Illinois Administrative Code › Title 62 - MINING › Part 1817 - PERMANENT PROGRAM PERFORMANCE STANDARDS - UNDERGROUND MINING OPERATIONS › Section 1817.49 - Impoundments

Current through Register Vol. 48, No. 28, July 12, 2024
a) The requirements
			 of this subsection apply to both temporary and permanent impoundments.
1) Impoundments meeting the Class B or C
			 criteria for dams in the U.S. Department of Agriculture, Soil Conservation
			 Service Technical Release No. 60 (210-VI-TR60, Oct. 1985), "Earth Dams and
			 Reservoirs," shall comply with "Minimum Emergency Spillway Hydrologic Criteria"
			 table in TR-60 and the requirements of this Section.
2) Impoundments meeting the size and other
			 qualifying criteria of
			 30
			 CFR 77.216(a) shall comply
			 with the requirements of
			 30
			 CFR 77.216(1998) and this
			 Section.
			 30
			 CFR 77.216 does not include any later
			 editions or amendments. The plan required to be submitted to the District
			 Manager of the Mine Safety and Health Administration (MSHA) under
			 30
			 CFR 77.216 shall also be submitted to the
			 Department as part of the permit application, insofar as the MSHA informational
			 design standard requirements are duplicative of the requirements of 62 Ill.
			 Adm. Code 1784. In addition, the operator shall submit to the Department any
			 certification issued by MSHA with respect to the design plan.
3) The design of impoundments shall be sealed
			 in accordance with 62 Ill. Adm. Code
			 1784.16(a)
			 as designed to meet the requirements of this Part using current, prudent
			 engineering practices. The qualified registered professional engineer shall be
			 experienced in the design and construction of impoundments.
4) Stability.
A) An impoundment meeting the Class B or C
			 criteria for dams in TR-60, or the size or other criteria of
			 30
			 CFR 77.216(a), shall have a
			 minimum static safety factor of
			 1.5 for a normal pool with
			 steady state seepage saturation conditions, and a seismic safety factor of at
			 least 1.2.
B) Impoundments not
			 included in subsection (a)(4)(A), except for a coal mine waste impounding
			 structure, and located where failure would not be expected to cause loss of
			 life or serious property damage shall have a minimum static safety factor of
			 1.3 for a normal pool
			 with steady state seepage saturation conditions, or meet the design,
			 construction and maintenance requirements of U.S. Natural Resources
			 Conservation Service Practice Standard IL 378, "Ponds," June 1992. Practice
			 Standard 378 is hereby incorporated by reference and does not include later
			 editions or amendments.
5) Impoundments shall have adequate freeboard
			 to resist overtopping by waves and by sudden decreases in storage volume.
			 Impoundments meeting the SCS Class B or C criteria for dams in TR-60 shall
			 comply with the freeboard hydrology criteria in the "Minimum Emergency Spillway
			 Hydrologic Criteria" table in TR-60.
6) Foundations.
A) Foundations and abutments for an
			 impounding structure shall be stable during all phases of construction and
			 operation and shall be designed based on adequate and accurate information on
			 the foundation conditions. For an impoundment meeting the Class B or C criteria
			 for dams in TR-60, or the size or other criteria of
			 30
			 CFR 77.216(a), foundation
			 investigation, as well as any necessary laboratory testing of foundation
			 material, shall be performed to determine the design requirements for
			 foundation stability.
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.
7)
			 Slope protection shall be provided to protect against surface erosion at the
			 site and protect against sudden drawdown.
8) Faces of embankments and surrounding areas
			 shall be vegetated, except that faces where water is impounded may be riprapped
			 or otherwise stabilized in accordance with accepted design practices.
9) Impoundments shall include a combination
			 of principal and emergency spillways which shall be designed and constructed to
			 safely pass the design precipitation event specified in subsection (b) or
			 (c).
10) 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, as evidenced by the placement of a registered
			 professional engineer's seal on the inspection report.
A) Impoundments meeting the SCS Class B or C
			 criteria for dams in TR-60, or the size or other criteria of
			 30
			 CFR 77.216(a), shall be
			 inspected, examined and certified in accordance with
			 30
			 CFR 77.216. Annual status reports required
			 under
			 30
			 CFR 77.216-4 shall be submitted to the
			 Department within 30 days after the reporting period.
B) All other impoundments shall be inspected
			 at least quarterly during construction, provided at least one inspection is
			 conducted for impoundments completed in less than one quarter, and upon
			 completion of construction. The qualified registered professional engineer
			 shall submit to the Department, within 30 days after each inspection, a sealed
			 report that the impoundment has been constructed as designed and in accordance
			 with the approved plan and this Part.
C) A copy of the reports required in
			 subsections (a)(10)(A) and (B), and the examination reports required in
			 subsection (a)(11), shall be retained at or near the mine site. The Department
			 may approve reports being retained at a different location if there is no
			 permanent mine office.
11) Impoundments which do not meet the SCS
			 Class B or C criteria for dams in TR-60, or subject to
			 30
			 CFR 77.216(a), shall be
			 examined at least quarterly by a qualified person designated by the permittee
			 for appearances of instability, structural weakness or other hazardous
			 conditions. At least one of the quarterly examinations conducted during the
			 calendar year shall be sealed by a qualified registered professional engineer
			 and shall include a discussion of any appearances of instability, structural
			 weakness or other hazardous conditions, and any other aspects of the structure
			 affecting stability, and a statement indicating the pond has been maintained in
			 accordance with the approved plan and these regulations. This examination shall
			 be conducted during the period of October 1 through December 31 of each
			 calendar year. The sealed examination report shall be submitted to the
			 Department within 30 days of the examination. Impoundment examinations shall be
			 conducted until the impoundment has been removed or until final bond release in
			 accordance with 62 Ill. Adm. Code
			 1800.40. If the
			 operator can demonstrate that failure of the structure would not create a
			 potential threat to public health and safety or threaten significant
			 environmental harm, the following impoundments shall be exempt from all
			 examination requirements of this subsection following approval by the
			 Department:
A) Impoundments that are
			 completely incised;
B) Water
			 impounding structures that impound water to a design elevation no more than
			 five feet above the upstream toe of the structure and that can have a storage
			 volume of not more than 20 acre-feet; provided the exemption request is
			 accompanied by a report sealed by a registered professional engineer licensed
			 in the State of Illinois, accurately describing the hazard potential of the
			 structure. Hazard potential must be such that failure of the structure would
			 not create a potential threat to public health and safety or threaten
			 significant environmental harm. The report shall be field verified by the
			 Department prior to approval and periodically thereafter. The Department may
			 terminate the exemption if so warranted by changes in the area downstream of
			 the structure or in the structure itself; and
C) Impoundments that do not facilitate mining
			 or reclamation including, but not limited to, sewage lagoons, landscaping
			 ponds, pools or wetlands in replaced stream channels, existing impoundments not
			 yet used to facilitate mining, ephemeral waterbodies, active mining pits and
			 differential settlement pools.
12) If any examination or inspection
			 discloses that a potential hazard exists, the person who examined the
			 impoundment shall promptly inform the Department of the finding and of the
			 emergency procedures formulated for public protection and remedial action. If
			 adequate procedures cannot be formulated or implemented, the Department shall
			 be notified immediately. The Department shall then notify the appropriate
			 agencies that other emergency procedures are required to protect the
			 public.