S.C. Code Regs. § 61-107.19.IV.E

Current through Register Vol. 48, No. 10, October 25, 2024

Section 61-107.19.IV.E - Groundwater Monitoring and Corrective Action

1. General Groundwater Monitoring Requirements.

a. All submittals made to the Department in compliance with this Section shall be signed and stamped by a qualified professional.

b. All Class Two landfills shall implement a groundwater monitoring program as follows:

(1) New Class Two landfills, or lateral expansions of existing Class Two landfills shall submit a groundwater monitoring plan to monitor the entire landfill that meets the requirements of this Section as part of the permit application; and,

(2) Existing Class Two landfills shall, within 180 days of the effective date of this regulation, submit to the Department either a groundwater detection monitoring plan that meets the requirements of this Section, or written notification that the landfill plans to cease accepting waste within one year or less from the effective date of this regulation. Within 180 days of the Department's approval of the groundwater detection monitoring plan, the monitoring system shall be installed at the landfill. Facilities that cease accepting waste within one year of the effective date of this regulation are exempt from the groundwater monitoring requirements outlined herein. Landfills meeting this exemption shall submit a closure plan to the Department within 180 days of the effective date of this regulation. Additional time may be allowed for the installation of the groundwater monitoring system with prior approval from the Department;

(3) Existing Class Two landfills which have been performing groundwater monitoring prior to the requirements of this regulation shall within 90 days of the effective date submit to the Department certification by a qualified professional that the existing groundwater monitoring program meets the intent of this regulation. Any changes necessary to the existing groundwater monitoring system to ensure compliance with this regulation should be discussed in the certification letter.

c. A groundwater monitoring system shall consist of a sufficient number of wells installed at appropriate locations and depths to yield representative groundwater samples from the uppermost aquifer that can determine if contamination has occurred due to a release from the landfill. There shall be a minimum of one well up-gradient and three wells down-gradient of the disposal unit. These wells shall:

(1) Represent the quality of background groundwater that has not been affected by the landfill; and,

(2) Represent the quality of groundwater passing from beneath the waste disposal area footprint. The downgradient monitoring system shall be installed as close as practical to the actual disposal area but no further than 150 feet from the actual disposal area unless previously installed with Department approval, and shall ensure detection of any groundwater contamination in the uppermost aquifer.

d. The number, spacing, and depths of the wells in the monitoring network shall be determined based upon site-specific technical information that shall include thorough characterization of:

(1) Aquifer thickness, groundwater flow rate, groundwater flow direction including seasonal and temporal fluctuations in groundwater flow; and,

(2) Saturated and unsaturated geologic units and fill materials overlying the uppermost aquifer, materials comprising the uppermost aquifer, and materials comprising the confining unit defining the lower boundary of the uppermost aquifer, including, but not limited to: thicknesses, stratigraphy, lithology, hydraulic conductivities, porosities and effective porosities.

e. Monitoring wells shall be approved by the Department prior to installation and shall be constructed, at a minimum, to the standards established in the South Carolina Well Standards, R.61-71.H.

(1) The permittee shall maintain an operating record that contains documentation of the design, installation, development, and abandonment of any monitoring wells, piezometers and other measurement, sampling, and analytical devices; and,

(2) The monitoring wells, piezometers, and other measurement, sampling, and analytical devices must be maintained and operated so that they perform to design specifications throughout the life of the monitoring program.

(3) All monitoring wells, piezometers or other environmental sampling locations shall be located by a South Carolina Certified Land Surveyor. For wells, the elevation of the ground surface and the elevation of the top of the well casing shall also be determined to the nearest 0.01 ft above mean sea level.

f. Routine groundwater monitoring shall continue while the facility is performing detection monitoring, assessment or remediation activities.

g. The groundwater monitoring program shall include consistent sampling and analysis procedures that are designed to ensure monitoring results that provide an accurate representation of groundwater quality. A laboratory certified by South Carolina under R.61-81 State Environmental Laboratory Certification Program for the sample preparations and analysis methods employed shall conduct all groundwater analysis required by this regulation.

(1) The permittee shall submit to the Department for review and approval, a sampling and analysis plan outlining procedures and protocols to be used at the facility. The plan shall include procedures and techniques for:

(a) Sample collection;

(b) Sample preservation and shipment;

(c) Analytical procedures;

(d) Chain of custody control; and,

(e) Quality assurance and quality control.

