N.M. Admin. Code § 19.8.36.26
Current through Register Vol. 36, No. 1, January 14, 2025
Section 19.8.36.26 - GENERAL PERFORMANCE STANDARDS: DISPOSAL OF SPOIL AND WASTE MATERIALS IN AREAS OTHER THAN THE MINE WORKINGS OR EXCAVATIONS (715.15)A. Disposal of spoil in other than valley or head-of-hollow fills. Spoil not required to achieve the approximate original contour shall be transported to and placed in a controlled (engineered) manner in disposal areas other than the mine workings or excavations only if all the following conditions, in addition to the other requirements of this part, are met: (1) The disposal areas shall be within the permit area, and they must be approved by the regulatory authority as suitable for construction of fills in accordance with the requirements of this paragraph.(2) The disposal areas shall be located on the most moderate sloping and naturally stable areas available as approved by the regulatory authority. Where possible, fill materials suitable for disposal shall be placed upon or above a natural terrace, bench or berm if such placement provides additional stability and prevents mass movement.(3) The fill shall be designed using recognized professional standards, certified by a professional engineer, registered in the state of New Mexico and approved by the regulatory authority.(4) Where the slope in the disposal area exceeds lv:2.8h (36 percent), or such lesser slope designated by the regulatory authority based on local conditions, measures such as keyway cuts (excavations to stable bedrock) or rock toe buttresses shall be constructed to stabilize the fill.(5) The disposal area does not contain springs, natural water courses, or wet weather seeps unless lateral drains are constructed from the wet areas to the underdrains in such a manner that infiltration of the water into the spoil pile will be prevented.(6) All organic material shall be removed from the disposal area and the topsoil must be removed and segregated pursuant to Section 715.16 before the material is placed in the disposal area. However, if approved by the regulatory authority, organic material may be used as mulch or may be included in the topsoil.(7) The spoil shall be transported and placed in a controlled manner, concurrently compacted as necessary to ensure mass stability and prevent mass movement, covered, and graded to allow surface and subsurface drainage to be compatible with the natural surroundings, and to ensure long-term stability. The final configuration of the fill must be suitable for postmining land uses approved in accordance with Section 715.13. Terraces shall not be constructed unless approved by the regulatory authority.(8) If any portion of the fill interrupts, obstructs or encroaches upon any natural drainage channel, the entire fill is classified as a valley or head-or-hollow fill and must be designed and constructed in accordance with the requirements of Paragraph (b) [now Subsection B of 19.8.36.26 NMAC] of this Section.(9) The fill shall be inspected for stability by a registered engineer or other qualified professional specialist during critical construction periods to assure removal of all organic material and topsoil, placement of under-drainage systems, and proper construction of terraces according to the approved plan. The registered engineer or other qualified professional specialist shall provide a certified report after each inspection that the fill has been constructed as specified in the design approved by the regulatory authority.B. Disposal of spoil in valley or head-of-hollow fills. Waste material must not be disposed of in valley or head-of-hollow fills. Spoil to be disposed of in natural valleys must be placed in accordance with the following requirements: (1) The disposal areas shall be within the permit area, and they must be approved by the regulatory authority as suitable for construction of fills in accordance with the requirements of Paragraph (b) [now Subsection B of 19.8.36.26 NMAC].(2) The disposal site shall be near the ridge top of a valley selected to increase the stability of the fill and to reduce the drainage area above the fill. Where possible, spoil shall be placed above a natural terrace, bench or berm, if such placement provides additional stability and prevents mass movement.(3) The fill shall be designed using recognized professional standards, certified by a professional engineer registered in the State of New Mexico and approved by the regulatory authority.(4) All organic material shall be removed from the disposal area and the topsoil must be removed and segregated pursuant to Section 715.16 of this Part before the material is placed in the disposal area. However, if approved by the regulatory authority, organic material may be used as mulch or may be included in the topsoil.(5) Where the slope in the disposal area exceeds lv:2.8h (36 percent), or such lesser slope designated by the regulatory authority based on local conditions, measures such as keyway cuts (excavations to stable bedrock) or rock toe buttresses shall be constructed to stabilize the fill.(6) A system of underdrains constructed of durable rock shall be installed along the natural drainage system, shall extend from the toe to the head of the fill and contain lateral drains to each area of potential drainage or seepage. In constructing the underdrains, no more than ten percent of the rock may be less than 12 inches in size and no single rock may be larger than 25 percent of the width of the drain. No rock shall be used in underdrains if it tends to easily disintegrate and thereby clog the drain or if it is acid-forming or toxic-forming. The minimum size of the main underdrain shall be: ________________________________________________________________________________________
Total amount of Predominant Minimum size of
Fill material type of fill drain in feet
Material
______________
Width Height
Less than 1 million Sandstone-- 10 4
yd3.
Do---------- Shale--------- 16 8
More than 1 million Sandstone------ 16 8
yd3.
Do---------- Shale--------- 16 8
(7) Spoil shall be transported and placed in a controlled manner and concurrently compacted as specified by the regulatory authority in lifts that are less than four feet thick in order to achieve the densities designed to ensure mass stability, to prevent mass movement, to avoid contamination of the rock underdrain and to prevent formation of voids. The final configuration of the fill must be suitable for postmining land uses approved in accordance with Section 715.13.(8) Terraces shall be constructed to stabilize the face of the fill. The outslope of each terrace shall not exceed 50 feet in length and the width of the terrace shall not be less than 20 feet.(9) The tops of the fill and each terrace shall be graded no steeper than 1v:20h (five percent) and shall be constructed to drain surface water to the sides of the fill where stabilized surface channels shall be established off the fill to carry drainage away from the fill. Drainage shall not be directed over the outslope of the fill unless approved by the regulatory authority.(10) All surface drainage from the undisturbed area above the fill shall be diverted away from the fill by approved structures leading into water courses.(11) The outslope of the fill shall not exceed 1v:2h (50 percent). The regulatory authority may require a flatter slope.(12) The fill shall be inspected for stability by a professional engineer registered in the State of New Mexico or other qualified professional specialist during critical construction periods and at least quarterly throughout construction to assure removal of all organic material and topsoil, placement of underdrainage systems and proper construction of terraces according to the approved plan. The registered engineer or other qualified professional specialist shall provide a certified report after each inspection that the fill has been constructed as specified in the design approved by the regulatory authority.N.M. Admin. Code § 19.8.36.26