Current through September 17, 2024
004.01 Systems must
complete the applicable corrosion control treatment requirements described in
179 NAC
12-005 by the deadlines established
in 179 NAC 12-004.
12-004.01A A large system
(serving more than 50,000 persons) must complete the corrosion control
treatment steps specified in 179 NAC 12-004.04 unless it is deemed to have
optimized corrosion control under 179 NAC 12-004.02B or 12-004.02C.
12-004.01B A small system (serving <=3300
persons) and a medium-size system (serving >3,300 and <=50,000 persons)
must complete the corrosion control treatment steps specified in 179 NAC
12-004.05 unless it is deemed to have optimized corrosion control under 179 NAC
12-004.02A,
12-004.02B, or
12-004.02C.
004.02 A system is deemed to have
optimized corrosion control and is not required to complete the applicable
corrosion control treatment steps identified in 179 NAC 12-004 if the system
satisfies one of the following criteria. Any such system deemed to have
optimized corrosion control under 179 NAC
12-004.02, and which has treatment
in place, must continue to operate and maintain optimal corrosion control
treatment and meet any requirements that the Director determines appropriate to
ensure optimal corrosion control treatment is maintained.
12-004.02A A small or medium-size water
system is deemed to have optimized corrosion control if the system meets the
lead and copper action levels during each of two consecutive six-month
monitoring periods conducted in accordance with 179 NAC
12-009.
12-004.02B Any water system may be deemed by
the Director to have optimized corrosion control treatment if the system
demonstrates to the satisfaction of the Director that it has conducted
activities equivalent to the corrosion control steps applicable to such system
under 179 NAC 12-004. If the Director makes this determination, s/he must
provide the system with written notice explaining the basis for his/her
decision and must specify the water quality control parameters representing
optimal corrosion control in accordance with 179 NAC 12-005.06. Water systems
deemed to have optimized corrosion control under 179 NAC
12-004.02B must
operate in compliance with the Director-designated optimal water quality
control parameters in accordance with 179 NAC 12-005.07 and continue to conduct
lead and copper tap and water quality parameter sampling in accordance with 179
NAC
12-009.04C and
179 NAC 12-010.04, respectively. A system must provide the Director with the
following information in order to support a determination under 179 NAC
12-004.02B:
1. The results of all test samples collected
for each of the water quality parameters in 179 NAC 12-005.03C.
2. A report explaining the test methods used
by the water system to evaluate the corrosion control treatments listed in 179
NAC
12-005.03A, the
results of all tests conducted, and the basis for the system's selection of
optimal corrosion control treatment;
3. A report explaining how corrosion control
has been installed and how it is being maintained to insure minimal lead and
copper concentrations at consumers' taps; and
4. The results of tap water samples collected
in accordance with 179 NAC
12-009 at least once every six months
for one year after corrosion control has been installed.
12-004.02C Any water system is deemed to have
optimized corrosion control if it submits results of tap water monitoring
conducted in accordance with 179 NAC
12-009 and source water monitoring
conducted in accordance with 179 NAC
12-011 that demonstrates for two
consecutive six-month monitoring periods that the difference between the
90th percentile tap water lead level computed under
179 NAC
12-003.01C, and
the highest source water lead concentration, is less than the Practical
Quantitation Level (PQL) for lead specified in 179 NAC
12-012.01A item
2.
12-004.02C(1) Those systems whose highest
source water lead level is below the Method Detection Limit may also be deemed
to have optimized corrosion control under 179 NAC
12-004.02C(1) if
the 90th percentile tap water lead level is less
than or equal to the Practical Quantitation Level for lead for two consecutive
six-month monitoring periods.
12-004.02C(2) Any water system deemed to have
optimized corrosion control in accordance with 179 NAC
12-004.02C(2)
must continue monitoring for lead and copper at the tap no less frequently than
once every three calendar years using the reduced number of sites specified in
179 NAC 12-009.03 and collecting the samples at times and locations specified
in 179 NAC
12-009.04D4.
12-004.02C(3) Any water system deemed to have
optimized corrosion control pursuant to 179 NAC
12-004.02C(3)
must notify the Director in writing pursuant to 179 NAC
12-013.01C of any
change in treatment or the addition of a new source. The Director may require
any such system to conduct additional monitoring or to take other action the
Director deems appropriate to ensure that such systems maintain minimal levels
of corrosion in the distribution system.
12-004.02C(4) As of [the effective date of
these regulations], a system is not deemed to have optimized corrosion control
under 179 NAC
12-004.02C(4),
and must implement corrosion control treatment pursuant to 179 NAC
12-004.02C(5)
unless it meets the copper action level.
