40 CFR Part 264 -- STANDARDS FOR
OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES
Subpart K -- Surface Impoundments
§264.220 Applicability.
The regulations in this subpart apply to owners and operators of facilities that use
surface impoundments to treat, store, or dispose of hazardous waste except as §264.1
provides otherwise.
§264.221 Design and operating requirements.
(a) Any surface impoundment that is not covered by paragraph (c) of this section or
§265.221 of this chapter 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 this
section if the Regional Administrator 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 Regional Administrator 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 unit 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 this chapter 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 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 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 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 Regional Administrator may approve alternative design or operating practices to
those specified in paragraph (c) of this section if the owner or operator demonstrates to
the Regional Administrator 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 double liner requirement set forth in paragraph (c) of this section may be waived
by the Regional Administrator for any monofill, if:
(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 of
this chapter; and
(2)(i)(A) The monofill has at least one liner for which there is no evidence that such
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 a liner 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 ground-water monitoring and corrective action;
(B) The monofill is located more than one-quarter mile from an underground source of
drinking water (as that term is defined in §144.3 of this chapter); and
(C) The monofill is in compliance with generally applicable ground-water monitoring
requrements for facilities with permits under RCRA section 3005(c); 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) of 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; 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 Regional Administrator will specify in the permit all design and operating
practices that are necessary to ensure that the requirements of this section are
satisfied.
(Approved by the Office of Management and Budget under control number 2050-0007)
(47 FR 32357, July 26, 1982, as amended at 50 FR 4514, Jan. 31, 1985; 50 FR 28747, July
15, 1985; 57 FR 3487, Jan. 29, 1992)
Effective Date Note: At 57 FR 3487, Jan. 29, 1992, 264.221 was amended by redesignating
paragraphs (f), (g), and (h) as paragraphs (g), (h), and (i), by revising paragraphs (c)
and (d) and by adding new paragraph (f), effective July 29, 1992. For the convenience of
the reader, the superseded text is set forth below.
§264.221 Design and operating requirements.
* * * * *
(c) The owner or operator of each new surface impoundment, each new surface impoundment
unit at an existing facility, each replacement of an existing surface impoundment unit,
and each lateral expansion of an existing surface impoundment unit, must install two or
more liners and leachate collection system between such liners. The liners and leachate
collection system must protect human health and the environment. The requirements of this
paragraph shall apply with respect to all waste received after insurance of the permit for
units where the Part B of the permit application is received by the Regional Administrator
after November 8, 1984. The requirement for the installation of two or more liners in this
paragraph may be satisfied by the installation of a top liner designed, operated, and
constructed of materials to prevent the migration of any constituent into such liner
during the period such facility remains in operation (including any post-closure
monitoring period), and a lower liner designed, operated, and constructed to prevent the
migration of any constituent through such liner during such period. For the purpose of the
preceding sentence, a lower liner shall be deemed to satisfy such requirement if it is
constructed of at least a 3-foot thick layer of recompacted clay or other natural material
with a permeability of no more than 1 10^ /7/ centimeter per second.
(d) Paragraph (c) of this section will not apply if the owner or operator demonstrates to
the Regional Administrator, and the Regional Administrator finds for such surface
impoundment, that alternative design and operating practices, together with location
characteristics, will prevent the migration of any hazardous constituent into the ground
water or surface water at least as effectively as such liners and leachate collection
systems.
* * * * *
§264.222 Action leakage rate.
(a) The Regional Administrator shall approve an action leakage rate for surface
impoundment units subject to §264.221 (c) or (d). The action leakage rate is the maximum
design flow rate that the leak detection system (LDS) can remove without the fluid head on
the bottom liner exceeding 1 foot. The action leakage rate must include an adequate safety
margin to allow for uncertainties in the design (e.g., slope, hydraulic conductivity,
thickness of drainage material), construction, operation, and location of the LDS, waste
and leachate characteristics, likelihood and amounts of other sources of liquids in the
LDS, and proposed response actions (e.g., the action leakage rate must consider decreases
in the flow capacity of the system over time resulting from siltation and clogging, rib
layover and creep of synthetic components of the system, overburden pressures, etc.).
(b) To determine if the action leakage rate has been exceeded, the owner or operator must
convert the weekly or monthly flow rate from the monitoring data obtained under 264.226(d)
to an average daily flow rate (gallons per acre per day) for each sump. Unless the
Regional Administrator approves a different calculation, the average daily flow rate for
each sump must be calculated weekly during the active life and closure period, and if the
unit is closed in accordance with §264.228(b), monthly during the post-closure care
period when monthly monitoring is required under §264.226(d).
(57 FR 3487, Jan. 29, 1992)
Effective Date Note: At 57 FR 3487, Jan. 29, 1992 264.222 was added, effective July 29,
1992.
§264.223 Response actions.
(a) The owner or operator of surface impoundment units subject to §264.221 (c) or (d)
must have an approved response action plan before receipt of waste. The response action
plan must set forth the actions to be taken if the action leakage rate has been exceeded.
