10 CSR 40-3.060 - Requirements for the Disposal of Excess Spoil
PURPOSE: This amendment incorporates by reference the federal regulations that sets forth the requirements for the disposal of excess spoil pursuant to sections 444.810 and 444.855.2(22), RSMo.
PUBLISHER'S NOTE: The secretary of state has determined that the publication of the entire text of the material which is incorporated by reference as a portion of this rule would be unduly cumbersome or expensive. This material as incorporated by reference in this rule shall be maintained by the agency at its headquarters and shall be made available to the public for inspection and copying at no more than the actual cost of reproduction. This note applies only to the reference material. The entire text of the rule is printed here.
(A) Spoil not required to achieve
the approximate original contour within the area where overburden has been
removed shall be hauled or conveyed to and placed in designated disposal areas
within a permit area, within a time approved by the director in the permit and
plan, if the disposal areas are authorized for those purposes in the approved
permit and plan in accordance with sections (1)-(4) of this rule. The spoil
shall be placed in a controlled manner to ensure that-
1. Leachate and surface runoff
from the fill will not degrade surface or ground waters or exceed the effluent
limitations of
10
CSR 40-3.040(2);
2. The fill is stable;
and
3. The land mass designated as the
disposal area is suitable for reclamation and revegetation compatible with the
natural surroundings.
(B) The fill and appurtenant
structures shall be designed using recognized professional standards, certified
by a registered professional engineer experienced in the design of earth and
rock fills and approved in the permit and plan.
(C) All vegetative and organic
materials shall be removed from the disposal area and the topsoil shall be
removed, segregated, and stored or replaced under
10
CSR 40-3.030(1)-(5). If approved in
the permit and plan, 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.
(D) Slope protection shall be
provided to minimize surface erosion at the site. Diversion design shall
conform with the requirements of
10
CSR 40-3.040(3). All disturbed areas,
including diversion ditches that are not riprapped, shall be vegetated upon
completion of construction.
(E) If placed on a slope, the
spoil is placed upon the most moderate slope among those upon which, in the
judgment of the commission, the spoil could be placed in compliance with all
the requirements of this law and shall be placed, where possible, upon or
above, a natural terrace, bench, or berm, if this placement provides additional
stability and prevents mass movement.
(F) The spoil shall be hauled or
conveyed and placed in horizontal lifts in a controlled manner, not exceeding
four feet (4') in thickness; 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 five tenths (1.5). The commission or
director may approve a design which incorporates placement of excess spoil in
horizontal lifts other than four feet (4') in thickness when it is demonstrated
by the operator 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.
(G) The final configuration of the
fill must be suitable for postmining land uses approved in accordance with
10 CSR
40-3.130(1), except that no
depressions or impoundments shall be allowed on the completed
fill.
(H) 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
10
CSR 40-3.040, to prevent sustained combustion and to
minimize adverse effects on plant growth and the approved postmining land
use.
(I) Terraces may be utilized to
control erosion and enhance stability if approved in the permit and plan and
consistent with
10 CSR
40-3.110(2)(B).
(J) Where the slope in the
disposal area exceeds 1v:2.8h (36%), or a lesser slope as may be designated in
the permit or plan 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
including, but not limited to, strength parameters, pore pressures, and
long-term seepage conditions, shall be performed to determine the size of rock
toe buttresses and keyway cuts and in accordance with
10
CSR 40-6.050(17).
(K) Fill
Inspection.
1. A registered professional
engineer or other qualified professional specialist under the direction of a
registered professional engineer, approved in the permit and plan and
experienced in the construction of earth and rockfill embankments, shall
inspect the fill for stability at least quarterly throughout construction and
during the following critical construction periods:
A. Removal of all organic material
and topsoil;
B. Placement of underdrainage
systems;
C. Installation of surface
drainage systems;
D. Placement and compaction of
fill materials; and
E. Revegetation.
2. Within two (2) weeks after each
inspection, the registered professional engineer shall provide the director
with a certified report stating that the fill has been constructed as specified
in the design approved in the permit and plan. The report shall include
appearances of instability, structural weakness and other hazardous
conditions.
3. Certified
report.
A. 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.
B. Where excess durable rock spoil
is placed in single or multiple lifts so that the underdrain system is
constructed simultaneously with excess spoil placement by the natural
segregation of dumped materials, color photographs shall be taken of the
underdrain as the underdrain system is being formed.
C. 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 the report shall be
retained at the minesite.
(L) Coal processing wastes shall
not be disposed of in head-of-hollow or valley fills and may only be disposed
of in other excess spoil fills, if the waste is-
1. Placed in accordance with
10
CSR 40-3.080(4);
2. Demonstrated to be nontoxic-
and nonacid-forming; and
3. Demonstrated to be consistent
with the design stability of the fill.
