N.M. Admin. Code § 19.8.36.29

Current through Register Vol. 36, No. 1, January 14, 2025

Section 19.8.36.29 - GENERAL PERFORMANCE STANDARDS: WATER QUALITY STANDARDS AND EFFLUENT LIMITATIONS (715.17)(A)

¹The standards in this section will be enjoined to the extent that they supersede, amend, repeal or modify the provisions of the Federal Water Pollution Control Act and its regulations.

A. All surface drainage from the disturbed area, including disturbed areas that have been graded, seeded, or planted, shall be passed through a sedimentation pond or a series of sedimentation ponds before leaving the permit area. Sedimentation ponds shall be retained until drainage from the disturbed area has met the water quality requirements of this section and the revegetation requirements of Section 715.20 have been met. The regulatory authority may grant exemptions from this requirement only when the disturbed drainage area within the total disturbed area is small and if the permittee shows that sedimentation ponds are not necessary to meet the effluent limitations of this paragraph and to maintain water quality in downstream receiving waters. For purpose of this section only, disturbed area shall not include those areas in which only diversion ditches, sedimentation ponds, or roads are installed in accordance with this section and the upstream area is not otherwise disturbed by the permittee. Sedimentation ponds required by this paragraph shall be constructed in accordance with Paragraph (e) [now Subsection E of 19.8.36.29 NMAC] of this section in appropriate locations prior to any mining in the affected drainage area in order to control sedimentation or otherwise treat water in accordance with this paragraph. Discharges from areas disturbed by surface coal mining and reclamation operations must meet all applicable Federal and State laws and regulations and, at a minimum, the following numerical effluent limitations:

EFFLUENT LIMITATIONS IN MILLIGRAMS PER LITER

mg/1, Except For pH

__________________________________________________________________________________________

Average of

Daily values

Effluent Maximum for 30

Characteristics allowable¹ consecutive

discharge days¹

__________________________________________________________________________________________

Iron, total---------------- 7.0 3.5

Manganese, total----- 4.0 2.0

Total suspended solids 70.0 35.0

pH² Within the-------------------------------------------------

range 6.0 to 9.0.

¹Based on representative sampling.

² Where the applications of neutralization and sedimentation treatment technology results in inability to comply with the manganese limitations set forth, the regulatory authority may allow the pH level in the discharge to exceed to a small extent the upper limit of 9.0 in order that the manganese limitations will be achieved.

_________________________________________________________________________________________

(1) Any overflow or other discharge of surface water from the disturbed area within the permit area demonstrated by the permittee to result from a precipitation event larger than a ten-year 24-hour frequency event will not be subject to the effluent limitations of Paragraph (a) [now Subsection A of 19.8.36.29 NMAC].

(2) The permittee shall install, operate, and maintain adequate facilities to treat any water discharged from the disturbed area that violates applicable federal or state laws or regulations or the limitations of Paragraph (a) [now Subsection A of 19.8.36.29 NMAC]. If the pH of waters to be discharged from the disturbed area is normally less than 6.0, an automatic lime feeder or other neutralization process approved by the regulatory authority shall be installed, operated and maintained. If the regulatory authority finds (1) that small and infrequent treatment requirements to meet applicable standards do not necessitate use of an automatic neutralization process, and (2) that the mine normally produces less than 500 tons of coal per day, then the regulatory authority may approve the use of a manual system if the permittee ensures consistent and timely treatment.

B. Surface-water monitoring.

(1) The permittee shall submit for approval by the regulatory authority a surface-water monitoring program which meets the following requirements:

(a) Provides adequate monitoring of all discharge from the disturbed area.

(b) Provides adequate data to describe the likely daily and seasonal variation in discharges from the disturbed area in terms of water flow, pH, total iron, total manganese and total suspended solids and, if requested by the regulatory authority, any other parameter characteristic of the discharge.

(c) Provides monitoring at appropriate frequencies to measure normal and abnormal variations in concentrations.

(d) Provides an analytical quality control system including standard methods of analysis such as those specified in 40 CFR 136.

