020-3 Wyo. Code R. §§ 3-9 - Monitoring 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) Industrial landfills shall comply with the following groundwater monitoring requirements:

(A) Applicability:

(I) Once established at a facility or unit, the groundwater monitoring program required under this Section shall be conducted throughout the active life and post-closure care period, unless modified by the Administrator.

(II) The Administrator may establish an alternate schedule for compliance with any deadline specified in paragraphs (b)(i)(B) through (E) of this Section.

(III) The Administrator may suspend the groundwater monitoring requirements of this Section if the operator demonstrates that there is no potential for migration of hazardous 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 solid 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.

(IV) The groundwater monitoring requirements of this Section do not apply to:

(1.) Industrial landfills which ceased receiving solid wastes before January 1, 1998;

(2.) Industrial landfills which do not receive very small quantity generator (VSQG) hazardous wastes; or

(3.) Industrial landfills which accept less than twenty tons of solid waste per day (annual average) for disposal, have no evidence of existing groundwater contamination, serve communities that have no practicable solid waste management alternatives and are located in an area that receives less than or equal to twenty-five inches of precipitation annually.

(B) Groundwater monitoring systems:

(I) A groundwater monitoring system must be installed with a sufficient number of groundwater monitoring wells to monitor water from the uppermost aquifer that may be affected by leakage from the facility. The system must be capable of monitoring the background water quality and groundwater passing the relevant point of compliance pursuant to Section 7(g) of this Chapter. Groundwater monitoring well locations must be approved by the Administrator, and downgradient groundwater monitoring wells shall be placed in locations within 150 meters (492 feet) of the solid 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 solid waste disposal units, if the system is determined to be capable of adequately detecting groundwater pollution. In approving a facility-wide groundwater monitoring system, the Administrator shall consider:

(1.) Number, spacing, and orientation of the individual solid waste units at the facility;

(2.) Hydrologic setting;

(3.) Site history and design; and

(4.) Type of solid waste accepted at the individual solid 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), soil information, and 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 shall meet the requirements of Chapter 2, Section 9(b)(i)(C)(I) through (VII).

(D) Detection monitoring:

(I) Each facility shall institute a detection monitoring program by sampling each groundwater monitoring well at least semiannually and testing each sample for the constituents specified in Appendix A, unless the Administrator:

(1.) Deletes a constituent because the operator shows that it is not likely to be present in the solid waste disposed at the facility;

(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 solid wastes managed at the facility or unit;

b. The mobility, stability, and persistence of solid waste constituents or their reaction products in the groundwater;

c. The detectability of indicator parameters, solid 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 solid waste boundary at the facility or unit and the downgradient groundwater monitoring well(s); and

e. The classification of the aquifer under Chapter 8 of the Water Quality Rules.

(II) A minimum of four individual samples must be collected and analyzed from each groundwater monitoring well (background and downgradient) during the first year of sampling. At least one sample must be collected and analyzed from each groundwater monitoring well during subsequent sampling events.

(III) If a statistically significant difference in water quality between background and any groundwater monitoring well at the relevant point of compliance is detected, 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 days and start assessment monitoring within ninety days; or

(2.) Demonstrate to the Administrator 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 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 operator shall continue detection monitoring. If, after ninety days, a successful demonstration is not made, the operator must initiate an assessment monitoring program.

(E) Assessment monitoring:

(I) Assessment monitoring is required whenever a statistically significant increase over background water quality has been detected, subject to the exception in paragraph (b)(i)(D)(III)(2.) of this Section.

(II) Within ninety days of triggering an assessment monitoring requirement, and annually thereafter, the operator must sample and analyze all downgradient groundwater monitoring wells for all Appendix B constituents. A minimum of one sample from each downgradient groundwater monitoring well must be collected during each annual sampling event. If any Appendix B constituent is detected for the first time in any downgradient groundwater monitoring well, the owner or operator must promptly collect a minimum of four 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 groundwater monitoring 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 solid 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 and the downgradient groundwater monitoring well(s);

(5.) Classification of the aquifer under Chapter 8 of the Water Quality Rules; 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 operator must:

(1.) Within fourteen 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 days, and on at least a semiannual basis thereafter, resample all groundwater monitoring wells, conduct analyses for all constituents required under detection monitoring of this Section, and for all Appendix B constituents that have been detected under assessment monitoring, and record their concentrations in the operating record. At least one must be collected from each groundwater monitoring 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 days after completing sampling and analysis, unless an alternate time-frame is approved by the Administrator, the operator must determine whether there has been a statistically significant increase over established groundwater protection standards at each groundwater monitoring well specified by the Administrator.

(VI) If the concentrations of all Appendix B constituents are at or below background values for two consecutive sampling events, the operator must notify the Administrator and may return to detection monitoring under this Section.

(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 operator must continue assessment monitoring.