(M) If the disposal area contains
springs, natural or man-made 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.
(N) 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.
(O) Excess spoil may be returned
to underground mine workings, but only in accordance with a disposal program
approved in the permit and plan and Mine Safety and Health Administration
(MSHA) upon the basis of a plan submitted under
10
CSR 40-6.120(17).
(2) Valley Fills. Valley fills
shall meet all of the requirements of section (1) of this rule and the
additional requirements of this section.
(A) The fill shall be designed to
attain a long-term static safety factor of one and five-tenths (1.5) based upon
data obtained from subsurface exploration, geotechnical testing, foundation
design, and accepted engineering analyses.
(B) A subdrainage system for the
fill shall be constructed in accordance with the following:
1. A system of underdrains
constructed of durable rock shall meet the requirements of paragraph (2)(B)4.
of this rule and shall-
A. Be installed along the natural
drainage system;
B. Extend from the toe to the head
of the fill; and
C. Contain lateral drains to each
area of potential drainage or seepage;
2. A filter system to insure the
proper functioning of the rock underdrain system shall be designed and
constructed using standard geotechnical engineering methods;
3. In constructing the
underdrains, no more than ten percent (10%) of the rock may be less than twelve
inches (12") in size and no single rock may be larger than twenty-five percent
(25%) of the width of the drain. Rock used in underdrains shall meet the
requirements of paragraph (2)(B)4. of this rule. The minimum size of the main
under-drain shall be-
Total Amount of Fill
Material
Predominant Type of Fill
Material
Minimum Size of Drain in
Feet
Width
Height
Less than 1,000,000
yd3
Sandstone
10
4
Do
Shale
16
8
More than 1,000,000
yd3
Sandstone
16
8
Do
Shale
16
16
4. Underdrains shall consist of
nondegradable, nonacid-and nontoxic-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.
(C) Spoil shall be hauled or
conveyed and placed in a controlled manner and concurrently compacted, as
specified in the permit and plan, in lifts no greater than four feet (4') or
less, if required in the permit and plan, to-
1. Achieve the densities designed
to ensure mass stability;
2. Prevent mass
movement;
3. Avoid contamination of the rock
underdrain or rock core; and
4. Prevent formation of
voids.
(D) Surface water runoff from the
area above the fill shall be diverted away from the fill and into stabilized
diversion channels designed to safely pass the runoff from a one hundred-
(100-) year, twenty-four- (24-) hour precipitation or longer event specified in
the permit and plan. Surface runoff from the fill surface shall be diverted
through stabilized channels off the fill which will safely pass the runoff from
the one hundred- (100-) year, twenty-four- (24-) hour precipitation event.
Diversion design shall comply with the requirements of
10
CSR 40-3.040(3)(F).
(E) The tops of the fill and any
terrace constructed to stabilize the face shall be graded no steeper than
1v:20h (5%). The vertical distance between terraces shall not exceed fifty feet
(50').
(F) Drainage shall not be directed
over the outslope of the fill.
(G) The outslope of the fill shall
not exceed 1v:2h (50%). The permit and plan may require a flatter slope to
control erosion and insure stability.
(3) Head-of-Hollow Fills. Disposal
of spoil in the head-of-hol-low fill shall meet all standards set forth in
sections (1) and (2) of this rule and the additional requirements of this
section.
(A) The fill shall be designed to
completely fill the disposal site to the approximate elevation of the
ridgeline. A rock-core chimney drain may be utilized instead of the subdrain
and surface diversion system required for valley fills. If the crest of the
fill is not approximately at the same elevation as the low point of the
adjacent ridgeline, the fill must be designed as specified in section (2) of
this rule, with diversion of runoff around the fill. A fill associated with
contour mining placed at or near the coal seam, which does not exceed two
hundred fifty thousand (250,000) cubic yards, may use the rock-core chimney
drain.
(B) The alternative rock-core
chimney drain system shall be designed and incorporated into the construction
of head-of-hollow fills as follows:
1. The fill shall have, along the
vertical projection of the main buried stream channel or rill, a vertical core
of durable rock at least sixteen feet (16') thick which shall extend from the
toe of the fill to the head of the fill, and from the base of the fill to the
surface of the fill. A system of lateral rock underdrains shall connect this
rock core to each area of potential drainage or seepage in the disposal area.
