New Mexico Administrative Code › Title 20 - ENVIRONMENTAL PROTECTION › Chapter 6 - WATER QUALITY › Part 7 - GROUND WATER PROTECTION - SUPPLEMENTAL PERMITTING REQUIREMENTS FOR COPPER MINE FACILITIES › Section 20.6.7.35 - POST-CLOSURE REQUIREMENTS

Current through Register Vol. 35, No. 13, July 16, 2024
For each unit closed at a copper mine facility, the closure
				  period shall cease, and the post-closure period shall commence, following the
				  permittee's submission and department approval of a final CQA/CQC report that
				  includes as-built drawings and a closure report documenting completion of
				  regrading, covering, seeding, and construction of any other elements required
				  for closure of a unit. The post-closure period for a copper mine facility or
				  unit shall begin when the final CQA report is approved and only monitoring,
				  inspections, maintenance, or operation of a closure water treatment and
				  management plan remain to be conducted. During the post-closure period, a
				  permittee shall conduct post-closure monitoring, inspection, reporting,
				  maintenance, and implementation of contingency actions as specified by this
				  section. The post-closure period shall end for a unit of a copper mine facility
				  upon the completion of post-closure monitoring, inspection and maintenance for
				  the unit as required by this section. The post-closure period shall cease when
				  all monitoring, inspections, maintenance, and operation of the water management
				  and treatment plan required under this section may cease. For units of a copper
				  mine facility subject to an abatement plan, monitoring, inspection, reporting,
				  and operation of abatement systems shall be conducted in accordance with the
				  approved abatement plan rather than this section.
A.
Interceptor system
				inspections.
A permittee shall perform quarterly inspections and annual
				evaluations of all interceptor systems and perform maintenance as necessary to
				ensure that the systems are performing as designed and are functioning in a
				manner that is protective of ground water quality. The inspection results and
				any maintenance performed by the permittee on interception systems shall be
				reported pursuant to Subsection D of this section.
B.
Water quality monitoring and
				reporting.
A permittee shall perform water quality monitoring and
				reporting during the post-closure period pursuant to 20.6.7.28 and 20.6.7.29
				NMAC, as applicable and modified by this section. Ground water elevation
				contour maps required pursuant to Subsection L of 20.6.27 NMAC shall be
				submitted annually during the post-closure period. A permittee may request to
				reduce the frequency of or cease sampling a water quality monitoring location
				if the water contaminants in a monitoring well have been below the applicable
				standards for eight consecutive quarters, provided an adequate monitoring well
				network remains. If sampling of a monitoring well ceases in accordance with
				this subsection, the monitoring well shall be abandoned in accordance with
				applicable requirements unless the permittee requests and the department
				approves the monitoring well to remain in place for an alternative use or
				future monitoring.
C.
Reclamation monitoring, maintenance, and inspections.
(1)
Vegetation
.
To ensure that vegetated covers required by the copper mine rule or the
				approved discharge permit are protective of water quality, a permittee shall
				perform post-closure monitoring of vegetation pursuant to schedules and
				monitoring requirements approved by the mining and minerals division. Any
				proposed changes to the closure or post-closure vegetation monitoring plan to
				meet Mining Act requirements shall be submitted to the department to ensure
				monitoring is protective of water quality. The permittee shall provide the
				department with a copy of monitoring results for vegetated covers, including
				photographic documentation as required by the mining and minerals division. At
				such time as the mining and minerals division vegetation success requirements
				under the Mining Act have been met, the permittee shall provide a final report
				to the department and vegetation monitoring may cease.
(2)
Erosion, subsidence, slope
				instability, ponding, and other features.
The permittee shall visually
				inspect closed discharge permit areas where a cover was installed for signs of
				excessive erosion, subsidence features, slope instability, ponding, development
				of fissures, or any other feature that may compromise the functional integrity
				of the cover system or drainage channels. Drainage channels, diversion
				structures, retention ponds, and auxiliary erosion control features shall be
				inspected in accordance with professionally recognized standards (e.g., U.S.
				department of agriculture natural resources conservation service standards).
				The inspections shall be conducted monthly for the first year following
				submission of the final CQA/CQC report for the unit, and quarterly thereafter
				until the end of post-closure monitoring, provided the department may approve a
				schedule allowing less-frequent monitoring. Discharge permit areas where covers
				were installed shall also be inspected for evidence of excessive erosion within
				24 hours, or the next business day, following storm events of one inch or
				greater as measured at the nearest rain gauge on the copper mine facility. The
				permittee shall report and take corrective action pursuant to 20.6.2.7.30 NMAC
				regarding signs of excessive erosion, subsidence features, slope instability,
				ponding, development of fissures, or any other feature that may compromise the
				functional integrity of the cover system or drainage channels. Monitoring and
				inspection results shall be reported as required by Subsection D of this
				section.
(3)
Entry.
A
				permittee shall inspect and maintain the fencing or other management systems
				required by the discharge permit to prevent access by wildlife and unauthorized
				members of the public to an open pit, reservoir, impoundment or any sump that
				contains water that may present a hazard to public health or
				wildlife.
(4)
Cover
				maintenance.
A permittee shall perform maintenance on all areas where a
				cover system was installed as required by the copper mine rule, including
				associated drainage channels and diversion structures if their performance may
				affect cover system function. Based on monitoring of vegetation and erosion
				required by Paragraphs (1) and (2) of this subsection, a permittee shall
				provide recommendations for maintenance work in semiannual monitoring reports
				described in Subsection D of this section, including a schedule for completion
				of work.
(5)
Other inspection
				and maintenance.
A permittee shall routinely inspect and maintain all
				structures, units, and equipment the failure of which may impact ground water
				quality. Water collected that exceeds the ground water quality standards in
				Section 20.6.2.3103 NMAC shall be stored, conveyed, treated and discharged in a
				manner that is consistent with the closure water treatment and management plan
				any other applicable regulatory requirements. The inspection results shall be
				reported as required in Subsection D of this section. Inspections and
				maintenance shall include but are not limited to:
(a) storm water retention
				reservoir(s);
(b) water treatment
				plant(s);
(c) pumps and pipelines
				to deliver water to water treatment plant(s); and
(d) seepage collection ponds.
(6) Implementation of water
				management and treatment plan. The permittee shall continue to implement the
				water management and treatment plan required by Subsection H of 20.6.7.33 NMAC
				during the post-closure period. The water management and treatment plan may be
				modified in accordance with its terms or by approval of the department to
				reflect changes in site conditions.