(VIII) If one or more Appendix B constituents are detected at statistically significant levels above the groundwater protection standard in any sampling event, the operator must, within fourteen days of this finding, notify the Administrator of the constituents detected above the groundwater protection standard in a written report with supporting documentation and place a copy of the report in the operating record. The operator must notify all local government officials in writing, as determined by the Administrator, and:

(1.) Characterize the nature and extent of the release by installing additional groundwater monitoring wells as necessary;

(2.) Install at least one additional groundwater monitoring well at the facility boundary downgradient of the release and sample the groundwater monitoring well in accordance 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 a plume of contamination that migrated off-site; and

(4.) Initiate an assessment of corrective measures within ninety days; or

(5.) Demonstrate to the Administrator in writing that the contamination was caused by another source or resulted from an error in sampling, analysis or statistical evaluation, or from natural variation in groundwater quality. The 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 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 operator must comply with paragraph (b)(i)(E)(VIII) of this Section including initiating an assessment of corrective measures under Section 13 of this Chapter.

(IX) The 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 for such constituents, 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 level established under subsection (b)(i)(E)(X), 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. For constituents where a MCL does not exist, the alternative groundwater protection standard shall be the more stringent standard meeting the requirements of Water Quality Rules, Chapter 8, Table 1 based on groundwater class of use or the Drinking Water Equivalent Level as determined by the procedures found in the Storage Tank Rules Chapter 1, Section 39(e).

(ii) Industrial landfills excluded from groundwater monitoring requirements under paragraph (b)(i)(A)(IV) of this Section, shall, if required by the Administrator, comply with the following groundwater monitoring and corrective action requirements:

(A) Groundwater monitoring well placement: All facilities required to install groundwater monitoring wells shall place them in locations approved by the Administrator. Following initial placement of the groundwater monitoring wells, the operator shall confirm that the groundwater monitoring wells are capable of measuring groundwater quality that is representative of conditions hydraulically upgradient and downgradient of the solid waste disposal facility.

(B) Groundwater monitoring well design, construction/installation and abandonment: All groundwater monitoring wells shall be designed, constructed and installed in accordance with the Water Quality Rules Chapter 26 requirements. All abandoned groundwater monitoring wells shall be plugged and sealed in accordance with the Water Quality Rules Chapter 26 requirements.

(C) Permits required: Prior to groundwater monitoring well installation, the groundwater monitoring well design, construction and location specifications shall be approved by the Administrator.

(D) Analyses:

(I) Baseline monitoring: The initial groundwater samples shall be analyzed for pH, Total Dissolved Solids (TDS), Chemical Oxygen Demand (COD), Total Organic Carbon (TOC), Ammonia as N, Nitrate as N, Bicarbonate, Carbonate, Chloride, Fluoride, Calcium, Magnesium, Potassium, Sodium, Sulfate, Copper, Iron, Manganese, Nickel, Zinc, Arsenic, Barium, Cadmium, Chromium, Cyanide, Lead, Mercury, Selenium, and Silver. Additionally, water temperature, specific conductance, pH and static water level shall be measured in the field during each baseline monitoring event. The length of this baseline monitoring period shall not exceed one year, and samples shall be obtained at least quarterly during this period.

(II) Detection monitoring: Following the initial baseline monitoring period, the Administrator may specify a reduced set of sampling parameters to be analyzed at least semi-annually. The reduced set of parameters shall include, at a minimum: pH, temperature, static water level, Total Dissolved Solids (TDS), Chlorides, Ammonia (as N), Iron, Hardness, and Total Organic Carbon (TOC). Additionally, water temperature, specific conductance, pH, and static water level shall be measured in the field during each semi-annual monitoring event.

(III) Assessment monitoring: Should groundwater monitoring data cause the Administrator to determine the facility may be impacting groundwater quality, additional groundwater monitoring wells, a revised set of sampling parameters, and a revised sampling schedule may be required by the Administrator to define the nature and extent of contamination.

(IV) The Administrator may specify alternative or additional water quality parameters for analyses, including organic chemical constituents, based on the Administrator's review of the solid wastes likely to be disposed at any specific solid waste disposal facility.

(E) Corrective actions: Whenever there is a release of contamination which adversely impacts groundwater quality, the operator shall institute corrective actions approved by the Administrator, as specified in Section 13 of this Chapter.

(iii) Operators of industrial landfills that are subject to the groundwater monitoring requirements shall 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 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 days of detection, place a copy of the methane test data and a written description of the steps taken to protect human health in the operating record; and

(C) Within sixty days of detection, implement a remediation plan that 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) 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 in accordance with Department recommendations.

(v) Analyses: Methane analyses shall be conducted at least quarterly, if required, using equipment capable of monitoring LEL and percent volume methane and following the manufacturer's recommended procedures.

(d) Air monitoring: Air monitoring, if required, shall be conducted in accordance with the Air Quality Rules.

(e) Soil core monitoring: Soil core monitoring, if required, shall be conducted in accordance with a plan approved by the Administrator.

(f) Vadose zone monitoring: Vadose zone monitoring, if required, shall be conducted in accordance with a plan approved by the Administrator.

Notes

020-3 Wyo. Code R. §§ 3-9

Adopted, Eff. 1/13/2023.