Two rules can apply to facilities with above ground tanks, 1) Federal SPCC Rules (40 CFR 112), and 2) Wisconsin Rules on Storage of Flammable, Combustible and Hazardous Liquids (Chapter Comm 10). For any given facility, some tank systems may only be subject to SPCC Rules, some may only need to comply with Wisconsin Chapter Comm 10, and still other tanks may actually need to comply with both sets of rules.
There is a significant amount of over lap and similarity between the two rules; however, they differ in many aspects, included when a written spill plan is required and in situations where documents need to be prepared by and certified by a Wisconsin-licensed professional engineer. Whether or not a facility needs to use a PE to approve their plans will depend on a number of factors, including the size and location of their tanks, and the specific liquids being stored in them.
If you want further information on above ground tank rules and SPCC rule compliance in Wisconsin, email Caltha at firstname.lastname@example.org