&EPA
Unirad Suit*
Environmental Pro(«cnon
Agency
0cv
9476,00-9
DIRECTIVE NUMBER
>
TITLE: part 265 Land Treatment Closure/Post Closure
Guidance
APPROVAL DATE: 4/14/87
EFFECTIVE DATE: 4/14/87
ORIGINATING OFFICE: Osw
O FINAL
D DRAFT
STATUS:
I
[ ]
[ )
A- Pending OMB approval
B- Pending AA-OSWER approval
] C- For review &/or comment
[ ] D- In development or circulating
REFERENCE (other document*): headquarters
1. Guidance Manual on Unsaturated Zone Monitoring for
Hazardous Waste Land Treatment Units
2. Permit Guidance Manual on Hazardous Waste Land
Treatment Demonstrations
'E DIRECTIVE DIRECTIVE L
-------
United SU(««
Environmental Protection
Office of
Solid vvuta end
Emergency Retoonte
DIRECTIVE NUMBER:
9476.00-9
TITLE: part 265 Land Treatment Closure/Post Closure
Guidance
APPROVAL DATE: 4/14/87
EFFECTIVE DATE: 4/14/87
ORIGINATING OFFICE: OSw
O FINAL
D DRAFT
STATUS:
I
A- Pending OMB approval
B- Pending AA-OSWER approval
[ ] C- For review &/or comment
[ ] D- In development or circulating
REFERENCE (other document*): headquarters
1. Guidance Manual on Unsaturated Zone Monitoring for
Hazardous Waste Land Treatment Units
2. Permit Guidance Manual on Hazardous Waste Land
Treatment Demonstrations
'E DIRECTIVE DIRECTIVE L
-------
&EPA
Wasnmgion uC 2W60
OSWER Directive Initiation Reauest
rf T 0 it c „ '„*
9476.00-9
Name ol Contact Person
Jon Perry
Leac Office Q 0UST
D OERR Q OWPE
GO OSW Q AA-OSWER
WH-565E T?DB e'e°n0n?382-4654
Aoorov-ed »jr Sev.ew
Signature of Office 0 rector Qat9
i
Or q rater
T.tie
Part 265 Land Treatment Closure/Post Closure Guidance
Summary of Directive
Manual-Addresses Closure and Post-Closure of Hazardous Waste Land Treatment
(HWLT) Units Under 40 CFR Part 265 Subpart G and Section 265.280 of Subpart M
Key Words:
Land Treatment, Closure, Refinery Waste
Type ot Oneuive tManual Policy Directive. Announcement etc i
Guidance Manual
Status
1 Li Draft
! IS Final
\ I—i New
D
Revision
\\
Ooe» tnis Directive Supersede Previous Direcnweis,' | | Yes |X| No Does It Supplement Previous Directweisi'
If Yes to Either Question What Directive tnumber nttel
Yes
No
Review Plan
D AA OSWER U OUST
D OERR O OWPE
LJ OSW LJ Regions
U OECM
D OGC
D OPPE
D
Other Specify/
This Request Meets OSWER Directives Svstem Format
Signature of Lead Office Directives Officer
Date
Signature of OSWER Directives Officer
Date
-------
r
\ UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
\ VNl/^L 5 WASHINGTON DC 20460
\ ~ UA^^ ^
Office ot Solid Waste I
TO: Hazardous »vaste Management Division Directors
Regions I-X
To assist permit writers and owners/operators of those land
treatment, units that' may be closing, ObW is issuing the Guidance
Manual on hazardous y>aste Land Treatment Clobure/ Post-Closure ;
40 CFR Part 2b5 . A copy of the manual is attacned. This guidance
manual aadresses closure and post-closure of uazaraous waste land
treatment (n'^LT) units unaer 40 CFR Part 265 Subpart G and Section
2oD.2dO ot Subpart M. Th& guidance is not intended to be a detailed
technical document, but rather a document tuat provides general
guidance to owners and operators of HWLT units and permit writers on
implementing Part 265 closure regulations. I want to emphasize that
the methods described in the manual are for guidance only and are
neitner requirements nor regulations. An applicant may use alter-
native methods, provided that these methods comply with applicable
regulatory requirements.
This manual specifically addresses five areas,:
(1) general information on HVvLT and methods of closure, (2) objec-
tives of closure and post-closure, (3) factors affecting closure and
post-closure, (4; methods for addressing closure and post-closure
based on migration potential, and (5) management during closure and
post-closure.
Finally, I want to stress that completion of a successful land
treatment closure .vould provide valuable information that should be
shared among Regions. Therefore, when such information becomes
available, I would appreciate your efforts to irirorm the appropriate
Headquarters Permit Assistance Team members.
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If your staff has questions regarding this jUi^ri'ice,
contact Jon Perry, on ts-3a2-4654 in the Land ui^^osdl Branca for
further information.
