PB96-780 267
EPA530-R-95-056
November 1995
RCRA/UST, Superfund, & EPCRA
Hotline Training Module
Introduction to:
Land Disposal Units
(40 CFR Parts 264/265, Subparts K, L, M, N)
Updated as of July 1995
DISCLAIMER
This document was developed by Booz-Allen & Hamilton Inc. under
contract 68-WO-0039 to EPA. It is intended to be used as a
training tool for Hotline specialists and does not represent a
statement of EPA policy.
The information in this document is not by any means a complete
representation of EPA's regulations or policies. This document
is used only in the capacity of Hotline training and is not used
as a reference tool on Hotline calls. The Hotline revises and
updates this document as regulatory program areas change.
The information in this document may not necessarily reflect the
current position of the Agency. This document is not intended
and cannot be relied upon to create any rights, substantive or
procedural, enforceable by any party litigation with the United
States.
RCRA/UST, Superfund & EPCRA Phone Numbers:
National toll-free (outside of DC area)	(800) 424-9346
Local number (within DC area)	(703) 412-9810
National toll-free for the hearing impaired (TDD) (800) 553-7672
The Hotline is open from 9 am to 6 pm Eastern Standard Time,
Monday through Friday, except for federal holidays.

-------
LAND DISPOSAL UNITS
CONTENTS
1.	Introduction 		1
2.	Regulatory Summary 		3
2.1	Surface Impoundments 		3
2.2	Waste Piles 		7
2.3	Landfills	9
2.4	Land Treatment Units	11

-------
Land Disposal Units - 1
1. INTRODUCTION
Subtitle C of RCRA creates a cradle-to-grave management system
for hazardous waste to ensure proper treatment, storage, and
disposal in a manner protective of human health and the
environment. Under RCRA §3004(a), Congress authorized EPA to
promulgate regulations establishing design and operating
requirements for land disposal units (LDUs). The requirements
are intended to minimize pollution resulting from the disposal of
hazardous waste in or on the land. The statute lists nine types
of LDUs. Section 3004(k) of RCRA defines land disposal as
placement of hazardous waste in any of the following:
•	Landfill	•	Salt dome formation
•	Surface impoundment	•	Salt bed formation
•	Waste pile	•	Underground mine
•	Injection well	•	Underground cave
•	Land treatment facility
EPA has promulgated unit-specific technical standards for four of
these LDUs within the treatment, storage, and disposal facility
(TSDF) requirements of Parts 264/265. This module provides an
overview of the requirements for' these four LDUs: landfills,
surface impoundments, waste piles, and land treatment units.
LDUs that do not qualify as one of these units are considered
miscellaneous units (see the "Miscellaneous Units" module for
more details)
When you have completed this module, you will be able to
summarize the land disposal standards and list the relevant
statutory and regulatory citations. Specifically, you will be
able to:
•	Summarize the differences between interim status (Part
265) and permitted (Part 264) standards for land disposal
units
•	Find the definition of "surface impoundment" and
distinguish surface impoundments from tanks
•	Explain the connection between land disposal standards,
post-closure, and groundwater monitoring
•	Cite the statutory and regulatory minimum technological
requirements
•	Describe surface impoundment retrofitting and
retrofitting variance procedures.
The information in this document is not by any means a complete
representation of EPA's regulations or policies, but is an
introduction used for Hotline training purposes. For complete
and current information, please call the RCRA/UST, Superfund, and
EPCRA Hotline.

-------
2 - Land Disposal Units
Use this list of objectives to check your knowledge of this topic
after you complete the training session.
The information in this document is not by any means a complete
representation of EPA's regulations or policies, but is an
introduction used for Hotline training purposes. For complete
and current information, please call the RCRA/UST, Superfund, and
EPCRA Hotline.

