Current through Register Vol. 48, No. 9, September 27, 2024
This section sets forth the requirements applicable to systems
and states in the designation of optimal corrosion control treatment (OCCT) for
a system that is optimizing or re-optimizing corrosion control treatment. Each
system must complete the corrosion control treatment requirements in this
section as applicable to such system under R.61-58.11.C.
(1) System Recommendation Regarding Corrosion
Control Treatment for Systems that do not Contain Lead Service Lines and
Systems with Lead Service Lines that do not Exceed the Lead Action Level.
(a) Any system under this paragraph (1)
without corrosion control treatment that is required to recommend a treatment
option in accordance with R.61-58.11.C(5)
must, based on the results of lead and copper tap sampling and water quality
parameter monitoring, recommend designation of one or more of the corrosion
control treatments listed in paragraph (3)(a)(i) of this section. Small
community water systems and non-transient, non-community water systems that
exceed the copper action level must comply with this paragraph (1)(a). The
Department may require the system to conduct additional water quality parameter
monitoring to assist the Department in reviewing the system's
recommendation.
(b) Any small
community water system or non-transient, non-community water system in this
paragraph (1) without corrosion control treatment that chooses to pursue a
small water system compliance flexibility option and is required to recommend
an option in accordance with R.61-58.11.C(6)
must, based on the results of lead tap sampling and water quality parameter
monitoring, recommend designation of one of the options listed in
R.61-58.11.O. Systems with no lead
service lines that exceed the lead action level and select corrosion control
under R.61-58.11.O(1)(b)
must recommend designation of one or more of the corrosion control treatments
listed in paragraph (3)(a) of this section as the optimal corrosion control
treatment for that system.
(c) Any
system under this paragraph (1) that exceeds the lead action level and selects
corrosion control under R.61-58.11.O(1)(b)
must recommend designation of one or more of the corrosion control treatments
listed in paragraph (3)(a)(i) of this section as the optimal corrosion control
treatment for that system. A corrosion control study under paragraph (3) of
this section is not required for medium and small systems that exceed the lead
trigger level but do not exceed the lead and copper action levels, unless
required by the Department.
(d) Any
small community water system or non-transient, non-community water system with
corrosion control treatment that exceeds the lead action level and selects
corrosion control under R.61-58.11.O(1)(b)
must recommend designation of one or more of the corrosion control treatments
listed in paragraph (3)(b) of this section as the optimal corrosion control
treatment for that system.
(e) The
Department may waive the requirement for a system to recommend OCCT if the
Department requires the system, in writing, to complete a corrosion control
study within three (3) months after the end of the tap sampling period during
which the exceedance occurred. Such systems shall proceed directly to paragraph
(3) of this section and complete a corrosion control study.
(2) Department Decision to Require
Studies to Identify Initial Optimal Corrosion Control Treatment and
Re-optimized Optimal Corrosion Control Treatment Except for Large Systems and
Small and Medium Systems with Lead Service Lines that Exceed the Lead Action
Level.
Corrosion control treatment studies are always required for
large systems that exceed the lead action level, large water systems without
corrosion control treatment with 90th percentile
results that exceed either the lead practical quantitation level of 0.005 mg/L
or the copper action level, medium-size systems with lead service lines that
exceed the lead action level, and small systems with lead service lines that
exceed the lead action level and select the corrosion control treatment option
under R.61-58.11.O(1).
(a) The
Department may require any small or medium-size system without corrosion
control that exceeds either the lead or copper action level to perform
corrosion control treatment studies under paragraph (3)(a) of this section to
identify optimal corrosion control treatment for the system.
(b) The Department may require any small or
medium-size system without corrosion control that exceeds the lead trigger
level but not the lead or copper action level to perform corrosion control
treatment studies under paragraph (3)(a) of this section to identify optimal
corrosion control treatment for the system. This corrosion control treatment
shall be installed if the lead or copper action level is subsequently
exceeded.
