All facilities shall meet the following standards:
(a) Collection and management of samples: Groundwater, soil core, vadose zone, and decomposition gas samples shall be collected and managed in accordance with Department guidance or equivalent methods approved by the Administrator.
(b) Groundwater monitoring: - (i) Except as provided in paragraph (b)(i)(A) of this section, landfill operators shall comply with the following groundwater monitoring requirements:
- (A) Applicability:
- (I) The Administrator may suspend the groundwater monitoring requirements of paragraph (B) of this section if the owner or operator demonstrates that there is no potential for migration of constituents from the facility or unit to the uppermost aquifer. This demonstration must be made by a qualified scientist or engineer, and must consider:
- (1.) Site-specific field measurements, and information about the specific wastes to be disposed at the facility or unit; and
- (2.) Contaminant fate and transport predictions which maximize contaminant migration and consider impacts on human health and the environment.
- (II) Once established at a facility or unit, the groundwater monitoring program shall be conducted throughout the active life and post-closure care period.
- (III) The Administrator may establish an alternate schedule for compliance with any deadline specified in paragraphs (b)(i)(B), (b)(i)(C), (b)(i)(D), (b)(i)(E), or (b)(i)(F) of this section.
- (B) Groundwater monitoring systems:
- (I) A groundwater system must be installed which consists of a sufficient number of wells to monitor water from the uppermost aquifer which may be affected by leakage from the facility or unit. The system must be capable of monitoring the quality of background groundwater and groundwater passing the relevant point of compliance pursuant to Section 7(f). Well locations must be approved by the Administrator, and downgradient wells shall be placed in locations within 150 meters (492 feet) of the waste management unit boundary on land owned, leased, or otherwise controlled by the operator.
- (II) The Administrator may approve a groundwater monitoring system designed to monitor groundwater from the facility, in lieu of individual waste disposal units, if the system is determined to be capable of adequately detecting groundwater pollution. In approving a facility-wide groundwater monitor system, the Administrator shall consider:
- (1.) Number, spacing, and orientation of the individual waste units;
- (3.) Site history and design; and
- (4.) Type of waste accepted at the individual waste units.
- (III) The design of the groundwater monitoring system must be based on site-specific information on aquifer thickness, aquifer properties, groundwater flow direction and rate (including seasonal variations), and on geologic information on the soils, any aquitards, aquicludes, or confining formations, at the site. The design of the system must be approved by the Administrator.
- (C) Groundwater sampling and analysis requirements:
- (I) Each facility must have an approved groundwater sampling and analytical plan and maintain that plan as a part of the facility permit application. The plan must address:
- (2.) Sample preservation and shipment;
- (3.) Analytical procedures;
- (4.) Chain of custody control; and
- (5.) Quality assurance and quality control.
- (II) The groundwater sampling and analysis methods must be appropriate and accurate. Sample handling procedures shall be as required by the Administrator. Groundwater samples shall not be field filtered prior to laboratory analysis, although an operator may choose to collect additional filtered samples. Water temperature, specific conductance, and pH shall also be measured in the field during each monitoring event.
- (III) Groundwater elevations must be measured in each well prior to purging for sample collection, each time groundwater is sampled. The owner or operator must determine groundwater flow direction at each sampling event. The owner or operator must measure or calculate groundwater flow rate(s) as appropriate to establish an adequate groundwater monitoring system, or when requested to do so by the Administrator.
- (IV) The owner or operator must establish background water quality in a hydraulically upgradient or other background well approved by the Administrator.
- (V) Prior to conducting the statistical analysis of groundwater data, the owner or operator shall collect a sufficient number of samples to meet the requirements of the statistical analysis procedure selected.
- (VI) The owner or operator must include in the permit application a description of the statistical method(s) to be used to evaluate groundwater quality data. The statistical test shall be conducted separately for each constituent in each well. The owner or operator may select any of the following statistical analysis procedures:
- (1.) A parametric analysis of variance 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 and the background mean levels for each constituent;
- (2.) An analysis of variance 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 and the background median levels for each constituent;
- (3.) A tolerance or prediction interval procedure in which an interval for each 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 method approved by the Administrator.