(e) Provides a regular report of all measurements to the regulatory authority within 60 days of sample collection unless violations of permit conditions occur in which case the regulatory authority shall be notified immediately after receipt of analytical results by the permittee. If the discharge is subject to regulation by a federal or state permit issued in compliance with the Federal Water Pollution Control Act Amendment of 1972 (33 U.S.C. ' 1251-1-378), a copy of the completed reporting form supplied to meet the permit requirements may be submitted to the regulatory authority to satisfy the reporting requirements if the data meet the sampling frequency and other requirements of this paragraph.

(2) After disturbed areas have been regraded and stabilized in accordance with this Part, the permittee shall monitor surface water flow and quality. Data from this monitoring shall be used to demonstrate that the quality and quantity of runoff without treatment will be consistent with the requirement of this section to minimize disturbance to the prevailing hydrologic balance and with the requirements of this part to attain the approved postmining land use. These data shall provide a basis for approval by the regulatory authority for removal of water quality or flow control systems and for determining when the requirements of this Section are met. The regulatory authority shall determine the nature of data, frequency of collection and reporting requirements.

(3) Equipment, structures and other measures necessary to accurately measure and sample the quality and quantity of surface water discharges from the distrubed area of the permit area shall be properly installed, maintained and operated and shall be removed when no longer required.

C. Diversion and conveyance of overland flow away from disturbed areas. In order to minimize erosion and to prevent or remove water from contacting toxic-producing deposits, overland flow from undisturbed areas may, if required or approved by the regulatory authority, be diverted away from disturbed areas by means of temporary or permanent diversion structures. The following requirements shall be met:

(1) Temporary diversion structures shall be constructed to safely pass the peak runoff from a precipitation event with a one year recurrence interval, or a larger event as specified by the regulatory authority. The design criteria must assure adequate protection of the environment and public during the existence of the temporary diversion structure.

(2) Permanent diversion structures are those remaining after mining and reclamation and approved for retention by the regulatory authority and other appropriate state and federal agencies. To protect fills and property and to avoid danger to public health and safety, permanent diversion structures shall be constructed to safely pass the peak runoff from a precipitation event with a 100-year recurrence interval, or a larger event as specified by the regulatory authority. Permanent diversion structures shall be constructed with gently sloping banks that are stabilized by vegetation. Asphalt, concrete or other similar linings shall not be used unless specifically required to prevent seepage or to provide stability and are approved by the regulatory authority.

(3) Diversions shall be designed, constructed and maintained in a manner to prevent additional contributions of suspended solids to streamflow or to runoff outside the permit area to the extent possible, using the best technology currently available. In no event shall such contributions be in excess of requirements set by applicable state or federal law. Appropriate sediment control measures for these diversions shall include, but not be limited to, maintenances of appropriate gradients, channel lining, revegetation, roughness structures and detention basins.

D. Stream channel diversions.

(1) Flow from perennial and intermittent streams within the permit area may be diverted only when the diversions are approved by the regulatory authority and they are in compliance with local, state, and federal statutes and regulations. When streamflow is allowed to be diverted, the new stream channel shall be designed and constructed to meet the following requirements:

(a) The average stream gradient shall be maintained and the channel designed, constructed, and maintained to remain stable and to prevent additional contributions of suspended solids to streamflow, or to runoff outside the permit area to the extent possible, using the best technology currently available. In no event shall such contributions be in excess of requirements set by applicable state or federal law. Erosion control structures such as channel lining structures, retention basins and artificial channel roughness structures shall be used only when approved by regulatory agency for temporary diversions where necessary or for permanent diversions where they are stable and will require only infrequent maintenance.

(b) Channel, bank and flood-plain configurations shall be adequate to safely pass the peak runoff of a precipitation event with a ten-year recurrence interval for temporary diversions and a 100-year recurrence interval for permanent diversions, or larger events as specified by the regulatory authority.

(c) Fish and wildlife habitat and water and vegetation of significant value for wildlife shall be protected in consultation with appropriate state and federal fish and wildlife management agencies.