12-004.02C(5) Any system triggered into
corrosion control because it is no longer deemed to have optimized corrosion
control under 179 NAC
12-004.02C(5)
must implement corrosion control treatment in accordance with the deadlines in
179 NAC 12-004.05. Any such large system must adhere to the schedule specified
in 179 NAC 12-004.05 for medium-size systems, with the time periods for
completing each step being triggered by the date the system is no longer deemed
to have optimized corrosion control under 179 NAC
12-004.02C(5).
004.03 Any small or
medium-size water system that is required to complete the corrosion control
steps due to its exceedance of the lead or copper action level may cease
completing the treatment steps whenever the system meets both action levels
during each of two consecutive monitoring periods conducted pursuant to 179 NAC
12-009 and submits the results to the
Director. If any such water system thereafter exceeds the lead or copper action
level during any monitoring period, the system (or the Director, as the case
may be) must recommence completion of the applicable treatment steps, beginning
with the first treatment step which was not previously completed in its
entirety. The Director may require a system to repeat treatment steps
previously completed by the system where the Director determines that this is
necessary to implement properly the treatment requirements of 179 NAC 12-004.
The Director must notify the system in writing of such a determination and
explain the basis for his/her decision. The requirement for any small- or
medium-size system to implement corrosion control treatment steps in accordance
with 179 NAC 12-004.05 (including systems deemed to have optimized corrosion
control under 179 NAC
12-004.02A) is
triggered whenever any small- or medium-size system exceeds the lead or copper
action level.
004.04 Treatment
Steps and Deadlines for Large Systems Serving > 50,000 individuals
Except as provided in 179 NAC
12-004.02B and
12-004.02C large
systems must complete the following corrosion control treatment steps
(described in the referenced portions of 179 NAC
12-005,
12-009 and
12-010) by the indicated dates (which
are included for informational purposes only).
1.
Step 1: The
system must conduct initial monitoring during two consecutive six-month
monitoring periods by January 1, 1993.
2.
Step 2: The
system must complete corrosion control studies by July 1, 1994.
3.
Step 3: The
Director must designate optimal corrosion control treatment by January 1,
1995.
4.
Step
4: The system must install optimal corrosion control treatment by
January 1, 1997.
5.
Step 5: The system must complete follow-up sampling by
January 1, 1998.
6.
Step 6: The Director must review installation of
treatment and designate optimal water quality control parameters by July 1,
1998.
7.
Step
7: The system must operate in compliance with the optimal water
quality control parameters specified by the Director (179 NAC 12-005.07) and
continue to conduct tap sampling (179 NAC
12-009.04C and
12-010.04).
004.05
Treatment Steps and Deadlines for Small and Medium-Size Systems
Except as provided in 179 NAC
12-004.02, small and medium-size
systems must complete the following corrosion control treatment steps
(described in the referenced portions of 179 NAC
12-005,
12-009 and
12-010) by the indicated time
periods.
1.
Step
1: The system must conduct initial tap sampling (179 NAC
12-009.04A and
12-010.02) until the system either exceeds the lead or copper action level or
becomes eligible for reduced monitoring under 179 NAC
12-009.04D. A
system exceeding the lead or copper action level must recommend optimal
corrosion control treatment (179 NAC 12-005.01) within six months after it
exceeds one of the action levels.
2.
Step 2: Within 12
months after a system exceeds the lead or copper action level, the Director may
require the system to perform corrosion control studies (179 NAC 12-005.02). If
the Director does not require the system to perform such studies, the Director
must specify optimal corrosion control treatment (179 NAC 12-005.04) within the
following time frames:
a. For medium-size
systems, within 18 months after such system exceeds the lead or copper action
level,
b. For small systems, within
24 months after such system exceeds the lead or copper action level.
3.
Step
3: If the Director requires a system to perform corrosion control
studies under step 2, the system must complete the studies (179 NAC
12-005.03) within 18 months after
the Director requires that such studies be conducted.
4.
Step 4: If the
system has performed corrosion control studies under step 2, the Director must
designate optimal corrosion control treatment (179 NAC 12-005.04) within six
months after completion of step 3.
5.
Step 5: The
system must install optimal corrosion control treatment (179 NAC 12-005.05)
within 24 months after the Director designates such treatment.
6.
Step 6: The
system must complete follow-up sampling (179 NAC
12-009.04B and
179 NAC 12-010.03) within 36 months after the Director designates optimal
corrosion control treatment.
7.
Step 7: The Director must review the system's
installation of treatment and designate optimal water quality control
parameters (179 NAC 12-005.06) within six months after completion of step
6.
8.
Step
8: The system must operate in compliance with the optimal water
quality control parameters that have been designated by the Director (179 NAC
12-005.07) and continue to conduct tap sampling (179 NAC
12-009.04C and
12-010.04).
