North Carolina Administrative Code › Title 15A - Environmental Quality › Chapter 13 - SOLID WASTE MANAGEMENT › Subchapter B - SOLID WASTE MANAGEMENT › Section .1600 - REQUIREMENTS FOR MUNICIPAL SOLID WASTE LANDFILL FACILITIES (MSWLFS) › Section 13B .1634 - ASSESSMENT MONITORING PROGRAM

Current through Register Vol. 39, No. 2, July 15, 2024
(a)
				  Assessment monitoring shall be required if, in any sampling event, one or more
				  constituents listed in 40
				  CFR 258 Appendix I is detected above the
				  groundwater quality standards or interim maximum allowable concentrations
				  (IMACs) established in accordance with
				  15A NCAC
				  02L .0202, or the groundwater protection
				  standards established in accordance with Paragraph (b) of this Rule.
(b) Assessment Requirements. Within 90 days
				  of triggering an assessment monitoring program in accordance with Rule
				  .1633(d)(2) of this Section, the owner or operator shall conduct an assessment
				  in accordance with the following:
(1) Install
				  additional wells downgradient of the compliance wells where exceedances have
				  been detected to characterize the nature and extent of the contamination. The
				  additional wells shall include no less than one additional groundwater
				  monitoring well at the facility's property boundary or the compliance boundary,
				  as defined in
				  15A NCAC
				  02L .0102, in the direction of contaminant
				  migration most likely to show impact based on the established geology and
				  hydrogeology.
(2) Collect no less
				  than one groundwater sample from each downgradient monitoring well, including
				  any well installed in accordance with Subparagraph (1) of this Paragraph, and
				  analyze for the constituents listed in
				  40 CFR
				  258 Appendix II. The Division may remove any
				  of the 40 CFR
				  258 Appendix II constituents, not also listed
				  in Appendix I, from the monitoring list for a MSWLF unit if the owner or
				  operator can show that the constituents proposed for removal are not expected
				  to be in or derived from the waste contained in the unit. After the initial
				  sampling event, for any constituent detected in the downgradient wells as a
				  result of the Appendix II analysis, no less than three additional independent
				  samples from each downgradient monitoring well and no less than four
				  independent samples from each background well shall be collected and analyzed
				  to establish a baseline for the new detected constituents. Once determined,
				  baseline data for the new detected constituents shall be reported to the
				  Division.
(3) For constituents that
				  do not have a groundwater quality standard or IMAC established in accordance
				  with 15A
				  NCAC 02L .0202, the Division shall establish
				  a groundwater protection standard for each constituent detected in groundwater.
				  The groundwater protection standard shall be the most protective of the
				  following:
(A) for constituents for which a
				  maximum contaminant level (MCL) has been promulgated under
				  40 CFR
				  141, the MCL for that constituent;
(B) for constituents for which a public water
				  quality standard has been established under
				  15A NCAC
				  18C, the public water quality standard for
				  that constituent; or
(C) for
				  constituents for which no MCLs or public water quality standards have been
				  promulgated, the background concentration for the constituent established from
				  the monitoring wells required in accordance with Rules .1631(a)(1) and .1632 of
				  this Section.
(4) The
				  Division may establish an alternative groundwater protection standard for
				  constituents for which no MCL or public water quality standard have been
				  established. These groundwater protection standards shall be health-based
				  levels that satisfy the following criteria:
(A) the level is derived in a manner
				  consistent with U.S. E.P.A. guidelines provided in
				  40 CFR
				  258.55(i)(1) for assessing
				  the health risks of environmental pollutants;
(B) the level is based on scientifically
				  valid studies conducted in accordance with
				  40 CFR
				  792;
(C) for carcinogens, the level represents a
				  concentration associated with an excess lifetime cancer risk level due to
				  continuous lifetime exposure of 1 x 10-6;
				  and
(D) for systemic toxicants, the
				  level represents a concentration to which the human population, including
				  sensitive subgroups, could be exposed on a daily basis that is likely to be
				  without appreciable risk of deleterious effects during a lifetime. For the
				  purposes of this Rule, systemic toxicants include toxic chemicals that cause
				  effects other than cancer or mutation.
(5) In establishing groundwater protection
				  standards under this Paragraph, the Division shall consider the following:
(A) multiple contaminants in the
				  groundwater;
(B) exposure threats
				  to sensitive environmental receptors; and
(C) other site-specific exposure or potential
				  exposure to groundwater.
(6) The owner or operator may request that
				  the Division approve a background level for the unit that is higher than the
				  groundwater quality standard or IMAC established in
				  15A NCAC
				  02L .0202 or the groundwater protection
				  standard established in Subparagraph (3) or (4) of this Paragraph. The
				  background level shall be established in accordance with Rule .1632(e) of this
				  Section. The approved background level shall be the established groundwater
				  protection standard.