-------
Land Disposal Units - 3
2. REGULATORY SUMMARY
Regulations governing surface impoundments, waste piles, land
treatment units, and landfills appear under Subparts K through N
of Parts 264/265. The standards for permitted and interim status
units address, among other things, design and operating
requirements, including a liner and a leachate collection and
removal system (LCRS); closure and post-closure requirements; and
special standards for ignitable, reactive, and dioxin-containing
wastes. In addition to these unit-specific requirements, LDUs
managing hazardous waste are subject to the general facility
standards found in Subparts A through E of Parts 264/265, as well
as the appropriate groundwater monitoring, closure and post-
closure, and financial assurance requirements.
For each unit, this module will address five different topic
areas: design and operation, inspections, response actions,
closure and post-closure, and special issues. Using these topic
areas will enable the reader to compare and contrast the
regulations for each unit.
2.1 SURFACE IMPOUNDMENTS
Subpart K of Parts 264/265 contains the design and operating
standards for surface impoundments used to treat, store, or
dispose of hazardous waste. Surface impoundments are very
similar to landfills in "that both units are either a natural
topographic depression, man-made excavation, or diked area formed
primarily of earthen materials, such as soil (although the unit
may be lined with man-made materials). The units are, however,
very different in their use. Surface impoundments are generally
used for temporary storage or treatment, whereas a landfill is a
designated area for final disposal. Therefore, while the design
and operating standards are very similar, the closure and post-
closure standards differ. More detail will follow in the
applicable sections.
Most of the design, operating, and inspection requirements are in
fact very similar for surface impoundments, waste piles, and
landfills. The requirements are thus discussed in detail in this
section, with successive sections referring to this section for
specifics.
DESIGN AND OPERATION
In developing design and operation requirements for surface
impoundments (as well as landfills and waste piles), EPA adopted
a regulatory goal of minimizing the formation and migration of
The information in this document is not by any means a complete
representation of EPA's regulations or policies, but is an
introduction used for Hotline training purposes. For complete
and current information, please call the RCRA/UST, Superfund, and
EPCRA Hotline.

-------
4 - Land Disposal Units
leachate to the adjacent subsurface soil, groundwater, or surface
water.
The most comprehensive technical requirements for surface
impoundments are the minimum technological requirements (MTRs)
mandated by RCRA (§§3004(o) (1) (A) and 3004 (o) (4)) . These
sections require a double liner, a leachate collection and
removal system (LCRS) and a leak detection system (§§264.221(c)
and 265.221(a)). The MTRs apply to all new units, lateral
expansions, and replacement units for which construction (or
reuse) commences after July 29, 1992. The double'liner system
consists of a top liner to prevent migration of hazardous
constituents into the liner and a composite bottom liner
consisting of a synthetic geomembrane and three feet of compacted
soil material. The unit must also be equipped with an LCRS,
which also serves as the leak detection system. The LCRS, along
with the leak detection system drainage layers, must be designed
with a bottom slope of at least one percent, be made of materials
chemically resistant to the wastes placed in the unit, and be
able to remove the liquids at a specified minimum rate. The LCRS
itself must be designed to collect liquids in a sump and
subsequently pump out those liquids. In addition to the
performance and design requirements, the LCRS must be located
between the liners immediately above the bottom composite liner.
This location standard should enable the LCRS to collect the
largest amount of leachate, while also representing the most
efficient place to identify leaks.
Existing units are subject only to the single liner requirements
(§264.221(a)). In addition, a surface impoundment must be
designed to prevent the flow of liquids over the top of an
impoundment (or overtopping) and ensure the structural integrity
of any dikes.
Section 264.222 requires that the owner or operator establish a
leachate flow rate, called the action leakage rate (ALR), for
each regulated unit. Based on site-specific considerations, the
owner or operator must identify an ALR that will indicate that
the system is not functioning properly.
No design criteria will be effective if the impoundment is
installed improperly or uses inferior materials. To ensure that
a surface impoundment meets all technical criteria, EPA requires
a construction quality assurance (CQA) program (see the "TSDFs"
module). The CQA program requires a CQA plan which identifies
how construction materials and their installation will be
monitored and tested and how the results will be documented
(§264.19) . The CQA program is developed and implemented under
the direction of a registered professional engineer, who must
also certify that the CQA plan has been successfully carried out
The information in this document is not by any means a complete
representation of EPA's regulations or policies, but is an
introduction used for Hotline training purposes. For complete
and current information, please call the RCRA/UST, Superfund, and
EPCRA Hotline.