(2) The groundwater monitoring program shall include approved sampling and analytical methods that are appropriate for groundwater sampling and that accurately measure the constituents in groundwater samples. Analytical methods chosen shall have a practical quantitation limit (PQL) that is less than the Maximum Concentration Level (MCL) for those constituents that have a MCL as established by the State Primary Drinking Water RegulationR.61-58. Groundwater samples required by this regulation shall not be field-filtered prior to laboratory analysis.

(3) Groundwater potentiometric elevations shall be measured and recorded for each well prior to initiating sampling procedures each time groundwater is sampled. Groundwater elevations in wells must be measured on the same day to avoid temporal variations in groundwater elevations that could preclude an accurate determination of groundwater flow rate and direction. The permittee must determine the potentiometric surface of each aquifer unit comprising the uppermost aquifer and report the rate and direction of groundwater flow each time groundwater is sampled.

(4) The results and supporting documentation, e.g., field data sheets, laboratory quality assurance /quality control testing, for all groundwater sample analysis taken during detection monitoring shall be submitted to the Department in accordance with the reporting requirements in this Subpart.

h. The permittee shall submit to the Department on or before the anniversary date of issuance of the permit, an annual report for the previous year containing the results of the requirements of this Section. The annual report shall contain the following:

(1) A summary of all analytical testing performed at the site during the previous year, and any applicable data concerning sampling and analysis of monitoring wells at the site;

(2) A determination of the technical sufficiency of the monitoring well network in detecting a release from the facility;

(3) A determination of groundwater elevations, groundwater flow directions and groundwater flow rates as specified in Section E.1.g. (3) above. Groundwater flow directions shall be based upon interpretation of a potentiometric map prepared utilizing the groundwater elevations measured at the site; and,

(4) Recommendations for any changes to the groundwater monitoring system, or any necessary actions to be performed at the site to ensure compliance with the groundwater monitoring requirements.

2. Groundwater Detection Monitoring Requirements.

a. Groundwater detection monitoring is required at Class Two solid waste landfills. The detection monitoring program shall include at a minimum, monitoring for the constituents listed in Appendix III.

(1) The Department may require additional groundwater monitoring parameters for routine monitoring based on the chemical and physical nature of the waste stream received by the landfill.

(2) The Department may delete specific monitoring parameters for a Class Two solid waste landfill if it can be shown that the constituent(s) are not reasonably expected to be contained in or derived from the waste contained in the unit. The deletion of specific constituents will be based on the permittee's knowledge of each waste stream disposed of in the facility and the operational controls of the facility.

b. For Class Two solid waste landfills, the detection monitoring frequency for all constituents required by this subpart shall be at least semiannual during the active life of the facility (including closure) and annual during the post-closure period. At least one sample from each well (background and downgradient) shall be collected and analyzed during each sampling event.

c. For Class Two solid waste landfills, the Department may approve an appropriate alternate frequency for repeated sampling and analysis for the constituents listed in Appendix III during the active life (including closure) and the post-closure care period to ensure protection of human health and the environment. The alternative frequency during the active life (including closure) shall be no less than the frequency specified in Section E.2.b. above. The alternative frequency shall be based on consideration of 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 upgradient edge of the Class Two solid waste landfill footprint and downgradient monitoring well screen (minimum distance of travel); and

(5) Resource value of the aquifer.

d. During semiannual groundwater sampling, the two sampling events shall be scheduled approximately six (6) months apart. The submittal of data for one of the sampling events shall meet annual report requirements outlined in E.1.h.. For the other semiannual sampling event, the analytical data only shall be submitted to the Department. In all cases, the groundwater analytical results shall be submitted to the Department within 60 days of sample collection. In cases where the Department has approved an alternate sampling frequency, the Department will approve an appropriate schedule for submittal of groundwater data.

e. If the permittee determines that groundwater concentrations are above the PQL but below the MCL for any constituent listed in Appendix III, at any monitoring well (unless the constituent is being addressed by Section E.3. below) the permittee shall:

(1) Place a notice in the operating record showing which constituents have shown an exceedance above the PQL; and,

(2) Provide a notification of the results to the Department in the next regularly scheduled report and provide a discussion on the cause of this result.

f. If the permittee determines that groundwater concentrations are above the MCL, for any constituent listed in Appendix III at any monitoring well, the permittee shall:

(1) Notify the Department within 14 days of receiving the analytical results;

