RELATES TO:
KRS
151.100,
151.250(3),
350.100,
350.420,
350.455,
350.465,
30 C.F.R. Parts 730-733, 735,
816.49,
917,
30 U.S.C. 1253,
1255,
1265
NECESSITY, FUNCTION, AND CONFORMITY:
KRS 350.028(2),
(5),
350.151(1),
and
350.465(2)
authorize the cabinet to promulgate administrative regulations relating to
surface and underground coal mining operations. This administrative regulation
establishes the requirements for the design, construction, certification,
inspection, and maintenance of temporary and permanent impoundments for surface
mines. This administrative regulation differs from federal regulations as
follows:
(1) Section 1 of this
administrative regulation provides criteria related to the stability,
settlement, embankment height and width, and freeboard of impoundments which is
not found in the federal regulations. These criteria have been retained because
they have long been effective guidelines for embankment safety and
stability.
(2) Section 1(9)(c) of
this administrative regulation provides an exemption from engineering
inspection for certain types of impoundments without embankments. These
inspections are unnecessary because the embankments do not present a safety
hazard or environmental concern that would warrant routine, detailed
inspection.
(3) Section 1(10)(b) of
this administrative regulation provides an exemption from quarterly inspections
for certain small nonhazardous impoundments without embankment structures.
These inspections are unnecessary because the structures cannot develop the
hazardous conditions which the inspections were intended to detect.
Section 1. General Requirements. The
requirements of this section apply to both temporary and permanent
impoundments.
(1)
(a) Impoundments meeting the criteria of
MSHA,
30
C.F.R.
77.216(a), shall
comply with the requirements of
30
C.F.R.
77.216 and this administrative
regulation. The plan required to be submitted to the district manager of MSHA
under
30
C.F.R.
77.216 shall be submitted to the
cabinet as part of the permit application in accordance with
405 KAR
8:030, Section 34(3).
(b) All impoundments classified as Class
B-moderate hazard or Class C-high hazard, and all permanent "dams," as defined
by
KRS
151.100, shall comply with
405 KAR
7:040, Section 5 and with
401 KAR
4:030.
(2) Design certification. The design of
impoundments shall be certified by a qualified registered professional engineer
as designed to meet the requirements of this administrative regulation using
current, prudent engineering practices, and any design criteria established by
the cabinet in accordance with 405 KAR Chapters 7 through 24. The qualified
registered professional engineer shall be experienced in the design and
construction of impoundments.
(3)
Stability.
(a)
1. Permanent and temporary impoundments
meeting the criteria of MSHA,
30
C.F.R.
77.216(a), all Class
B and C impoundments, and all permanent impoundments, shall have a minimum
static safety factor of 1.5 for the normal pool with steady seepage saturation
conditions, and a seismic safety factor of at least 1.2.
2. Impoundments not included in subparagraph
1 of this paragraph, except coal mine waste impoundments, shall have a minimum
static safety factor of 1.3 for the normal pool with steady state seepage
saturation conditions.
(b) The constructed height of the dam shall
be increased a minimum of five (5) percent over the design height to allow for
settlement, unless it has been demonstrated to the cabinet that the material
used and the design shall ensure against all settlement.
(c) The minimum top width of the embankment
shall not be less than the quotient of (H+35)/5, where H is the height, in
feet, of the embankment as measured from the upstream toe of the
embankment.
(d) Unless the cabinet
approves steeper slopes, based on site and slope stability, the sum of the
upstream and downstream side slopes (h/v) of the settled embankment shall not
be less than 5h:1v, with neither slope steeper than 2h:1v. Slopes shall be
designed to be stable in all cases, even if flatter side slopes are
required.
(e) The fill material
shall be free of sod, large roots, other large vegetative matter, and frozen
soil and shall not contain coal mine waste except for coal mine waste
impounding structures pursuant to
405 KAR
16:160.
