| (a) Applicability for total trihalomethanes (TTHM)
and haloacetic acids (group of five) (HAA5). All community and nontransient,
noncommunity water systems shall comply with the requirements of this
section for TTHM and HAA5.
(1) Systems must comply with the initial monitoring
requirements starting on the dates given in subsection (c) of this
section.
(2) Systems must comply with all of the additional
requirements in this section starting on the date shown in the table
entitled "Date to Start Stage 2 Compliance."
Attached Graphic
(A) Systems required to conduct quarterly monitoring,
must begin monitoring in the first full calendar quarter that includes
the compliance date in the table titled "Date to Start Stage 2 Compliance."
(B) Systems required to conduct routine monitoring
less frequently than quarterly must begin monitoring in the calendar
month approved by the executive director in their Initial Distribution
System Evaluation (IDSE) report or revised monitoring plan identifying
Stage 2 sample sites.
(3) Systems must complete their monitoring plan for
the additional Stage 2 TTHM and HAA5 requirements according to §290.121
of this title (relating to Monitoring Plans) before the date shown
in the table entitled "Date to Start Stage 2 Compliance."
(b) Maximum contaminant levels (MCL) and operational
evaluation levels (OELs) for TTHM and HAA5. Systems shall comply with
MCLs and OELs.
(1) The locational running annual average (LRAA) concentration
of TTHM and HAA5 shall not exceed the MCLs. A public water system
that exceeds a MCL shall determine compliance as described in subsection
(f) of this section.
(A) The MCL for TTHM is 0.080 milligrams/liter (mg/L).
(B) The MCL for HAA5 is 0.060 mg/L.
(2) The OEL at any monitoring location is the sum of
the two previous quarters' results plus twice the current quarter's
result, divided by 4 to determine an average. A public water system
that exceeds an OEL shall perform operation evaluation monitoring
and reporting described in subsection (e) of this section.
(A) The OEL for TTHM is 0.080 mg/L.
(B) The OEL for HAA5 is 0.060 mg/L.
(c) Monitoring requirements for TTHM and HAA5. Monitoring
shall be performed at locations and frequency specified in the system's
monitoring plan as approved by the executive director. The executive
director may require changes to a system's sampling locations. The
executive director may require sampling at additional sampling locations.
(1) Monitoring locations. Systems must establish Stage
2 compliance monitoring sites throughout the distribution system at
locations with the potential for relatively high disinfection byproduct
formation. Systems must determine Stage 2 compliance monitoring locations
by the dates shown in the table titled "Date to Establish Stage 2
Sites."
Attached Graphic
(A) Systems that perform IDSE sampling in accordance
with paragraph (5) of this subsection must use the IDSE and Stage
1 results to set Stage 2 compliance monitoring sites.
(B) Systems that do not perform IDSE sampling must
set Stage 2 compliance monitoring sites through consultation with
the executive director in accordance with this subparagraph.
(i) Systems required to sample at the same number of
sites under Stage 1 and Stage 2, can use the Stage 1 sites for Stage
2 compliance monitoring.
(ii) Systems required to sample at more sites under
Stage 2 than Stage 1 must identify Stage 2 sites in addition to the
existing Stage 1 sites. Systems must identify additional sites representing
areas of the distribution system with potentially high TTHM or HAA5
levels and provide the rationale for identifying these locations as
having high levels of TTHM or HAA5. The required number of compliance
monitoring locations must be identified.
(iii) Systems required to sample at fewer sites under
Stage 2 than Stage 1 must identify which locations will be used for
Stage 2. Stage 2 sites will be selected by alternating selection of
Stage 1 locations representing the highest TTHM levels and highest
HAA5 levels until the required number of compliance monitoring locations
have been identified.
(C) The protocol given in 40 Code of Federal Regulations
(CFR) §141.605(c) - (e) for selecting Stage 2 sample sites is
hereby adopted by reference.
