Ill. Admin. Code tit. 77, pt. 920, ILLUSTRATION FDownload PDFCurrent through Register Vol. 49, No. 2, January 10, 2025Creviced Formations: Earth Cover Over 30 Feet Thick - Mechanically Driven CasingClick here to view imageIll. Admin. Code tit. 77, pt. 920, ILLUSTRATION FAmended at 24 Ill. Reg. 11934, effective August 1, 2000