Illinois Administrative Code › Title 35 - ENVIRONMENTAL PROTECTION › Part 611 - PRIMARY DRINKING WATER STANDARDS › Subpart Y - STAGE 2 DISINFECTION BYPRODUCTS REQUIREMENTS › Section 611.971 - Routine Monitoring

Current through Register Vol. 48, No. 28, July 12, 2024
a)
				Monitoring
1) If a supplier submitted an IDSE
				report, it must begin monitoring at the locations and during the months that
				the supplier has recommended in its IDSE report submitted under Section
				611.925,
				following the schedule set forth in Section
				611.970(c),
				unless the Agency, by a SEP, requires other locations or additional locations
				after its review. If the supplier submitted a 40/30 certification under Section
				611.923, it
				qualified for a very small system waiver under Section
				611.924,
				or it is a NTNCWS that serves fewer than 10,000 persons, the supplier must
				monitor at the locations and on the dates identified in its monitoring plan as
				described in Section
				611.382(f),
				updated as required by Section
				611.972.
2) The supplier must monitor at no fewer than
				the number of locations identified in the applicable of subsections (a)(2)(A)
				through (a)(2)(M), subject to the limitations of subsections (a)(2)(N) and
				(a)(2)(O).
A) A Subpart B system supplier
				that serves fewer than 500 persons must monitor annually at two distribution
				system monitoring locations during each monitoring period.
B) A Subpart B system supplier that serves
				500 to 3,300 persons must monitor quarterly at two distribution system
				monitoring locations during each monitoring period.
C) A Subpart B system supplier that serves
				3,301 to 9,999 persons must monitor quarterly at two distribution system
				monitoring locations during each monitoring period.
D) A Subpart B system supplier that serves
				10,000 to 49,999 persons must monitor quarterly at four distribution system
				monitoring locations during each monitoring period.
E) A Subpart B system supplier that serves
				50,000 to 249,999 persons must monitor quarterly at eight distribution system
				monitoring locations during each monitoring period.
F) A Subpart B system supplier that serves
				250,000 to 999,999 persons must monitor quarterly at 12 distribution system
				monitoring locations during each monitoring period.
G) A Subpart B system supplier that serves
				1,000,000 to 4,999,999 persons must monitor quarterly at 16 distribution system
				monitoring locations during each monitoring period.
H) A Subpart B system supplier that serves
				5,000,000 or more persons must monitor quarterly at 20 distribution system
				monitoring locations during each monitoring period.
I) A groundwater system supplier that serves
				fewer than 500 persons must monitor annually at two distribution system
				monitoring locations during each monitoring period.
J) A groundwater system supplier that serves
				500 to 9,999 persons must monitor annually at two distribution system
				monitoring locations during each monitoring period.
K) A groundwater system supplier that serves
				10,000 to 99,999 persons must monitor quarterly at four distribution system
				monitoring locations during each monitoring period.
L) A groundwater system supplier that serves
				100,000 to 499,999 persons must monitor quarterly at six distribution system
				monitoring locations during each monitoring period.
M) A groundwater system supplier that serves
				500,000 or more persons must monitor quarterly at eight distribution system
				monitoring locations during each monitoring period.
N) The supplier must monitor during month of
				highest DBP concentrations.
O) A
				supplier on quarterly monitoring must take dual sample sets every 90 days at
				each monitoring location, except for a Subpart B system supplier that serves
				500 to 3,300. A groundwater system supplier that serves 500 to 9,999 persons
				which is on annual monitoring must take dual sample sets at each monitoring
				location. Any other supplier that is on annual monitoring or which is a Subpart
				B system supplier that serves 500 to 3,300 is required to take individual TTHM
				and HAA5 samples (instead of a dual sample set) at the locations with the
				highest TTHM and HAA5 concentrations, respectively. For a supplier that serves
				fewer than 500 people, only one location with a dual sample set per monitoring
				period is needed if the highest TTHM and HAA5 concentrations occur at the same
				location and month.
3) If
				a supplier is an undisinfected system that begins using a disinfectant other
				than UV light after the dates set forth in Subpart W for complying with the
				IDSE requirements, the supplier must consult with the Agency to identify
				compliance monitoring locations for this Subpart Y. The supplier must then
				develop a monitoring plan under Section
				611.972
				that includes those monitoring locations.