(2) All temporary diversion structures shall be removed and the affected land regraded and revegetated consistent with the requirements of Section 715.14 and Section 715.20. At the time such diversions are removed, the permittee shall ensure that downstream water treatment facilities previously protected by the diversion are modified or removed to prevent overtopping or failure of the facilities.

(3) Buffer zone. No land within 100 feet of an intermittent or perennial stream shall be disturbed by surface coal mining and reclamation operations unless the regulatory authority specifically authorizes surface coal mining and reclamation operations through such a stream. The area not to be disturbed shall be designated a buffer zone and marked as specified in Section 715.12.

E.² Sediment control measures. Appropriate sediment control measures shall be designed, constructed, and maintained to prevent additional contributions of sediment to streamflow or to runoff outside the permit area to the extent possible, using the best technology currently available. ²The standards in Section 715.17(e) will be preliminarily enjoined.

(1) Sediment control measures include practices carried out within and adjacent to the disturbed area. The scale of downstream practices shall reflect the degree to which successful techniques are applied at the sources of the sediment. Sediment control measures consist of the utilization of proper mining, reclamation methods, and sediment control practices (singly or in combination) including but not limited to:

(a) Disturbing the smallest practicable area at any one time during the mining operation through progressive backfilling, grading and timely revegetation.

(b) Consistent with the requirements of Section 715.14 and Section 715.15 shaping the backfill material to promote a reduction of the rate and volume of runoff.

(c) Retention of sediment within the pit and disturbed area.

(d) Diversion of overland and channelized flow from undisturbed areas around or in protected crossings through the disturbed area.

(e) Utilization of straw dikes, riprap, check dams, mulches, vegetative sediment filters, dugout ponds and other measures that reduce overland flow velocity, reduce runoff volume or entrap sediment.

(f) Sedimentation ponds.

(2) Sedimentation ponds, may be used individually or in series, should be located as near as possible to the disturbed area and where possible out of major stream courses, and shall (either individually or in series) meet the following criteria:

(a) Sedimentation ponds must provide 24-hour theoretical detention time for the inflow or runoff entering the ponds from a ten-year, 24-hour precipitation event. Runoff diverted, in accordance with Paragraphs (c) and (d) [now Subsections C and D of 19.8.36.29 NMAC] of this Section, away from the disturbed drainage areas need not be considered in sedimentation pond design. In determining the runoff volume the characteristics of the mine site, reclamation procedures and on-site sediment control practices shall be considered.

(b) Upon approval of the regulatory authority theoretical detention time may be reduced to not less than ten hours, as demonstrated by the permittee, equal to the improvement in sedimentation removal efficiency as a result of pond design including but not limited to pond configuration, inflow-outflow facilities and their relative location, baffles to decrease inflow velocity and short circuiting, a surface area sufficient to achieve the sediment trap efficiency necessary to meet effluent limitations (Sec. 715.17 (a)) and sediment control measures provided in Section 715.17 (e)(1).

(c) The regulatory authority may approve a detention time less than the time required by Paragraph (e)(2) (i) or (ii) [now Subparagraphs a and b of Paragraph 2 of Subsection E of 19.8.36.29 NMAC] of this section, when the permittee has demonstrated that the size distribution or the specific gravity of the suspended matter or the utilization of chemical treatment or flocculation are such that the effluent limitations can be met. The detention time shall be stipulated.

(3) An additional sediment storage volume must be provided equal to 0.2 acre-feet for each acre of disturbed area within the upstream drainage area. Upon approval of the regulatory authority, the sediment storage volume may be reduced in an amount, as demonstrated by the permittee, equal to the sediment removed by other appropriate sediment control measures such as those identified in Paragraph (e)(1) [now Paragraph 1 of Subsection E of 19.8.36.29 NMAC] of this section, or by lesser sediment yields as evidenced by empirical data for runoff characteristics.

(4) Ponds may be of the permanent pool or self-dewatering type. Dewatering-type ponds shall use siphon or other dewatering methods approved by the regulatory authority to prevent discharges of pollutants within the design flow.

