N.M. Admin. Code § 19.10.5.508 - NEW UNITS

New discrete processing, leaching, excavation, storage or stockpile units located within the permit area of an existing mining operation and not identified in the permit of an existing mining operation, and for each expansion of such a unit identified in the permit for an existing mining operation that exceeds the design limits specified in the permit must meet the reclamation standard set forth in Subsection A of 19.10.5.507 NMAC above and must also comply with the standards and requirements set forth below. Site-specific characteristics, including the existing mining operation, must be considered in applying the standards and requirements.

A. Most Appropriate Technology and Best Management Practices The mining operation and the reclamation plan shall be designed and operated using the most appropriate technology and the best management practices.

B. Assure Protection The mining operation and completed reclamation shall meet the following requirements established to assure protection of human health and safety, the environment, wildlife and domestic animals.

(1) Signs, Markers and Safeguarding Measures will be taken, to safeguard the public from unauthorized entry into shafts, adits, and tunnels and to prevent falls from highwalls or pit edges. Depending on site-specific characteristics, the following measures shall be required:

(a) closing shafts, adits or tunnels to prevent entry;

(b) posting warning signs in locations near hazardous areas;

(c) restricting access to hazardous areas;

(d) marking the permit area boundaries;

(e) posting a sign at the main entrances giving a telephone number of a person to call in the event of emergencies related to the mine; or

(f) other measures as needed to protect human safety.

(2) Wildlife Protection Measures shall be taken to minimize adverse impacts on wildlife and important habitat. Based on site-specific characteristics, the following measures will be required:

(a) restricting access of wildlife and domestic animals to toxic chemicals or otherwise harmful materials;

(b) minimizing harm to wildlife habitat during mining; and

(c) reclaiming areas of wildlife habitat if not in conflict with the approved post-mining land use.

(3) Cultural Resources Cultural resources listed on or eligible for listing on the National Register of Historic Places or the State Register of Cultural Properties, and any cemeteries or burial grounds shall be protected until clearance has been granted by the State Historic Preservation Office or other appropriate authority.

(4) Hydrologic Balance Operations shall be planned and conducted to minimize negative impact to the hydrologic balance in both the permit and potentially affected areas.

(a) Operations shall be designed so that non-point source surface releases of acid or other toxic substances shall be contained within the permit area, and that all other surface flows from the disturbed area are treated to meet all applicable state and federal regulations.

(b) The disturbed areas shall not contribute suspended solids above background levels, or where applicable the Water Quality Control Commission's standards, to intermittent and perennial streams.

(c) To provide data to determine background levels for surface water entering the permit area, appropriate monitoring shall be conducted on drainages leading into the permit area.

(d) All diversions of overland flow shall be designed, constructed and maintained to minimize adverse impacts to the hydrologic balance and to assure the safety of the public.

(i) No diversion shall be located so as to increase the potential for landslides.

(ii) Unless site-specific characteristics require a different standard which is included in the approved permit, diversions which have watersheds larger than 10 acres shall be designed, constructed and maintained to safely pass the peak runoff from a 10-year, 24-hour precipitation event.

(iii) All diversion designs which have watersheds larger than 10 acres shall be certified by a professional engineer registered in New Mexico as having been designed in accordance with 19.10 NMAC. Diversion designs shall be kept on-site or otherwise be made available, upon request, to the Director for inspection.

(iv) When no longer needed, temporary diversions shall be removed and the disturbed area reclaimed.

(5) Stream Diversions When streams are to be diverted, the stream channel diversion shall be designed, constructed, and removed in accordance with the following:

(a) Unless site-specific characteristics require different measures to meet the performance standard and are included in the approved permit, the combination of channel, bank and flood plain configurations shall be adequate to safely pass the peak run-off of a 10-year, 24-hour precipitation event for temporary diversions, a 100-year, 24-hour precipitation event for permanent diversions;

(b) The design and construction of all intermittent and perennial stream channel diversions shall be certified as meeting 19.10 NMAC by a professional engineer registered in New Mexico. As-built drawings shall be completed promptly after construction and be retained on site or otherwise made available upon request to the Director; and

(c) When no longer needed, temporary stream channel diversions shall be removed and the disturbed area reclaimed.

(6) Impoundments If impoundments are required they shall be designed, constructed and maintained to minimize adverse impacts to the hydrologic balance and adjoining property and to assure the safety of the public.

(a) Unless site-specific characteristics require different measures to meet the performance standard and are included in the approved permit, impoundments having earthen embankments but not subject to the jurisdiction of the Mine Safety and Health Administration or the State Engineer shall:

(i) have a minimum elevation at the top of the settled embankment of 1.0 foot above the water surface in the pond with the spillway flowing at the design depth;

(ii) have a top width of the embankment not less than 6 feet;

(iii) have combined upstream and downstream side slopes of the settled embankment not less than 5 horizontal : 1 vertical with neither slope steeper than 2 horizontal : 1 vertical. Slopes shall be vegetated or otherwise stabilized to control erosion;

(iv) have the embankment foundation cleared of all vegetative matter, all surfaces sloped to no steeper than 1 horizontal : 1 vertical and the entire foundation area scarified;

(v) have fill material free of vegetative matter and frozen soil;

(vi) have spillways provided to safely discharge the peak runoff of a 25-year, 24-hour precipitation event, or an event with a 90-percent chance of not being exceeded for the design life of the structure;

(vii) have other site-specific design criteria for embankments as long as they result in a minimum static safety factor of 1.3 with water impounded to the design level;

(viii) be designed and certified by a professional engineer registered in New Mexico as having been designed and constructed in accordance with 19.10 NMAC. As-built drawings shall be completed promptly after construction and be retained on site or otherwise made available upon request to the Director; and

(viiii) if necessary for sediment control, be in place before any other disturbance is made to the watershed for the impoundment.

