N.M. Admin. Code § 20.6.7.35

Current through Register Vol. 35, No. 21, November 5, 2024

Section 20.6.7.35 - POST-CLOSURE REQUIREMENTS

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.

D.Reporting. A permittee shall submit to department semi-annual reports pursuant to the schedule in Subsection A of 20.6.7.29 NMAC until the post-closure period ends for the copper mine facility. The reports shall contain:

(1) a description and the results of all post-closure monitoring conducted pursuant to this section;

(2) a description of any work completed during the preceding semi-annual period including but not limited to:

(a) the status of post-closure activities for the copper mine facility; and

(b) any maintenance and repair work conducted for any closure unit; and

(3) semi-annual potentiometric maps including data from all monitoring wells, extraction wells, piezometers, seeps and springs appropriate to the water table being mapped.

E. The contingency requirements of 20.6.7.30 NMAC apply to any deficiencies in the implemented closure systems discovered during the post-closure monitoring and inspections required pursuant to this section.

N.M. Admin. Code § 20.6.7.35

20.6.7.35 NMAC - N, 12/1/13