Current through Register Vol. 47, No. 17, September 10, 2024
(a)
Any surface impoundment that is not covered by paragraph (c) of this section or
§ 265.221 of these regulations must have a liner for all portions of the
impoundment (except for existing portions of such impoundments). The liner must
be designed, constructed, and installed to prevent any migration of wastes out
of the impoundment to the adjacent subsurface soil or ground water or surface
water at any time during the active life (including the closure period) of the
impoundment. The liner may be constructed of materials that may allow wastes to
migrate into the liner (but not into the adjacent subsurface soil or ground
water or surface water) during the active life of the facility, provided that
the impoundment is closed in accordance with § 264.228(a)(1). For
impoundments that will be closed in accordance with § 264.228(a)(2), the
liner must be constructed of materials that can prevent wastes from migrating
into the liner during the active life of the facility. The liner must be:
(1) Constructed of materials that have
appropriate chemical properties and sufficient strength and thickness to
prevent failure due to pressure gradients (including static head and external
hydrogeologic forces), physical contact with the waste or leachate to which
they are exposed, climatic conditions, the stress of installation, and the
stress of daily operation;
(2)
Placed upon a foundation or base capable of providing support to the liner and
resistance to pressure gradients above and below the liner to prevent failure
of the liner due to settlement, compression, or uplift; and
(3) Installed to cover all surrounding earth
likely to be in contact with the waste or leachate.
(b) The owner or operator will be exempted
from the requirements of paragraph (a) of the section if the Department finds,
based on a demonstration by the owner or operator, that alternate design and
operating practices, together with location characteristics, will prevent the
migration of any hazardous constituents (see § 264.93) into the ground
water or surface water at any future time. In deciding whether to grant an
exemption, the Department will consider:
(1)
The nature and quantity of the wastes;
(2) The proposed alternate design and
operation;
(3) The hydrogeologic
setting of the facility, including the attenuative capacity and thickness of
the liners and soils present between the impoundment and ground water or
surface water, and
(4) All other
factors which would influence the quality and mobility of the leachate produced
and the potential for it to migrate to ground water or surface water.
(c) The owner or operator of each
new surface impoundment on which construction commences after January 29, 1992,
each lateral expansion of a surface impoundment unit on which construction
commences after July 29, 1992 and each replacement of an existing surface
impoundment unit that is to commence reuse after July 29, 1992 must install two
or more liners and a leachate collection and removal system between such
liners. "Construction commences" is as defined in § 260.10 of these
regulations under "existing facility" .
(1)
(i) The liner system must include:
(A) A top liner designed and constructed of
materials (e.g., a geomembrane) to prevent the migration of hazardous
constituents into such liner during the active life and post-closure care
period; and
(B) A composite bottom
liner, consisting of at least two components. The upper component must be
designed and constructed of materials (e.g., a geomembrane) to prevent the
migration of hazardous constituents into this component during the active life
and post-closure care period. The lower component must be designed and
constructed of materials to minimize the migration of hazardous constituents if
a breach in the upper component were to occur. The lower component must be
constructed of at least 3 feet (91 cm) of compacted soil material with a
hydraulic conductivity of no more than 1 x 10
-7 cm/sec.
(ii) The liners must comply with paragraphs
(a)(1), (2), and (3) of this section.
(2) The leachate collection and removal
system between the liners, and immediately above the bottom composite liner in
the case of multiple leachate collection and removal systems, is also a leak
detection system. This leak detection system must be capable of detecting,
collecting, and removing leaks of hazardous constituents at the earliest
practicable time through all areas of the top liner likely to be exposed to
waste or leachate during the active life and post-closure care period. The
requirements for a leak detection system in this paragraph are satisfied by
installation of a system that is, at a minimum:
(i) Constructed with a bottom slope of one
percent or more;
(ii) Constructed
of granular drainage materials with a hydraulic conductivity of 1 x 10
-1 cm/sec or more and a thickness of
12 inches (30.5 cm) or more; or constructed of synthetic or geonet drainage
materials with a transmissivity of 3 x 10-
4 m
2 /sec or more;
(iii) Constructed of materials that are
chemically resistant to the waste managed in the surface impoundment and the
leachate expected to be generated, and of sufficient strength and thickness to
prevent collapse under the pressures exerted by overlying wastes and any waste
cover materials or equipment used at the surface impoundment;
(iv) Designed and operated to minimize
clogging during the active life and post-closure care period; and
(v) Constructed with sumps and liquid removal
methods (e.g., pumps) of sufficient size to collect and remove liquids from the
sump and prevent liquids from backing up into the drainage layer. Each unit
must have its own sump(s). The design of each sump and removal system must
provide a method for measuring and recording the volume of liquids present in
the sump and of liquids removed.