-------
Land Disposal Units - 5
and that the unit meets all specifications before any waste may
be received in the unit.
INSPECTION
Inspection requirements are found under two sections of
regulations. First, the owner/operator of the surface
impoundment must inspect the leak detection sump to measure the
amount of liquid in the sump and determine whether the ALR has
been exceeded. If a leak which causes the system flow rate to
exceed the ALR occurs, the owner or operator must notify the
Agency and respond in accordance with the response action plan
(§§264/265.223) .
Whereas the first requirement is meant to ensure that the unit is
meeting performance requirements, the second inspection
requirement addresses the design and structural integrity of the
unit (§§264/265.226). Basically, the owner/operator must inspect
liners and covers for any problems after construction or
installation and continue inspections weekly and after storms to
monitor for evidence of deterioration, malfunctions, improper
operation of overtopping systems, sudden drops in the level of
the impoundment contents, and severe erosion of dikes and other
containment devices. Owners/operators must also monitor leak
detection sumps at least once a week. This final inspection
requirement, which is also used to check the ALR requirement, is
designed to verify that the pump used to drain liquids from the
sump is working properly.
RESPONSE ACTIONS
There are also two different types of response actions for the
design and performance of the unit. The response action for the
performance of the unit is determined by the terms of the
response action plan, triggered when the ALR has been exceeded
(§§264/265.223). If the action leakage rate has been exceeded,
the owner/operator must: notify the Regional Administrator;
determine what short term actions must be taken (e.g., shut down
of the facility for repairs); determine the location, size, and
cause of any leak; and send the assessments to the Region.
There are also emergency repair provisions for unit design
failure at permitted facilities only (§264.227). Essentially, if
there is positive indication of a failure of the containment
system (e.g., a sudden drop in the level of the contents when the
drop is not attributable to changes in the flow in or out of the
impoundment), the surface impoundment must be removed from
service. When this occurs, the owner/operator must follow the
procedures in the contingency plan, including any necessary
emergency repairs.
The information in this document is not by any means a complete
representation of EPA's regulations or policies, but is an
introduction used for Hotline training purposes. For complete
and current information, please call the RCRA/UST, Superfund, and
EPCRA Hotline.

-------
6 - Land Disposal Units
CLOSURE
Closure of a hazardous waste surface impoundment can take one of
two forms. The first option, called clean closure, requires for
the owner/operator to remove or decontaminate all wastes and unit
components at closure (§§264/265.228(a) (1)). If the unit cannot
be clean-closed, then the owner/operator must employ the second
alternative. Under this approach, wastes are left in place and
stabilized, free liquids are removed, and a cap or cover is
placed on top of the waste. Since surface impoundments are
generally used for storage, the second option is equivalent to
closing as a landfill (which is always a final resting place of
hazardous wastes) and also requires the operator to take certain
precautions for a certain time period after closure (known as
post-closure care (§§264/265.228(a)(2) and (b)).
REGULATIONS FOR SPECIAL WASTES
The regulations place special requirements on surface
impoundments that handle ignitable or reactive wastes because
these wastes require continuing protection from conditions that
could cause them to ignite or react (§§264/2 65.229).
Additionally, §§264/265.230 prohibit the placement of
incompatible waste or materials, as described in Appendix V of
Parts 264/265, in the same surface impoundment unless certain
precautions are taken.
Further, if an owner/operator of a surface impoundment plans to
manage dioxin-containing waste (F020, F021, F022, F023, F026, and
F027), they must employ a special management plan approved by the
Regional Administrator (§264.231). These wastes can only be_
disposed of in a permitted surface impoundment.
SURFACE IMPOUNDMENT RETROFITTING
Owner/operators of newly-regulated surface impoundments have four
years to upgrade the units to meet MTR while continuing to manage
wastes that contain (or generate) newly identified or listed
wastes. The statute contains conflicting language regarding the
timing of surface impoundment retrofitting. RCRA §3 005 (j) (6)
provides a retrofitting period lasting for four years from the
promulgation of a new listing or waste identification. This
conflicts with §3004 (j) (11), which states that wastes subject to
land disposal restrictions treatment standards may only be placed
in an impoundment if the unit meets MTR. This would effectively
limit the retrofitting period to roughly one year (including the
maximum of six months for EPA to promulgate Part 268 treatment
standards for newly identified or listed wastes, as required
under §3004(g)(4), plus the standard six months before treatment
The information in this document is not by any means a complete
representation of EPA's regulations or policies, but is an
introduction used for Hotline training'purposes. For complete
and-current information, please call the RCRA/UST, Superfund, and'
EPCRA Hotline.

