Illinois Administrative Code
Title 35 - ENVIRONMENTAL PROTECTION
Part 611 - PRIMARY DRINKING WATER STANDARDS
Subpart G - LEAD AND COPPER
Section 611.351 - Applicability of Corrosion Control

Universal Citation: 35 IL Admin Code ยง 611.351

Current through Register Vol. 48, No. 38, September 20, 2024

a) Corrosion Control Treatment. This Section provides when a supplier must complete the corrosion control treatment steps in subsection (d) or (e) to optimize or re-optimize corrosion control treatment based on size, whether the supplier has corrosion control treatment, and whether the supplier exceeded the lead trigger level, lead action level, or copper action level.

1) Large Suppliers
A) A large supplier applying corrosion control treatment that exceeds either the lead trigger level or copper action level must complete the corrosion control treatment steps subsection (d) specifies.

B) A large supplier not applying corrosion control treatment with 90th percentile concentration results under Section 611.350(c)(4) that exceeds either the lead practical quantitation limit of 0.005 mg/L or the copper action level must complete the corrosion control treatment steps subsection (e) specifies.

C) The Agency may issue a SEP requiring a large supplier applying corrosion control treatment with 90th percentile concentration results under Section 611.350(c)(4) exceeding the lead practical quantitation limit but not exceeding the lead trigger level or the copper action level to complete the corrosion control treatment steps in subsection (d).

2) Mid-Sized Suppliers (serving >10,000 and [LESS THAN OR EQUAL TO]50,000 people)
A) A mid-sized supplier applying corrosion control treatment that exceeds either the lead trigger level or the copper action level must complete the corrosion control treatment steps subsection (d) specifies.

B) A mid-sized supplier not applying corrosion control treatment that exceeds either the lead or copper action level must complete the corrosion control treatment steps subsection (e) specifies.

C) A mid-sized supplier not applying corrosion control treatment that exceeds the lead trigger level but does not exceed the lead or copper action level must complete the treatment recommendation step subsection (e)(1) specifies (Step 1). The water system must complete the remaining steps subsection (e) specifies if the supplier subsequently exceeds either the lead or copper action level.

3) Small CWS and Non-Transient, Non-Community Water System Suppliers
A) A small CWS or NTNCWS supplier applying corrosion control treatment that exceeds the lead trigger level or the lead action level but does not exceed the copper action level must complete the corrosion control treatment steps subsection (d) specifies if the Agency issues a SEP approving corrosion control treatment as a compliance option under Section 611.363(a).

B) A small CWS or NTNCWS supplier applying corrosion control treatment that exceeds the copper action level must complete the corrosion control treatment steps subsection (d) specifies.

C) A small CWS or NTNCWS supplier not applying corrosion control treatment that exceeds the lead action level must complete the corrosion control treatment steps subsection (e) specifies if the Agency issues a SEP approving corrosion control treatment as a compliance option under Section 611.363.

D) A small CWS or NTNCWS supplier not applying corrosion control treatment that exceeds the copper action level must complete the corrosion control treatment steps subsection (e) specifies.

b) Suppliers Deemed to Have Optimized Corrosion Control. Subsection (b)(1), (b)(2), or (b)(3) deems a supplier to have OCCT or re-optimized OCCT if the supplier satisfies one of the criteria specified in the subsection. Any system subsection (b)(1), (b)(2), or (b)(3) deems to have OCCT having corrosion control treatment in place must continue operating and maintaining that treatment and meeting any additional requirements the Agency determines are appropriate to ensure that the supplier maintains OCCT.

1) Small and Mid-Sized Suppliers Not Applying Corrosion Control Treatment. A small or mid-sized supplier not applying corrosion control treatment is deemed to have OCCT if it does not exceed the lead or copper action level during two consecutive six-month tap monitoring cycles and remains at or below the lead trigger level and copper action level in all subsequent tap monitoring cycles under Section 611.356.

