Section 611.353  Source Water Treatment

A supplier must complete source water monitoring and treatment requirements (under subsection (b) and Sections 611.356 and 611.358) before specific deadlines.

a)         Deadlines for Completing Source Water Treatment Steps

1)         Step 1:  A supplier exceeding the lead or copper action level must complete lead and copper source water monitoring (under Section 611.358(b)) and recommend treatment to the Agency (under subsection (b)(1)) within 180 days after the end of the tap monitoring period during which the supplier exceeded the action level.

2)         Step 2:  The Agency must issue a SEP determining source water treatment (under subsection (b)(2)) within six months after the supplier submits monitoring results under step 1.

3)         Step 3:  If the Agency requires installing source water treatment, the supplier must install that treatment (under subsection (b)(3)) within 24 months after the Agency completes step 2.

4)         Step 4:  The supplier must complete follow-up tap water monitoring (under Section 611.356(d)(2)) and source water monitoring (under Section 611.358(c)) within 36 months after completion of step 2.

5)         Step 5:  The Agency must issue a SEP reviewing the supplier's installation and operation of source water treatment and specify MPCs for lead and copper (under subsection (b)(4)) within six months after the supplier completes step 4.

6)         Step 6:  The supplier must comply with the Agency-specified lead and copper MPCs (under subsection (b)(4)) and continue source water monitoring (under Section 611.358(d)).

b)         Source Water Treatment Requirements

1)         System Treatment Recommendation.  Any supplier exceeding the lead or copper action level must recommend to the Agency in writing one of the source water treatments in subsection (b)(2).  A supplier may recommend installing no treatment based on a demonstration that source water treatment is not necessary to minimize lead and copper levels at users' taps.

2)         Agency Determination Regarding Source Water Treatment

A)        The Agency must evaluate the results of all source water samples the supplier submitted to determine whether source water treatment is necessary to minimize lead or copper levels in water the supplier delivers to users' taps.

B)        If the Agency determines treatment is necessary, the Agency must issue a SEP requiring the supplier to install and operate either the source water treatment the supplier recommended (if any) or another from among specific source water treatment techniques:

i)          ion exchange;

ii)         reverse osmosis;

iii)        lime softening; or

iv)        coagulation/filtration.

C)        The Agency may require the supplier to submit, on or before a certain date, any additional information as the Agency determines is necessary to aid its review.

D)        The Agency must notify the supplier in writing of its determination, stating the basis for its decision.

3)         Installing Source Water Treatment.  A supplier must properly install and operate the source water treatment the Agency approves under subsection (b)(2).

4)         Agency Reviewing Source Water Treatment and Specifying Maximum Permissible Source Water Levels (MPCs)

A)        The Agency must review the source water samples the supplier took both before and after the supplier installs source water treatment and determine whether the supplier properly installs and operates the approved source water treatment.

B)        Based on its review, the Agency must issue a SEP approving the lead and copper MPCs for finished water entering the supplier's distribution system.  The MPC levels must reflect the contaminant removal capability of the treatment when properly operated and maintained.

C)        The SEP issued under subsection (b)(4)(B) must include the Agency's explanation of the basis for its decision under subsection (b)(4)(B).

5)         Continued Operation and Maintenance.  A supplier must maintain lead and copper levels below the MPCs the Agency approved at every sampling point the supplier monitors under Section 611.358.  The supplier does not comply with this subsection (b) if the level of lead or copper at any sampling point is greater than the MPC the Agency approved under subsection (b)(4)(B).

6)         Modifying Agency Treatment Decisions

A)        On its own initiative, or in response to a request by the supplier, the Agency may issue a SEP modifying its determination of the source water treatment under subsection (b)(2) or the lead and copper MPCs under subsection (b)(4).

B)        A supplier must make a request to modify in writing, explaining the propriety of the modification, and providing supporting documentation.

C)        The Agency may issue a SEP modifying its determination if it concludes that the change is necessary to ensure that the supplier continues minimizing lead and copper concentrations in source water.

D)        A revised determination under subsection (b)(6)(C) must state the new treatment requirements, explain the basis for the Agency's decision, and provide a schedule for completing the treatment modifications.

E)        Any interested person may submit information to the Agency in writing bearing on whether the Agency should exercise its discretion and issue a SEP modifying its determination under subsection (b)(2).  An Agency determination not to act on information an interested person submits is not an Agency determination for the purposes of Sections 39 and 40 of the Act.

7)         USEPA Treatment Decisions.  Under 40 CFR 142.19, USEPA reserves the prerogative to review Agency treatment determinations under subsections (b)(2), (b)(4), or (b)(6) and issue federal treatment determinations consistent with 40 CFR 141.83(b)(2), (b)(4), and (b)(6) if USEPA finds that certain conditions exist:

A)        the Agency fails to issue a treatment determination by the applicable deadline in subsection (a);

B)        the Agency abuses its discretion in a substantial number of instances or in instances affecting a substantial population; or

C)        the technical aspects of the Agency's determination would be indefensible in a federal enforcement action taken against the supplier.

BOARD NOTE:  This Section derives from 40 CFR 141.83.

(Source:  Amended at 47 Ill. Reg. 16486, effective November 2, 2023)