Wisconsin Administrative Code
Department of Natural Resources
NR 600-699 - Environmental Protection - Hazardous Waste Management
Chapter NR 667 - Standards For Owners And Operators Of Hazardous Waste Facilities Operating Under A Standardized License
Subchapter J - Tank Systems
Section NR 667.0201 - What shall I do when I stop operating the tank system?

When you close a tank system, remove or decontaminate all waste residues, contaminated containment system components (for example, liners), contaminated soils and structures and equipment contaminated with waste, and manage them as hazardous waste, unless s. NR 661.0003(4) applies. The closure plan, closure activities, cost estimates for closure, and financial responsibility for tank systems shall meet all of the requirements specified in subchs. G and H.