Current through Register Vol. 18, September 20, 2024
(1) An owner or operator required to monitor
ground water under this subchapter shall implement a ground water monitoring program
that includes consistent sampling and analysis procedures that are designed to
ensure monitoring results that provide an accurate representation of ground water
quality at the background and downgradient wells installed in compliance with ARM
17.50.1304(1). The
owner or operator shall submit to the department for approval a sampling and
analysis plan that documents sampling and analysis procedures and techniques for:
(a) sample collection;
(b) sample preservation and shipment;
(c) analytical procedures;
(d) chain of custody control; and
(e) quality assurance and quality
control.
(2) The owner or
operator of a facility shall notify the department that the approved sampling and
analysis plan has been placed in the operating record.
(3) The ground water monitoring program required
in (1) must include sampling and analytical methods that are appropriate for ground
water sampling and that accurately measure constituents and parameters that are
required to be monitored in ground water samples. Any requirement in this subchapter
for analysis of the concentration in ground water of a metal listed in Appendix I or
II to 40 CFR Part 258 (July 1, 2008) is for analysis of the dissolved metal
concentration, unless another alternative for analysis is approved in writing by the
department on an individual facility basis.
(4) The sampling procedures and frequency must be
protective of human health and the environment.
(5) Ground water elevations must be measured in
each well immediately prior to purging, each time ground water is sampled. The owner
or operator shall determine the rate and direction of ground water flow each time
ground water is sampled. Ground water elevations in wells that monitor the same
waste management area must be measured within a period of time short enough to avoid
temporal variations in ground water flow that could preclude accurate determination
of ground water flow rate and direction.
(6) The owner or operator shall establish
background ground water quality in a hydraulically upgradient or background well(s)
for each of the constituents and parameters required in the particular ground water
monitoring program that applies to the Class II or Class IV landfill unit, as
determined under ARM
17.50.1306(1) or
17.50.1307(1).
Background ground water quality may be established at wells that are not located
hydraulically upgradient from the Class II and Class IV landfill unit if they meet
the requirements of ARM
17.50.1304(1)(a).
(7) The number of samples collected to establish
ground water quality data must be consistent with the appropriate statistical
procedures determined pursuant to (8). The sampling procedures must be those
specified under ARM
17.50.1306(2) for
detection monitoring, ARM
17.50.1307(2) and (4)
for assessment monitoring, and ARM
17.50.1308(2) for
corrective action.
(8) The owner or
operator shall specify in the operating record one of the statistical methods in
(8)(a) through (e) to be used in evaluating ground water monitoring data for each
constituent or parameter. The statistical test chosen must be conducted separately
for each constituent and parameter in each well:
(a) a parametric analysis of variance (ANOVA)
followed by multiple comparisons procedures, to identify statistically significant
evidence of contamination. The method must include estimation and testing of the
contrasts between each compliance well's mean levels and the background mean levels
for each constituent or parameter;
(b)
an analysis of variance (ANOVA) based on ranks followed by multiple comparisons
procedures, to identify statistically significant evidence of contamination. The
method must include estimation and testing of the contrasts between each compliance
well's median levels and the background median levels for each constituent or
parameter;
(c) a tolerance or prediction
interval procedure in which an interval for each constituent or parameter is
established from the distribution of the background data, and the level of each
constituent or parameter in each compliance well is compared to the upper tolerance
or prediction limit;
(d) a control chart
approach that provides control limits for each constituent or parameter;
or
(e) another statistical test method
that meets the performance standards of (9). The owner or operator shall place a
justification for this alternative in the operating record and notify the department
of the use of this alternative test. The justification must demonstrate that the
alternative method meets the performance standards of (9).
(9) Any statistical method chosen under (8) must
comply with the following performance standards, as appropriate:
(a) the statistical method used to evaluate ground
water monitoring data must be appropriate for the distribution of constituents and
parameters. If the distribution of the constituents or parameters is shown by the
owner or operator to be inappropriate for a normal theory test, then the data should
be transformed or a distribution-free theory test should be used. If the
distributions for the constituents or parameters differ, more than one statistical
method may be needed;
(b) if an
individual well comparison procedure is used to compare a constituent or parameter
concentration in an individual compliance well with background constituent or
parameter concentrations or a ground water protection standard, the test must be
performed at a Type I error level no less than 0.01 for each testing period. If a
multiple comparisons procedure is used, the Type I experiment wise error rate for
each testing period must be no less than 0.05; however, the Type I error of no less
than 0.01 for individual well comparisons must be maintained. This performance
standard does not apply to tolerance intervals, prediction intervals, or control
charts;
(c) if a control chart approach
is used to evaluate ground water monitoring data, the specific type of control chart
and its associated parameter values must be protective of human health and the
environment. The parameters must be determined after considering the number of
samples in the background data base, the data distribution, and the range of the
concentration values for each constituent and parameter of concern;
(d) if a tolerance interval or a predictional
interval is used to evaluate ground water monitoring data, the levels of confidence
and, for tolerance intervals, the percentage of the population that the interval
must contain, must be protective of human health and the environment. These
parameters must be determined after considering the number of samples in the
background data base, the data distribution, and the range of the concentration
values for each constituent or parameter of concern;
(e) the statistical method must account for data
below the limit of detection with one or more statistical procedures that are
protective of human health and the environment. Any practical quantitation limit
(pql) that is used in the statistical method must be the lowest concentration level
that reliably can be achieved within specified limits of precision and accuracy
during routine laboratory operating conditions that are available to the facility;
and
(f) if necessary, the statistical
method must include procedures to control or correct for seasonal and spatial
variability as well as temporal correlation in the data.
(10) The owner or operator shall determine whether
there is a statistically significant increase over background values for each
constituent or parameter required to be monitored in the particular ground water
monitoring program that applies to the Class II or Class IV landfill unit, as
determined under ARM
17.50.1306(1) or
17.50.1307(1).
(11) In determining whether a statistically
significant increase described in (10) has occurred, the owner or operator shall:
(a) compare the ground water quality for each
constituent or parameter at each monitoring well designated pursuant to ARM
17.50.1304(1)(b) to
the background value of that constituent or parameter, according to the statistical
procedures and performance standards specified under (8) and (9); and
(b) within a reasonable period of time after
completing sampling and analysis, determine, for each monitoring well, whether there
has been a statistically significant increase over background levels.
75-10-204, MCA; IMP,
75-10-204,
75-10-207,
MCA;