(c) The Department may
require any small or medium-size water systems with corrosion control treatment
exceeding either the lead trigger level or copper action level to perform
corrosion control treatment studies under paragraph (3)(b) of this section to
identify re-optimized optimal corrosion control treatment for the system (i.e.,
optimal corrosion control treatment after a re-optimization
evaluation).
(3)
Performance of Corrosion Control Studies
(a)
Water systems without corrosion control treatment that are required to conduct
corrosion control studies must complete the following:
(i) Any water system without corrosion
control treatment must evaluate the effectiveness of each of the following
treatments, and if appropriate, combinations of the following treatments to
identify the optimal corrosion control treatment for the system:
(A) Alkalinity and pH adjustment;
(B) The addition of an orthophosphate- or
silicate-based corrosion inhibitor at a concentration sufficient to maintain an
effective corrosion inhibitor residual concentration in all test
samples;
(C) The addition of an
orthophosphate-based corrosion inhibitor at a concentration sufficient to
maintain an orthophosphate residual concentration of one milligram per liter (1
mg/L) (as PO4) in all test samples; and
(D) The addition of an orthophosphate-based
corrosion inhibitor at a concentration sufficient to maintain an orthophosphate
residual concentration of three milligrams per liter (3 mg/L) (as PO4) in all
test samples.
(ii) The
water system must evaluate each of the corrosion control treatments using
either pipe rig/loop tests, metal coupon tests, partial-system tests, or
analyses based on documented analogous treatments with other systems of similar
size, water chemistry, and distribution system configurations. Large and medium
systems, and small community water systems and non-transient, non-community
water systems that select the corrosion control treatment option under
R.61-58.11.O with lead service lines
that exceed the lead action level must conduct pipe rig/loop studies using
harvested lead service lines from their distribution systems to assess the
effectiveness of corrosion control treatment options on the existing pipe
scale. For these systems, metal coupon tests can be used as a screen to reduce
the number of options that are evaluated using pipe rig/loops to the current
conditions and two (2) options.
(iii) The water system must measure the
following water quality parameters in any tests conducted under this paragraph
(3)(a)(iii) before and after evaluating the corrosion control treatments listed
in paragraphs (3)(a)(i) and (ii) of this section:
(A) Lead;
(B) Copper;
(C) pH;
(D) Alkalinity;
(E) Orthophosphate as PO4 (when an
orthophosphate-based inhibitor is used); and
(F) Silicate (when a silicate-based inhibitor
is used).
(iv) The water
system must identify all chemical or physical constraints that limit or
prohibit the use of a particular corrosion control treatment and document such
constraints with one of the following:
(A)
Data and documentation showing that a particular corrosion control treatment
has adversely affected other drinking water treatment processes when used by
another water system with comparable water quality characteristics. Systems
using coupon studies to screen and/or pipe loop/rig studies to evaluate
treatment options must not exclude treatment strategies from the studies based
on the constraints identified in this section.
(B) Data and documentation demonstrating that
the water system has previously attempted to evaluate a particular corrosion
control treatment and has found that the treatment is ineffective or adversely
affects other drinking water quality treatment processes. Systems using coupon
studies to screen and/or pipe loop/rig studies to evaluate treatment options
must not exclude treatment strategies from the studies based on the constraints
identified in this section unless the treatment was found to be ineffective in
a previous pipe loop/rig study.
(v) The water system must evaluate the effect
of the chemicals used for corrosion control treatment on other drinking water
quality treatment processes. Systems using coupon studies to screen and/or pipe
loop/rig studies to evaluate treatment options shall not exclude treatment
strategies from the studies based on the effects identified in this
section.
(vi) On the basis of an
analysis of the data generated during each evaluation, the water system must
recommend to the Department in writing the treatment option that the corrosion
control studies indicate constitutes optimal corrosion control treatment for
that system as defined in R.61-58.B. The water
system must provide a rationale for its recommendation along with all
supporting documentation specified in paragraphs (3)(b)(i) through (v) of this
section.