-------
Land Disposal Units - 7
standards become effective). RCRA §3005(h)(4) also conflicts
with §3004 (j) (6), by stating that wastes subject to a national
capacity variance may only be placed in units which meet MTR.
Thus, §§3005 (j) (11) and 3004 (h) (4) apparently curtail the four-
year retrofitting period by precluding non-MTR impoundments from
managing prohibited wastes, including wastes subject to national
capacity variances.
To resolve these conflicts, EPA clarified on August 18, 1992 (57
FR 37194), that owner/operators of surface impoundments have four
years from the promulgation of a new listing or waste
identification to retrofit the unit, regardless of whether or not
EPA promulgates treatment standards for the wastes in question or
issues a national capacity variance within the four-year
retrofitting period. For example, owner/operators of surface
impoundments brought under regulation by the promulgation of the
F037 and F038 listings need not retrofit or close the affected
units until November 2, 1994, although land disposal restriction
(LDR) treatment standards for F037 and F038 sludges will have
become effective prior to that date.
SURFACE IMPOUNDMENT VS. TANK
The definitions of surface impoundment and tank are very similar
and tend to create confusion. The major difference in the two
definitions is what provides the structural support to the unit.
Surface impoundments are supported by earthen materials while
tanks are supported by non-earthen materials (e.g., wood,
concrete, steel, plastic). In determining whether a unit is
supported by earthen or non-earthen material, it should be
evaluated as if it were free-standing and filled to its design
capacity. If the unit can maintain its structural integrity it
is considered a tank. If the unit cannot retain, its structural
integrity, it is considered a surface impoundment.
2.2 WASTE PILES
Regulations governing the management of hazardous waste in waste
piles are found in Parts 264/265, Subpart L. Waste piles, which
are essentially non-containerized piles of solid, nonflowing
hazardous waste, are temporary units, for storage or treatment
only (§260.10). Because waste piles are temporary units, not
intended for final disposal of wastes, Subpart L does not contain
post-closure care regulations for waste piles that are closed
with waste in place; such units are considered permanent or
disposal units, and are subject to post-closure regulation as
landfills (see Section 2.4).
The information in this document is not by any means a complete
representation of EPA's regulations or policies, but is an
introduction used for Hotline training purposes. For complete
and current information, please call the RCRA/UST, Superfund, and
LPCRA Hotline.

-------
8 - Land Disposal Units
Owner s'/opera tors of permitted waste piles that meet special
requirements are subject to reduced regulations. Specifically,
the waste pile must be located inside or under a structure and
not receive free liquid, be protected from surface water run-on,
be designed and operated to control dispersal of waste, and be
managed to prevent the generation of leachate. If these
standards are met, the owner/operator of the permitted waste pile
is exempt from groundwater monitoring requirements as well as the
design and operation requirements for waste piles.
DESIGN AND OPERATION
Waste piles are subject to nearly the same MTRs as surface
impoundments. Specifically, new units, lateral expansions, and
replacement units require a double liner and LCRS (§§264.251(c)
and 265.254). In addition, waste piles, with certain exceptions,
require a second leachate collection and removal system above the
top liner. If the permitted waste pile is not subject to MTR
(i.e., a unit, lateral expansion, or replacement for which
construction commenced before July 29, 1992), then the unit is
subject to a single liner and basic LCRS requirements. Interim
status waste piles that are not subject to MTR are subject only
to liner, run-on, and run-off controls if leachate or run-off is
found to be a hazardous waste.
Permitted waste piles are subject to stormwater run-on and run-
off controls to minimize leachate generation during storms
(§§264.251(g),(h) and (i)). These requirements are designed to
keep stormwater from contacting the hazardous wastes and to keep
any contaminated stormwater from being released into the
environment. Owners/operators of waste piles must also cover or
manage their wastes to prevent any wind dispersal. Interim
status waste piles are not subject to the stormwater controls,
but are subject to wind dispersal provisions (§265.251).
INSPECTION AND RELEASE RESPONSE
Waste piles are subject to the same inspection and release
response requirements as surface impoundments. Specifical'ly,
waste piles are required to establish an ALR (§§264.252 and
265.255), a response action plan (§§264.253 and §265.259),
monitoring and inspection schedule (§264.254), and a CQA plan
(§§264/265.19). The interim status monitoring and inspection
provision only requires the owner/operator of a waste pile
meeting MTR to record the amount of liquids removed from the leak
detection system sump at least once a week (§265.260). Note that
waste piles are not subject to the emergency repair provisions
for surface impoundments.
The information in this document is not by any means a complete
representation of EPA's regulations or policies, but is an
introduction used for Hotline training purposes. For complete
and current information, please call the RCRA/UST, Superfund, and
EPCRA Hotline.

