Wis. Stat. § 287.29: Iron and steel slag recovery.

(1) In this section, “slag” means slag generated by the production or processing of iron or steel that is managed as an item of value in a controlled manner and is not discarded.

(2) No person may use unencapsulated slag on private property within 100 feet of a residential dwelling or a building intended to be used in whole or in part as a school or daycare facility without prior approval of the department.