(a) Unless § 153.1114 allows the prewash to be omitted, a cargo tank from which a Category B NLS is unloaded must be prewashed using the procedures in § 153.1120(b) if the tank—

(1) Operates under the interim standard in § 153.481(b); or

(2) Has a waiver issued under § 153.483.

(b) Unless § 153.1114 allows the prewash to be omitted, a cargo tank from which a Category C NLS is unloaded must be prewashed using the procedures in § 153.1120(b) if the tank has a waiver issued under § 153.483.