(b) Systems
with corrosion control treatment that are required to conduct corrosion control
studies to determine re-optimized OCCT must complete the following:
(i) The water system must evaluate the
effectiveness of the following treatments, and if appropriate, combinations of
the following treatments to identify the re-optimized optimal corrosion control
treatment for the system:
(A) Alkalinity
and/or pH adjustment, or re-adjustment;
(B) The addition of an orthophosphate- or
silicate-based corrosion inhibitor at a concentration sufficient to maintain an
effective corrosion inhibitor residual concentration in all test samples if no
such inhibitor is utilized;
(C) The
addition of an orthophosphate-based corrosion inhibitor at a concentration
sufficient to maintain an orthophosphate residual concentration of one
milligram per liter (1 mg/L) (PO4) in all test samples unless the current
inhibitor process already meets this residual; and
(D) The addition of an orthophosphate-based
corrosion inhibitor at a concentration sufficient to maintain an orthophosphate
residual concentration of three milligrams per liter (3 mg/L) (PO4) in all test
samples unless the current inhibitor process already meets this
residual.
(ii) The water
system must evaluate each of the corrosion control treatments using either pipe
rig/loop tests, metal coupon tests, partial-system tests, or analyses based on
documented analogous treatments with other systems of similar size, water
chemistry, and distribution system configurations. If the water system has lead
service lines and exceeds the lead action level, it must conduct pipe rig/loop
studies using harvested lead service lines from their distribution systems to
assess the effectiveness of corrosion control treatment options on the existing
pipe scale. For these systems, metal coupon tests can be used as a screen to
reduce the number of options that are evaluated using pipe rig/loops to the
current conditions and two (2) options.
(iii) The water system must measure the
following water quality parameters in any tests conducted under this paragraph
(3)(b)(iii) before and after evaluating the corrosion control treatments listed
in paragraphs (3)(b)(i) and (ii) of this section:
(A) Lead;
(B) Copper;
(C) pH;
(D) Alkalinity;
(E) Orthophosphate as PO4 (when an
orthophosphate-based inhibitor is used); and
(F) Silicate (when a silicate-based inhibitor
is used).
(iv) The water
system must identify all chemical or physical constraints that limit or
prohibit the use of a particular corrosion control treatment and document such
constraints with one of the following:
(A)
Data and documentation showing that a particular corrosion control treatment
has adversely affected other drinking water treatment processes when used by
another water system with comparable water quality characteristics. Systems
using coupon studies to screen and/or pipe loop/rig studies to evaluate
treatment options must not exclude treatment strategies from the studies based
on the constraints identified in this section.
(B) Data and documentation demonstrating that
the water system has previously attempted to evaluate a particular corrosion
control treatment and has found that the treatment is ineffective or adversely
affects other drinking water quality treatment processes. Systems using coupon
studies to screen and/or pipe loop/rig studies to evaluate treatment options
shall not exclude treatment strategies from the studies based on the
constraints identified in this section unless the treatment was found to be
ineffective in a previous pipe loop/rig study.
(v) The water system must evaluate the effect
of the chemicals used for corrosion control treatment on other drinking water
quality treatment processes. Systems using coupon studies to screen and/or pipe
loop/rig studies to evaluate treatment options shall not exclude treatment
strategies from the studies based on the effects identified in this
section.
(vi) On the basis of an
analysis of the data generated during each evaluation, the water system must
recommend to the Department in writing the treatment option that the corrosion
control studies indicate constitutes optimal corrosion control treatment for
that system as defined in R.61-58.B. The water
system must provide a rationale for its recommendation along with all
supporting documentation specified in paragraph (3)(a)(i) through (v) of this
section.
(4)
Department Designation of Optimized Optimal Corrosion Control Treatment and
Re-optimized Optimal Corrosion Control Treatment.