(D) To change monitoring locations, a system 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. Changes must be approved by
the executive director and included in the monitoring plan.
(2) Monitoring frequency and number of sample sites.
Routine sampling frequency and number of sample sites are given in
the following table, titled "Routine Stage 2 Monitoring Frequency
and Number of Sites." Systems must take all routine compliance TTHM
and HAA5 samples during normal operating conditions.
Attached Graphic
(3) Reduced monitoring for TTHM and HAA5. Monitoring
may be reduced when the LRAA is less than or equal to 0.040 mg/L for
TTHM and less than or equal to 0.030 mg/L for HAA5 at all Stage 2
compliance monitoring locations. The Stage 2 reduced sampling frequency
and number of sample sites are given in the following table, titled
"Reduced Stage 2 Monitoring Frequency and Number of Sites."
Attached Graphic
(A) Only data collected under the provisions of §290.113
of this title (relating to Stage 1 Disinfection Byproducts (TTHM and
HAA5)) and under this section may be used to qualify for reduced monitoring.
(B) In order to remain on reduced monitoring, a system
must meet the applicable conditions of this subparagraph.
(i) Systems with annual or less frequent reduced monitoring
qualify to remain on reduced monitoring as long as each TTHM sample
is less than or equal to 0.060 mg/L and each HAA5 sample is less than
or equal to 0.045 mg/L.
(ii) Systems on quarterly reduced monitoring qualify
to remain on reduced monitoring as long as the TTHM LRAA is less than
or equal to 0.040 mg/L and the HAA5 LRAA is less than or equal to
0.030 mg/L at each monitoring location.
(iii) To qualify for and remain on reduced monitoring,
the source water annual average Total Organic Carbon (TOC) level,
before any treatment, must be less than or equal to 4.0 mg/L at each
treatment plant treating surface water or groundwater under the direct
influence of surface water, based on monitoring conducted under §290.112(c)(2)(C)
of this title (relating to Total Organic Carbon (TOC)).
(C) Systems will be returned to routine monitoring:
(i) if the LRAA at any monitoring location exceeds
either 0.040 mg/L for TTHM or 0.030 mg/L for HAA5 based on quarterly
monitoring, or
(ii) if the annual (or triennial) sample at any location
exceeds either 0.060 mg/L for TTHM or 0.045 mg/L for HAA5, or
(iii) if the source water annual average TOC level,
before any treatment, exceeds 4.0 mg/L at any treatment plant treating
surface water or groundwater under the direct influence of surface
water.
(D) The executive director may return a system on reduced
monitoring to routine monitoring at any time.
(E) A system that is on reduced Stage 1 monitoring
in accordance with §290.113(c)(4) of this title that has monitoring
locations for Stage 2 different from those under Stage 1 must initiate
routine monitoring in accordance with paragraph (2) of this subsection
on the schedule given in subsection (a) of this section.
(F) A system that is on reduced monitoring in accordance
with §290.113(c)(4) of this title may remain on reduced monitoring
after the dates identified in subsection (a)(2) of this section only
if the system:
(i) received a very small system (VSS) IDSE waiver
under paragraph (5)(A) of this subsection or received a 40/30 IDSE
waiver under paragraph (5)(B) of this subsection,
(ii) meets the reduced monitoring criteria in subparagraph
(B) of this paragraph, and
(iii) is approved to use the same monitoring locations
under Stage 1 and Stage 2.
(G) The executive director may choose to perform calculations
and determine whether the system is eligible for reduced monitoring
in lieu of having the system report that information.
(4) Increased monitoring for TTHM and HAA5. The executive
director may increase monitoring in accordance with this paragraph.
(A) A system required to routinely monitor at a particular
location annually or less frequently than annually under paragraph
(2) of this subsection must increase monitoring to quarterly dual
sample sets (every 90 days) at all locations if any TTHM compliance
sample is greater than 0.080 mg/L or if any HAA5 compliance sample
is greater than 0.060 mg/L at any location.
