1. Four classes of tanks are excluded from regulation in the final rule: UST systems containing mixtures of hazardous waste and regulated substances; equipment and machinery that contain regulated substances for operational purposes; wastewater treatment tanks regulated under the Clean Water Act; and UST systems excluded via one of three de minimus exclusions.

2. This exclusion now applies to all tanks subject to regulation under Subtitle C that contain mixtures of hazardous wastes and either petroleum or non-petroleum regulated substances.

3. Equipment and machinery that contain regulated substances for operational purposes, such as hydraulic lift tanks and electrical equipment, are excluded from today's regulations.


4. This category of tanks includes hydraulic lifts and electrical equipment. Although commentors did not suggest other specific types of tanks that would fall within this class, EPA believes that other tanks of this type would also be included, provided that the tanks meet two major criteria: the equipment or machinery contains small amounts of regulated substances solely for operational purposes; and a loss of regulated substance is accompanied by faulty operation of the eqipment.