At a minimum, the response action plan must describe the actions specified in paragraph
(b) of this section.
(b) If the flow rate into the leak detection system exceeds the action leakage rate for
any sump, the owner or operator must:
(1) Notify the Regional Administrator in writing of the exceedence within 7 days of the
determination;
(2) Submit a preliminary written assessment to the Regional Administrator within 14 days
of the determination, as to the amount of liquids, likely sources of liquids, possible
location, size, and cause of any leaks, and short-term actions taken and planned;
(3) Determine to the extent practicable the location, size, and cause of any leak;
(4) Determine whether waste receipt should cease or be curtailed, whether any waste should
be removed from the unit for inspection, repairs, or controls, and whether or not the unit
should be closed;
(5) Determine any other short-term and longer-term actions to be taken to mitigate or stop
any leaks; and
(6) Within 30 days after the notification that the action leakage rate has been exceeded,
submit to the Regional Administrator the results of the analyses specified in paragraphs
(b) (3), (4), and (5) of this section, the results of actions taken, and actions planned.
Monthly thereafter, as long as the flow rate in the leak detection system exceeds the
action leakage rate, the owner or operator must submit to the Regional Administrator a
report summarizing the results of any remedial actions taken and actions planned.
(c) To make the leak and/or remediation determinations in paragraphs (b) (3), (4), and (5)
of this section, the owner or operator must:
(1)(i) Assess the source of liquids and amounts of liquids by source,
(ii) Conduct a fingerprint, hazardous constituent, or other analyses of the liquids in the
leak detection system to identify the source of liquids and possible location of any
leaks, and the hazard and mobility of the liquid; and
(iii) Assess the seriousness of any leaks in terms of potential for escaping into the
environment; or
(2) Document why such assessments are not needed.
(57 FR 3488, Jan. 29, 1992)
Effective Date Note: At 57 FR 3488, Jan. 29, 1992, 264.223 was added, effective July 29,
1992.
§264.224 -- 264.225 (Reserved)
§264.226 Monitoring and inspection.
(a) During construction and installation, liners (except in the case of existing portions
of surface impoundments exempt from §264.221(a)) and cover systems (e.g., membranes,
sheets, or coatings) must be inspected for uniformity, damage, and imperfections (e.g.,
holes, cracks, thin spots, or foreign materials). Immediately after construction or
installation:
(1) Synthetic liners and covers must be inspected to ensure tight seams and joints and the
absence of tears, punctures, or blisters; and
(2) Soil-based and admixed liners and covers must be inspected for imperfections including
lenses, cracks, channels, root holes, or other structural non-uniformities that may cause
an increase in the permeability of the liner or cover.
(b) While a surface impoundment is in operation, it must be inspected weekly and after
storms to detect evidence of any of the following:
(1) Deterioration, malfunctions, or improper operation of overtopping control systems;
(2) Sudden drops in the level of the impoundment's contents; and
(3) Severe erosion or other signs of deterioration in dikes or other containment devices.
(c) Prior to the issuance of a permit, and after any extended period of time (at least six
months) during which the impoundment was not in service, the owner or operator must obtain
a certification from a qualified engineer that the impoundment's dike, including that
portion of any dike which provides freeboard, has structural integrity. The certification
must establish, in particular, that the dike:
(1) Will withstand the stress of the pressure exerted by the types and amounts of wastes
to be placed in the impoundment; and
(2) Will not fail due to scouring or piping, without dependence on any liner system
included in the surface impoundment construction.
(d)(1) An owner or operator required to have a leak detection system under §264.221 (c)
or (d) must record the amount of liquids removed from each leak detection system sump at
least once each week during the active life and closure period.
(2) After the final cover is installed, the amount of liquids removed from each leak
detection system sump must be recorded at least monthly. If the liquid level in the sump
stays below the pump operating level for two consecutive months, the amount of liquids in
the sumps must be recorded at least quarterly. If the liquid level in the sump stays below
the pump operating level for two consecutive quarters, the amount of liquids in the sumps
must be recorded at least semi-annually. If at any time during the post-closure care
period the operating level is exceeded at units on quarterly or semi-annual recording
schedules, the owner or operator must return to monthly recording of amounts of liquids
removed from each sump until the liquid level again stays below the pump operating level
for two consecutive months.
(3) "Pump operating level'' is a liquid level proposed by the owner or operator and
approved by the Regional Administrator based on pump activation level, sump dimensions,
and level that avoids backup into the drainage layer and minimizes head in the sump.
(Approved by the Office of Management and Budget under control number 2050-0007)
(47 FR 32357, July 26, 1982, as amended at 50 FR 4514, Jan. 31, 1985; 50 FR 28748, July
15, 1985; 57 FR 3488, Jan. 29, 1992)
Effective Date Note: At 57 FR 3488, Jan. 29, 1992 264.226 was amended by adding paragraph
(d), effective July 29, 1992.