2) Small and Mid-Sized Suppliers Applying Corrosion Control Treatment and Not Exceeding Levels. A small or mid-sized supplier applying corrosion control treatment is deemed to have OCCT if it does not exceed the lead or copper action level during two consecutive six-month tap monitoring cycles under Section 611.356 and remains at or below the lead trigger level and copper action level in all subsequent tap monitoring cycles under Section 611.356. If a small or mid-sized supplier applying corrosion control treatment exceeds the lead trigger level but does not exceed the lead or copper action level during two consecutive six-month tap monitoring cycles and remains at or below the lead and copper action levels in all subsequent tap monitoring cycles the supplier conducts under Section 611.356, that supplier is deemed to have re-optimized OCCT by complying with this Section. If the Agency issued a SEP setting optimal water quality parameters (OWQPs) under subsection (d) or (e), a supplier is not eligible to be deemed as having optimized or re-optimized OCCT under subsection (b).

3) Results Less Than or Equal to the Practical Quantitation Level (PQL) for Lead. Monitoring results deem a supplier to have optimized or re-optimized OCCT if the supplier submits results of tap water monitoring under Section 611.356 demonstrating that the 90th percentile lead concentration is less than or equal to the lead PQL of 0.005 mg/L and does not exceed the copper action level for two consecutive six-month tap monitoring cycles, and the Agency did not issue a SEP setting OWQPs under subsection (d) or (e). Any water system this subsection (b)(3) deems to have optimized corrosion control must continue tap water monitoring for lead and copper no less frequently than once every three calendar years using the reduced number of sites Section 611.356(c) specifies and collecting the samples at times and locations Section 611.356(d)(4)(E) specifies. If 90th percentile tap sample results exceeds the lead practical quantitation level (0.005 mg/L) or copper action level during any tap sampling period, the supplier is no longer eligible to be deemed to have optimized OCCT under this subsection without first completing the treatment steps specified in subsection (d) and (e) of this section.

c) Completing Corrosion Control Steps for Small and Mid-Sized Suppliers Not Applying Corrosion Control Treatment

1) Any small or mid-sized supplier not applying corrosion control treatment, otherwise required to complete the corrosion control steps in subsection (e) because it exceeded the lead or copper action level, may cease completing the steps after not exceeding either the lead or copper action levels during each of two consecutive six-month tap monitoring cycles under Section 611.363 before beginning Step 3 under subsection (e)(3) or Step 5 under subsection (e)(5). The supplier needs not begin the applicable of Step 3 or Step 5, except that a mid-sized supplier with lead service lines or a small supplier with lead service lines choosing the corrosion control option under Section 611.363 must complete a corrosion control treatment study under subsection (e)(3)(A). A supplier initiating Step 5 may not cease the steps and must complete all remaining steps in subsections (e)(6) through (e)(8).

2) A supplier ceasing the steps prior to either Step 3 or Step 5 and later exceeding the lead or copper action level may not cease the steps a second time and must complete the applicable treatment steps beginning with the first treatment step that the supplier previously did not complete in its entirety.

3) The Agency may issue a SEP requiring a supplier to repeat treatment steps the supplier previously completed if the Agency determines that this is necessary to properly implement the treatment requirements of this Section. The Agency must explain the basis for its decision in any SEP.

4) A small or mid-sized supplier exceeding the lead or copper action level must implement corrosion control treatment steps under subsection (e) (including a supplier deemed to have optimized corrosion control under subsection (b)(1)).

d) Treatment Steps and Deadlines for Suppliers Re-Optimizing OCCT. Except as subsection (b)(2) or Section 611.363 provides otherwise, a supplier with corrosion control treatment must complete certain corrosion control treatment steps (the referenced portions of Sections 611.352, 611.356, and 611.357 the steps describe) before the indicated times:

1) Step 1
A) A supplier other than one to which subsection (d)(1)(B) applies must recommend re-optimized OCCT (Section 611.352(c)) within six months after the end of the tap sampling period during which the supplier exceeds either the lead trigger level or copper action level. The Agency may issue a SEP allowing a supplier to modify its existing corrosion control treatment without a study for a supplier exceeding the lead trigger level but not the lead or copper action level. The Agency must specify re-optimized OCCT within six months after receiving the supplier's treatment recommendation. The supplier must modify its corrosion control treatment to install re-optimized OCCT within six months after the Agency specifies re-optimized OCCT.

