Section 611.602  Asbestos Monitoring Frequency

The frequency of monitoring conducted to determine compliance with the MCL for asbestos in Section 611.301 is as follows:

a)         Unless the Agency has determined under subsection (c) that the PWS is not vulnerable, each CWS and NTNCWS supplier must monitor for asbestos during the first compliance period of each compliance cycle.

b)         CWS suppliers may apply to the Agency, by way of an application for a SEP, for a determination that the CWS is not vulnerable based on consideration of the criteria listed in subsection (c).

c)         The Agency must determine that the CWS is "not vulnerable" if the CWS is not vulnerable to contamination either from asbestos in its source water, from corrosion of asbestos-cement pipe, or from both, based on a consideration of the following factors:

1)         Potential asbestos contamination of the water source; and

2)         The use of asbestos-cement pipe for finished water distribution and the corrosive nature of the water.

d)         A SEP based on a determination that a CWS is not vulnerable to asbestos contamination expires at the end of the compliance cycle for which it was issued.

e)         A supplier of a PWS vulnerable to asbestos contamination due solely to corrosion of asbestos-cement pipe must take one sample at a tap served by asbestos-cement pipe and under conditions where asbestos contamination is most likely to occur.

f)         A supplier of a PWS vulnerable to asbestos contamination due solely to source water must monitor in accordance with Section 611.601.

g)         A supplier of a PWS vulnerable to asbestos contamination due both to its source water supply and corrosion of asbestos-cement pipe must take one sample at a tap served by asbestos-cement pipe and under conditions where asbestos contamination is most likely to occur.

h)         A supplier that exceeds the MCL, as determined in Section 611.609, must monitor quarterly beginning in the next quarter after the violation occurred.

i)          Reduction of Quarterly Monitoring

1)         The Agency must issue a SEP that reduces the monitoring frequency to that specified by subsection (a) if it determines that the sampling point is reliably and consistently below the MCL.

2)         The request must, at a minimum, include the following information:

A)        For a GWS:  two quarterly samples.

B)        For an SWS or mixed system:  four quarterly samples.

3)         In issuing a SEP, the Agency must specify the level of the contaminant upon which the "reliably and consistently" determination was based.  All SEPs that allow less frequent monitoring based on an Agency "reliably and consistently" determination must include a condition requiring the supplier to resume quarterly monitoring under subsection (h) if it violates the MCL specified by Section 611.609.

j)          This subsection (j) corresponds with 40 CFR 141.23(b)(10), which pertains to a compliance period long since expired.  This statement maintains structural consistency with the federal regulations.

BOARD NOTE:  Derived from 40 CFR 141.23(b).

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