listed. While the Solid Waste Disposal Act addresses the management of solid waste, the Clean Air Act and the Clean Water Act are primarily concerned with the control of air and water pollution, respectively. Therefore, CERCLA's specific mandate for hazardous waste site cleanup is why it is the correct answer.