Current through Register Vol. 56, No. 6, March 18, 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.