- (VII) Any statistical method chosen under paragraph (b)(i)(C)(VI) of this section shall comply with the following performance standards:
- (1.) The method shall be appropriate for the distribution of chemical parameters or constituents. If the distribution is not normal, then the data should be transformed or a distribution-free theory test should be used. If the distributions for different 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 constituent concentrations or a groundwater 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 comparisons must 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 groundwater monitoring data, the specific type of control chart and its associated parameter values must be approved by the Administrator;
- (4.) If a tolerance interval or a prediction interval is used to evaluate groundwater monitoring data, the levels of confidence and, for tolerance intervals, the percentage of the population that the interval must contain, shall be approved by the Administrator;
- (5.) Any data reported as below detection limits shall be entered into the statistical analysis as a value equal to one-half the practical quantitation limit (PQL) for the constituent unless the Administrator approves alternate statistical procedures. The PQL 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. A statistical evaluation is not necessary when all concentrations for a constituent are reported below the PQL. Samples reported with estimated concentrations shall be treated as valid measurements for statistical purposes; and
- (6.) If approved by the Administrator, the statistical method may include procedures to adjust data to account for seasonal and spatial variability, as well as temporal correlation.
- (VIII) The owner or operator must determine whether or not there is a statistically significant increase over background values as follows:
- (1.) The owner or operator must compare the groundwater quality of each parameter or constituent at each monitoring well using the approved statistical method; and
- (2.) Within thirty (30) days after completing sampling and analysis, unless an alternate time frame is approved by the administrator, the owner or operator must determine whether there has been a statistically significant increase over background at each monitoring well.
- (D) Detection monitoring:
- (I) Each facility shall institute a detection monitoring program by sampling each well at least semiannually, and testing each sample for the constituents specified in Appendix A and C, unless the Administrator:
- (1.) Deletes a constituent because the owner or operator shows that it is not likely to be contained in or derived from the waste disposed at the facility or unit;
- (2.) Establishes an alternate list of inorganic indicator parameters in lieu of some or all of the heavy metals, if the alternative parameters provide a reliable indication of inorganic releases from the facility or unit, considering the following factors:
- a. The types, quantities, and concentrations of constituents in wastes managed at the facility or unit;
- b. The mobility, stability, and persistence of waste constituents or their reaction products in the unsaturated zone beneath the facility or unit;
- c. The detectability of indicator parameters, waste constituents, and reaction products in the groundwater; and
- d. The concentration or values and coefficients of variation of monitoring parameters or constituents in the groundwater background; or
- (3.) Determines that a different, but no less frequent than annual, monitoring schedule is appropriate, considering the following factors:
- a. Lithology of the aquifer and unsaturated zone;
- b. Hydraulic conductivity of the aquifer and unsaturated zone;
- c. Groundwater flow rates;
- d. Minimum distance between the edge of the waste boundary at the facility or unit and the downgradient monitor well(s); and
- e. The classification of the aquifer.
- (II) A minimum of four (4) individual samples is required to be collected and analyzed from each well (background and downgradient) during the first year of sampling. At least one (1) sample must be collected and analyzed from each well during subsequent sampling events.
- (III) If there is a statistically significant increase over background for one or more Appendix A constituents in any well at the relevant point of compliance established by the Administrator pursuant to Section 7(f), the operator must:
- (1.) Notify the Administrator in a written report with supporting documentation and place a copy of the report in the facility operating record within fourteen (14) days and start assessment monitoring within ninety (90) days; or
- (2.) Demonstrate to the Administrator in writing that the statistically significant increase over background is not due to the solid waste disposal facility or unit, but that the difference is due to another source of pollution, error in sampling, analysis or statistical evaluation, or natural variation in groundwater quality. The owner or operator shall prepare a report documenting this demonstration, and following approval by the Administrator, place the report in the operating record for the facility. If the report is approved, the owner or operator shall continue detection monitoring. If, after ninety (90) days, a successful demonstration is not made, the owner or operator must initiate an assessment monitoring program.