When designating optimal corrosion control treatment, the
Department must consider the effects that additional corrosion control
treatment will have on water quality parameters and on other drinking water
quality treatment processes. The Department must notify the water system of its
designation of optimal corrosion control treatment in writing and explain the
basis for this determination. If the Department requests additional information
to aid its review, the water system must provide the information.
(a) Designation of OCCT for systems without
corrosion control treatment.
Based upon considerations of available information including,
where applicable, studies conducted under paragraph (3)(a) of this section
and/or a system's recommended corrosion control treatment option, the
Department must either approve the corrosion control treatment option
recommended by the system or designate alternative corrosion control
treatment(s) from among those listed in paragraph (3)(a)(i) of this section or,
where applicable, an alternate small water system compliance flexibility option
under R.61-58.11.O(1).
(b)
Designation of re-optimized OCCT for systems with corrosion control treatment.
Based upon considerations of available information including,
where applicable, studies conducted under paragraph (3)(b) of this section
and/or a system's recommended treatment alternative, the Department must either
approve the corrosion control treatment option recommended by the water system
or designate alternative corrosion control treatment(s) from among those listed
in paragraph (3)(b)(i) of this section or, where applicable, an alternate small
water system compliance flexibility option under R.61-58.11.O.
(5) Installation of
Optimal Corrosion Control Treatment and Re-optimization of Corrosion Control
Treatment.
Each system shall properly install and operate throughout its
distribution system the optimal corrosion control treatment designated by the
Department under paragraph (4) of this section.
(6) Department Review of Treatment and
Specification of Optimal Water Quality Control Parameters for Optimal Corrosion
Control Treatment and Reoptimized Corrosion Control Treatment.
The Department must evaluate the results of all lead and copper
tap sampling and water quality parameter sampling submitted by the water system
and determine whether the water system has properly installed and operated the
optimal corrosion control treatment designated by the Department in paragraph
(4)(a) or (b) of this section, respectively. Upon reviewing the results of tap
water and water quality parameter monitoring by the water system, both before
and after the water system installs optimal corrosion control treatment, the
Department must designate:
(a) A
minimum value or a range of values for pH measured at each entry point to the
distribution system.
(b) A minimum
pH value, measured in all tap samples. Such a value shall be equal to or
greater than 7.0, unless the Department determines that meeting a pH level of
7.0 is not technologically feasible or is not necessary for the system to
optimize corrosion control.
(c) If
a corrosion inhibitor is used, a minimum concentration or a range of
concentrations for the orthophosphate (as PO4) or silicate measured at each
entry point to the distribution.
(d) If a corrosion inhibitor is used, a
minimum orthophosphate or silicate concentration measured in all tap samples
that the Department determines is necessary to form a passivating film on the
interior walls of the pipes of the distribution system. When orthophosphate is
used, such an orthophosphate concentration shall be equal to or greater than
0.5 mg/L (as PO4) for OCCT designations under paragraph (4)(a) of this section
and 1.0 mg/L for OCCT designations under paragraph (4)(b) of this section,
unless the Department determines that meeting the applicable minimum
orthophosphate residual is not technologically feasible or is not necessary for
optimal corrosion control treatment.
(e) If alkalinity is adjusted as part of
optimal corrosion control treatment, a minimum concentration or a range of
concentrations for alkalinity, measured at each entry point to the distribution
system and in all tap samples.
(f)
The values for the applicable water quality control parameters, previously
listed in this section, shall be those that the Department determines to
reflect optimal corrosion control treatment for the water system. The
Department may designate values for additional water quality control parameters
determined by the Department to reflect optimal corrosion control treatment for
the water system. The Department must notify the system in writing of these
determinations and explain the basis for its decisions.
(7) Continued Operation and Monitoring for
Optimal Corrosion Control Treatment and Re-optimized Optimal Corrosion Control
Treatment.
