(a) Underground development waste and spoil not required
to achieve the approximate original contour and which is not used
as backfill shall be hauled or conveyed to and placed in designated
disposal areas within a permit area if the disposal areas are authorized
for such purposes in the approved permit application in accordance
with this section and §§12.532-12.534 of this title (relating
to Disposal of Underground Development Waste and Excess Spoil: Valley
Fills, to Disposal of Underground Development Waste and Excess Spoil:
Head-of-Hollow fills, and to Disposal of Underground Development Waste
and Excess Spoil: Durable Rock Fills). The material shall be placed
in a controlled manner to ensure:
(1) that leachate and surface runoff from the fill
will not degrade surface or ground waters or exceed the effluent limitations
referenced in §12.510 of this title (relating to Hydrologic Balance:
Water-Quality Standards and Effluent Limitations);
(2) stability of the fill; and
(3) that the land mass designated as the disposal area
is suitable for reclamation and revegetation compatible with the natural
surroundings.
(b) The fill shall be designed using recognized professional
standards, certified by a qualified professional engineer, and approved
by the Commission.
(c) All vegetative and organic materials shall be removed
from the disposal area and the topsoil shall be removed, segregated
and stored or replaced in accordance with §§12.504-12.508
of this title (relating to Topsoil: General Requirements, to Topsoil:
Removal, to Topsoil: Storage, to Topsoil: Redistribution, and to Topsoil:
Nutrients and Soil Amendments). If approved by the Commission, organic
material may be used as mulch or may be included in the topsoil to
control erosion, promote growth of vegetation, or increase the moisture
retention of the soil.
(d) Slope protection shall be provided to minimize
surface erosion at the site. Diversion design shall conform with the
requirements of §12.511 of this title (relating to Hydrologic
Balance: Diversions). All disturbed areas, including diversion ditches
that are not riprapped, shall be vegetated upon completion of construction.
(e) The disposal areas shall be located on the most
moderately sloping and naturally stable areas available as approved
by the Commission. If such placement provides additional stability
and prevents mass movement, fill materials suitable for disposal shall
be placed upon or above a natural terrace, bench, or berm.
(f) The fill materials shall be hauled or conveyed
and placed in horizontal lifts 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 ensure a long-term static
safety factor of 1.5.
(g) The final configuration of the fill must be suitable
for postmining land uses approved in accordance with §12.568
of this title (relating to Postmining Land Use), except that no depressions
or impoundments shall be allowed on the completed fill.
(h) Terraces may be utilized to control erosion and
enhance stability if approved by the Commission and consistent with §12.552(b)
of this title (relating to Backfilling and Grading: General Grading
Requirements).
(i) Where the slope in the disposal area exceeds 2.8h:1v
(36%), or such lesser slope as may be designated by the Commission
based on local conditions, keyway cuts (excavations to stable bedrock)
or rock toe-buttresses shall be constructed to stabilize the fill.
Where the toe of the spoil rests on a downslope, stability analyses
shall be performed in accordance with §12.183 of this title (relating
to Cross Sections, Maps, and Plans) to determine the size of the rock
toe-buttresses or keyway cuts.
(j) The fill shall be inspected for stability by a
qualified professional engineer experienced in the construction of
earth and rockfill embankments at least quarterly throughout construction,
and during the following critical construction periods:
(1) removal of all organic material and topsoil;
(2) placement of underdrainage systems and protective
filter systems;
(3) installation of surface drainage systems;
(4) placement and compaction of fill materials; and
(5) revegetation.
(k) The qualified professional engineer shall provide
to the Commission a certified report, within two weeks after each
inspection that the fill has been constructed as specified in the
design approved by the Commission. The certified report on the drainage
system and protective filters shall include color photographs taken
during and after construction, but before underdrains are covered
with excess spoil. If the underdrain system is constructed in phases,
each phase shall be certified separately. A copy of the report shall
be retained at the minesite.
(l) Coal mine waste shall not be disposed of in valley
or head-of-hollow fills and may only be disposed of with underground
development waste, or in other excess spoil fills, if such waste is:
(1) placed in accordance with §12.538 of this
title (relating to Coal Mine Waste Banks: Construction Requirements);
(2) demonstrated to be non-toxic and non-acid forming;
and
(3) demonstrated to be consistent with the design stability
of the fill.
(m) If the disposal area contains springs, natural
or manmade watercourses, or wet-weather seeps, an underdrain system
consisting of durable rock shall be constructed from the wet areas
in a manner that prevents infiltration of the water into the spoil
material. The underdrain system shall be protected by an adequate
filter and shall be designed and constructed using standard geotechnical
engineering methods. Where excess durable rock spoil is placed in
single or multiple lifts such that the underdrain system is constructed
simultaneously with excess spoil placement by the natural segregation
of dumped materials, color photographs shall be taken of the underdrain
as the underdrain system is being formed.
(n) The foundation and abutments of the fill shall
be stable under all conditions of construction and operation. Sufficient
foundation investigations and laboratory testing of foundation materials
shall be performed in order to determine the design requirements for
stability of the foundation. Analyses of foundation conditions shall
include the effect of underground mine workings, if any, upon the
stability of the structure.
(o) Underground development waste and excess spoil
may be returned to underground workings only in accordance with the
disposal plans submitted under §12.193 of this title (relating
to Underground Development Waste/Return of Coal Processing Waste to
Abandoned Underground Workings) and approved by the Commission and
MSHA.
(p) Excess spoil that is acid-forming or toxic-forming
or combustible shall be adequately covered with non-acid, non-toxic
and noncombustible material, or treated, to control the impact on
surface and ground water in accordance with this chapter (relating
to Coal Mining Regulations), to prevent sustained combustion, and
to minimize adverse effects on plant growth and the approved postmining
land use.
(q) The photographs required by this section to accompany
each certified report shall be taken in adequate size and number,
with enough terrain or other physical features of the site shown,
to provide a relative scale to the photographs and to specifically
and clearly identify the site.
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Source Note: The provisions of this §12.531 adopted to be effective April 7, 1997, 22 TexReg 3093; amended to be effective November 4, 1997, 22 TexReg 10640; amended to be effective December 28, 2020, 45 TexReg 9503 |