(f) The placing and spreading of fill
material shall be started at the lowest point of the foundation. The fill shall
be brought up in horizontal layers of thickness as is required to facilitate
compaction and meet the design requirement of this administrative regulation.
Compaction shall be conducted as specified in the design approved by the
cabinet pursuant to subsection (2) of this section.
(g) The entire embankment including the
surrounding areas disturbed by construction shall be stabilized with respect to
erosion by a vegetative cover or other means immediately after the embankment
is completed. The active upstream face of the embankment where water will be
impounded may be riprapped or otherwise stabilized. Areas in which the
vegetation is not successful or where rills and gullies develop shall be
repaired and revegetated in accordance with
405 KAR
16:190, Section 6.
(h) Slope protection shall be provided to
protect against surface erosion at the site and protect against sudden
drawdown.
(4) Freeboard.
Impoundments shall have adequate freeboard to resist overtopping by waves and
by sudden increases in storage volume. The minimum elevation at the top of the
settled embankment shall be one (1.0) foot above the water surface in the pond
with the emergency spillway flowing at design depth. For embankments subject to
settlement, this one (1.0) foot minimum elevation requirement shall apply at
all times, including the period after settlement. Freeboard requirements shall
not apply to incised impoundments that have no embankment or levee.
(5) Foundation.
(a)
1.
Foundation and abutments for the impounding structure shall be designed to be
stable under all conditions of construction and operation of the impoundment
and shall be designed based on adequate and accurate information on the
foundation conditions.
2. For
permanent and temporary impoundments meeting the criteria of MSHA,
30
C.F.R.
77.216(a), for all
Class B and C impoundments, and for all permanent impoundments, foundation
investigations as well as any necessary laboratory testing of materials shall
be performed in order to determine the design requirements for foundation and
embankment stability.
3. If an
approved temporary impoundment has been constructed and the permittee
subsequently seeks a permit revision to upgrade the structure to a permanent
impoundment, the cabinet may waive the foundation investigations and laboratory
testing required by subparagraph 2 of this paragraph under the following
circumstances:
a. The structure has been
recently verified as being a Class A-low hazard structure;
b. The structure does not meet the definition
of the term "dam," as defined by
KRS
151.100(12); and
c. The cabinet approves conservative, assumed
values for the strength parameters used in the stability analyses to ensure
compliance with subsection (3)(a) of this section.
(b) All vegetative and organic
materials shall be removed and foundations excavated and prepared to resist
failure. Cutoff trenches shall be installed if necessary to ensure
stability.
(6)
Impoundments shall include a combination of principal and emergency spillways,
which shall be designed and constructed to safely pass the design precipitation
event established in this subsection unless the cabinet requires a design based
on a larger precipitation event due to site specific conditions. Twenty-four
(24) hours may be used in lieu of six (6) hours for the duration of a design
precipitation event established in this subsection.
(a) Except as established in paragraph (c) of
this subsection, Class A structures that do not meet the criteria of MSHA,
30
C.F.R.
77.216(a), shall pass
the:
1. Twenty-five (25) year, six (6) hour
precipitation event if it is a temporary structure; or
2. The fifty (50) year, six (6) hour
precipitation event if it is a permanent structure.
(b) Class A structures that meet the criteria
of MSHA,
30
C.F.R.
77.216(a), shall pass
the 100 year, six (6) hours precipitation event.
(c) Class B and C structures and all
permanent "dams," as defined by
KRS
151.100(12) shall comply
with the criteria established in
401 KAR
4:030.
(7) Class A impoundments not meeting the
criteria of MSHA,
30
C.F.R.
77.216(a), may use a
single spillway (if allowed pursuant to subsection (1)(b) of this section) if
the spillway:
(a) Is an open channel of
nonerodible construction and capable of maintaining sustained flows;
and
(b) Is not earth or grass
lined.
(8) The vertical
portion of any remaining highwall shall be located far enough below the
low-water line along the full extent of the highwall to provide adequate safety
and access for the proposed water users.
