N.J. Admin. Code § 7:14A-7.7 - Ground water sampling procedures and statistical analysis requirements
(a) The person
responsible for conducting the Ground Water Protection Program established
pursuant to
7:14A-7.6 shall conduct ground
water sampling in accordance with the edition of the Department's Field
Sampling Procedures Manual applicable at the time of sampling, an alternate
method approved by the Department, or as set forth in the NJPDES-DGW
permit.
(b) When statistical data
evaluations are specified by the Department to implement the Ground Water
Protection Program, the statistical test chosen shall be conducted separately
for each specified constituent in each well, and one of the following
statistical methods shall be used to evaluate ground-water monitoring data for
each specified constituent:
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 each compliance well's
mean and the background water quality mean levels for each
constituent;
2. An analysis of
variance (ANOVA) based on ranks followed by multiple comparison 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 water quality median levels 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 water quality 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 (c) below, and has been approved
by the Department in writing.
(c) Any statistical method chosen under this
section 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
parameters. If the distribution of the parameters is shown by the permittee to
be inappropriate for a normal theory test, then the data must be transformed or
a distribution free theory test used. If the distributions for the constituents
differ, more than one statistical method may be needed.
2. If an individual well comparison procedure
is used to compare an individual compliance well constituent concentration with
background water quality 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 water quality data base, the date 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 water quality 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 level (PQL) as defined in N.J.A.C. 7:9C 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.
(d) When conducting a leak
detection monitoring program, the permittee shall determine whether or not
there is a statistically significant increase over background water quality
values for each parameter or constituent required in the permit.
1. In determining whether a statistically
significant increase has occurred, the permittee shall compare the ground water
quality of each parameter or constituent at each compliance point monitoring
well designated pursuant to the permit to the background water quality value of
that constituent, according to the statistical procedures and performance
standards specified under this section.
2. Within the period of time specified in the
NJPDES discharge to ground water permit, and after completing sampling and
analysis, the permittee shall determine whether there has been a statistically
significant increase over background water quality at each monitoring
well.
(e) When
conducting an attenuation monitoring program, the permittee shall determine
whether the discharge complies with the ground water constituent standards for
the classification area established pursuant to N.J.A.C. 7:9C.
1. In determining whether the discharge
complies with the ground water constituent standards for the classification
area, the permittee shall compare the ground water quality of each parameter or
constituent at each compliance point monitoring well designated pursuant to the
permit to the background water quality value of that constituent, according to
the statistical procedures and performance standards specified under this
section.
2. Within the period of
time specified in the NJPDES discharge to ground water permit, and after
completing sampling and analysis, the permittee shall determine whether there
has been a statistically significant contravention of the ground water quality
standards.
Notes
See: 37 N.J.R. 4245(a).
Amended by R.2009 d.7, effective
See: 40 N.J.R. 1478(a), 41 N.J.R. 142(a).
In the introductory paragraph of (e), updated the N.J.A.C. reference.
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