Current through Register Vol. 18, September 20, 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
