Illinois Administrative Code › Title 35 - ENVIRONMENTAL PROTECTION › Part 611 - PRIMARY DRINKING WATER STANDARDS › Subpart Y - STAGE 2 DISINFECTION BYPRODUCTS REQUIREMENTS › Section 611.973 - Reduced Monitoring

Current through Register Vol. 48, No. 28, July 12, 2024
a) A
				supplier may reduce monitoring to the level specified in the applicable of
				subsections (a)(1) through (a)(13), subject to the limitation of subsection
				(a)(14), any time the LRAA is 0.040 mg/l or less for TTHM and 0.030 mg/l or
				less for HAA5 at all monitoring locations. The supplier may only use data
				collected under the provisions of this Subpart Y or pursuant to Subpart I to
				qualify for reduced monitoring. In addition, the source water annual average
				TOC level, before any treatment, must be 4.0 mg/l or less at each treatment
				plant treating surface water or groundwater under the direct influence of
				surface water, based on monitoring conducted under either Section
				611.382(b)(1)(C)
				or Section
				611.382(d).
1) A Subpart B system supplier that serves
				fewer than 500 persons may not qualify for reduced monitoring.
2) A Subpart B system supplier that serves
				500 to 3,300 persons qualifies for reduced monitoring to a minimum of one TTHM
				sample collected annually from the location and during the quarter with the
				highest single TTHM measurement and one HAA5 sample collected annually from the
				location and during the quarter with the highest single HAA5 measurement, with
				the two samples collected as one dual sample set if the highest TTHM and HAA5
				measurements occurred at the same location and during the same
				quarter.
3) A Subpart B system
				supplier that serves 3,301 to 9,999 persons qualifies for reduced monitoring to
				a minimum of one dual sample set collected annually for TTHM from the location
				and during the quarter with the highest single TTHM measurement and one dual
				sample set collected annually for HAA5 from the location and during the quarter
				with the highest single HAA5 measurement.
4) A Subpart B system supplier that serves
				10,000 to 49,999 persons qualifies for reduced monitoring to a minimum of two
				dual sample sets collected quarterly from the locations with the highest TTHM
				and HAA5 LRAAs.
5) A Subpart B
				system supplier that serves 50,000 to 249,999 persons qualifies for reduced
				monitoring to a minimum of four dual sample sets collected quarterly from the
				locations with the two highest TTHM and two HAA5 LRAAs.
6) A Subpart B system supplier that serves
				250,000 to 999,999 persons qualifies for reduced monitoring to a minimum of six
				dual sample sets collected quarterly from the locations with the three highest
				TTHM and three HAA5 LRAAs.
7) A
				Subpart B system supplier that serves 1,000,000 to 4,999,999 persons qualifies
				for reduced monitoring to a minimum of eight dual sample sets collected
				quarterly from the locations with the four highest TTHM and four HAA5
				LRAAs.
8) A Subpart B system
				supplier that serves more than 5,000,000 persons qualifies for reduced
				monitoring to a minimum of 10 dual sample sets collected quarterly from the
				locations with the five highest TTHM and five HAA5 LRAAs.
9) A groundwater system supplier that serves
				fewer than 500 persons qualifies for reduced monitoring to a minimum of one
				TTHM sample collected triennially from the location and during the quarter with
				the highest single TTHM measurement and one HAA5 sample collected annually from
				the location and during the quarter with the highest single HAA5 measurement,
				with the two samples collected as one dual sample set if the highest TTHM and
				HAA5 measurements occurred at the same location and during the same
				quarter.
10) A groundwater system
				supplier that serves 500 to 9,999 persons qualifies for reduced monitoring to a
				minimum of one TTHM sample collected annually from the location and during the
				quarter with the highest single TTHM measurement and one HAA5 sample collected
				annually from the location and during the quarter with the highest single HAA5
				measurement, with the two samples collected as one dual sample set if the
				highest TTHM and HAA5 measurements occurred at the same location and during the
				same quarter.
11) A groundwater
				system supplier that serves 10,000 to 99,999 persons qualifies for reduced
				monitoring to a minimum of one TTHM dual sample set collected annually from the
				location and during the quarter with the highest single TTHM measurement and
				one HAA5 dual sample set collected annually from the location and during the
				quarter with the highest single HAA5 measurement.
12) A groundwater system supplier that serves
				100,000 to 499,999 persons qualifies for reduced monitoring to a minimum of two
				dual sample sets collected quarterly from the locations with the highest TTHM
				and highest HAA5 LRAAs.
13) A
				groundwater system supplier that serves more than 500,000 persons qualifies for
				reduced monitoring to a minimum of four dual sample sets collected quarterly
				from the two locations with the highest TTHM and two highest HAA5
				LRAAs.
14) A supplier on quarterly
				monitoring must take dual sample sets every 90 days.