CLOSURE AND POST-CLOSURE PLANS
warranted (see para 8-5), and maintaining the
effectiveness of the final cover.
a. Subpart G of 40 CFR 264 establishes
disposal units, the leak detection system must be
performance standards that must be met by individual
monitored as part of post-closure care.
hazardous waste treatment, storage or disposal facilities
d. Closure of a land treatment unit may be
to extend protection of human health and the
accomplished by either (1) establishing a permanent
environment beyond the active life of the facility. These
vegetative cover capable of maintaining growth without
closure and post-closure standards are the basis for
extensive maintenance, (2) removing and landfilling the
written plans that the facility owner or operator must
zone of incorporation, or (3) capping the land treatment
prepare, amend as necessary, and submit with the
area to control wind and water erosion. General closure
permit application. Approval of the designated closure
practices called for include minimizing run off from the
procedures and, where applicable, post-closure plans is
treatment zone, continuing ground-water monitoring, and
a condition of facility operation.
continuing restrictions on food-chain crops. In addition,
b. The plan must identify the steps necessary
the unsaturated zone should be monitored as part of the
to close or partially close the facility at any point during
closure procedures; however, soil-pore liquid monitoring
its intended operating life, and to completely close it at
may be suspended 90 days after the last application of
the end of its intended life. Copies of the closure and
waste at the unit. Each of these practices is described in
post-closure plans must be kept at the facility and
chapter 12 of EPA SW-874.
revised whenever changes in the operating plans or
e. Closure requirements for waste piles are
facility design affect the closure or post-closure
less stringent than those for facilities such as landfills
procedures, or whenever the anticipated year of closure
since waste piles cannot be used for permanent
disposal. The principal closure requirement for a waste
9-2. Closure Procedures
pile that has achieved adequate waste containment
a. Each hazardous waste management unit
during its active life is removal or decontamination of all
must be closed in a manner that minimizes the need for
waste and waste residue, and all system components
further maintenance, particularly with respect to escape
(e.g., liners), subsoils, structures and equipment which
of hazardous waste, leachate, contaminated rainfall or
have been contaminated by contact with the waste.
waste constituents to ground water, surface water, soil or
the atmosphere. The owner or operator and a certified
as to preclude complete removal or decontamination, the
engineer should certify that the land disposal/land
closure and post-closure requirements applying to
treatment facility has been closed in accordance with the
landfills must be observed.
approved closure plan. Closure procedures for each
containment of waste should therefore be an important
disposal mode are summarized below.
consideration in initial design of a waste pile.
b. Landfill closure is achieved by installing a
final cover which has a permeability less than or equal to
9-3. Components of closure plan
that of the bottom liner. The cover should be capable of
a. The components of the closure plan
(1) minimizing infiltration of liquids, (2) functioning with
summarized below apply to all hazardous waste disposal
minimum maintenance, (3) promoting drainage and
facilities, as well as to storage facilities, i.e., those from
minimizing erosion of cover, and (4) accommodating
which the wastes will be removed at closure. In addition
settling and subsidence.
to the general requirements, there are special provisions
c. Surface impoundments can be closed in
for the different types of hazardous waste land treatment
one of two ways:
and disposal facilities.
Specific procedures to be
(1) Removing or decontaminating all
followed in closure of hazardous waste landfills, waste
wastes, waste residues, system components (such as
piles, surface impoundments and land treatment units
liners), subsoils and structures or equipment. No post-
are contained in chapter 5.
closure care is required as long as removal or
b. At a minimum, the closure plan for all
decontamination is complete.
facilities must include the following elements:
Removing liquid waste or solidifying the
(1) Procedures for partial and final
remaining waste. A final cover must be placed over the
closure: partial closure may involve closing part of a unit,
impoundments closed by solidification. Post-closure
such as a landfill cell, while other parts of the same
care of such impoundments will consist of monitoring
facility continue to operate.
ground water and conducting corrective action if it is