At closure, the owner or operator shall remove all hazardous waste and hazardous waste residues (including but not limited to ash, scrubber waters and scrubber sludges) from the incinerator.
Wis. Admin. Code Department of Natural Resources NR 665.0351
At closure, as throughout the operating period, unless the owner or operator can demonstrate, according to s. NR 661.0003(4), that the residue removed from the owner or operator's incinerator is not hazardous waste, the owner or operator becomes a generator of hazardous waste and shall manage it according to all applicable requirements of chs. NR 662 to 666.