- (E) Assessment monitoring for Appendix B constituents:
- (I) Assessment monitoring is required whenever a statistically significant increase over background water quality has been detected for an Appendix A constituent.
- (II) Within ninety (90) days of triggering an assessment monitoring requirement, and annually thereafter, the owner or operator must sample and analyze all downgradient monitor wells for all Appendix B constituents. A minimum of one (1) sample from each downgradient well must be collected during each annual sampling event. If any Appendix B constituent is detected for the first time in any downgradient well, the owner or operator must promptly collect a minimum of four (4) additional independent samples from each background and downgradient well. These samples must be analyzed for each Appendix B constituent which was detected in the initial assessment monitoring sampling event.
- (III) The Administrator may specify an appropriate subset of wells to be sampled and analyzed during assessment monitoring, and may delete Appendix B constituents from the monitoring requirements if it can be shown that the deleted constituents are not reasonably expected to be contained in or derived from the waste contained in the facility or unit. The Administrator may also specify an appropriate alternate frequency for the collection of the additional independent samples considering the following factors:
- (1.) Lithology of the aquifer and unsaturated zone;
- (2.) Hydraulic conductivity of the aquifer and unsaturated zone;
- (3.) Groundwater flow rates;
- (4.) Minimum distance between the facility or unit and the downgradient monitor well(s);
- (5.) Classification of the aquifer under Chapter 8 of the Water Quality Rules and Regulations; and
- (6.) Nature (fate and transport) of any constituents detected under assessment monitoring.
- (IV) After obtaining the results from any assessment monitoring sampling event the owner or operator must:
- (1.) Within fourteen (14) days, notify the Administrator in a written report and place a copy of the report in the operating record identifying the Appendix B constituents that have been detected;
- (2.) Within ninety (90) days, and on at least a semiannual basis thereafter, resample all wells, conduct analyses for all constituents required under detection monitoring of this section), and for all Appendix B constituents which have been detected under assessment monitoring , and record their concentrations in the operating record. At least one (1) sample must be collected from each well during each sampling event under this paragraph. The Administrator may approve an alternate sampling frequency, no less than annual, considering the factors in paragraph (b)(i)(E)(III) of this section;
- (3.) Establish background concentrations for any constituents detected for the first time; and
- (4.) Request in writing that the Administrator establish groundwater protection standards for all constituents detected.
- (V) Within thirty (30) days after completing sampling and analysis, unless an alternate time frame is approved by the administrator, the owner or operator must determine whether there has been a statistically significant increase over established groundwater protection standards at each monitoring well specified by the Administrator.
- (VI) If the concentrations of all Appendix B constituents are at or below background values using the approved statistical procedures, for two (2) consecutive sampling events, the owner or operator must notify the Administrator in writing and may return to detection monitoring.
- (VII) If the concentrations of any Appendix B constituents are above background values, but all concentrations are below the groundwater protection standard, using the approved statistical procedures, the owner or operator must continue assessment monitoring.
- (VIII) If one (1) or more Appendix B constituents are detected at statistically significant levels above the groundwater protection standard in any sampling event, the owner or operator must, within fourteen (14) days of this finding notify the Administrator of the constituents detected above the groundwater protection standard in a written report with supporting documentation, place a copy of the report in the operating record, and notify all appropriate, as determined by the administrator, local government officials in writing, and:
- (1.) Characterize the nature and extent of the release by installing additional monitor wells as necessary;
- (2.) Install at least one (1) additional monitor well at the facility boundary downgradient of the release and sample the well in accord with paragraph (b)(i)(E)(IV)(2.) of this section;
- (3.) Notify all persons who own or reside on the land that directly overlies any part of the plume of contamination, if that plume has migrated off-site; and
- (4.) Initiate an assessment of corrective measures within ninety (90) days; or
- (5.) Demonstrate to the Administrator in writing that the contamination was caused by another source, resulted from an error in sampling, analysis or statistical evaluation, or from natural variation in groundwater quality. The owner or operator shall prepare a report documenting this demonstration, and following approval by the Administrator, place the report in the operating record. If a successful demonstration is made, the owner or operator must continue monitoring under the assessment monitoring program, or may return to detection monitoring if all Appendix B constituents are at or below background. Until a successful demonstration is made, the owner or operator must comply with paragraph (b)(i)(E)(VII) of this section including initiating an assessment of corrective measures under Section 14 of this chapter.
