Does the compliance audit requirement cover all of the Part 68 requirements or just the prevention program requirements?

The compliance audit requirement applies only to the prevention programs under Subpart C. If you have a Program 2 process, you must certify that you have evaluated compliance with the Program 2 prevention program provisions at least every three years to verify that the procedures and practices developed under the rule are adequate and are being followed. You may want to expand your audit to check other Part 68 elements, but you are not required to do so.