(5) Spillway systems shall be properly located to maximize the distances from the point of inflow into the pond to maximize detention times. Spillway systems shall be provided to safely discharge the peak runoff from a precipitation event with a 25-year recurrence interval, or larger event as specified by the regulatory authority.

(6) Sediment shall be removed from sedimentation ponds so as to assure maximum sediment removal efficiency and attainment and maintenance of effluent limitations. Sediment removal shall be done in a manner that minimizes adverse effects on surface waters due to its chemical and physical characteristics, on infiltration, on vegetation, and on surface and groundwater quality. Sediment that has been removed from sedimentation ponds and that meets the requirements for topsoil may be redistributed over graded areas in accordance with Section 715.16.

(7) If a sedimentation pond has an embankment that is more than 20 feet in height, as measured from the downstream toe of the embankment to the top of the embankment, or has a storage volume of 20 acre-feet or more, the following additional requirements shall be met:

(a) An appropriate combination of principal and emergency spillways shall be provided to safely discharge the runoff resulting from a 100-year six-hour precipitation event, or larger event as specified by the regulatory authority.

(b) Ponds shall be designed and constructed with an acceptable static safety factor of at least 1.5 of maximum design flood elevation of the pool to ensure embankment slope stability.

(c) The minimum top width of the embankment shall not be less than the quotient of H+35/5 where H is the height of the embankment as measured from the downstream toe to the top of the embankment.

(d) Ponds shall have appropriate barriers to control seepage along conduits that extend through the embankment.

(8) All ponds shall be designed and inspected under the supervision of, and certified after construction by a professional engineer registered in the state of New Mexico.

(9) All ponds, including those not meeting the size or other criteria of 'Section 77.216(a) of this title, shall be examined for structural weakness, erosion, and other hazardous conditions in accordance with the inspection requirements contained in' Section 77.216-3 of this title.

(10) All ponds shall be removed and the affected land regraded and revegetated consistent with the requirements of Section 715.14 and Section 715.20, unless the regulatory authority approves retention of the ponds pursuant to Paragraph (k) [now Subsection K of 19.8.36.29 NMAC] of this Section.

F. Discharge structures. Discharges from sedimentation ponds and diversions shall be controlled, where necessary, using energy dissipators, surge ponds and other devices to reduce erosion and prevent deepening or enlargement of stream channels and to minimize disturbances to the hydrologic balance.

G. Acid and toxic materials. Drainage from acid-forming and toxic-forming mine waste materials and soils into ground and surface water shall be avoided by:

(1) Identifying, burying and treating where necessary, spoil or other materials that, in the judgment of the regulatory authority, will be toxic to vegetation or that will adversely affect water quality if not treated or buried. Such material shall be disposed of in accordance with the provision of Section 715.14(j).

(2) Preventing or removing water from contact with toxic-producing deposits.

(3) Burying or otherwise treating all toxic or harmful materials within 30 days, if such materials are subject to wind and water erosion, or within a lesser period designated by the regulatory authority. If storage of such materials is approved, the materials shall be placed on impermeable material and protected from erosion and contact with surface water. Coal waste ponds and other coal waste materials shall be maintained according to Section 715.17(g) (4), and Section 715.18 shall apply.

(4) Burying or otherwise treating waste materials from coal preparation plants no later than 90 days after the cessation of the filling of the disposal area. Burial or treatment shall be in accordance with Section 715.14(j).

(5) Casing, sealing or otherwise managing boreholes, shafts, wells and auger holes or other more or less horizontal holes to prevent pollution of surface or groundwater and to prevent mixing of groundwaters of significantly different quality. All boreholes that are within the permit area but are outside the surface coal mining area or which extend beneath the coal to be mined and into water bearing strata shall be plugged permanently in a manner approved by the regulatory authority, unless the boreholes have been approved for use in monitoring.

(6) Taking such other actions as required by the regulatory authority.