B) A supplier having lead service lines that exceeds the lead action level must harvest lead pipes from its distribution system, construct flow-through pipe loops, and operate the loops with finished water within one year after the end of the tap sampling period during which the supplier exceeds the lead action level. The supplier must proceed to Step 3 under subsection (d)(3) and conduct the corrosion control studies for re-optimizing OCCT under subsection (d)(3)(A) using the pipe loops.

2) Step 2
A) A large supplier must conduct the corrosion control studies for re-optimizing OCCT under subsection (d)(3) (Step 3), unless the system is at or below the lead action level and the Agency issues a SEP modifying the existing corrosion control treatment the Agency specified under subsection (d)(1)(A) (Step 1).

B) Within 12 months after the end of the tap sampling period during which a small or mid-sized supplier applying corrosion control treatment exceeds the lead trigger level or copper action level, the Agency may issue a SEP requiring the supplier to perform corrosion control studies for re-optimizing OCCT (Section 611.352(c)(1) or (c)(2)). If the Agency does not require the supplier to perform corrosion control studies, the Agency must issue a SEP specifying re-optimized OCCT (Section 611.352(d)(2)) within the timeframes in subsections (d)(2)(B)(i) and (d)(2)(B)(ii).
i) A mid-sized supplier must perform corrosion control studies for re-optimizing OCCT within 12 months after the end of the tap sampling period during which the supplier exceeded the lead trigger level or copper action level.

ii) A small supplier must perform corrosion control studies for re-optimizing OCCT within 18 months after the end of the tap sampling period during which the supplier exceeded the lead trigger level or copper action level.

3) Step 3
A) A supplier having lead service lines that exceeds the lead action level must complete the corrosion control treatment studies for re-optimizing OCCT within 30 months after the end of the tap sampling period during which the supplier exceeded the lead action level.

B) If subsection (d)(2) (Step 2) requires the supplier to perform corrosion control studies, the supplier must complete the studies (Section 611.352(c)(2)) within 18 months after the Agency issues a SEP requiring the supplier to conduct the studies.

4) Step 4
A) The Agency must issue a SEP designating re-optimized OCCT (subsection (d)(3)(A) within six months after the supplier completes subsection (d)(3)(A) (Step 3).

B) If the supplier performed corrosion control studies under subsection (d)(2) (Step 2), the Agency must issue a SEP designating re-optimized OCCT (Section 611.352(d)(2) or (d)(4)) within six months after the supplier completes subsection (d)(3)(B) (Step 3).

5) Step 5
A) A large supplier must complete modifying its corrosion control treatment to have installed re-optimized OCCT within 12 months after the supplier completes subsection (d)(4)(A) (Step 4).

B) A small or mid-sized supplier must install re-optimized OCCT (Section 611.352(e)(1)) within 12 months after the supplier completes subsection (d)(4)(B) (Step 4).

6) Step 6 A supplier must complete follow-up sampling (Sections 611.356(d)(2) and 611.357(c)) within 12 months after the supplier completes subsection (d)(5)(A) or (d)(5)(B) (Step 5).

7) Step 7 The Agency must review the supplier's installed treatment and designate optimal water quality control parameters (Section 611.352(f)(1)) within six months after completing subsection (d)(6) (Step 6)..

8) Step 8 The supplier must operate complying with the Agency-designated optimal water quality control parameters (Section 611.352(g)) and continue conducting tap sampling (Section 611.356(d)(3) and monitoring water quality parameters under Section 611.357(d)).

e) Treatment Steps and Deadlines for Suppliers Not Applying Corrosion Control Treatment. Except as subsection (b) or Section 611.363 provides otherwise, a supplier not applying corrosion control treatment must complete certain corrosion control treatment steps (described in the referenced portions of Sections 611.352, 611.356, and 611.357) before the indicated times.

1) Step 1
A) A supplier other than one to which subsection (e)(1)(B) or (e)(1)(C) applies must recommend OCCT (Section 611.352(a)(1), (a)(2), (a)(3), or (a)(4)) within six months after the end of the tap sampling period during which the supplier exceeds either the lead trigger level or copper action level.

