What must be done if a UST is permanently closed?

When a UST is permanently closed, it is essential to empty, clean, and properly dispose of the tank to ensure that any remaining hazardous materials or contaminants are removed. This process helps to prevent environmental hazards and contamination of the surrounding soil and groundwater. Proper cleaning and disposal are essential in complying with regulations and minimizing risks associated with buried tanks, such as leaks or contamination after closure.

Leaving the tank intact or filling it with concrete are not acceptable practices because they do not address the potential risks associated with the tank and its contents. Simply removing the tank from the site can also be insufficient if proper procedures for cleaning and disposal are not followed prior to removal, as contaminants could still be present in the tank or surrounding areas. Therefore, option C reflects the necessary steps to ensure a safe and compliant closure of a UST.