Rocks used in the rock core and underdrains shall meet the requirements of
subsection (2)(B) of this rule;
2. A filter system to ensure the
proper functioning of the rock core shall be designed and constructed using
standard geotechnical engineering methods; and
3. The grading may drain surface
water away from the outslope of the fill and toward the rock core. The maximum
slope of the fill shall be 1v:33h (3%). Instead of the requirements of
subsection (1)(G) of this rule, a drainage pocket may be maintained at the head
of the fill during and after construction, to intercept surface runoff and
discharge the runoff through or over the rock drain, if stability of the fill
is not impaired. In no case shall this pocket or sump have a potential for
impounding more than ten thousand (10,000) cubic feet of water. Terraces on the
fill shall be graded with the three percent to five percent (3%-5%) grade
toward the fill and a one percent (1%) slope toward the rock core. (C) The
drainage control system shall be capable of safely passing the runoff from a
one hundred- (100-) year, twenty-four- (24-) hour precipitation event or larger
event specified in the permit and plan.
(4) Durable Rock Fills. In lieu of
the requirements of sections (2) and (3) of this rule, approval may be given in
the permit and plan for alternate methods for disposal of hard rock spoil,
including fill placement by dumping in a single lift, on a site-specific basis,
provided the services of a registered professional engineer experienced in the
design and construction of earth and rockfill embankments are utilized and
provided the requirements of this section and of section (1) of this rule are
met. For this section, hard rock spoil shall be defined as rockfill consisting
of at least eighty percent (80%) by volume of sandstone, limestone or other
rocks that do not slake in water. Resistance of the hard rock spoil to slaking
shall be determined by using the slake index and slake durability tests in
accordance with guidelines and criteria established in the permit and
plan.
(A) Spoil is to be transported and
placed in a specified and controlled manner which will ensure stability of the
fill.
1. The method of spoil placement
shall be designed to ensure mass stability and prevent mass movement in
accordance with the additional requirements of this section.
2. Loads of noncemented clay
shale, clay spoil, or both, in the fill shall be mixed with hard rock spoil in
a controlled manner to limit, on a unit basis, concentrations of noncemented
clay shale and clay in the fill. The materials shall comprise no more than
twenty percent (20%) of the fill volume as determined by tests performed by a
registered professional engineer and approved in the permit and
plan.
(B) Stability Analyses and Bank
Design.
1. Stability analyses shall be
made by the registered professional engineer. Parameters used in the stability
analyses shall be based on adequate field reconnaissance, subsurface
investigations, including borings and laboratory tests.
2. The embankment which
constitutes the valley fill or head-of-hollow fill shall be designed with the
following factors of safety:
Case
Design
Condition
Minimum Factor of
Safety
I
End of
construction
1.5
II
Earthquake
1.1
(C) The design of a head-of-hollow
fill shall include an internal drainage system which will ensure continued free
drainage of anticipated seepage from precipitation, springs, or wet weather
seeps.
1. Anticipated discharge from
springs and seeps and due to precipitation shall be based on records, field
investigations, or both, to determine seasonal variation. The design of the
internal drainage system shall be based on the maximum anticipated
discharge.
2. All granular material used for
the drainage system shall be 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.
3. The internal drain shall be
protected by a properly designed and constructed filter system using standard
geotechnical engineering methods.
(D) Surface water runoff from the
areas adjacent to and above the fill shall not be allowed to flow onto the fill
and shall be diverted into stabilized channels which are designed to safely
pass the runoff from a one hundred- (100-) year, twenty-four- (24-) hour
precipitation event. Diversion design shall comply with the requirements of
10
CSR 40-3.040(3)(F).
(E) The top surface of the
completed fill shall be graded so that the final slope after settlement will be
no steeper than 1v:20h (5%) toward properly designed drainage channels in
natural ground along the periphery of the fill. Surface runoff from the top
surface of the fill shall not be allowed to flow over the outslope of the
fill.
(F) Surface runoff from the
outslope of the fill shall be diverted off the fill to properly designed
channels which will safely pass a one hundred- (100-) year, twenty-four- (24-)
hour precipitation event. Diversion design shall comply with the requirements
of
10
CSR 40-3.040(3)(F).
(G) Terraces shall be constructed
on the outslope if required for control of erosion or for roads included in the
approved postmining land use plan. Terraces shall meet the following
requirements:
1. The slope of the outslope
between terrace benches shall not exceed 1v:2h (50%);
2. To control surface runoff, each
terrace bench shall be graded to a slope of 1v:20h (5%) toward the embankment.
Runoff shall be collected by a ditch along the intersection of each terrace
bench and the outslope; and
3. Terrace ditches shall have a
five percent (5%) slope toward the channels specified in subsection (4)(F) of
this rule, unless steeper slopes are necessary in conjunction with approved
roads.
Notes
*Original authority: 444.530, RSMo 1979, amended 1983, 1990, 1993, 1995 and 444.810, RSMo 1979, amended 1983, 1993, 1995.
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