-------
Land Disposal Units - 9
CLOSURE
Since waste piles are storage, as opposed to disposal,
facilities, all waste residues and contaminated subsoils and
equipment must be removed or decontaminated at closure
(§§264/265.258(a)). This requirement is identical to clean
closure of a surface impoundment. If the owner or operator
removes or decontaminates all waste residues and makes all
reasonable efforts to remove or decontaminate all structures and
soils and finds that some contamination remains, the waste pile
will then be subject to the closure requirements for landfills,
including post-closure care (§§264/265.258(b)).
Special Requirements For Certain Wastes
Waste piles are subject to the same specialized standards for
ignitable, reactive, incompatible, and dioxin-containing waste as
surface impoundments. These requirements are discussed in
Section 2.1.
SPECIAL ISSUES
Containment Buildings
Containment buildings, sometimes characterized as "indoor waste
piles," are units used to hold uncontainerized piles of hazardous
waste. The difference between waste piles and containment
buildings, from a regulatory standpoint, is that containment
buildings are not land disposal units. For this reason,
containment buildings are designed with a containment system
rather than a liner and leak detection system (Parts 264/265,
Subpart DD). The "Containment Buildings" module provides more
information about the standards that apply to containment
buildings.
2.3 LANDFILLS
Since landfills serve as final disposal for a large portion of
the nation's hazardous waste, it is critical that they-are
monitored during the entire active life (which includes closure)
and the post-closure period. The regulations concerning
hazardous waste landfills are promulgated as Subpart N of Parts
264/265.
DESIGN AND OPERATION
Landfills are subject to virtually the same MTRs as surface
impoundments and waste piles. They must have a double-liner,
LCRSs, leak detection (§§264/265.301), and an ALR
The information in this document is not by any means a complete
representation of EPA's regulations or policies, but is an
introduction used for Hotline training purposes. For complete
and current information, please call the RCRA/UST, Superfund, and
EPCRA Hotline.

-------
10 - Land Disposal Units
(§§264/265.302). Like waste piles, landfills require the second
LCRS above the top liner. In addition, landfills must have
stormwater run-on and run-off controls to prevent migration of
hazardous constituents for at least a 25-year storm, and a cover
to prevent wind dispersal.
INSPECTION AND RESPONSE ACTIONS
Once again, the inspection and response action plans are almost
identical to the requirement for surface impoundments, including
a response action plan (§§264.304 and 265.303), if the ALR is
exceeded, and a CQA program (§§264/265.19). In addition, the
owner/operator of a hazardous waste landfill must perform
monitoring and inspections (§§264.303 and 265.304). As with
surface impoundments and waste piles, these requirements ensure
that the unit is maintained in good working condition and that
any problems are promptly detected.
Since landfills typically serve as permanent disposal sites, the
closure and post-closure requirements for landfills are somewhat
different from those for other land-based units. The
requirements for a final cover that can provide long-term
minimization of migration of liquids through the closed landfill,
promote drainage, accommodate settling, and function with a
minimum amount of maintenance (§§264/265.310 (a)). After closure,
the owner or operator must comply with the post-closure
requirements of §§264/265.117 through 264/265.120 covering such
actions as monitoring and maintenance (see the "Closure/Post -
Closure" module). In addition, the owner/operator must maintain
the final cover, leak detection system, and groundwater
monitoring system, as well as prevent run-on and run-off from
damaging the final cover, and protect the surveyed benchmarks
(i.e., location and characteristics) of the landfill.
Special Requirements For Certain Wastes
Like surface impoundments and waste piles, landfills are subject
to certain restrictions on the management of ignitable, reactive,
incompatible, and dioxin-containing wastes. Unlike other units,
though, the placement of bulk or noncontainerized liquid
hazardous waste or hazardous waste containing free liquids in any
landfill is prohibited (§§264/265.314(b)). The placement of
nonhazardous liquids in a landfill is also essentially prohibited
(§§264.314 (e) and 265.314 (f)). There are only certain situations
when containers holding free liquids can be placed in a landfill
(e.g., small containers such as ampules, containers that are
products such as batteries, or lab packs) (§§264.314(d) and
265.314(c)). If sorbents are used to treat hazardous wastes so
that the waste no longer contains free liquids, the
owner/operator must use nonbiodegradable sorbents.
The information in this document is not by any means a complete
representation of EPA's regulations or policies, but is an
introduction used for Hotline training purposes. For complete
and current information, please call the RCRA/UST, Superfund, and
EPCRA Hotline.

