1. a) Consistent sampling and analysis procedures that are designed to ensure monitoring results that provide a reliable indication of groundwater quality below the unit. At a minimum, the program must include procedures and techniques for:

   1. 1) Sample collection;
   2. 2) Sample preservation and shipment;
   3. 3) Analytical procedures; and
   4. 4) Chain of custody control.
2. b) Sampling and analytical methods that are appropriate for groundwater monitoring and that allow for detection and quantification of contaminants specified in this Subpart, and that are consistent with the sampling and analytical methods specified in 35 Ill. Adm. Code 620.
3. c) A determination of the groundwater head elevation each time groundwater is sampled. A determination of the groundwater head elevation is not required for samples taken from a potable well used as a monitoring well under Section 615.204(b).
4. d) A determination at least annually of the groundwater flow rate and direction.
5. e) If the owner or operator determines that the groundwater monitoring program no longer satisfies the requirements of this Section, the owner or operator must, within 90 days, make appropriate changes to the program and must notify the Agency of the changes when submitting the groundwater monitoring reports under Section 615.208.

The owner or operator must develop a groundwater monitoring program that consists of:

(Source: Amended at 47 Ill. Reg. 7581, effective May 16, 2023)