Current through Register Vol. 6, March 22, 2024
(1) To determine
compliance with treatment requirements of this subchapter, to judge variations
in water quality, to identify objectionable water characteristics, and to
detect the presence of foreign substances which may adversely affect the
quality of the water, control tests must be performed, recorded, and reported
by water suppliers in accordance with procedures and reporting formats approved
by the department.
(2) Disinfectant
residual tests must be conducted daily by:
(a) surface water systems and consecutive
systems to a surface water system in accordance with the requirements in
40 CFR
141.72 and with the other requirements in
this subchapter for disinfectant residual monitoring for surface water
supplies. At least two disinfectant residual tests must be conducted daily, one
at each entry point to the distribution system and one in the distribution
system;
(b) ground water systems in
accordance with 40 CFR Par 141, subpart S. Disinfectant residual tests must be
conducted daily at each entry point to the distribution system to prove
compliance with the four-log virus inactivation or removal requirement;
and
(c) ground water systems
required by the department under ARM
17.38.229 to maintain a residual,
and by consecutive systems connected to those systems, at each entry point to
the distribution system and, if required to maintain a residual in the
distribution system, one in the distribution system. For consecutive systems,
the entry point is the point at which the purchased water enters the
distribution system of the consecutive system.
(3) The department may waive, on a
case-by-case basis, disinfection residual testing at the entry point, in the
distribution system, or both for ground water and consecutive
systems.
(4) A test for chlorine
residual in the distribution system must be made at selected points consistent
with the department-approved microbiological sample siting plan and changed
regularly so as to cover the system completely at least each week.
(5) Only the following analytical methods or
other methods approved by the department may be used to demonstrate compliance
with the requirements of this rule:
(a)
Turbidity measurements must be taken as set forth in
40 CFR
141.74. Secondary turbidity standards may be
used for daily calibration of turbidimeters if those standards are calibrated
against an EPA-approved primary at least quarterly. Documentation of the date,
analyst performing the procedure, procedures used, and results of the quarterly
calibration checks must be maintained by the water system and reported to the
department within ten days following the end of the month during which this
procedure took place.
(b) Residual
disinfectant concentrations must be measured as set forth in
40 CFR
141.74. Residual disinfectant concentrations
for free chlorine and combined chlorine may also be measured by using DPD
colorimetric test kits if approved by the department.
(c) Temperature measurements must be taken as
set forth in 40 CFR
141.23(k)(1).
(d) Measurements for pH must be taken as set
forth in 40 CFR
141.23(k)(1).
(6) All control test measurements,
except for bacteriological samples, for community and nontransient noncommunity
water supply systems must be conducted by a person certified under the
provisions of Title 37, chapter 42, MCA, or by a person who has been properly
trained to conduct these measurements by the operator in responsible charge or
by the department. Bacteriological samples for community and nontransient
noncommunity water supply systems must be collected by a person approved by the
department or certified under the provisions of Title 37, chapter 42, MCA.
Measurements for total coliform bacteria, fecal coliform bacteria, and
heterotrophic plate count must be conducted by an approved
laboratory.
(7) The department
adopts and incorporates by reference the following:
(a)
40 CFR
141.22, which sets forth turbidity sampling
and analytical requirements, except for the second and third sentences in
141.22(a).
(b)
40 CFR
141.74, which sets forth analytical and
monitoring requirements, except for the following changes:
(i) "1 NTU" means 1.0 nephelometric turbidity
unit for the purposes of this subchapter;
(ii) The first sentence in
40 CFR
141.74(b)(4)(i)(B)(ii) is
replaced with the following: "If the system uses more than one point of
disinfectant application before or at the first customer, the system must
determine the CT value of each disinfection sequence immediately prior to the
next point of disinfectant application during peak hourly flow, except that
contact time achieved prior to filtration is not included in this
calculation.";
(iii) The following
phrase is inserted after the phrase "system's filtered water" in the first
sentence in 40 CFR
141.74(c)(1): "and
individual filter effluent";
(iv)
The last sentence in 40 CFR
141.74(c)(1) is not adopted;
and
(v)
40 CFR
141.74(b)(5) and
141.74(c)(2) are
modified to read: "The residual disinfectant concentration of the water
entering the distribution system must be monitored continuously, and the lowest
value must be recorded each day, except that if there is a failure in the
continuous monitoring equipment, grab sampling every four hours may be
conducted in lieu of continuous monitoring, but for no more than five working
days following the failure of the equipment."
(c)
40 CFR
141.172, which sets forth disinfection
profiling and benchmarking requirements;
(d)
40 CFR
141.174, which sets forth filtration sampling
requirements;
(e)
40 CFR
141.530,
141.531,
141.532,
141.533,
141.534,
141.535,
141.536,
141.540,
141.541,
141.542,
141.543 and
141.544, which set forth
requirements for disinfection profiling and benchmarking for public water
suppliers using surface water or GWUDISW and that serve fewer than 10,000
people;
(f)
40 CFR
141.553, which describes turbidity monitoring
provisions for systems that utilize lime softening;
(g)
40 CFR
141.560, which describes individual filter
monitoring requirements for public water suppliers that utilize direct or
conventional filtration treatment;
(h)
40 CFR
141.561, which describes monitoring
requirements for public water suppliers when continuous turbidity monitoring
equipment fails;
(i)
40 CFR
141.562, which describes turbidity monitoring
requirements for public water suppliers that utilize two or fewer filters;
and
(j) Title 37, chapter 42, MCA,
which sets forth requirements for water treatment plant
operators.
(8) Copies of
Title 37, chapter 42, MCA, may be obtained from the Department of Environmental
Quality, P.O. Box 200901, Helena, MT 59620-0901.
AUTH:
75-6-104, MCA; IMP:
75-6-104,
MCA