-------
Land Disposal Units - 11
Special Requirements For Certain Containers
To prevent significant voids that could cause collapse of final
covers when containers erode and to maintain and extend available
capacity in hazardous waste landfills, containers placed in a
landfill must be either at least 90 percent full or crushed,
shredded, or in some other way reduced in volume, unless they are
very small, such as ampules (§264.315).
Finally, there are special standards for labpacks or overpacked
drums being placed in a landfill (§§264./265.316). Labpacks
generally contain small containers of a wide variety of hazardous
wastes in relatively small volumes that are packed in sorbent
material to prevent leaking. This sorbent material must be
nonbiodegradable.
2.4 LAND TREATMENT UNITS
While surface impoundments, waste piles, and landfills share many
regulatory standards, land treatment units (LTUs) are
significantly different both in purpose and in management. Land
treatment involves the application of waste on the soil surface
or the incorporation of waste into the upper layers of the soil
in order to degrade, transform, or immobilize hazardous
constituents present in hazardous waste. Essentially, the waste
is treated within the matrix of the surface soil, whereas the
major goal of the other units is to prevent migration to the
surface soil. Specifically, the waste must be placed only in the
unsaturated zone, which is the portion of the surface soil above
the water table (or the highest point of the groundwater flow)
Based upon the proximity to the groundwater, the success of land
treatment is highly dependent on the operational management of
the unit.
Because the goal of land treatment is to let the soil microbes
and sunlight degrade the hazardous waste, the design and
operating standards are significantly different from those
imposed on the three types of units already covered. Land
treatment units generally do not use impermeable liners to
contain wastes. Instead, units rely on the physical, chemical,
and biological processes occurring in the top soil layers. In a
sense, these units can be viewed as an open system.
Maintenance of proper soil pH, careful management of waste
application rate, and control of surface water run-off are all
key to the operation of a land treatment unit. The regulations
concerning hazardous waste land treatment units are promulgated
in Subpart M of Parts 264/265.
The information in this document is not by any means a complete
representation of EPA's regulations or policies, but is an
introduction used for Hotline training purposes. For complete
and current information, please call the RCRA/UST, Superfund, and
EPCRA Hotline.

-------
12 - Land Disposal Units
Because placement of hazardous waste in a land treatment unit is
considered land disposal, LDR standards must be considered. If
the hazardous waste does not meet the applicable treatment
standard prior to placement in the land treatment unit, the unit
owner or operator must obtain a no-migration variance before
applying any hazardous waste to the unit. See the "Land Disposal
Restrictions" module for more details concerning the LDR
standards and no-migration variances.
DESIGN AND OPERATION
Land treatment units must devise a program and demonstrate its
effectiveness given the design of the unit and characteristics of
the area. In addition, the regulations set out specific
operating requirements that must be met in the treatment program.
The following discussion details these requirements.
Treatment Program and Demonstration
The requirements outlined in the treatment program, including
design and operating criteria and unsaturated zone monitoring,
stem from a treatment demonstration. The purpose of the
treatment demonstration is to show that hazardous constituents in
the waste can be completely degraded or immobilized in the
treatment unit. A treatment demonstration may involve field
testing on a sample soil plot or laboratory testing. The
Regional Administrator uses information provided by the treatment
demonstration to set permit standards. Interim status units are
not required to establish a treatment program because the interim
status regulations are self-implementing. However,
owners/operators can only place hazardous waste in the LTU if the
waste will be rendered non-hazardous or less hazardous
(§265.272(a)).
During the treatment demonstration, the owner/operator must
establish the following parameters:
1)	Specify the wastes that may be handled at the unit. In
general, land treatment is confined to wastes that are
primarily organic and that can be greatly reduced in
volume by physical, chemical, and biological
decomposition in surface soils. The owner/operator must
be able to account for smaller fractions of heavy metals
and persistent organic compounds by immobilizing those
constituents.
2)	Formulate a set of operating measures. The LTU must be
operated in a manner that will maximize degradation,
transformation, and immobilization of hazardous waste
The information in this document is not by any means a complete
representation of EPA's regulations or policies, but is an
introduction used for Hotline training purposes. For complete
and.current information, please call the RCRA/UST, Superfund, and
EPCRA Hotline.