§264.227 Emergency repairs; contingency plans.
(a) A surface impoundment must be removed from service in accordance with paragraph (b) of
this section when:
(1) The level of liquids in the impoundment suddenly drops and the drop is not known to be
caused by changes in the flows into or out of the impoundment; or
(2) The dike leaks.
(b) When a surface impoundment must be removed from service as required by paragraph (a)
of this section, the owner or operator must:
(1) Immediately shut off the flow or stop the addition of wastes into the impoundment;
(2) Immediately contain any surface leakage which has occurred or is occurring;
(3) Immediately stop the leak;
(4) Take any other necessary steps to stop or prevent catastrophic failure;
(5) If a leak cannot be stopped by any other means, empty the impoundment; and
(6) Notify the Regional Administrator of the problem in writing within seven days after
detecting the problem.
(c) As part of the contingency plan required in subpart D of this part, the owner or
operator must specify a procedure for complying with the requirements of paragraph (b) of
this section.
(d) No surface impoundment that has been removed from service in accordance with the
requirements of this section may be restored to service unless the portion of the
impoundment which was failing is repaired and the following steps are taken:
(1) If the impoundment was removed from service as the result of actual or imminent dike
failure, the dike's structural integrity must be recertified in accordance with
§264.226(c).
(2) If the impoundment was removed from service as the result of a sudden drop in the
liquid level, then:
(i) For any existing portion of the impoundment, a liner must be installed in compliance
with §264.221(a); and
(ii) For any other portion of the impoundment, the repaired liner system must be certified
by a qualified engineer as meeting the design approved in the permit.
(e) A surface impoundment that has been removed from service in accordance with the
requirements of this section and that is not being must be closed in accordance with the
provisions of §264.228.
(47 FR 32357, July 26, 1982, as amended at 50 FR 28748, July 15, 1985)
§264.228 Closure and post-closure care.
(a) At closure, the owner or operator must:
(1) Remove or decontaminate all waste residues, contaminated containment system components
(liners, etc.), contaminated subsoils, and structures and equipment contaminated with
waste and leachate, and manage them as hazardous waste unless 261.3(d) of this chapter
applies; or
(2)(i) Eliminate free liquids by removing liquid wastes or solidifying the remaining
wastes and waste residues;
(ii) Stabilize remaining wastes to a bearing capacity sufficient to support final cover;
and
(iii) Cover the surface impoundment with a final cover designed and constructed to:
(A) Provide long-term minimization of the migration of liquids through the closed
impoundment;
(B) Function with minimum maintenance;
(C) Promote drainage and minimize erosion or abrasion of the final cover;
(D) Accommodate settling and subsidence so that the cover's integrity is maintained; and
(E) Have a permeability less than or equal to the permeability of any bottom liner system
or natural subsoils present.
(b) If some waste residues or contaminated materials are left in place at final closure,
the owner or operator must comply with all post-closure requirements contained in
§§264.117 through 264.120, including maintenance and monitoring throughout the
post-closure care period (specified in the permit under §264.117). The owner or operator
must:
(1) Maintain the integrity and effectiveness of the final cover, including making repairs
to the cap as necessary to correct the effects of settling, subsidence, erosion, or other
events;
(2) Maintain and monitor the leak detection system in accordance with
§§264.221(c)(2)(iv) and (3) and 264.226(d), and comply with all other applicable leak
detection system requirements of this part;
(3) Maintain and monitor the ground-water monitoring system and comply with all other
applicable requirements of subpart F of this part; and
(4) Prevent run-on and run-off from eroding or otherwise damaging the final cover.
(c)(1) If an owner or operator plans to close a surface impoundment in accordance with
paragraph (a)(1) of this section, and the impoundment does not comply with the liner
requirements of §264.221(a) and is not exempt from them in accordance with §264.221(b),
then:
(i) The closure plan for the impoundment under §264.112 must include both a plan for
complying with paragraph (a)(1) of this section and a contingent plan for complying with
paragraph (a)(2) of this section in case not all contaminated subsoils can be practicably
removed at closure; and
(ii) The owner or operator must prepare a contingent post-closure plan under §264.118 for
complying with paragraph (b) of this section in case not all contaminated subsoils can be
practicably removed at closure.
(2) The cost estimates calculated under §§264.142 and 264.144 for closure and
post-closure care of an impoundment subject to this paragraph must include the cost of
complying with the contingent closure plan and the contingent post-closure plan, but are
not required to include the cost of expected closure under paragraph (a)(1) of this
section.
(47 FR 32357, July 26, 1982, as amended at 50 FR 28748, July 15, 1985; 57 FR 3488, Jan.
29, 1992)
Effective Date Note: At 57 FR 3488, Jan. 29, 1992 264.228 was amended by redesignating
paragraphs (b)(2) and (b)(3) as paragraphs (b)(3) and (b)(4), and by adding a new
paragraph (b)(2), effective July 29, 1992.