For existing Class II UIC wells which do not have surface casing completely covering the fresh water zone, further cementing is not required unless it is necessary to establish external mechanical integrity in accordance with Section 240.770.
The top of the cement behind the production casing shall be a sufficient distance above the top of the uppermost permitted interval of injection to prevent upward migration of injected fluid. In determining the sufficiency of cement, the Department shall consider the amount of existing cement, the location of the packer and the injection pressure.
Ill. Admin. Code tit. 62, § 240.730
Added at 15 Ill. Reg. 15493, effective October 10, 1991