(2) Resample the monitoring well(s) in question for the constituents(s) in question to determine the validity of the data within 30 days of receiving the analytical results, unless the Department approves an alternate frequency. If the permittee chooses not to resample, then the initial exceedance(s) of the MCL shall be considered valid;

(3) Within 14 days of receiving the results of validation sampling required by Section E.2.f. (2) above, place a notice in the operating record and notify the Department of the results of the resampling;

(4) If resampling does not validate that the results are above applicable levels, return to routine detection monitoring; or,

(5) If resampling does validate the initial exceedance of the MCL, then establish an assessment monitoring program meeting the requirements of Section E.3. within 90 days of receiving the results of validation sampling required by Section E.2.f. (2), except as provided for in Section E.2.g. below.

g. The permittee may demonstrate that a source other than the Class Two landfill caused the contamination or that the concentration resulted from an error in sampling, analysis, or natural variation in groundwater quality. A report documenting this demonstration shall be placed in the operating record after being signed and stamped by a qualified professional and approved by the Department. If a successful demonstration is made and documented, the permittee may continue detection monitoring as specified in this Section. If, after 90 days of completing Section E.2.f. (2) above, a successful demonstration is not made, the permittee shall initiate an assessment monitoring program as required in Section E.3.

3. Assessment of Groundwater Impact.

a. Assessment monitoring is required whenever a release has been detected and validated, in accordance with Section E.2.f. above for any constituent listed in Appendix III, unless a successful demonstration has been made in accordance with Section E.2.g. above.

b. Within 90 days of validating an exceedance as outlined in E.2.f. (2), the permittee shall sample all groundwater monitoring wells identified as impacted for all constituents listed in Appendix V. Any additional constituents detected during this sampling shall be added to the assessment program.

c. The permittee shall establish a groundwater protection standard for each constituent detected in the groundwater. The groundwater protection standard shall be:

(a) For constituents for which a MCL has been promulgated under South Carolina R.61-58, State Primary Drinking Water Regulations, the MCL for that constituent;

(b) For constituents for which MCLs have not been promulgated, the drinking water risk-based number recognized by EPA Region IV; or,

(c) For constituents for which the background level is higher than the MCL identified under Section E.3.b. (3)(a) above or risk-based concentration identified under Section E.3.b. (3)(b) above, as applicable, the background concentration.

(d) For any parameter for which a groundwater protection standard cannot be established per E.3.c. (a), (b), or (c) above, the Department, using input from the permittee, will develop an appropriate groundwater protection standard. In establishing this groundwater protection standard, the Department may consider the following provided these criteria meet the intent of the South Carolina Water Classifications and Standards R.61-68:

(1) Multiple contaminants in the groundwater;

(2) Exposure threats to sensitive environmental receptors; and,

(3) Other site-specific exposure or potential exposure to groundwater.

d. The permittee shall submit to the Department for review and approval a groundwater quality assessment plan for characterizing the nature and extent of the release within 90 days of receiving the results of the sampling outlined in Section E.3.b. above. The groundwater quality assessment plan shall:

(a) Ensure that the nature and extent of the release is fully characterized by installing additional monitoring wells, as necessary;

(b) Install at least one additional monitoring well at the facility boundary in the direction of contaminant migration and sample this well in accordance with this section;

(c) In cases where contamination is present at the property boundary, take reasonable measures to gain access for offsite sampling;

(d) Notify all persons who own the land or reside on the land that directly overlies any part of the plume of contamination if contaminants have migrated off-site if indicated by sampling of wells in accordance with this section; and,

(e) Contain a detailed schedule for the implementation and completion of the provisions of the plan.

e. Upon completion of assessment activities outlined in this section, the permittee shall initiate an assessment of corrective measures as required by Section E.4.a. below within 90 days.

f. Based upon the outcome of the assessment outlined in this section, the Department may add additional monitoring wells, additional constituents, or additional sampling frequency to the routine detection monitoring program, required by Section E.2.above.