-------
Land Disposal Units - 13
constituents. The specifics of the operation are
discussed in the following section of this module.
3)	Establish unsaturated zone monitoring. The purpose of
this program is to make sure that treatment is occurring
within the treatment zone, and that all hazardous
constituents are being adequately treated. The
information provided from the monitoring can help the
owner/operator "fine tune" the treatment process to
maximize the success of the treatment. Unsaturated zone
monitoring involves soil monitoring (e.g., obtaining
soil samples) immediately below the treatment zone.
4)	Define the treatment zone. This zone is comprised of
the horizontal and vertical dimensions of the
unsaturated zone in which the owner/operator intends to
perform the actual treatment. The zone can be no deeper
than 1.5 meters (5 feet) and the bottom of the zone must
be at least one meter (3 feet) from the seasonal high
water table.
Operation
Basic design and operating requirements are outlined in §§264.273
and 265.272. These sections require the Regional Administrator
to specify certain parameters in the facility permit:
•	Rate and method of application
•	Measures to control soil pH
•	Measures to enhance microbial and chemical reactions
•	Measures to control the moisture content of the treatment
zone.
In addition, land treatment units are subject to requirements for
stormwater run-on and run-off controls. Management to control
wind dispersal and weekly inspections are also required.
Food Chain Crops
In some cases, an owner/operator may grow food-chain crops on a
land treatment unit (§§264/265.276). The Agency believes that
this can be done safely if certain conditions are met that
require the owner or operator to demonstrate that hazardous
constituents are not present in the crop in abnormally high
concentrations. Additionally, if cadmium is present in the unit,
the owner/operator must comply with additional management
standards specified under §§264/265.276(b).
The information in this document is not by any means a complete
representation of EPA's regulations or policies, but is an
introduction used for Hotline training purposes. For complete
and current information, please call the RCRA/UST, Superfund, and
EPCRA Hotline.

-------
14 - Land Disposal Units
INSPECTIONS AND RESPONSE ACTIONS
Although there are no requirements to inspect the unit, the
owner/operator must maintain unsaturated zone monitoring to
assure that the unit is meeting its performance standards
(§§264/265.278).
As discussed earlier, the purpose of unsaturated zone monitoring
is to provide feedback on the success of treatment in the
treatment zone and to determine if hazardous constituents are
migrating out of the treatment zone (i.e.,- the monitoring program
must be designed to determine the presence of hazardous
constituents below the treatment zone). Generally this means
that the owner/operator would monitor for the most stable
hazardous constituents found in the wastes placed in or on the
treatment zone. Keep in mind that unsaturated zone monitoring is
not a substitute for groundwater monitoring. Both are required
for land treatment units.
To perform unsaturated zone monitoring, the owner/operator must
first establish which constituents must be monitored and the
background levels of those constituents in the soil. The
frequency of the monitoring is based upon the elements of the
operation of the LTU, such as the frequency, timing, and rate of
application of the waste. Once the samples have been taken, the
owner/operator must determine whether there is a statistically
significant change over the background values (i.e., the natural
constituent levels in the soil) for any hazardous constituent.
If there is a statistically significant increase in the hazardous
constituents of concern, the owner/operator must notify the
Regional Administrator within seven days, and submit a permit
modification within 90 days to change the operating practices at
the facility to sufficiently treat hazardous constituents within
the treatment zone.
CLOSURE
When a land treatment unit is being closed, the owner/operator
maintains all operating parameters to continue the treatment
processes, and continues run-on and run-off controls and
unsaturated zone monitoring. The major element of the closure
procedure is placing a vegetative cover over the closing unit
that is capable of maintaining growth without extensive
maintenance. At completion of closure the owner or operator may
submit the closure certification by an independent qualified soil
scientist in lieu of an independent registered professional
engineer. Closure and post-closure are waived if the hazardous
constituents in the treatment zone no longer exceed background
levels.
The information in this document is not by any means a complete
representation of EPA's regulations or policies, but is an
introduction used for Hotline training purposes. For complete
and current information, please call the RCRA/UST, Superfund, and
EPCRA Hotline.

-------
Land Disposal Units - 15
Special Requirements £or Certain Wastes
Like other LDUs, land treatment units are subject to limitations
regarding ignitable, reactive, incompatible, and dioxin-
containing wastes (§§264/265.281-.283).
The information in this document is not by any means a complete
representation of EPA's regulations or policies, but is an
introduction used for Hotline training purposes. For complete
and current information, please call the RCRA/UST, Superfund, and
EPCRA Hotline.

-------