Section
1. General Requirements.
(1)
Spoil and
spent shale not disposed of in the mine workings shall be transported
and placed in designated disposal areas within a
permit area in a manner
approved by the
cabinet. The spoil and spent shale shall be placed in a
controlled manner to ensure:
(a) That
leachate and surface run-off from the fill will not degrade surface or
groundwaters or exceed the
effluent limitations of
405
KAR 30:320;
(b) Stability of the fill; and
(c) That the land mass designated as the
disposal area is suitable for reclamation and revegetation compatible with the
natural surroundings.
(2) The fill shall be designed using
recognized professional standards, certified by a registered professional
engineer, and approved by the cabinet.
(3) Vegetative and organic materials shall,
either progressively or in a single operation, be removed from the disposal
area and the
topsoil shall be removed, segregated, and stored or replaced under
405 KAR 30:290. If
approved by the
cabinet, 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.
(4) All surface drainage from the undisturbed
area above the fill shall be diverted away from the fill.
Diversion design
shall conform with the requirements of
405 KAR
30:310. All
disturbed areas, including diversion
ditches that are not riprapped, shall be vegetated upon completion of
construction.
(5) The disposal
areas shall be located on the most moderately sloping and naturally stable
areas available as approved by the cabinet. Slope protection shall be provided
to minimize surface erosion at the site. 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.
(6) The spoil and spent shale shall be
transported 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
one and three-tenths (1.3).
(7) A
minimum of four (4) feet of nontoxic and nonacid forming material shall be
placed on the final layer of
spent shale. In addition, the
cabinet may require
an impermeable cover between the final layer of spent shale and the four (4)
feet of nontoxic and nonacid forming material. Greater depths may be specified
by the
cabinet if deemed necessary. This four (4) foot cover does not include
the topsoil required in
405 KAR 30:290.
(8) The final configuration of the fill must
be suitable for proposed postmining land uses approved in accordance with
405 KAR
30:220, except that no impoundments shall be allowed
on the completed fill, and no depressions shall be allowed on the completed
fill unless they are determined by the
cabinet to have no potential adverse
effect on the stability of the fill and to have no potential for interference
with the approved postmining land use.
(9) Fills shall not be constructed in the
100-year flood plain of any perennial stream. A stream channel may not be
changed to circumvent this requirement.
(10) Terraces may be utilized to control
erosion and enhance stability.
(11)
Where the natural land slope in the disposal area exceeds 1v:2.8h (thirty-six
(36) percent), or such lesser slope as may be designated by the cabinet 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 to determine
the size of rock toe buttresses and keyway cuts.
(12) The fill shall be inspected for
stability by a registered engineer or other qualified person under the direct
supervision of the responsible registered professional engineer experienced in
the construction of earth and rockfill embankments at least monthly throughout
construction and during the following critical construction periods: removal of
all organic material and topsoil; placement of underdrainage systems;
installation of surface drainage systems; placement and compaction of fill
materials; and revegetation. The responsible registered professional engineer
shall provide to the cabinet a certified report within two (2) weeks after each
inspection that the fill has been constructed as specified in the design
approved by the cabinet. A copy of the report shall be retained at the mine
site.
(13) Leachate ponds shall be
constructed below all spent shale disposal areas at locations approved by the
cabinet. Ponds shall be sized to contain all leachate from excess spoil and
spent shale disposal areas. Leachate ponds shall be constructed in accordance
with the requirements of
405 KAR
30:340.
(14) Oil shale processing wastes and spent
shale shall not be disposed of in head-of-hollow or valley fills with excess
spoil unless specific approval is granted by the cabinet.
(15) 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.
(16) 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 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.
Section 2.
Additional Requirements for
Spent Shale Disposal.
(1) At a minimum, the permit applicant shall
conduct tests to determine the active and potential acid levels of spent shale
and an EP toxicity test to identify toxic contaminants. The results of these
tests shall be submitted to the cabinet prior to receiving a permit. The
cabinet will use the results of these tests to determine if the proposed
handling method for spent shale in conjunction with excess spoil will fulfill
the requirements of Section 1(1) of this administrative regulation. The cabinet
may require additional tests as necessary to make this determination.
(2) If the
cabinet determines that the
proposed handling method for spent shale in combination with excess spoil will
not adequately fulfill the requirements of Section 1(1) of this administrative
regulation spent shale shall be handled according to the provisions of
405 KAR
30:360. Excess
spoil shall be handled in accordance
with the provisions of Section 1 of this administrative regulation excluding
subsections (7) and (13) of that section.
(3) Spent shale shall be cooled to a
temperature approved by the cabinet, prior to disposal.
Section 3. Valley Fills and Head-of-hollow
Fills. Disposal of excess
spoil in valley fills and head-of-hollow fills shall
meet all requirements of Section 1 of this administrative regulation and the
additional requirements of this section, except as provided in Section 2 of
this administrative regulation.
(1) The fill
shall be designed to attain a long-term static safety factor of one and
three-tenths (1.3) based upon data obtained from subsurface exploration,
geotechnical testing, foundation design, and accepted engineering
analyses.
(2) A subdrainage system
for the fill shall be constructed in accordance with the following:
(a) A system of underdrains constructed of
durable rock shall meet the requirements of paragraph (d) of this subsection
and:
1. Be installed along the natural
drainage system;
2. Extend from the
toe to the head of the fill; and
3.
Contain lateral drains to each area of potential drainage or seepage.
(b) A filter system to insure the
proper functioning of the rock underdrain system shall be designed and
constructed using standard geotechnical engineering methods.
(c) In constructing the underdrains, no more
than ten (10) percent of the rock may be less than twelve (12) inches in size
and no single rock may be larger than twenty-five (25) percent of the width of
the drain. Rock used in underdrains shall meet the requirement of paragraph (d)
of this subsection. The main underdrain shall be sized so as to function
properly under all probable conditions and must meet the approval of the
cabinet.
(d) Underdrains shall
consist of nondegradable, nonacid or toxic forming rock such as natural sand
and gravel, sandstone, limestone, or other durable rock that will not slake in
water and will be free of coal, clay or shale.
(3) Spoil shall be transported and placed in
a controlled manner and concurrently compacted as specified by the
cabinet, in
lifts no greater than four (4) feet. The
cabinet may require lifts of less than
four (4) feet in order to:
(a) Achieve the
densities designed to ensure mass stability;
(b) Prevent mass movement;
(c) Avoid contamination of the rock
underdrain or rock core; and
(d)
Prevent formation of voids.
(4) Surface water run-off from the area above
the fill shall be diverted away from the fill and into stabilized
diversion
channels designed to pass safely the run-off from a 100-year, twenty-four (24)
hour precipitation event or larger event specified by the
cabinet. Surface
run-off from the fill surface shall be diverted to stabilized channels off the
fill which will safely pass the run-off from a 100-year, twenty-four (24) hour
precipitation event. Diversion design shall comply with the requirements of
405 KAR
30:310, Section 1(2).
(5) The tops of the fill and any terrace
constructed to stabilize the face shall be graded no steeper than 1v:20h (five
(5) percent). The vertical distance between terraces shall not exceed fifty
(50) feet.
(6) Drainage shall not
be directed over the outslope of the fill.
(7) The outslope of the fill shall not exceed
1v:2h (fifty (50) percent). The cabinet may require a flatter slope.
(8) The cabinet may approve other methods of
design and construction if demonstrated by the applicant using sound
engineering principles that such design and construction meets or exceeds the
requirement of this administrative regulation.