4. Groundwater Remediation.

a. Upon completion of the groundwater quality assessment, the permittee shall evaluate potential corrective actions to address groundwater quality. Based on the outcome of this evaluation, the permittee shall select a remedial action strategy and submit a remedial action plan to be approved by the Department. The remedial action plan shall contain a schedule for the initiation and completion of remedial activities.

b. The remedial action plan shall:

(1) Be protective of human health and the environment;

(2) Attain the groundwater protection standard as specified pursuant to Section E.3.b. (3) above;

(3) Control the source(s) of releases so as to reduce or eliminate, to the maximum extent practicable, further releases of constituents into the environment that may pose a threat to human health or the environment;

(4) Consider the long- and short-term effectiveness and protectiveness of the potential remedy(s), along with the degree of certainty that the remedy will prove successful based on consideration of the following:

(a) Magnitude of reduction of existing risks;

(b) Magnitude of residual risks in terms of likelihood of further releases due to waste remaining following implementation of a remedy;

(c) The type and degree of long-term management required, including monitoring, operation, and maintenance;

(d) Short-term risks that might be posed to the community, workers, or the environment during implementation of such a remedy, including potential threats to human health and the environment associated with excavation, transportation, and redisposal or containment;

(e) Time until full protection is achieved;

(f) Potential for exposure of humans and environmental receptors to remaining wastes, considering the potential threat to human health and the environment associated with excavation, transportation, redisposal, or containment;

(g) Long-term reliability of the engineering and institutional controls; and,

(h) Potential need for replacement of the remedy.

(5) Consider the effectiveness of the remedy in controlling the source to reduce further releases based on the extent to which containment practices will reduce further releases; and,

(6) Contain monitoring considerations to prove the effectiveness of the selected remedial action, which may be in addition to those constituents contained in the detection monitoring program.

c. The Department may determine that remediation of a release of a constituent from a Class Two landfill is not necessary if the permittee satisfactorily demonstrates to the Department that:

(1) The groundwater is additionally contaminated by substances that have originated from a source other than the Class Two solid waste landfill and those substances are present in concentrations such that cleanup of the release from the Class Two solid waste landfill would provide no significant reduction in risk to actual or potential receptors; or,

(2) The constituent(s) is present in groundwater that:

(a) Does not currently meet the definition of an underground source of drinking water per South Carolina Water Classifications and Standards R.61-68; and,

(b) Is not hydraulically connected with waters to which the constituents are migrating or are likely to migrate in a concentration(s) that would exceed the groundwater protection standards established under Section E.3.c. above; or,

(3) Remediation of the release(s) is technically impracticable; or,

(4) Remediation results in unacceptable cross-media impacts.

d. A determination by the Department pursuant to Section E.4.c.above shall not affect the authority of the Department to require the permittee to undertake source control measures or other measures that may be necessary to eliminate or minimize further releases to the groundwater, to prevent exposure to the groundwater, or to remediate the groundwater to concentrations that are technically practicable and significantly reduce threats to human health or the environment.

e. During the course of implementing the corrective action, the permittee may be required to take any interim measures necessary to ensure the protection of human health and the environment. Interim measures should, to the greatest extent practicable, be consistent with the objectives of and contribute to the performance of any remedy that may be required pursuant to this section. A permittee in determining whether interim measures are necessary shall consider the following factors:

(1) Time required to develop and implement a final remedy;

(2) Actual or potential exposure of nearby populations or environmental receptors to hazardous constituents;

(3) Actual or potential contamination of drinking water supplies or sensitive ecosystems;

(4) Further degradation of the groundwater that may occur if remedial action is not initiated expeditiously;

(5) Weather conditions that may cause hazardous constituents to migrate or be released;

(6) Risks of fire or explosion, or potential for exposure to hazardous constituents as a result of an accident or failure of a container or handling system; and,

(7) Other situations that may pose threats to human health and the environment.

f. If the permittee determines that compliance with requirements of this section cannot be practically achieved with any currently available methods, the permittee shall:

(1) Obtain certification of a qualified professional and approval by the Department, that compliance with requirements under Section E.4. cannot be practically achieved with any currently available methods;

(2) Implement alternate measures to control exposure of humans or the environment to residual contamination, as necessary to protect human health and the environment; and,

(3) Implement alternate measures for control of the sources of contamination, or for removal or decontamination of equipment, units, devices, or structures that are:

(a) Technically practicable; and,

(b) Consistent with the overall objective of the remedy.

g. Upon completion of the remedy, the permittee shall submit to the Department a certification signed by a qualified professional stating that the remedy has been completed in compliance with the requirements of Section E.4.

h. Upon the Department's approval of the certification required in Section E.4.g. above, the Class Two landfill shall return to detection monitoring as outlined in Section E.2. of this Part.

S.C. Code Regs. 61-107.19.IV.E