H. Groundwater.

(1) Recharge capacity of reclaimed lands. The disturbed area shall be reclaimed to restore approximate premining recharge capacity through restoration of the capability of the reclaimed areas as a whole to transmit water to the groundwater system. The recharge capacity should be restored to support the approved postmining land use and to minimize disturbances to the prevailing hydrologic balance at the mined area and in associated offsite areas. The permittee shall be responsible for monitoring according to Paragraph (h) (3) [now Paragraph 3 of Subsection H of 19.8.36.29 NMAC] of this section to ensure operations conform to this requirement.

(2) Groundwater systems. Backfilled materials shall be placed to minimize adverse effects on groundwater flow and quality, to minimize offsite effects, and to support the approved postmining land use. The permittee shall be responsible for performing monitoring according to Paragraph (h)(3) [now Paragraph 3 of Subsection H of 19.8.36.29 NMAC] of this section to ensure operations conform to this requirement.

(3) Monitoring. Groundwater levels, infiltration rates, subsurface flow and storage characteristics, and the quality of groundwater shall be monitored in a manner approved by the regulatory authority to determine the effects of surface coal mining and reclamation operations on the recharge capacity of reclaimed lands and on the quantity and quality of water in groundwater systems at the mine area and in associated off-site areas. When operations are conducted in such a manner that may affect the groundwater system, groundwater levels and groundwater quality shall be periodically monitored using wells that can adequately reflect changes in groundwater quantity and quality resulting from such operations. Sufficient water wells must be used by the permittee. The regulatory authority may require drilling and development of additional wells if needed to adequately monitor the groundwater system. As specified and approved by the regulatory authority, additional hydrologic tests, such as infiltration tests and aquifer tests, must be undertaken by the permittee to demonstrate compliance with Subparagraphs (1) and (2) [now Paragraphs 1 and 2 of Subsection H of 19.8.36.29 NMAC] of this paragraph.

I. Water rights and replacement. The permittee shall replace the water supply of an owner of interest in real property who obtains all or part of his supply of water for domestic, agricultural, industrial or other legitimate use from an underground or surface source where such supply has been affected by contamination, diminution or interruption proximately resulting from surface coal mine operation by the permittee.

J. Alluvial valley floors west of the 100th meridian west longitude.

(1) Surface coal mining operations conducted in or adjacent to alluvial valley floors shall be planned and conducted so as to preserve the essential hydrologic functions of these alluvial valley floors throughout the mining and reclamation process. These functions shall be preserved by maintaining or reestablishing those hydrologic and biologic characteristics of the alluvial valley floor that are necessary to support the functions. The permittee shall provide information to the regulatory authority as required in Paragraph (j)(3) [now Paragraph 3 of Subsection J of 19.8.36.29 NMAC] of this section to allow identification of essential hydrologic functions and demonstrate that the functions will be preserved. The characteristics of an alluvial valley floor to be considered include, but are not limited to:

(a) The longitudinal profile (gradient), cross-sectional shape and other channel characteristics of streams that have formed within the alluvial valley floor and that provide for maintenance of the prevailing conditions of surface flow;

(b) Aquifers (including capillary zones and perched water zones) and confining beds within the mined area which provide for storage, transmission and regulation of natural groundwater and surface water that supply the alluvial valley floors;

(c) Quantity and quality of surface and groundwater that supply alluvial valley floors;

(d) Depth to and seasonal fluctuations of groundwater beneath alluvial valley floors;

(e) Configuration and stability of the land surface in the flood plain and adjacent low terraces in alluvial valley floors as they allow or facilitate irrigation with flood waters or subirrigation and maintain erosional equilibrium; and

(f) Moisture-holding capacity of soils (or plant growth medium) within the alluvial valley floors, and physical and chemical characteristics of the subsoil which provide for sustained vegetation growth or cover through dry months.

