Illinois Administrative Code › Title 35 - ENVIRONMENTAL PROTECTION › Part 611 - PRIMARY DRINKING WATER STANDARDS › Subpart AA - REVISED TOTAL COLIFORM RULE › Section 611.1053 - General Monitoring Requirements for all PWSs

Current through Register Vol. 48, No. 28, July 12, 2024
a) Sample Siting Plans
1) A supplier must develop a written sample
				siting plan that identifies sampling sites and a sample collection schedule
				that are representative of water throughout the distribution system. These
				plans are subject to Agency review and revision. The supplier must collect
				total coliform samples according to the written sample siting plan. Monitoring
				required by Sections
				611.1054
				through
				611.1058
				may take place at a customer's premises, a dedicated sampling station, or
				another designated compliance sampling location. Routine and repeat sample
				sites and any sampling points necessary to meet the requirements of Subpart S
				must be reflected in the sampling plan.
2) A supplier must collect samples at regular
				time intervals throughout the month, except that systems that use only ground
				water and serve 4,900 or fewer people may collect all required samples on a
				single day if they are taken from different sites.
3) A supplier must take at least the minimum
				number of required samples even if the system has had an E. coli MCL violation
				or has exceeded the coliform treatment technique triggers in Section
				611.1059(a).
4) A supplier may conduct more compliance
				monitoring than is required by this Subpart AA to investigate potential
				problems in the distribution system and use monitoring as a tool to assist in
				uncovering problems. A supplier may take more than the minimum number of
				required routine samples and must include the results in calculating whether
				the coliform treatment technique trigger in Section
				611.1059(a)(1)(A)
				and (a)(1)(B) has been exceeded only if the
				samples are taken in accordance with the existing sample siting plan and are
				representative of water throughout the distribution system.
5) A supplier must identify repeat monitoring
				locations in the sample siting plan. Unless the provisions of subsection
				(a)(5)(A) or (a)(5)(B) are met, the supplier must collect at least one repeat
				sample from the sampling tap where the original total coliform-positive sample
				was taken, and at least one repeat sample at a tap within five service
				connections upstream and at least one repeat sample at a tap within five
				service connections downstream of the original sampling site. If a total
				coliform-positive sample is at the end of the distribution system, or one
				service connection away from the end of the distribution system, the supplier
				must still take all required repeat samples. However, the Agency may grant a
				SEP that allows an alternative sampling location in lieu of the requirement to
				collect at least one repeat sample upstream or downstream of the original
				sampling site. Except as provided for in subsection (a)(5)(B), a supplier
				required to conduct triggered source water monitoring under Section
				611.802(a)
				 must take ground water source samples in
				addition to repeat samples required under this Subpart AA.
A) A supplier may propose repeat monitoring
				locations to the Agency that the supplier believes to be representative of a
				pathway for contamination of the distribution system. A supplier may elect to
				specify either alternative fixed locations or criteria for selecting repeat
				sampling sites on a situational basis in a standard operating procedure (SOP)
				in its sample siting plan. The supplier must design its SOP to focus the repeat
				samples at locations that best verify and determine the extent of potential
				contamination of the distribution system area based on specific situations. The
				Agency may, by a SEP, modify the SOP or require alternative monitoring
				locations as the Agency determines is necessary.
B) A GWS supplier that serves 1,000 or fewer
				people may propose repeat sampling locations to the Agency that differentiate
				potential source water and distribution system contamination (e.g., by sampling
				at entry points to the distribution system). A GWS supplier that has a single
				well and which is required to conduct triggered source water monitoring may, as
				allowed by a SEP, take one of its repeat samples at the monitoring location
				required for triggered source water monitoring under Section
				611.802(a).
				The supplier must justify an Agency determination that the sample siting plan
				remains representative of water quality in the distribution system. If approved
				by a SEP, the supplier may use that sample result to meet the monitoring
				requirements in both Section
				611.802(a)
				and this Section.
i) If a repeat sample taken
				at the monitoring location required for triggered source water monitoring is E.
				coli-positive, the supplier has violated the E. coli MCL and must also comply
				with Section
				611.802(a)(3).
				If a supplier takes more than one repeat sample at the monitoring location
				required for triggered source water monitoring, the supplier may reduce the
				number of additional source water samples required under Section
				611.802(a)(3)
				by the number of repeat samples taken at that location that were not E.
				coli-positive.
ii) If a supplier
				takes more than one repeat sample at the monitoring location required for
				triggered source water monitoring under Section
				611.802(a),
				and more than one repeat sample is E. coli-positive, the supplier has violated
				the E. coli MCL and must also comply with Section
				611.803(a)(1).
iii) If all repeat samples taken at the
				monitoring location required for triggered source water monitoring are E.
				coli-negative and a repeat sample taken at a monitoring location other than the
				one required for triggered source water monitoring is E. coli-positive, the
				supplier has violated the E. coli MCL, but is not required to comply with
				Section
				611.802(a)(3).
6) The Agency may, by a SEP,
				review, revise, and approve, as appropriate, repeat sampling proposed by a
				supplier under subsections (a)(5)(A) and (a)(5)(B). The supplier must justify
				an Agency determination that the sample siting plan remains representative of
				the water quality in the distribution system. The Agency may determine that
				monitoring at the entry point to the distribution system (especially for
				undisinfected ground water systems) is effective to differentiate between
				potential source water and distribution system problems.