25 Pa. Code § 87.131 - Disposal of excess spoil
(a) Spoil
not required to achieve the approximate original contour shall be transported
and placed in designated disposal areas approved by the Department within the
permit area. The disposal area shall be designed, constructed and maintained to
ensure:
(1) That leachate and surface runoff
from the fill will not degrade surface or groundwater or exceed the effluent
limitations of §
87.102 (relating to hydrologic
balance: effluent standards).
(2)
The prevention of combustion.
(3)
The stability of the fill.
(4) 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 registered professional
engineer, and approved by the Department.
(c) The excess spoil disposal fill shall be
designed to attain a long-term static factor of safety of 1.5 and a seismic
factor of safety of 1.1 based upon dataobtained from subsurface exploration,
geotechnical testing, foundation design, fill design and accepted engineering
analyses.
(d) Vegetative and
organic materials shall be removed from the disposal area and the topsoil shall
be removed, segregated and stored or replaced as provided in §§
87.96-87.100. If approved by the
Department, 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.
(e)
The excess spoil disposal area should be located in areas where groundwater
discharge and surface water flows are minimal.
(f) The disposal areas shall be located on
the most moderately sloping and naturally stable areas available as approved by
the Department. If the 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.
(g) The spoil shall be hauled or conveyed and
placed in a controlled manner and concurrently compacted as approved by the
Department in lifts no greater than 4 feet, or less if required 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.
(h) The final
configuration of the fill shall be suitable for postmining land uses approved
in accordance with §
87.159 (relating to postmining
land use), except that no depressions or impoundments may be allowed on the
completed fill. The fill may not exceed the approximate elevation of the
ridgeline.
(i) 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 clay 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.
(j) Terraces may be utilized
to control erosion and enhance stability or for roads if approved by the
Department and consistent with the approved postmining land use.
(k) When the slope in the disposal area
exceeds lv:2.8h-36% or a lesser slope designated by the Department based on
local conditions, keyway cuts (excavations to stable bedrock) or rock toe
buttresses shall be constructed to stabilize the fill. When the toe of the
spoil rests on a downslope, stability analyses shall be performed in accordance
with §
87.79 (relating to disposal of
excess spoil) to determine the size of rock toe buttresses and key way
cuts.
(l) Surface water runoff from
the areas adjacent to and above the fill may not be allowed to flow onto the
fill and shall be diverted into stabilized channels which are designed to pass
safely the peak runoff from a 100-year precipitation event. Diversion design
shall comply with the requirements of §
87.105 (relating to hydrologic
balance: diversions).
(m) Surface
water runoff from the fill shall be diverted off the fill to properly designed
channels which will pass safely the peak runoff from a 100-year precipitation
event. Diversion design shall comply with the requirements of §
87.105.
(n) The fill shall be
inspected for stability by a qualified registered professional engineer or
other qualified professional specialist experienced in the construction of
earth and rockfill embankments and working under the direction of a qualified
registered professional engineer. These inspections shall occur at least
quarterly throughout construction and during the following critical
construction periods: removal of organic material and topsoil, placement of
underdrainage systems, installation of surface drainage systems, placement and
compaction of fill materials and revegetation. The qualified registered
professional engineer shall provide to the Department a certified report within
2 weeks after each inspection that the fill has been constructed and maintained
in accordance with the approved design, in accordance with the approved plan,
and in accordance with all applicable performance standards and this chapter.
The report shall include appearances of instability, structural weakness and
other hazardous conditions. A copy of the report shall be retained at the
minesite.
(o) Coal processing waste
may be disposed of in the disposal area if the requirements of Chapter 90
(relating to coal refuse disposal) are met.
(p) If the disposal area contains springs,
natural or manmade water courses, 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 ensure continued free
drainage.
(q) 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 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- or toxic-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 slake in water.
(2) An underdrain system shall be
designed to be installed along with 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.
(r) The
certified report required under subsection (n) shall include, as part of
reporting on the underdrain/subdrainage system and filter system, color
photographs taken during and after construction, but before the underdrains are
covered with excess spoil. If the underdrain is constructed in phases, each
phase shall be certified separately. Photographs 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.
(s) The
foundation and abutments of the fill shall be stable under all conditions of
construction and operation. Sufficient foundation investigation and laboratory
testing of foundation materials shall be performed 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.
(t)
Excess spoil may be returned to underground mine workings, but only in
accordance with a disposal program approved by the Department and MSHA in
accordance with Chapter 89 (relating to underground mining of coal and coal
preparation facilities).
Notes
The provisions of this §87.131 amended under the Surface Mining Conservation and Reclamation Act (52 P. S. §§ 1396.1-1396.19a); The Clean Streams Law (35 P. S. §§ 691.1-691.1001); and section 1920-A of The Administrative Code of 1929 (71 P. S. § 510-20).
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