46 CFR 148.110: Procedures followed after unloading.

(a) After a material covered by this part has been unloaded from a vessel, each hold or cargo compartment must be thoroughly cleaned of all residue of such material unless the hold is to be reloaded with that same cargo.

(b) When on U.S. territorial seas or inland waters, cargo associated wastes, cargo residue, and deck sweepings must be retained on the vessel and disposed of in accordance with 33 CFR parts 151.51 through 151.77.