Current through Register Vol. 48, No. 38, September 20, 2024
a)
The owner or operator of a CCR surface impoundment must conduct initial and
annual structural stability assessments and document whether the design,
construction, operation, and maintenance of the CCR surface impoundment is
consistent with recognized and generally accepted engineering practices for the
maximum volume of CCR and CCR wastewater that can be impounded in the CCR
surface impoundment. The assessment must, at a minimum, document whether the
CCR surface impoundment has been designed, constructed, operated, and
maintained with:
1) Stable foundations and
abutments;
2) Adequate slope
protection to protect against surface erosion, wave action, and adverse effects
of sudden drawdown;
3) Dikes
mechanically compacted to a density sufficient to withstand the range of
loading conditions in the CCR surface impoundment;
4) Slope protection consistent with Section
845.430;
5) A single spillway or a
combination of spillways configured as specified in subsection (a)(5)(A). The
combined capacity of all spillways must be designed, constructed, operated, and
maintained to adequately manage flow during and following the peak discharge
from the event specified in subsection (a)(5)(B).
A) All spillways must be either:
i) Of non-erodible construction and designed
to carry sustained flows; or
ii)
Earth- or grass-lined and designed to carry short-term, infrequent flows at
non-erosive velocities where sustained flows are not expected.
B) The combined capacity of all
spillways must adequately manage flow during and following the peak discharge
from a:
i) Probable maximum flood for a Class
1 CCR surface impoundment; or
ii)
1000-year flood for a Class 2 CCR surface impoundment.
6) Hydraulic structures underlying
the base of the CCR surface impoundment or passing through the dike of the CCR
surface impoundment that maintain structural integrity and are free of
significant deterioration, deformation, distortion, bedding deficiencies,
sedimentation, and debris that may negatively affect the CCR surface
impoundment; and
7) For CCR surface
impoundments with downstream slopes that can be inundated by the pool of an
adjacent water body, such as a river, stream or lake, downstream slopes that
maintain structural stability during low pool of the adjacent water body or
sudden drawdown of the adjacent water body.
b) The annual assessment described in this
Section must identify any structural stability deficiencies associated with the
CCR surface impoundment in addition to recommending corrective measures. If a
deficiency or a release is identified during the periodic assessment, the owner
or operator of the surface impoundment must submit to the Agency a construction
permit application including documentation detailing proposed corrective
measures and must obtain any necessary permits from the Agency as soon as
feasible.
c) The owner or operator
of the CCR surface impoundment must obtain a certification from a qualified
professional engineer stating that the initial structural stability assessments
and each annual assessment thereafter was conducted in accordance with the
requirements.
d) Timeframe for
Submission of Structural Stability Assessment
1) The owner or operator of a new CCR surface
impoundment must submit the initial structural stability assessment
certification with the initial operating permit application before the initial
receipt of CCR in the surface impoundment.
2) The owner or operator of an existing CCR
surface impoundment must submit the initial structural stability assessment
certification with its first annual inspection report required by Section
845.540(b).
3) The owner or
operator of a CCR surface impoundment must submit the annual structural
stability assessment certification each year with the annual inspection
required by Section 845.540(b).
4)
The owner or operator of a CCR surface impoundment must place each structural
stability assessment in the facility's operating record (see Section
845.800(d)(5)).
e) The
requirements of this Section apply to all CCR surface impoundments, except for
those CCR surface impoundments that are incised CCR surface impoundments. If an
incised CCR surface impoundment is subsequently modified (e.g., a dike is
constructed) such that the CCR surface impoundment no longer meets the
definition of an incised CCR surface impoundment, the CCR surface impoundment
is subject to the requirements of this Section.
