Current through Register Vol. 41, No. 3, September 23, 2024
(a) General. Excess spoil shall be placed in
designated disposal areas within the permit area, in a controlled manner to-
(1) Minimize the adverse effects of leachate
and surface water runoff from the fill on surface and ground waters;
(2) Ensure mass stability and prevent mass
movement during and after construction; and
(3) Ensure that the final fill is suitable
for reclamation and revegetation compatible with the natural surroundings and
the approved postmining land use.
(b) Design certification.
(1) The fill and appurtenant structures shall
be designed using current, prudent engineering practices and any criteria
established by the division as necessary to achieve the standards of this Part.
A qualified registered professional engineer experienced in the design of earth
and rock fills shall certify the design of the fill and appurtenant
structures.
(2) The fill shall be
designed to attain a minimum long-term static safety factor of 1.5. The
foundation and abutments of the fill must be stable under all conditions of
construction.
(c)
Location. The disposal area shall be located on the most moderately sloping and
naturally stable areas available, as approved by the division, and shall be
placed, where possible, upon or above a natural terrace, bench, or berm, if
such placement provides additional stability and prevents mass
movement.
(d) Foundation.
(1) Sufficient foundation investigations, as
well as any necessary laboratory testing of foundation material, shall be
performed in order to determine the design requirements for foundation
stability. The analyses of foundation conditions shall take into consideration
the effect of underground mine workings, if any, upon the stability of the fill
and appurtenant structures.
(2)
When the slope in the disposal area is in excess of 2.8h:1v (36 percent), or
such lesser slope as may be designated by the division based on local
conditions, keyway cuts (excavations to stable bedrock) or rock toe buttresses
shall be constructed to ensure stability of the fill. Where the toe of the
spoil rests on a downslope, stability analyses shall be performed in accordance
with 4VAC25-130-784.19 to determine the size of rock toe buttresses and keyway
cuts.
(e) Placement of
excess spoil.
(1) All vegetative and organic
materials shall be removed from the disposal area prior to placement of excess
spoil. Topsoil shall be removed, segregated and stored or redistributed in
accordance with 4VAC25-130-817.22. If approved by the division, 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.
(2) Excess spoil shall be
transported and placed in a controlled manner in horizontal lifts not exceeding
4 feet in thickness; concurrently compacted as necessary to ensure mass
stability and to prevent mass movement during and after construction; graded so
that surface and subsurface drainage is compatible with the natural
surroundings; and covered with topsoil or substitute material in accordance
with 4VAC25-130-817.22. The division may approve a design which incorporates
placement of excess spoil in horizontal lifts greater than 4 feet in thickness
when it is demonstrated by the permittee and certified by a qualified
registered professional engineer that the design will ensure the stability of
the fill and will meet all other applicable requirements.
(3) The final configuration of the fill shall
be suitable for the approved postmining land use. Terraces may be constructed
on the outslope of the fill if required for stability, control of erosion, to
conserve soil moisture, or to facilitate the approved postmining land use. The
grade of the outslope between terrace benches shall not be steeper than 2h:1v
(50 percent). Terraces, if constructed, shall be no less than 20 feet in width
and the vertical distance between terraces shall not exceed 50 feet. Terraces
on the fill shall be graded with a minimum 3.0% grade toward the fill and a
minimum 1.0% slope toward the drainage control system.
(4) No permanent impoundments are allowed on
the completed fill. Small depressions may be allowed by the division if they
are needed to retain moisture, minimize erosion, create and enhance wildlife
habitat, or assist revegetation; and if they are not incompatible with the
stability of the fill.
(5) Excess
spoil that is acid- or toxic-forming or combustible shall be adequately covered
with nonacid, nontoxic and noncombustible material, or treated, to control the
impact on surface and ground water in accordance with 4VAC25-130-817.41, to
prevent sustained combustion, and to minimize adverse effects on plant growth
and the approved postmining land use.
(f) Drainage control.
(1) If the disposal area contains springs,
natural or manmade water courses, or wet weather seeps, the fill design shall
include diversions and underdrains as necessary to control erosion, prevent
water infiltration into the fill, and ensure stability.
(2) Diversions shall comply with the
requirements of 4VAC25-130-817.43.
(3) Underdrains shall consist of durable rock
or pipe, be designed and constructed using current, prudent engineering
practices and any design criteria established by the division as necessary to
achieve the standards of this Part. The underdrain system shall be designed to
carry the anticipated seepage of water due to rainfall away from the excess
spoil fill and from seeps and springs in the foundation of the disposal area
and shall be protected from piping and contamination by an adequate filter.
Rock underdrains shall be constructed of durable, nonacid-, nontoxic-forming
rock (e.g., natural sand and gravel, sandstone, limestone, or other durable
rock) that does not slake in water or degrade to soil material, and which is
free of coal, clay or other nondurable material. Perforated pipe underdrains
shall be corrosion resistant and shall have characteristics consistent with the
long-term life of the fill.
(g) Surface area stabilization. Slope
protection shall be provided to minimize surface erosion at the site. All
disturbed areas, including diversion channels that are not riprapped or
otherwise protected, shall be revegetated upon completion of
construction.
(h) Inspections. A
qualified registered professional engineer or other qualified professional
specialist under the direction of the professional engineer, shall periodically
inspect the fill during construction. The professional engineer and specialist
shall be experienced in the construction of earth and rock fills.
(1) Such inspections shall be made at least
quarterly throughout construction and during critical construction periods.
Critical construction periods shall include at a minimum:
(i) Foundation preparation, including the
removal of all organic material and topsoil;
(ii)placement of underdrains and protective
filter systems;
(iii)installation
of final surface drainage systems; and
(iv)the final graded and revegetated fill.
Regular inspections by the engineer or specialist shall also be conducted
during placement and compaction of fill materials.
(2) The qualified registered professional
engineer shall provide a certified report to the division within two weeks
after each inspection that the fill has been constructed and maintained as
designed and in accordance with the approved plan and this chapter. The report
shall include appearances of instability, structural weakness, and other
hazardous conditions.
(3)
(i) 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.
(ii) 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, in accordance with
4VAC25-130-817.73, color photographs shall be taken of the underdrain as the
underdrain system is being formed.
(iii) The photographs accompanying 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.
(4) A copy of each inspection
report shall be retained at or near the mine site.
(i) Coal mine waste. Coal mine waste may be
disposed of in excess spoil fills if approved by the division and, if such
waste is-
(1) Placed in accordance with
4VAC25-130-817.83;
(2) Nontoxic and
nonacid forming; and
(3) Of the
proper characteristics to be consistent with the design stability of the
fill.
(j) Underground
disposal. Excess spoil may be disposed of in underground mine workings, but
only in accordance with a plan approved by the division and MSHA under
4VAC25-130-784.25.
(k) Face-up
operations. Spoil resulting from face-up operations for underground coal mine
development may be placed at drift entries as part of a cut and fill structure,
if the structure is less than 400 feet in horizontal length, and designed in
accordance with 4VAC25-130-817.71.
Statutory Authority
§§ 45.1-161.3 and 45.1-230 of the Code of
Virginia.