(9) Engineer inspections. A qualified
registered professional engineer or other qualified professional specialist,
under the direction of the professional engineer, shall inspect the
impoundment. The professional engineer or specialist shall be experienced in
the construction of impoundments.
(a)
Inspections shall be made regularly during construction, upon completion of
construction, and at least yearly until removal of the structure or release of
the performance bond.
(b) The
qualified registered professional engineer shall promptly, after each
inspection, provide to the cabinet a certified report that the impoundment has
been constructed and maintained as designed and in accordance with the plan
approved in the permit and 405 KAR Chapters 7 through 24. The report shall
include discussion of any appearances of instability, structural weakness, or
other hazardous conditions, depth and elevation of any impounded waters,
existing storage capacity, any existing or required monitoring procedures and
instrumentation, and any other aspects of the structure affecting stability.
The report shall also confirm the hazard classification of the impoundment, or
if the hazard classification has changed, the report shall contain a detailed
explanation of the change and the conditions causing the change. A copy of the
report shall be retained at or near the mine site.
(c) An impoundment with no embankment
structure, that is completely incised or is created by a depression left by
backfilling and grading, that is not a sedimentation pond or coal mine waste
impoundment and is not otherwise intended to facilitate active mining, shall be
exempt from this subsection unless the cabinet determines and notifies the
permittee in writing that engineering inspection and certification are
necessary to ensure public health and safety or environmental
conditions.
(10)
Operator examinations.
(a) Impoundments
subject to
30
C.F.R.
77.216, and Class B and C
impoundments, shall be examined in accordance with
30
C.F.R.
77.216-3.
(b) Impoundments not included in paragraph
(a) of this subsection shall be examined at least quarterly by a qualified
person designated by the operator for appearance of structural weakness and
other hazardous conditions. Quarterly examinations shall be conducted each
calendar quarter (i.e., January-March, April-June, July-September, and
October-December) and no two (2) examinations shall be within thirty (30) days
of each other unless additional examination within a quarter are required based
on evidence of structural weakness or hazardous conditions. Reports of the
examinations shall be retained at or near the mine site. An impoundment with no
embankment structure, that is completely incised or is created by a depression
left by backfilling and grading, shall be exempt from this paragraph.
(11) Emergency procedures. If any
examination or inspection discloses that a potential hazard exists, the person
who examined the impoundment shall immediately notify the department and the
Kentucky Division of Water, or if these agencies cannot be reached, Disaster
and Emergency Services. The permittee shall immediately implement emergency
procedures formulated for public protection and remedial action. If adequate
emergency procedures cannot be formulated or implemented by the permittee, the
cabinet shall be notified, and the cabinet shall notify the appropriate
agencies that other emergency procedures are required to protect the
public.
(12) Maintenance. An owner
or operator of an impoundment shall:
(a) Cut
vegetative growth where necessary to facilitate inspection and
repairs;
(b) Clean any ditches and
spillways; and
(c) Remove any
combustible material present on the surface, other than that used for
stability, such as mulch or dry vegetation.
Section 2. Permanent Impoundments. A
permanent impoundment of water may be created, if authorized by the cabinet in
the approved permit based upon compliance with subsections (1) through (6) of
this section.
(1) The size and configuration
of the impoundment will be adequate for its intended purposes.
(2) The quality of impounded water shall be
suitable on a permanent basis for its intended use and, after reclamation,
shall comply with applicable state and federal water quality standards, and
discharges from the impoundment shall comply with applicable effluent
limitations and shall not degrade the quality of receiving water below
applicable state and federal water quality standards.
(3) The water level shall be sufficiently
stable and be capable of supporting the intended use.
(4) Final grading shall provide for adequate
safety and access for proposed water users. Perimeter slopes shall be stable
and shall be protected against erosion.
(5) The impoundment shall not result in the
diminution of the quality and quantity of water utilized by adjacent or
surrounding landowners for agricultural, industrial, recreational, or domestic
uses.
(6) The impoundment shall be
suitable for the approved postmining land use.