Okla. Admin. Code § 252:517-9-6

Current through Vol. 41, No. 19, June 17, 2024

Section 252:517-9-6 - Assessment monitoring program

(a)Assessment monitoring required. Assessment monitoring is required whenever a statistically significant increase over background levels has been detected for one or more of the constituents listed in Appendix A to this Chapter.

(b)Initiation and number of samples. Within 90 days of triggering an assessment monitoring program, and annually thereafter, the owner or operator of the CCR unit must sample and analyze the groundwater for all constituents listed in Appendix B to this Chapter. The number of samples collected and analyzed for each well during each sampling event must be consistent with OAC 252:517-9-4(f), and must account for any unique characteristics of the site, but must be at least one sample from each well.

(c)Alternative monitoring frequency. The owner or operator of a CCR unit may demonstrate the need for an alternative monitoring frequency for repeated sampling and analysis for constituents listed in Appendix B to this Chapter during the active life and the post-closure care period based on the availability of groundwater. If there is not adequate groundwater flow to sample wells semiannually, the alternative frequency shall be no less than annual. The need to vary monitoring frequency must be evaluated on a site-specific basis and approved by the DEQ. The demonstration must be supported by, at a minimum, the information specified in paragraphs (c)(1) and (2) of this Section.

(1) The alternative sampling frequency must be based on consideration of the following factors:

(A) Lithology of the aquifer and unsaturated zone;

(B) Hydraulic conductivity of the aquifer and unsaturated zone; and

(C) Groundwater flow rates.

(2) Information documenting that the alternative frequency will be no less effective in ensuring that any leakage from the CCR unit will be discovered within a timeframe that will not materially delay the initiation of any necessary remediation measures.

(3) The owner or operator must obtain a certification from a qualified professional engineer stating that the demonstration for an alternative groundwater sampling and analysis frequency meets the requirements of this Section. The owner or operator must include the demonstration providing the basis for the alternative monitoring frequency and the certification by a qualified professional engineer in the annual groundwater monitoring and corrective action report required by OAC 252:517-9-1(e).

(d)Action required. After obtaining the results from the initial and subsequent sampling events required in paragraph (b) of this Section, the owner or operator must:

(1) Within 90 days of obtaining the results, and on at least a semiannual basis thereafter, resample all wells that were installed pursuant to the requirements of OAC 252-517-9-2, conduct analyses for all parameters in Appendix A to this Chapter and for those constituents in Appendix B to this Chapter that are detected in response to paragraph (b) of this Section, and record their concentrations in the facility operating record. The number of samples collected and analyzed for each background well and downgradient well during subsequent semiannual sampling events must be consistent with OAC 252:517-9-4(f), and must account for any unique characteristics of the site, but must be at least one sample from each background and downgradient well;

(2) Establish groundwater protection standards for all constituents detected pursuant to paragraph (b) or (d) of this Section. The groundwater protection standards must be established in accordance with paragraph (h) of this Section; and

(3) Include the recorded concentrations required by paragraph (d)(1) of this Section, identify the background concentrations established under OAC 252:517-9-5(b), and identify the groundwater protection standards established under paragraph (d)(2) of this Section in the annual groundwater monitoring and corrective action report required by OAC 252:517-9-1(e).

(e)Concentrations below background. If the concentrations of all constituents listed in Appendices A and B to this Chapter are shown to be at or below background values, using the statistical procedures in OAC 252:517-9-4(g), for two consecutive sampling events, the owner or operator may return to detection monitoring of the CCR unit, with DEQ approval. The owner or operator must prepare a notification stating that detection monitoring is resuming for the CCR unit. The owner or operator has completed the notification when the notification is placed in the facility's operating record as required by OAC 252:517-19-1(h)(7).

(f)Concentrations above background. If the concentrations of any constituent in Appendices A and B to this Chapter are above background values, but all concentrations are below the groundwater protection standard established under paragraph (h) of this Section, using the statistical procedures in OAC 252:517-9-4(g), the owner or operator must continue assessment monitoring in accordance with this Section.

