1. a) The owner or operator of a Class II injection well that is injecting carbon dioxide into an oil and gas reservoir for the primary purpose of long-term storage must apply for and obtain a Class VI injection well geologic sequestration permit when there is an increased risk to a USDW compared to usual Class II injection well operations. In determining if there is an increased risk to a USDW, the owner or operator must consider the factors specified for Agency consideration in subsection (b).

2. b) The Agency must determine when there is an increased risk to a USDW from injecting carbon dioxide into an oil and gas reservoir for the primary purpose of long-term storage compared to usual Class II injection well operations and that a Class VI injection well permit is required. In order to make this determination, the Agency must consider the following factors:

   1. 1) Any increase in reservoir pressure within the injection zones;
   2. 2) Any increase in carbon dioxide injection rates;
   3. 3) Any decrease in reservoir production rates;
   4. 4) The distance between the injection zones and USDWs;
   5. 5) The suitability of the Class II injection well area of review delineation;
   6. 6) The quality of abandoned well plugs within the area of review;
   7. 7) The owner's or operator's plan for recovery of carbon dioxide after the cessation of injection;
   8. 8) The source and properties of injected carbon dioxide; and

   9. 9) Any additional site-specific factors that the Agency determines are necessary to determine whether the injection poses greater risk than usual Class II operations.

      BOARD NOTE: Derived from 40 CFR 144.19 (2017).

(Source: Amended at 42 Ill. Reg. 21095, effective November 19, 2018)