Current through Register Vol. 56, No. 24, December 18, 2024
(a) The
ground water monitoring program shall include 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
N.J.A.C.
7:14A-9.3(a). The owner or
operator shall notify the Department, pursuant to the NJPDES permit, that the
sampling and analysis program documentation has been placed in the operating
record and the program shall include procedures and techniques for:
1. Sample collection;
2. Sample preservation and
shipment;
3. Analytical
procedures;
4. Chain of custody
control; and
5. Quality assurance
and quality control.
(b)
The ground water monitoring program shall include sampling and analytical
methods that are appropriate for ground water sampling and that accurately
measure hazardous constituents and other monitoring parameters in ground water
samples. Ground water samples shall not be field filtered prior to laboratory
analysis.
(c) The sampling
procedures and frequency shall be protective of human health and the
environment.
(d) Ground water
elevations shall 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 which monitor the same area shall be measured within
a period of time short enough to avoid temporal variations in ground water flow
which could preclude accurate determination of ground water flow rate and
direction.
(e) The owner or
operator shall establish background ground water quality in a hydraulically
upgradient or background well(s) for each of the monitoring parameters or
constituents required in the particular ground water monitoring program that
applies to the sanitary landfill, as determined pursuant to
N.J.A.C.
7:14A-9.7(a) or 9.8(a).
Background ground water quality may be established at wells that are not
located hydraulically upgradient from the sanitary landfill if it meets the
requirements of
N.J.A.C.
7:14A-9.3(a)1.
(f) The number of samples collected to
establish ground water quality data shall be consistent with the appropriate
statistical procedures determined pursuant to (g) below. The sampling
procedures shall be those specified under
N.J.A.C.
7:14A-9.7(b) for detection
monitoring,
N.J.A.C.
7:14A-9.8(b) and (d) for
assessment monitoring, and
N.J.A.C.
7:14A-9.9(b) for corrective
measures.
(g) The owner or operator
shall specify in the records maintained by the facility one of the following
statistical methods to be used in evaluating ground water monitoring data for
each hazardous constituent. The statistical test shall be conducted separately
for each hazardous constituent in each well. Guidance for selecting and
conducting the appropriate tests, and for evaluating the results of the tests
is described in detail in Statistical Analysis of Ground Water Monitoring Data
At RCRA Facilities--Interim Final Guidance Document, 4/89 (NTIS #PB 89-151-047.
EPA/530-SW-89-026).
1. A parametric analysis
of variance (ANOVA) followed by multiple comparison procedures to identify
statistically significant evidence of contamination. The method shall include
estimation and testing of the contrasts between the mean and the background
mean levels for each compliance well for each constituent;
2. An analysis of variance (ANOVA) based on
ranks followed by multiple comparisons procedures to identify statistically
significant evidence of contamination. The method shall include estimation and
testing of the contrasts between each compliance well's median and the
background median levels for each compliance well for each
constituent;
3. A tolerance or
prediction interval procedure in which an interval for each constituent is
established from the distribution of the background data, and the level of each
constituent in each compliance well is compared to the upper tolerance or
prediction limit;
4. A control
chart approach that gives control limits for each constituent; or
5. Another statistical test method that meets
the performance standards of (h) below. The owner or operator shall place a
justification for this alternative in the records maintained by the facility
and notify the Department, pursuant to the NJPDES permit, of the use of this
alternative test. The justification shall demonstrate that the alternative
method meets the performance standards of (h) below.
(h) Any statistical method chosen pursuant to
(g) above shall comply with the following performance standards, as
appropriate:
1. The statistical method used to
evaluate ground water monitoring data shall be appropriate for the distribution
of chemical parameters or hazardous constituents. If the distribution of the
chemical parameters or hazardous constituents is shown by the owner or operator
to be inappropriate for a normal theory test, then the data must be transformed
or a distribution free theory test must be used. If the distributions for the
constituents differ, more than one statistical method shall be
needed.
2. If an individual well
comparison procedure is used to compare an individual compliance well
constituent concentration with background constituent concentrations or a
ground water protection standard, the test shall be done 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
shall be no less than 0.05. However, the type I error of no less than 0.01 for
individual well comparison shall be maintained. The performance standard does
not apply to tolerance intervals, prediction intervals or control
charts.
3. If a control chart
approach is used to evaluate ground water monitoring data, the specific type of
control chart and its associated parameter values shall be protective of human
health and the environment. The parameters shall 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 of
concern.
4. If a tolerance interval
or a prediction 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 shall contain shall be protective of human health
and the environment. These parameters shall 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 of concern.
5. The statistical method shall 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 shall be the lowest
concentration level that can be reliably achieved within specified limits of
precision and accuracy during routine laboratory operating conditions that are
available to the facility.
6. If
necessary, the statistical method shall include procedures to control or
correct for seasonal and spatial variability as well as temporal correlation in
the data.
(i) The owner
or operator shall determine whether or not there is a statistically significant
increase over background values for each parameter or constituent required in
the particular ground water monitoring program that applies to the sanitary
landfill, as determined under
N.J.A.C.
7:14A-9.7(a) or 9.8(a).
1. In determining whether a statistically
significant increase has occurred, the owner or operator shall compare the
ground water quality of each parameter or constituent at each monitoring well
designated pursuant to
N.J.A.C.
7:14A-9.3(a)2 to the
background value of that constituent, according to the statistical procedures
and performance standards specified at (g) and (h) above.
2. Within a reasonable period of time after
completing sampling and analysis, not to exceed 90 days unless otherwise
approved by the Department in writing, the owner or operator shall determine
whether there has been a statistically significant increase over background at
each monitoring well.