(2) Surface coal mining operations located west of the 100th meridian west longitude shall not interrupt, discontinue or preclude farming on alluvial valley floors and shall not materially damage the quantity or quality of surface or groundwater that supplies these valley floors unless the premining land use has been undeveloped rangeland which is not significant to farming on the alluvial valley floors or unless the area of affected alluvial valley floor is small and provides negligible support for the production from one or more farms. This Subparagraph (2) [now Paragraph 2 of Subsection J of 19.8.36.29 NMAC] does not apply to those surface coal mining operations that:

(a) Were in production in the year preceding August 3, 1977, were located in or adjacent to an alluvial valley floor, and produced coal in commercial quantities during the year preceding August 3, 1977; or

(b) Had specific permit approval by the state regulatory authority before August 3, 1977, to conduct surface coal mining operations for an area within an alluvial valley floor.

(3)

(a) Before surface mining and reclamation operations authorized under Paragraph (j)(2) [now Paragraph 2 of Subsection J of 19.8.36.29 NMAC] of this section may be issued a new, revised or amended permit, the permittee shall submit, for regulatory authority approval, detailed surveys and baseline data to establish standards against which the requirements of Paragraph (j)(1) [now Paragraph 1 of Subsection J of 19.8.36.29 NMAC] of this section may be measured and from which the degree of material damage to the quantity and quality of surface and groundwater that supply the alluvial valley floors may be assessed. The surveys and data shall include--

(i) A map, at a scale determined by the regulatory authority, showing the location and configuration of the alluvial valley floor;

(ii) Baseline data covering a full water year for each of the hydrologic functions identified in Paragraph (j)(1) [now Paragraph 1 of Subsection J of 19.8.36.29 NMAC] of this section;

(iii) Plans showing how the operation will avoid, during mining and reclamation, interruption, discontinuance or preclusion of farming on the alluvial valley floors and will not materially damage the quantity or quality of water in surface and groundwater systems that supply such valley floors;

(iv) Historic land use data for the proposed permit area and for farms to be affected; and

(v) Such other data as the regulatory authority may require.

(b) Surface mining operations which qualify for the exceptions in Paragraph (j)(2) [now Paragraph 2 of Subsection J of 19.8.36.29 NMAC] of this section are not required to submit the plans prescribed in (i)(C) [now Sub-subparagraph (iii) of Subparagraph a of Paragraph 3 of Subsection J of 19.8.36.29 NMAC] of this subparagraph.

(4) The holder of a federal coal lease or the fee holder of any coal deposit located within or adjacent to an alluvial valley floor west of the 100th meridian west from which coal was not produced in commercial quantities between August 3, 1976, and August 3, 1977, and for which no specific permit by the appropriate state or federal regulatory authority to conduct surface coal mining operations in the alluvial valley floors has been obtained, may be entitled to an exchange of the federal coal lease for a lease of other federal coal deposits under section 510(b)(5) of the Act or to the conveyance by the secretary of fee title to other available federal coal deposits in exchange for the fee title to such deposits under Section 206 of the Federal Land Policy and Management Act of 1976 (90 Stat. 2743), if the secretary determines that substantial financial and legal commitments were made by the operator prior to January 1, 1977, in connection with surface coal mining operations on such lands.

(5) The secretary may, if he determines that the person is qualified for an exchange of federal coal leases under the provisions of section 510(b)(5) of the Act or a conveyance of other federal coal deposits under section 206 of the Federal Land Policy and Management Act, take appropriate steps to complete the exchange of lands. The secretary may require the person to submit additional information and a formal application for exchange.

K. Permanent impoundments. The permittee may construct, if authorized by the regulatory agency pursuant to this paragraph and Section 715.13, permanent water impoundments on mining sites as a part of reclamation activities only when they are adequately demonstrated to be in compliance with Section 715.13 and Section 715.14 in addition to the following requirements:

(1) The size of the impoundment is adequate for its intended purposes.

(2) The impoundment dam construction is designed to achieve necessary stability with an adequate margin of safety compatible with that of structures constructed under Pub. L. 83-566 (16 U.S.C.1006).

(3) The quality of the impounded water will be suitable on a permanent basis for its intended use and discharges from the impoundment will not degrade the quality of receiving waters below the water quality standards established pursuant to applicable federal and state law.

(4) The level of water will be reasonably stable.

(5) Final grading will comply with the provisions of Section 715.14 and will provide adequate safety and access for proposed water users.

