Current through Register Vol. 35, No. 18, September 24, 2024
A. The final graded slopes shall not exceed
in grade either the approximate premining slopes, or any lesser slopes approved
by the director based on consideration of soil, climate, or other
characteristics of the surrounding area. Postmining final graded slopes need
not be uniform but shall approximate the general nature of the premining
topography. The person who conducts surface coal mining operations shall, at a
minimum:
(1) retain all overburden and spoil
on the solid portion of existing or new benches; and
(2) backfill and grade to the most moderate
slope possible, to eliminate the highwall which does not exceed either the
angle of repose or such lesser slope as is necessary to achieve a minimum
static safety factor of 1.3. In all cases the highwall shall be eliminated
unless retention of portions of the highwall is approved by the director, if
the operator demonstrates that:
(a) it will
have a static safety factor of 1.3;
(b) it will not pose a hazard to persons or
wildlife in the area;
(c) it will
be backfilled to cover the uppermost minable coal seam to a minimum depth of 4
feet;
(d) the retained portion left
standing shall not exceed pre-existing cliff lengths. However, the director may
require shorter lengths.
(e) it is
necessary to replace cliff type habitats that existed in the natural topography
prior to mining; and
(f) the ends
of the highwall portions left standing will be contoured into the surrounding
topography with slopes of 3:1 or less. Retention of any portion of the highwall
must be approved by the director.
(3) spoil, except excess spoil disposed of in
accordance with 19.8.20.2034 through 2037 NMAC, shall be returned to the
mined-out area.
(4) spoil and
waste materials shall be compacted where advisable to ensure stability or to
prevent leaching of toxic materials.
(5) spoil may be placed on the area outside
the mind-out area in non-steep slope areas to restore the approximate original
contour by blending the spoil into the surrounding terrain if the following
requirements are met:
(a) all vegetative and
organic material shall be removed from the area.
(b) the topsoil on the area shall be removed,
segregated, stored and redistributed in accordance with 19.8.20.2005 through
2007 NMAC.
(c) the spoil shall be
backfilled and graded on the area in accordance with the requirements of
19.8.20 NMAC.
B. On approval by the director in order to
conserve soil moisture, ensure stability, and control erosion on final graded
slopes, cut-and-fill terraces may be allowed, if the terraces are compatible
with the approved postmining land use and are appropriate substitutes for
construction of lower grades on the reclaimed lands. The terraces shall meet
the following requirements:
(1) The width of
the individual terrace bench shall not exceed 20 feet, unless specifically
approved by the director as necessary for stability, erosion control, or roads
included in the approved postmining land use plan.
(2) The vertical distance between terraces
shall be as specified by the director, to prevent excessive erosion and to
provide long-term stability.
(3)
The slope of the terrace outslope shall not exceed 1v:3h (33 1/3 percent).
Outslopes which exceed lv:3h (33 1/3 percent) may be approved if they provide
adequate control over erosion and closely resemble the surface configuration of
land prior to mining. In no case may highwalls be left as part of
terraces.
(4) Culverts and
underground rock drains shall be used on the terrace only when approved by the
director.
C. Small
depressions may be constructed, if they:
(1)
are approved by the director to minimize erosion, conserve soil moisture,
create or enhance wildlife habitat, or promote vegetation;
(2) do not restrict normal access;
and
(3) are not inappropriate
substitutes for lower grades on the reclaimed lands.
D. All surface coal mining operations on
slopes averaging above 20 degrees, or on lesser slopes that the director
defines as steep slopes shall meet the provisions of 19.8.26 NMAC.
E. All final grading preparation of
overburden before replacement of topdressing and placement of topdressing,
shall be done along the contour to minimize subsequent erosion and instability.
If such grading, preparation, or placement along the contour is hazardous to
equipment operators, then grading, preparation, or placement in a direction
other than generally parallel to the contour may be used. In all cases,
grading, preparation, or placement shall be conducted in a manner which
minimizes erosion and provides a surface for replacement of topdressing which
will minimize slippage.
F. Remining
operations on previously mined areas that contain a preexisting highwall shall
comply with the requirements of 19.8.20.2054 through 2058 NMAC, except as
provided in 19.8.20 NMAC.
G. The
requirements of Subsection A of 19.8.20.2055 NMAC requiring the elimination of
highwalls shall not apply to remining operations where the volume of all
reasonably available spoil is demonstrated in writing to the director to be
insufficient to completely backfill the reaffected or enlarged highwall. The
highwall shall be eliminated to the maximum extent technically practical in
accordance with the following criteria:
(1)
all spoil generated by the remining operation and any other reasonably
available spoil shall be used to backfill the area; reasonably available spoil
in the immediate vicinity of the remining operation shall be included within
the permit area;
(2) the backfill
shall be graded to a slope which is compatible with the approved postmining
land use and which provides adequate drainage and long-term
stability;
(3) any highwall remnant
shall be stable and not pose a hazard to the public health and safety or to the
environment; the operator shall demonstrate, to the satisfaction of the
director, that the highwall remnant is stable;
(4) spoil placed on the outslope during
previous mining operations shall not be disturbed if such disturbances will
cause instability of the remaining spoil or otherwise increase the hazard to
the public health and safety to the environment.
