Section 611.976  Operational Evaluation Levels

a)         A supplier has exceeded the operational evaluation level at any monitoring location where the sum of the two previous quarters' TTHM results plus twice the current quarter's TTHM result, divided by four to determine an average, exceeds 0.080 mg/ℓ, or where the sum of the two previous quarters' HAA5 results plus twice the current quarter's HAA5 result, divided by four to determine an average, exceeds 0.060 mg/ℓ.

b)         Effects of Exceeding the Operational Evaluation Level

1)         If a supplier exceeds the operational evaluation level, the supplier must conduct an operational evaluation and submit a written report of the evaluation to the Agency no later than 90 days after being notified of the analytical result that causes it to exceed the operational evaluation level.  The written report must be made available to the public upon request.

2)         The supplier's operational evaluation must include an examination of system treatment and distribution operational practices, including storage tank operations, excess storage capacity, distribution system flushing, changes in sources or source water quality, and treatment changes or problems that may contribute to TTHM and HAA5 formation and what steps could be considered to minimize future exceedances.

A)        A supplier may request and the Agency may allow the supplier to limit the scope of its evaluation if the supplier is able to identify the cause of the operational evaluation level exceedance.

B)        A supplier's request to limit the scope of the evaluation does not extend the schedule in subsection (b)(1) for submitting the written report.  The Agency must approve this limited scope of evaluation in writing, and the supplier must keep that approval with the completed report.

BOARD NOTE:  Derived from 40 CFR 141.626.

(Source:  Amended at 44 Ill. Reg. 6996, effective April 17, 2020)