(3) The owner or operator shall collect and
remove pumpable liquids in the sumps to minimize the head on the bottom
liner.
(4) The owner or operator of
a leak detection system that is not located completely above the seasonal high
water table must demonstrate that the operation of the leak detection system
will not be adversely affected by the presence of ground water.
(d) The Department may approve
alternative design or operating practices to those specified in paragraph (c)
of this section if the owner or operator demonstrates to the Department that
such design and operating practices, together with location characteristics:
(1) Will prevent the migration of any
hazardous constituent into the ground water or surface water at least as
effectively as the liners and leachate collection and removal system specified
in paragraph (c) of this section; and
(2) Will allow detection of leaks of
hazardous constituents through the top liner at least as effectively.
(e) The Department is authorized
to exempt the owner or operator of a monofill from the requirements of
paragraph (c) of this section if the following conditions are met:
(1) The monofill contains only hazardous
wastes from foundry furnace emission controls or metal casting molding sand and
such wastes do not contain constituents which would render the wastes hazardous
for reasons other than the EP toxicity characteristics in § 261.24;
and
(2)
(i)
(A) The
monofill has at least one liner for which there is no evidence that the liner
is leaking. For the purposes of this paragraph, the term "liner" means a liner
designed, constructed, installed, and operated to prevent hazardous waste from
passing into the liner at any time during the active life of the facility, or
designed, constructed, installed, and operated to prevent hazardous waste from
migrating beyond the liner to adjacent subsurface soil, ground water, or
surface water at any time during the active life of the facility. In the case
of any surface impoundment which has been exempted from the requirements of
paragraph (c) of this section on the basis of a liner designed, constructed,
installed, and operated to prevent hazardous waste from passing beyond the
liner, at the closure of such impoundment, the owner or operator must remove or
decontaminate all waste residues, all contaminated liner material, and
contaminated soil to the extent practicable. If all contaminated soil is not
removed or decontaminated, the owner or operator of such impoundment will
comply with appropriate post-closure requirements, including but not limited to
groundwater monitoring and corrective action.
(B) The monofill is located more than
one-fourth mile from an underground source of drinking water as defined in
40 CFR §
144.3; and
(C) The monofill is in compliance with
generally applicable ground water monitoring requirements for facilities with
RCRA permits; or
(ii) The
owner or operator demonstrates that the monofill is located, designed, and
operated so as to assure that there will be no migration of any hazardous
constituent into ground water or surface water at any future
time.
(f) The
owner or operator of any replacement surface impoundment unit is exempt from
paragraph (c) this section if:
(1) The
existing unit was constructed in compliance with the design standards of
sections 3004(o)(1)(A)(i) and (o)(5) of the Resource Conservation and Recovery
Act [42 U.S.C. §
6924(0)] ; and
(2) There is no reason to believe that the
liner is not functioning as designed.
(g) A surface impoundment must be designed,
constructed, maintained, and operated to prevent overtopping resulting from
normal or abnormal operations; overfilling; wind and wave action; rainfall;
run-on; malfunctions of level controllers, alarms, and other equipment; and
human error.
(h) A surface
impoundment must have dikes that are designed, constructed and maintained with
sufficient structural integrity to prevent massive failure of the dikes. In
ensuring structural integrity, it must not be presumed that the liner system
will function without leakage during the active life of the unit.
(i) The Department will specify in the permit
all design and operating practices that are necessary to ensure that the
requirements of this section are satisfied.
