Current through Register Vol. 56, No. 18, September 16, 2024
(a) The owner or
operator shall comply with the following requirements for any ground water
monitoring program developed to satisfy
7:14A-10.12, 10.13 or 10.14. A ground
water monitoring system shall consist of a sufficient number of wells, installed at
appropriate locations and depths to yield ground water samples from the upper most
aquifer that:
1. Represent the quality of
background water that has not been affected by leakage from a hazardous waste
facility unit.
i. A determination of background
ground water quality may include sampling of wells that are not hydraulically
upgradient of the hazardous waste management area as described at
7:14A-10.9(b), where:
(1) Hydrogeologic conditions do not allow the
owner or operator to determine what wells are hydraulically upgradient;
and
(2) Sampling at other wells will
provide an indication of background ground water quality that is representative or
more representative than that provided by the upgradient wells;
2. Represent the quality of ground
water passing the relevant point of compliance; and
3. Allow for the detection of contamination when
hazardous waste or hazardous constituents have migrated from the hazardous waste
management area to the uppermost aquifer.
(b) If a facility contains more than one hazardous
waste facility unit, separate ground water monitoring systems are not required for
each hazardous waste facility unit provided that provisions for sampling the ground
water in the uppermost aquifer will enable detection and measurement at the relevant
point of compliance of hazardous constituents from the hazardous waste facility
units that have entered the ground water in the uppermost aquifer.
(c) Monitoring wells shall be cased in a manner
that maintains the integrity of the monitoring well bore hole. This casing shall be
screened or perforated and packed with gravel or sand, where necessary, to enable
collection of ground water samples. The annular space (that is, the space between
the bore hole and well casing) above the sampling depth shall be sealed to prevent
contamination of samples and the ground water. In addition to these general well
construction standards, all monitoring wells shall be constructed in accordance with
the edition of the Department's "Field Sampling Procedures Manual" applicable at the
time of construction, an alternate method approved by the Department, or as set
forth in the NJPDES-DGW permit.
(d) The
ground water monitoring system shall include sampling and analysis procedures that
are designed to ensure monitoring results that provide a reliable indication of
ground water quality below the hazardous waste management area as described at
7:14A-10.9(b). At a
minimum, the program shall include procedures and techniques for:
1. Sample collection;
2. Sample preservation and shipment;
3. Analytical procedures; and
4. Chain of custody control.
(e) The ground water monitoring system shall
include sampling and analytical methods that are appropriate for ground water
sampling and that accurately measure hazardous constituents in ground water
samples.
(f) The ground water monitoring
system shall include a determination of the ground water surface elevation each time
ground water is sampled.
(g) In
detection monitoring or, where appropriate, in compliance monitoring, data on each
hazardous constituent specified in the permit shall be collected from background
wells and wells at the compliance point(s). The number and kinds of samples
collected to establish background shall be appropriate for the form of statistical
test employed, following generally accepted statistical principles. The sample size
shall be as large as necessary to ensure with reasonable confidence that a
contaminant release to ground water from a facility will be detected. The owner or
operator shall determine an appropriate sampling procedure and interval for each
hazardous constituent listed in the NJPDES-DGW permit which shall be specified in
the NJPDES-DGW permit upon approval by the Department. This sampling procedure shall
be:
1. A sequence of at least four samples, taken
at an interval that ensures, to the greatest extent technically feasible, that an
independent sample is obtained, by reference to the uppermost aquifer's effective
porosity, hydraulic conductivity, and hydraulic gradient, and the fate and transport
characteristics of the potential contaminants; or
2. An alternate sampling procedure approved by the
Department.
(h) The owner or
operator shall specify one of the following statistical methods to be used in
evaluating ground water monitoring data for each hazardous constituent which, upon
approval by the Department, shall be specified in the NJPDES-DGW permit. The
statistical test shall be conducted separately for each hazardous constituent in
each well. Where practical quantification limits (PQLs) are used in any of the
following statistical procedures to comply with (i)5 below, the PQL shall be
approved by the Department. Use of any of the following statistical methods shall be
protective of human health and the environment and shall comply with the performance
standards in (i) below.
1. A parametric analysis
of variance (ANOVA) followed by multiple comparisons 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 the 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 approved by the
Department.
(i) Any
statistical method chosen pursuant to (h) 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
distribution 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 concentration 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 comparison procedure is used, the Type I
experimentwise 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. This 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 proposed by the owner or operator and approved by the
Department if it finds it to be protective of human health and the
environment.
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 proposed by the owner or operator and
approved by the Department if it finds these parameters to 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 quantification limit
(PQL) approved by the Department under (h) above 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.
(j) Ground water monitoring data collected in
accordance with (g) above, including actual levels of constituents, shall be
maintained in the permanent records maintained by the facility. The Department shall
specify in the permit when the data shall be submitted for review.
