Section 611.972  Subpart Y Monitoring Plan

a)         Development of a Monitoring Plan

1)         A supplier must develop and implement a monitoring plan that it must keep on file for Agency and public review.  The monitoring plan must contain the following elements, and it must be complete no later than the date when the supplier conducts its initial monitoring under this Subpart Y:

A)        The monitoring locations;

B)        The monitoring dates;

C)        The compliance calculation procedures; and

D)        The monitoring plans for any other systems in the combined distribution system if the Agency has reduced monitoring requirements under Section 611.161.

2)         If the supplier was not required to submit an IDSE report under either Section 611.921 or Section 611.922, and it does not have sufficient Subpart I monitoring locations to identify the required number of Subpart Y compliance monitoring locations indicated in Section 611.925(b), the supplier must identify additional locations by alternating selection of locations representing high TTHM levels and high HAA5 levels until the required number of compliance monitoring locations have been identified.  The supplier must also provide the rationale for identifying the locations as having high levels of TTHM or HAA5.  If the supplier has more Subpart I monitoring locations than required for Subpart Y compliance monitoring in Section 611.925(b), it must identify which locations it will use for Subpart Y compliance monitoring by alternating selection of locations representing high TTHM levels and high HAA5 levels until the required number of Subpart Y compliance monitoring locations have been identified.

b)         A Subpart B system supplier that serves more than 3,300 people must submit a copy of its monitoring plan to the Agency prior to the date it conducts its initial monitoring under this Subpart Y, unless the supplier's IDSE report submitted  under Subpart W contains all the information required by this Section.

c)         After consultation with the Agency regarding the need for and appropriateness of changes and issuance of a SEP that provides for the changes, a supplier may revise its monitoring plan to reflect changes in treatment, distribution system operations and layout (including new service areas), or other factors that may affect TTHM or HAA5 formation, or for Agency-approved reasons.  If the supplier changes monitoring locations, the supplier must replace existing compliance monitoring locations with the lowest LRAA with new locations that reflect the current distribution system locations with expected high TTHM or HAA5 levels.  The Agency may, by a SEP, also require modifications in the supplier's monitoring plan.  If a supplier is a Subpart B system supplier that serves more than 3,300 people, it must submit a copy of its modified monitoring plan to the Agency prior to the date when it is required to comply with the revised monitoring plan.

BOARD NOTE:  Derived from 40 CFR 141.622.

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