B) A supplier having lead service lines and exceeding the lead action level must harvest lead pipes from its distribution system, construct flow-through pipe loops, and operate the loops with finished water within one year after the end of the tap sampling period during which the supplier exceeds the lead action level. The supplier must proceed to Step 3 in subsection (e)(3) of this section and conduct the corrosion control studies under subsection (e)(3) using the pipe loops, for optimizing OCCT under subsection (e)(3)(A).

C) A large supplier subsection (a)(1)(B) directs to perform corrosion control treatment under this subsection (e) must conduct the corrosion control studies for optimizing OCCT under subsection (e)(3) (Step 3).

2) Step 2: Within 12 months after the end of the tap sampling period during which a supplier exceeds the lead or copper action level, if not otherwise required by this rule, the Agency may issue a SEP requiring the supplier to perform corrosion control studies (Section 611.352(b)(1)). If the Agency does not require the supplier to perform corrosion control studies, the Agency must issue a SEP specifying OCCT (under Section 611.352(d)(1)) within the applicable timeframe in subsections (e)(2)(A) and (e)(2)(B).
A) For a mid-sized supplier, within 18 months after the end of the tap monitoring cycle during which the supplier exceeded the lead trigger level or copper action level; or

B) For a small supplier, within 24 months after the end of the tap monitoring cycle during which the supplier exceeded the lead trigger level or copper action level.

3) Step 3
A) A large supplier having or not having lead service lines that exceeds the lead action level or a small or mid-sized supplier having lead service lines that exceeds the lead action level must complete the corrosion control treatment studies for optimizing OCCT within 30 months after the end of the tap sampling period during which the supplier exceeds the lead action level.

B) If the Agency requires a supplier to perform corrosion control studies under subsection (e)(2) (Step 2), the supplier must complete the studies (Section 611.352(c)(1)) within 18 months after the Agency issues a SEP requiring the supplier to conduct the studies.

4) Step 4
A) The Agency must issue a SEP designating re-optimized OCCT (Section 611.352(d)(3)) within six months after the supplier completes subsection (d)(3)(A) (Step 3).

B) If the supplier has performed corrosion control studies under subsection (e)(2) (Step 2), the Agency must issue a SEP designating OCCT (Section 611.352(d)(1)) within six months after subsection (e)(3) (Step 3) is complete.

5) Step 5 The supplier must install OCCT (Section 611.352(e)) within 24 months after the Agency designates OCCT under subsection (e)(2) or (e)(4) (Step 2 or Step 4).

6) Step 6 The supplier must complete follow-up sampling under Sections 611.356(d)(2)(A) and 611.357(c) within 12 months after completing subsection (e)(5) (Step 5).

7) Step 7 The Agency must review the supplier's installation of treatment and issue a SEP approving optimal water quality control parameters (Section 611.352(f)(1)) within six months after the supplier completes subsection (e)(5) (Step 5).

8) Step 8 The supplier must comply with the Agency-approved optimal water quality control parameters (Section 611.352(g)(1)) and continue tap sampling (Section 611.356(d)(3)) and monitoring water quality parameters (Section 611.357(d)).

f) Treatment Steps and Deadlines for Small CWS and NTNCWS Suppliers Electing Corrosion Control Treatment (CCT) As a Compliance Option under Section 611.363 or As the Agency Requires. A small CWS or NTNCWS supplier selecting the corrosion control treatment option as small supplier compliance flexibility under Section 611.363(a)(2) must complete two steps by the indicated times:

1) Step 1. A supplier must recommend the corrosion control treatment option as small supplier compliance flexibility under Section 611.363(a)(2) within six months after the end of the tap sampling period during which the supplier exceeds either the lead trigger level or the lead action level. When recommending to the Agency, the supplier must comply with Section 611.352(a)(1).

2) Step 2. The Agency must issue a SEP approving the recommendation of corrosion control treatment option as small supplier compliance flexibility or designating an alternative option under Section 611.363(a) within six months after the supplier recommends the option under subsection (f)(1) (Step 1). A supplier the Agency requires to optimize or re-optimize OCCT must follow the schedules in subsection (d) or (e), beginning with Step 3 in subsection (d)(3) or (e)(3), unless the Agency specifies OCCT under the applicable of subsection (d)(2)(B) or (e)(2)(B).

BOARD NOTE: This Section derives from 40 CFR 141.81.

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