(g)Concentration above groundwater protection standard. If one or more constituents in Appendix B to this Chapter are detected at statistically significant levels above the groundwater protection standard established under paragraph (h) of this Section in any sampling event, the owner or operator must prepare a notification identifying the constituents in Appendix B to this Chapter that have exceeded the groundwater protection standard and submit to DEQ, a proposed plan and schedule for analyzing the environmental release from the facility and for developing appropriate corrective action. The owner or operator has completed the notification when the notification is placed in the facility's operating record as required by OAC 252:517-19-1(h)(8). The owner or operator of the CCR unit also must:

(1) Characterize the nature and extent of the release and any relevant site conditions that may affect the remedy ultimately selected. The characterization must be sufficient to support a complete and accurate assessment of the corrective measures necessary to effectively clean up all releases from the CCR unit pursuant to OAC 252:517-9-7. Characterization of the release includes the following minimum measures:

(A) Install additional monitoring wells necessary to define the contaminant plume(s);

(B) Collect data on the nature and estimated quantity of material released including specific information on the constituents listed in Appendix B of this Chapter and the levels at which they are present in the material released;

(C) Install at least one additional monitoring well at the facility boundary in the direction of contaminant migration and sample this well in accordance with paragraph (d)(1) of this Section; and

(D) Sample all wells in accordance with paragraph (d)(1) of this Section to characterize the nature and extent of the release.

(2) 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 paragraph (g)(1) of this Section. The owner or operator has completed the notifications when they are placed in the facility's operating record as required by OAC 252:517-19-1(h)(8).

(3) Within 90 days of finding that any of the constituents listed in Appendix B to this Chapter have been detected at a statistically significant level exceeding the groundwater protection standards the owner or operator must either:

(A) Initiate an assessment of corrective measures as required by OAC 252:517-9-7; or

(B) Demonstrate that a source other than the CCR unit caused the contamination, or that the statistically significant increase resulted from error in sampling, analysis, statistical evaluation, or natural variation in groundwater quality. Any such demonstration must be supported by a report that includes the factual or evidentiary basis for any conclusions, must be certified to be accurate by a qualified professional engineer, and submitted to DEQ for approval. If a successful demonstration is made, the owner or operator must continue monitoring in accordance with the assessment monitoring program pursuant to this Section, and upon DEQ approval may return to detection monitoring if the constituents in Appendices A and B to this Chapter are at or below background as specified in paragraph (e) of this Section. The owner or operator must also include the demonstration in the annual groundwater monitoring and corrective action report required by OAC 252:517-9-1(e), in addition to the certification by a qualified professional engineer.

(4) If a successful demonstration has not been made at the end of the 90 day period provided by paragraph (g)(3)(B) of this Section, the owner or operator of the CCR unit must initiate the assessment of corrective measures requirements under OAC 252:517-9-7.

(5) The owner or operator must prepare a notification stating that an assessment of corrective measures has been initiated.

(h)Groundwater protection standard. The owner or operator of the CCR unit must establish a groundwater protection standard for each constituent in Appendix B to this Chapter detected in the groundwater. The groundwater protection standard shall be:

(1) For constituents for which a maximum contaminant level (MCL) has been established under 40 CFR 141.62 and 141.66, the MCL for that constituent;

(2) For the following constituents:

(A) Cobalt: 6 micrograms per liter (µg/L);

(B) Lead: 15 µg/L;

(C) Lithium: 40 µg/L; and

(D) Molybdenum: 100 µg/L;

(3) For constituents for which the background level is higher than the levels identified under paragraphs (h)(1) and (h)(2) of this Section, the background concentration.

(i)Recordkeeping. The owner or operator of the CCR unit must comply with the recordkeeping requirements specified in OAC 252:517-19-1(h), the notification requirements specified in OAC 252:517-19-2(g), and the Internet requirements specified in OAC 252:517-19-3(h).

Okla. Admin. Code § 252:517-9-6

Adopted by Oklahoma Register, Volume 33, Issue 24, September 1, 2016, eff. 9/15/2016

Amended by Oklahoma Register, Volume 38, Issue 24, September 1, 2021, eff. 9/15/2021