(6) Water impoundments will not result in the diminution of the quality or quantity of water used by adjacent or surrounding landowners for agricultural, industrial, recreational or domestic uses.

L. Hydrologic impact of roads.

(1) General. Access and haul roads and associated bridges, culverts, ditches and road rights-of-way shall be constructed, maintained and reclaimed to prevent additional contributions of suspended solids to streamflow, or to runoff outside the permit area to the extent possible, using the best technology currently available. In no event shall the contributions be in excess of requirements set by applicable state or federal law. All access and haul roads shall be removed and the land affected regraded and revegetated consistent with the requirements of Section 715.14 and Section 715.20, unless retention of a road is approved as part of a postmining land use under Section 715.13 as being necessary to support the postmining land use or necessary to adequately control erosion and the necessary maintenance is assured.

(2) Construction.

(a) All roads, insofar as possible, shall be located on ridges or on the available flatter and more stable slopes to minimize erosion. Stream fords are prohibited unless they are specifically approved by the regulatory authority as temporary routes across dry streams that will not adversely affect sedimentation and that will not be used for coal haulage. Other stream crossing shall be made using bridges, culverts or other structures designed and constructed to meet the requirements of this paragraph. Roads shall not be located in active stream channels nor shall they be constructed or maintained in a manner that increases erosion or causes significant sedimentation or flooding. However, nothing in this paragraph will be construed to prohibit relocation of stream channels in accordance with Paragraph (d) [now Subsection D of 19.8.36.29 NMAC] of this section.

(b) In order to minimize erosion and subsequent disturbances of the hydrologic balance, roads shall be constructed in compliance with the following grade restrictions or other grades determined by the regulatory authority to be necessary to control erosion.

(i) The overall sustained grade shall not exceed 1v:10h (ten percent).

(ii) The maximum grade greater than ten percent shall not exceed lv:6.5h (15 percent) for more than 300 feet.

(iii) There shall not be more than 300 feet of grade exceeding ten percent within each 1,000 feet.

(c) All access and haul roads shall be adequately drained using structures such as, but not limited to, ditches, water barriers, cross drains, and ditch relief drains. For access and haul roads that are to be maintained for more than one year, water-control structures shall be designed with a discharge capacity capable of passing the peak runoff from a ten-year, 24-hour precipitation event. Drainage pipes and culverts shall be constructed to avoid plugging or collapse and erosion at inlets and outlets. Drainage ditches shall be provided at the toe of all cut slopes formed by construction of roads. Trash racks and debris basins shall be installed in the drainage ditches wherever debris from the drainage area could impair the functions of drainage and sediment control structures. Ditch relief and cross drains shall be spaced according to grade. Effluent limitations of Paragraph (a) [now Subsection A of 19.8.36.29 NMAC] of this Section shall not apply to drainage from access and haul roads located outside the disturbed area as defined in this Section unless otherwise specified by the regulatory authority.

(d) Access and haul roads shall be surfaced with durable material. Toxic- or acid-forming substances shall not be used. Vegetation may be cleared only for the essential width necessary for road and associated ditch construction and to serve traffic needs.

(3) Maintenance.

(a) Access and haul roads shall be routinely maintained by means such as, but not limited to, wetting, scraping or surfacing.

(b) Ditches, culverts, drains, trash racks, debris basins and other structures serving to drain access and haul roads shall not be restricted or blocked in any manner that impedes drainage or adversely affects the intended purpose of the structure.

M. Hydrologic impacts of other transport facilities. Railroad loops, spurs, sidings and other transport facilities shall be constructed, maintained and reclaimed to control diminution or degradation of water quality and quantity and to prevent additional contributions of suspended solids to streamflow, or to runoff outside the permit area to the extent possible, using the best technology currently available. In no event shall contributions be in excess of requirements set by applicable State or Federal law.

N. Discharge of waters into underground mines. Surface and groundwaters shall not be discharged or diverted into underground mine workings.

N.M. Admin. Code § 19.8.36.29

Recompiled 6/4/02