All systems optimizing or re-optimizing corrosion control must
continue to operate and maintain optimal corrosion control treatment, including
maintaining water quality parameters at or above minimum values or within
ranges designated by the Department under paragraph (6) of this section, in
accordance with this paragraph (7) for all samples collected under
R.61-58.11.I(4) through
(6). The requirements of this paragraph (7)
apply to all systems, including consecutive systems that distribute water that
has been treated to control corrosion by another system, and any water system
with corrosion control treatment, optimal corrosion control treatment, or
re-optimized OCCT that is not required to monitor water quality parameters
under R.61-58.11.I. Compliance with the requirements of this paragraph (7)
shall be determined every six (6) months, as specified under R.61-58.11.I(4). A
water system is out of compliance with the requirements of this paragraph (7)
for a six (6)-month period if it has excursions for any Department-specified
parameter on more than nine (9) days, cumulatively, during the period. An
excursion occurs whenever the daily value for one or more of the water quality
parameters measured at a sampling location is below the minimum value or
outside the range designated by the Department. Daily values are calculated as
set out in paragraphs (7)(a) through (c) of this section. The Department has
the discretion to not include results of obvious sampling errors from this
calculation. Sampling errors must still be recorded even when not included in
calculations.
(a) On days when more
than one (1) measurement for the water quality parameter is collected at the
sampling location, the daily value must be the average of all results collected
during the day regardless of whether they are collected through continuous
monitoring, grab sampling, or a combination of both. If EPA has approved an
alternative formula under 40
CFR 142.16(d)(1)(ii) in the
Department's application for a program revision submitted pursuant to
40 CFR
142.12, the Department's formula shall be
used to aggregate multiple measurements taken at a sampling point for the water
quality parameters in lieu of the formula in this paragraph (7)(a).
(b) On days when only one (1) measurement for
the water quality parameter is collected at the sampling location, the daily
value shall be the result of that measurement.
(c) On days when no measurement is collected
for the water quality parameter at the sampling location, the daily value shall
be the daily value calculated on the most recent day on which the water quality
parameter was measured at the sampling location.
(8) Modification of Department Treatment
Decisions for Optimal Corrosion Control and Re-optimized Corrosion Control.
Upon its own initiative or in response to a request by a water
system or other interested party, the Department may modify its determination
of the optimal corrosion control treatment under paragraph (4) of this section,
or optimal water quality control parameters under paragraph (6) of this
section. A request for modification by a system or other interested party shall
be in writing, explaining why the modification is appropriate, and providing
supporting documentation. The Department may modify its determination where it
concludes that such change is necessary to ensure that the water system
continues to optimize corrosion control treatment. A revised determination must
be made in writing, set forth the new treatment requirements and/or water
quality parameters, explain the basis for the Department's decision, and
provide an implementation schedule for completing the treatment modifications
for re-optimized corrosion control treatment.
(9) Treatment Decisions by EPA in lieu of the
Department on Optimal Corrosion Control Treatment and Re-optimized Corrosion
Control Treatment.
Pursuant to the procedures in
40 CFR
142.19, EPA Regional Administrator may review
optimal corrosion control treatment determinations made by the Department under
paragraph (4)(a) or (b), (6), or (8) of this section and issue Federal
treatment determinations consistent with the requirements of paragraph (4)(a)
or (b), (6), or (8) of this section where the Regional Administrator finds
that:
(a) A Department has failed to
issue a treatment determination by the applicable deadlines contained in
R.61-58.11.C;
(b) A Department has
abused its discretion in a substantial number of cases or in cases affecting a
substantial population; or
(c) The
technical aspects of a Department's determination would be indefensible in a
Federal enforcement action taken against a water system.
(10) Find-and-fix Assessment for Tap Sample
Sites that Exceed the Lead Action Level.
The water system shall conduct the following steps, when a tap
sample site exceeds the lead action level under monitoring conducted under
R.61-58.11.H.
