(510 ILCS 77/10.24)
Sec. 10.24. Karst Area. "Karst area" means an area with a land surface containing sinkholes, large springs, disrupted land drainage, and underground drainage systems associated with karstified carbonate bedrock and caves or a land surface without these features but containing a karstified carbonate bedrock unit generally overlain by less than 60 feet of unconsolidated materials.
(Source: P.A. 91-110, eff. 7-13-99.)