- (IX) The owner or operator must request in writing that the Administrator establish a groundwater protection standard for each Appendix B constituent detected in the groundwater. The Administrator shall establish groundwater protection standards, which shall be:
- (1.) For constituents where a maximum contaminant level (MCL) has been promulgated, the MCL for that constituent;
- (2.) For constituents for which MCLs have not been promulgated, the background concentration; or
- (3.) For constituents for which the background level is higher than the MCL or health-based levels, the background concentration.
- (X) The Administrator may establish an alternative groundwater protection standard for constituents for which MCLs have not been established. These groundwater protection standards shall be health-based levels meeting the requirements of Chapter 8 of the Water Quality Rules and Regulations.
- (F) Assessment monitoring for Appendix C constituents:
- (I) Whenever there is a statistically significant increase over background for an Appendix C constituent with an MCL or a class of use based limit in the Wyoming Water Quality Rules and Regulations, the owner or operator shall:
- (1.) Notify the Administrator in a written report with supporting documentation and place a copy of the report in the operating record within fourteen (14) days of the finding of statistical significance.
- (2.) Request that the Administrator classify groundwater according to Wyoming Water Quality Rules and Regulations and establish groundwater protection standards for applicable Appendix C constituents.
- (II) After groundwater protection standards have been established, within thirty (30) days after completing sampling and analysis, unless an alternate time frame is approved by the administrator, the owner or operator shall determine if there has been a statistically significant increase over a groundwater protection standard in each downgradient well specified by the Administrator using a statistical method approved by the Administrator.
- (III) If one or more Appendix C constituents are detected at statistically significant levels above the groundwater protection standard, the owner or operator shall within fourteen (14) days notify the Administrator of the constituents detected above the groundwater protection standard in a written report with supporting documentation.
- (1.) Unless the owner or operator demonstrates that the statistically significant increase was caused by another source, resulted from an error in sampling, analysis, or statistical evaluation, or from natural variation in groundwater quality, the Administrator may require the owner or operator to characterize the nature and extent of the release.
- (2.) The owner or operator may be required to conduct an assessment of corrective measures and institute corrective actions approved by the Administrator.
- (ii) Groundwater monitoring data shall be provided to the administrator as follows:
- (A) Operators of all facilities shall submit paper copies of all groundwater monitoring data;
- (B) Operators shall also submit groundwater monitoring data electronically in a format specified by the administrator;
(c) Methane: - (i) Facilities shall be operated such that the concentration of methane at the facility boundary does not exceed the lower explosive limit (LEL) for methane and in facility structures does not exceed 25% of the LEL. If methane levels exceed these limits the operator must:
- (A) Immediately notify the Administrator and take steps to protect human health;
- (B) Within seven (7) days of detection, place a copy of the methane test data in the operating record, and a written description of the steps taken to protect human health; and
- (C) Within sixty (60) days of detection, implement a remediation plan which has been approved by the Administrator, and place a copy of that plan in the operating record.
- (ii) The Administrator may establish alternative schedules for demonstrating compliance with the requirements of paragraphs (c)(i)(B) and (c)(i)(C) of this section.
- (iii) Methane probe system design: Methane probe design, construction, installation and location shall be adequate to monitor compliance.
- (iv) Abandonment of methane probe boreholes: Abandoned methane probe boreholes shall be plugged and sealed as approved by the Administrator.
- (v) Analyses: Methane analyses shall be conducted at least quarterly using equipment capable of monitoring LEL and % volume methane and following the manufacturer's recommended procedures.
(d) Air monitoring: Air monitoring, if required, shall be conducted in accord with Air Quality Division regulations.
(e) Soil core monitoring: Soil core monitoring, if required, shall be conducted in accord with a plan approved by the Administrator.
(f) Vadose zone monitoring: Vadose zone monitoring, if required, shall be conducted in accord with a plan approved by the Administrator.