405 KAR 18:100 - Permanent and temporary impoundments
RELATES TO: KRS 151.100, 151.250(3), 350.100, 350.151, 350.420, 350.455, 350.465, 30 C.F.R. 77.216, 77.216-3, Parts 730-733, Part 735, 817.49, Part 917, 30 U.S.C. 1253, 1255, 1266
NECESSITY, FUNCTION, AND CONFORMITY:
KRS 350.028(1),
(5),
350.151(1),
and
350.465(2)
authorize the Energy and Environment Cabinet to promulgate administrative
regulations relating to surface and underground
(1) Section 1 of this administrative
regulation provides criteria related to the stability, settlement, embankment
height and width, and freeboard of impoundments, which are 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 after the plan has been approved by
MSHA .
(b) All impoundments
classified as Class B-moderate hazard or Class C-high hazard, and all permanent
"dams," as defined in
KRS
151.100(12), shall comply
with
405 KAR
7:040, Section 4 and with
401 KAR
4:030.
(2) Design certification. The design of
impoundments shall be certified by a qualified licensed 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 405 KAR Chapters 7 through 24. The qualified licensed
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. Upon request, the minimum height increase may be reduced if 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
18:160.
(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
18:190, Section 4.
(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 at
KRS
151.100; 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
that shall be designed and constructed to safely pass the design precipitation
event specified 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 specified in this subsection.
(a) Except as provided 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 do meet the
criteria of MSHA ,
30
C.F.R. 77.216(a), shall pass
the 100 year, six (6) hour precipitation event .
(c) Class B and C structures and all
permanent dams as defined in
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
licensed 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 design and 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 licensed 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 examinations 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, Kentucky Emergency Management. 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 the following demonstration:
(1) The size and configuration of the
impoundment will be adequate for its intended purposes.
(2) The quality of impounded water will be
suitable on a permanent basis for its intended use and, after reclamation, will
meet applicable state and federal water quality standards, and discharges from
the impoundment will meet applicable effluent limitations and will not degrade
the quality of receiving water below applicable state and federal water quality
standards.
(3) The water level will
be sufficiently stable and be capable of supporting the intended use.
(4) Final grading will provide for adequate
safety and access for proposed water users. Perimeter slopes shall be stable
and shall be protected against erosion.
(5) The impoundment will 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 will be
suitable for the approved postmining land use .
Notes
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No prior version found.