(B) The executive director may return a system on increased
quarterly monitoring to routine monitoring after at least four consecutive
quarters if the LRAA for every monitoring location is less than or
equal to 0.060 mg/L for TTHM and less than or equal to 0.045 mg/L
for HAA5.
(C) A system that is on increased monitoring under §290.113
of this title must remain on increased monitoring until the system
qualifies for a return to routine monitoring under subparagraph (B)
of this paragraph. The increased monitoring schedule must be conducted
at the Stage 2 monitoring locations approved under paragraph (1) of
this subsection, beginning on the date identified in subsection (a)(2)
of this section.
(5) IDSE requirements. All community systems of any
size and nontransient, noncommunity systems that serve at least 10,000
people must comply with these IDSE requirements.
(A) The executive director may grant a VSS IDSE monitoring
waiver to systems that serve fewer than 500 people. Systems that receive
a VSS IDSE monitoring waiver are not required to do IDSE monitoring.
Systems must be compliant with all of the Stage 1 monitoring requirements
of §290.113 of this title to be eligible for a VSS IDSE waiver.
(B) The executive director may grant a 40/30 IDSE monitoring
waiver to IDSE monitoring to systems with levels for TTHM less than
0.040 mg/L and levels for HAA5 less than 0.030 mg/L. Systems that
receive a 40/30 IDSE monitoring waiver are not required to do IDSE
monitoring. Systems must be compliant with all of the Stage 1 monitoring
requirements of §290.113 of this title to be eligible for a 40/30
IDSE waiver. The timing of samples that all need to be less than 0.040
mg/L and 0.030 mg/L respectively for TTHM and HAA5 are given in the
following table, titled "Timing of Stage 1 Samples Evaluated for 40/30
Initial Distribution System Evaluation (IDSE) Waiver."
Attached Graphic
(i) To qualify for a 40/30 IDSE waiver a system must
certify to the executive director that every individual sample taken
under §290.113 of this title were less than 0.040 mg/L for TTHM
and less than 0.030 mg/L for HAA5, and must have not had any TTHM
or HAA5 monitoring violations during the period specified in subsection
(a) of this section.
(ii) To qualify for a 40/30 IDSE waiver, a system must
submit compliance monitoring results, distribution system schematics,
and recommended Stage 2 compliance monitoring locations to the executive
director upon request. The executive director may require a system
that fails to submit the requested information to perform IDSE sampling.
(iii) The executive director may still require a system
that meets the 40/30 IDSE waiver or VSS IDSE waiver requirements to
do IDSE sampling under subparagraph (C) of this paragraph.
(C) Systems that must perform IDSE sampling must submit
any needed documentation for waivers, produce an IDSE Plan, do IDSE
sampling, and report the IDSE results to the executive director on
the schedule in the following table titled "Initial Distribution Schedule
Evaluation (IDSE) Schedule."
Attached Graphic
(i) The IDSE plan has required elements.
(I) The IDSE plan must include a schematic of the distribution
system (including distribution system entry points and their sources,
and storage facilities), with notes indicating locations and dates
of all projected standard monitoring, and also Stage 1 compliance
monitoring under §290.113 of this title.
(II) The IDSE plan must include justification of IDSE
monitoring location selection and a summary of data used to justify
IDSE monitoring location selection.
(III) The IDSE plan must include the system type and
population served by the system.
(ii) Systems must do required IDSE sampling in accordance
with this clause.
(I) Systems must monitor at the number and type of
sites indicated in the following table titled "Number and Type of
Initial Distribution System Evaluation (IDSE) Sample Sites:"
Attached Graphic
(II) Systems must collect dual sample sets at each
monitoring location. One sample in the dual sample set must be analyzed
for TTHM. The other sample in the dual sample set must be analyzed
for HAA5.
(III) IDSE sample locations must be different than
the existing Stage 1 monitoring locations established under §290.113
of this title.
(IV) IDSE sample locations must be distributed throughout
the distribution system.
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