(b) When no longer required, impoundments shall be graded to achieve positive drainage unless:

(i) the surface estate owner has requested in writing that they be retained;

(ii) they are consistent with the approved reclamation plan; and

(iii) they are appropriate for the post-mining land use or the self-sustaining ecosystem.

(7) Minimization of Mass Movement All man-made piles such as waste dumps, topsoil stockpiles and ore piles shall be constructed and maintained to minimize mass movement.

(8) Riparian and Wetland Areas Disturbance to riparian and wetland areas shall be minimized during mining. Adverse effects to riparian and wetland areas shall be mitigated during reclamation unless the mitigation conflicts with the approved post-mining land use.

(9) Roads Roads shall be constructed and maintained to control erosion.

(a) Drainage control structures shall be used as necessary to control runoff and to minimize erosion, sedimentation and flooding. Drainage facilities shall be installed as road construction progresses and shall be capable of safely passing a 10-year, 24 hour precipitation event unless site-specific characteristics indicate a different standard is appropriate and is included in the approved permit. Culverts and drainage pipes shall be constructed and maintained to avoid plugging, collapsing, or erosion.

(b) Roads to be constructed in or across intermittent or perennial streams require site-specific designs to be submitted with the permit application.

(c) Roads to be made permanent must be approved by the surface owner and be consistent with the approved post-mining land use.

(10) Subsidence Control Underground and in situ solution mining activities shall be planned and conducted, to the extent technologically and economically feasible, to prevent subsidence which may cause material damage to structures or property not owned by the operator.

(a) Underground and in situ solution mining activities near any aquifer that serves as a significant source of water supply to a public water system shall be conducted so as to avoid disruption of the aquifer and consequent exchange of ground water between the aquifer and other strata.

(b) Underground and in situ solution mining activities conducted beneath or adjacent to any perennial stream must be performed in a manner so that subsidence is not likely to cause material damage to streams, water bodies and associated structures.

(11) Explosives Blasting shall be conducted to prevent injury to persons or damage to property not owned by the operator. Fly rock shall be confined to the permit area. The Director may require a detailed blasting plan, pre-blast surveys or specify blast design limits to control possible adverse effects to structures.

C. Site Stabilization and Surface Configuration The permit area shall be stabilized, to the extent practicable, to minimize future impact to the environment and protect air and water resources. The final surface configuration of the disturbed area shall be suitable for achieving a self-sustaining ecosystem or approved post-mining land use.

(1) Final slopes and drainage configurations must be compatible with a self-sustaining ecosystem or approved post-mining land use.

(2) All reconstructed slopes, embankments and roads shall be designed, constructed and maintained to minimize mass movement.

(3) Measures must be taken to reduce, to the extent practicable, the formation of acid and other toxic drainage that may otherwise occur following closure to prevent releases that cause federal or state standards to be exceeded.

(4) Nonpoint source surface releases for acid or other toxic substances shall be contained within the permit area.

D. Erosion Control Reclamation of disturbed lands must result in a condition that controls erosion. Revegetated lands must not contribute suspended solids above background levels to intermittent and perennial streams. Acceptable practices to control erosion include but are not limited to the following:

(1) stabilizing disturbed areas through land shaping, berming, or grading to final contour;

(2) minimizing reconstructed slope lengths and gradients;

(3) diverting runoff;

(4) establishing vegetation;

(5) regulating channel velocity of water;

(6) lining drainage channels with rock, vegetation or other geotechnical materials; and

(7) mulching.

E. Revegetation To obtain the release of financial assurance revegetated lands must meet the following standards:

(1) Revegetation success for a self-sustaining ecosystem shall be determined through comparison of ground cover, productivity and diversity and shall be made on the basis of the following approved reference areas; through the use of technical guidance procedures published by the U. S. Department of Agriculture; other reasonably attainable standards approved by the Director; or a combination. Data collection shall be performed using the same methods and techniques on reference areas and reclaimed areas.

(a) foliar or basal cover and productivity of living perennial plants of the revegetated area shall be established equal to 90 percent of the reference area or equal to the approved revegetation standard to within a 90-percent statistical confidence;

(b) diversity of plant life forms (woody plants, grasses, forbs) shall consider what is reasonable based on the physical environment of the reclaimed area; and

(c) woody plant species shall be established to the approved density with an 80 percent statistical confidence.

(2) For areas for which the approved post-mining land use is for wildlife habitat or forest land, success of vegetation shall be determined on the basis of tree or shrub stocking (density) and ground cover.

(a) The ground cover of living perennial plants shall be equal to 90 percent of the native ground cover of the reference area or the approved standard to within a 90 percent statistical confidence and shall be adequate to control erosion.

(b) Tree stocking for forest land shall have stocking rates of plant species equal to 90 percent of the approved reference area or other approved standard with an 80 percent statistical confidence and shall be adequate to control erosion.

(c) If wildlife habitat is to be the post-mining land use, the operator shall select and use plant species on reclaimed areas based on the following criteria:

(i) their proven nutritional value for fish and wildlife;

(ii) their uses as cover and security for wildlife;

(iii) their ability to support and enhance fish and wildlife habitat; and

(iv) distribute plant life forms to maximize benefits of edge effect, cover and other benefits for fish and wildlife.

(3) Revegetation for other post-mining land shall be consistent with the approved post-mining land use. Site-specific standards may include standards for foliar or basal cover, production and diversity and will be included in the approved permit.

Notes

N.M. Admin. Code § 19.10.5.508

7-12-94, 2-15-96; 19.10.5.508 NMAC - Rn, 19 NMAC 10.2.5.507.C, 05-15-2001