(a) Coal
refuse shall be transported and placed in designated disposal areas approved by
the Department for this purpose. These areas shall be within the permit area.
The coal refuse disposal area shall be designed, constructed and maintained to
ensure:
(1) The leachate and surface runoff
from the permit area will not degrade surface water or groundwater or exceed
the effluent limitations of §
90.102 (relating to hydrologic
balance: water quality standards, effluent limitations and best management
practices).
(2) Prevention of
combustion.
(3) Prevention of
public health hazards.
(4)
Stability of the fill.
(5) The land
mass designated as the coal refuse 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 registered
professional engineer, and approved by the Department.
(c) The foundation and abutment of the fill
shall be stable under all conditions of construction and operation. Sufficient
foundation investigations and laboratory testing of foundation materials and
coal refuse shall be performed to determine the design requirements for
stability of the facility. Analyses of foundation conditions shall include the
effect of underground mine workings, if any, upon the stability of the
structure.
(d) The coal refuse
disposal fill shall be designed to attain a minimum long-term static factor of
safety of 1.5 and a minimum seismic factor of safety of 1.2, based upon data
obtained from subsurface exploration, geotechnical testing, foundation design,
fill design and accepted engineering analyses.
(e) When the average slope of coal refuse
disposal area exceeds lv:2.8h-36%, or lesser slopes as may be designated by the
Department based on local conditions, key way cuts, or excavation into stable
bedrock or bedrock toe buttresses shall be constructed to stabilize the fill.
When the toe of the fill rests on a downslope, stability analysis shall be
performed in accordance with §
90.39 (relating to ponds,
impoundments, banks, dams, embankments, piles and fills) to determine the size
of rock toe buttresses and key way cuts.
(f) If the disposal area contains springs,
natural or manmade watercourses, or wet-weather seeps, the Department may
approve an underdrain/subdrainage system, consisting of durable rock or other
materials, designed and placed in a manner that prevents infiltration of the
water into the fill material and ensures continued free drainage from the wet
areas.
(g) The disposal area shall
be provided with a system to prevent adverse impacts to the surface water and
groundwater. The system shall be constructed in accordance with design
schematics, test results, descriptions, plans, maps, profiles or cross-sections
approved in the permit and shall function to prevent adverse impacts to surface
water and groundwater.
(h) The
operator shall install a system to prevent precipitation from coming in contact
with the coal refuse. The system shall be constructed in accordance with the
design schematics, test results, descriptions, plans, maps, profiles or
cross-sections approved in the permit, and designed to allow for revegetation
of the site in accordance with the standard of success under §
90.159 (relating to revegetation:
standards for successful revegetation) and for the prevention of erosion:
(1) [Reserved].
(2) [Reserved].
(3) [Reserved].
(4) [Reserved].
(5) as phases reach capacity;
(6) as specified in the permit;
(7) if the operator temporarily ceases
operation of the coal refuse disposal area for a period in excess of 90 days,
unless the Department approves an operator's request for a longer period for
the installation of the system; or
(8) when the operation permanently
ceases.
(i) An
underdrain/subdrainage system for the fill shall be designed in accordance with
the following:
(1) It shall include an
underdrain system which will ensure continued free drainage of anticipated
seepage from precipitation and from spring or wet-weather seeps, and meet the
following:
(i) Anticipated discharges from
springs and seeps due to precipitation shall be based on records or field
investigation or both, to determine seasonal variation. The design of the
underdrain system shall be based on maximum anticipated discharges.
(ii) Granular material used for the drainage
system shall be nondegradable, nonacid-forming or nontoxic-forming rock free of
clay, and consist of durable particles such as natural sands and gravels,
sandstone, limestone or other durable rock which will not flake in
water.
(2) The underdrain
system shall be designed to be installed along the natural drainage system;
extend from toe to head of fill; and contain lateral drains to each area of
potential drainage or seepage.
(3)
A filter system to ensure the proper functioning of the rock underdrain system
shall be designed and constructed using standard geotechnical engineering
methods.
(j) The final
configuration of the fill shall be suitable for the post disposal land use
approved under §
90.165 (relating to prime
farmland: revegetation), except that no depression or impoundment may be
allowed on the completed fill. New coal refuse disposal piles and area of piles
active since May 17, 1973, shall blend into the local surroundings. Unless
otherwise approved by the Department, the fill may not be designed to exceed
the approximate elevation of the surrounding ridgeline.
(k) The maximum overall completed slope of
the coal refuse disposal pile measured from toe of the fill to crest of upper
terrace may not exceed 33% or 18 degrees.
(l) The top surface of the completed fill
shall be graded so that the final slope after settlement will be no steeper
than lv:20h-5.0% toward properly designed drainage channels in natural ground
along the periphery of the fill. Surface runoff from the top surface of the
fill may not be allowed to flow over the outslope of the fill.
(m) Terraces must be utilized to control
erosion and enhance stability, and may be utilized for roads included in
postmining land use.
(1) The slope of the
outslope between terraces may not exceed lv:2h-50%. The vertical distance
between terraces may not exceed 50 feet.
(2) To control surface runoff, each terrace
bench will be a minimum of 20 feet wide, shall be graded to a slope of
lv:20h-5.0% toward the embankment. Runoff shall be collected by a ditch along
the intersection of each terrace bank and the toe of the next higher
outslope.
(3) Terrace ditches shall
have a maximum 5.0% slope toward the channels specified in subsection (o)
unless steeper slopes are necessary in conjunction with approved
roads.
(n) Surface water
runoff from areas adjacent to and above the fill shall be diverted away from
the fill in stabilized channels which are designed to safely pass the peak
runoff from a 100-year precipitation event. Diversion channels shall also
comply with §
90.104(a) and
(c)-(h) (relating to hydrologic balance:
diversions).
(o) Surface water
runoff from the fill shall be collected and conveyed in properly designed
channels constructed in natural ground or engineered fill of inert material
along the periphery of the fill. The channels must safely pass the peak runoff
from a 100-year precipitation event.
(p) Slope protection shall be provided to
minimize surface erosion at the site. Disturbed areas, including diversion
ditches that are not riprapped, shall be vegetated upon completion of
construction.
(q) Coal refuse shall
be hauled or conveyed and placed in a controlled manner and concurrently
compacted as approved by the Department in lifts no greater than 2 feet, or
less, as required or approved by the Department, as the design to:
(1) Achieve the densities designed to ensure
mass stability.
(2) Prevent mass
movement.
(3) Avoid contamination
of the rock underdrain.
(4) Prevent
formation of voids.
(r)
Vegetative and organic materials shall be removed from the area where coal
refuse is disposed of, and for a distance of 50 feet from the perimeter of the
area where coal refuse is disposed, the topsoil shall be removed, segregated
and stored or replaced as provided in §§
90.96-
90.100. If approved by the
Department, organic material may be used a mulch or may be included in the
topsoil to control erosion, promote growth of vegetation or increase the
moisture retention of the soil.