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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