(a) Step 1: Corrosion
Control Treatment Assessment. The water system must sample at a new water
quality parameter site that is on the same size water main in the same pressure
zone and located within a half mile of the location with the action level
exceedance within five (5) days of receiving the sample results. Small water
systems without corrosion control treatment may have up to fourteen (14) days
to collect the samples. The water system must measure the following parameters:
(i) pH;
(ii) Alkalinity;
(iii) Orthophosphate (as PO4), when an
inhibitor containing an orthophosphate compound is used;
(iv) Silica, when an inhibitor containing a
silicate compound is used; and
(v)
Water systems with an existing water quality parameter location that meets the
requirements of this section can conduct this sampling at that
location.
(vi) All water systems
required to meet optimal water quality control parameters but that do not have
an existing water quality parameter location that meets the requirement of this
section must add new sites to the minimum number of sites as described in
R.61-58.11.I(7).
Sites must be added until a system has twice the minimum number of sites listed
in Table 1 to R.61-58.11.I(1)(b).
When a system exceeds this upper threshold for the number of sites, the
Department has discretion to determine if the newer site can better assess the
effectiveness of the corrosion control treatment and to remove existing sites
during sanitary survey evaluation of OCCT.
(b) Step 2: Site Assessment. Water systems
shall collect a follow-up sample at any tap sample site that exceeds the action
level within thirty (30) days of receiving the sample results. These follow-up
samples may use different sample volumes or different sample collection
procedures to assess the source of elevated lead levels. Samples collected
under this section must be submitted to the Department but shall not be
included in the 90th percentile calculation for
compliance monitoring under R.61-58.11.H. If the
water system is unable to collect a follow-up sample at a site, the water
system must provide documentation to the Department, explaining why it was
unable to collect a follow-up sample.
(c) Step 3: Water systems shall evaluate the
results of the monitoring conducted under this paragraph (10)(c) to determine
if either localized or centralized adjustment of the optimal corrosion control
treatment or other distribution system actions are necessary and submit the
recommendation to the Department within six months after the end of the tap
sampling period in which the site(s) exceeded the lead action level. Corrosion
control treatment modification may not be necessary to address every
exceedance. Other distribution system actions may include flushing to reduce
water age. Water systems must note the cause of the elevated lead level, if
known from the site assessment, in their recommendation to the Department as
site-specific issues can be an important factor in why the system is not
recommending any adjustment of corrosion control treatment or other
distribution system actions. Systems in the process of optimizing or
reoptimizing optimal corrosion control treatment under paragraphs (1) through
(6) of this section do not need to submit a treatment recommendation for
find-and-fix.
(d) Step 4: The
Department shall approve the treatment recommendation or specify a different
approach within six (6) months of completion of Step 3 as described in
paragraph (10)(c) of this section.
(e) Step 5: If the Department-approved
treatment recommendation requires the water system to adjust the optimal
corrosion control treatment process, the water system must complete
modifications to its corrosion control treatment within twelve (12) months
after completion of Step 4 as described in paragraph (10)(d) of this section.
Systems without corrosion control treatment required to install optimal
corrosion control treatment must follow the schedule in R.61-58.11.C(5).
(f) Step 6: Water systems adjusting its
optimal corrosion control treatment must complete follow-up sampling
(R.61-58.11.H(4)(b) and
R.61-58.11.I(3)) within twelve (12)
months after completion of Step 5 as described in paragraph (10)(e) of this
section.
(g) Step 7: For water
systems adjusting its optimal corrosion control treatment, the Department must
review the water system's modification of corrosion control treatment and
designate optimal water quality control parameters (R.61-58.11.D(6)(a))
within six (6) months of completion of Step 6 as described in paragraph (10)(f)
of this section.
(h) Step 8. For a
water system adjusting its optimal corrosion control treatment, the water
system must operate in compliance with the Department-designated optimal water
quality control parameters (R.61-58.11.D(7))
and continue to conduct tap sampling (R.61-58.11.H(4)(c)
and R.61-58.11.I(4)).