Attachment
cc with Attachmenti
RCRA Branch Chiefs, Regions I-X
Permit Section Chiets, Region I-X
Joe Carra
Susan 3romm
Sylvia Lowrance
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9476.00-9
GUIDANCE MANUAL ON
HAZARDOUS WASTE LAND TREATMENT CLOSURE/POST-CLOSURE
40 CFR PART 265
INTERIM FINAL
Prepared for
Office of Solid Waste
U.S. Environmental Protection Agency
Washington, D.C. 20460
Department of Civil and Environmental Engineering
Utah State University
Logan, Utah 84322
April, 1987
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TABLE OF CONTENTS
Page
1.0 Considerations for Closure and Post-closure of Hazardous Waste
Waste- Land Treatment Units Under 40 CFR Part 265 1
1.1 Purpose of manual 1
1.2 Overview of manual 1
1.3 Approach to closure and post-closure 1
1.4 General information on hazardous waste land treatment .... 7
2.0 Factors in Addressing Closure and Post-closure 9
2.1 Introduction 9
2.2 History of waste application 9
2.3 Mobilfty and migration potential 9
2.4 Environmental site conditions 11
2.5 Waste residue characterization in the unsaturated zone ... 11
3.0 Methods for Addressing Closure Based on Mobility and
Migration Potential ~~ 18
3.1 Suggested closure methods 18
3.2 Factors, to be considered in the selection of a closure
method " . ~ 18
3.3 Removal of contaminated soil as a closure method 21
3.4" Establishment of a fi'nal cover as a closure method 22
3.5 Continued groundwater monitoring 28
3.6 In-place treatment as a closure method 28
4.0 Management During Closure
4.1 Introduction 31
4.2 Unsaturated zone monitoring 31
4.3 Run-on and run-off control 32
4.4 Control of dispersal of particulates 32
5.0 Management during Post-closure 33
5.1 Post-closure requirements 33
5.2 Duration of post-closure care 33
References 35
Appendix A . - 38
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Chapter 1
CONSIDERATIONS FOR CLOSURE AND POST-CLOSURE OF HAZARDOUS WASTE
LAND TREATMENT UNITS UNDER 40 CFR PART 265
L.I PURPOSE OF MANUAL
This guidance manual addresses closure and post-closure of hazardous
waste land treatment (HWLT) units under 40 CFR Part 265 Subpart G and Section
265.280 of Subpart M. The guidance provided is not intended to be a detailed
technical document, but rather a document that provides general guidance to
owners and operators of HWLT units and permit writers on implementing Section
265 closure regulations. The guidance contains a discussion of options that
may.be pursued in implementing closure and post-closure requirements.
1.2 OVERVIEW OF MANUAL
This manual specifically addresses five areas including: (1) general
information on HWLT and methods of closure, (2) objectives of
closure/post-closure, (3) factors affecting closure and post-closure, (4)
methods for addressing closure and post-closure based on migration potential,
and (5) management during closure and post-closure. This guidance also
summarizes relevant information from additional U.S. Environmental Protection
Agency (EPA or Agency) publications and refers the user to EPA publications
,for background and for additional information supporting approaches for site
characterization, chemical analyses, establishment of cover, etc.
1.3 APPROACH TO CLOSURE AND POST-CLOSURE
The owner or operator of a hazardous waste management facility must
submit a closure plan to the EPA Regional Administrator at least 180 days
prior to the date on which closure is expected to begin at the first unit at
the facility. Owners or operators with approved closure plans must notify the
Regional Administrator in writing at least 60 days prior to the date on which
closure is expected to begin at a HWLT unit at the facility (Section 265.112
(d) (1)).
Within 30 days after receiving the known final volume of hazardous waste,
the owner or operator of the HWLT unit must commence closure in accordance
with the approved closure plan (Section 265.112 (d) (2)). The closure plan
should identify steps necessary to completely or partially close the facility
at anytime during the facility's intended operating life, and to completely
close the facility at the end of ics operating life. At a minimum, the
closure plan must include (Section 265.112(b)(!)-(?)):
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(1) a description of how each waste management unit at the facility will
be closed in accordance with the performance standards given in Section
265.111;
(2) a description of how final closure of the facility will be conducted
in accordance with Section 265.111, including a description of the maximum
extent of the operation that will be unclosed during the active life of the
facility;
(3) an estimate of the maximum inventory of hazardous wastes in storage
or treatment at the facility during its operating life;
(4) a description of methods to be used during partial and final closure,
including, but not limited to methods for removing, transporting, treating,
storing, or disposing of all hazardous waste, and identification of and the
type(s) of off-site hazardous waste management unit(s) to be used, if
applicable;
(&) a description of methods for decontamination of system components,
equipment, and structures, including criteria for determining the extent of
decontamination necessary to satisfy the closure performance standard (Section
265.111);
(6) a description of other activities necessary for closure, including
run-on and run-off control systems, groundwater monitoring and other
monitoring systems;
(7) a schedule of closure for each hazardous waste management unit and
for final closure of the facility, including specific periodic reporting dates
to monitor progress; and
(8) an est.imate of the expected year of final" closure for facilities that
use trust funds to demonstrate financial assurance (Sections 265.143 or
265.145) and whose remaining operating life is less than 20 years.
The owner or operator may amend the closure plan at any time prior to the
notification of partial or final closure of the facility in accordance with
Section 265.112 (c). The closure plan must be amended if there are changes in
operating plans or facility design that will affect the closure plan, if there
is a change in the expected year of closure, or if during the performance of
partial or final closure activities, unexpected events require a modification
of the closure plan (Section 265.112 (c) (1) (i), (ii), and (iii)).
Financial responsibility requirements to ensure that owners or operators
of hazardous waste management facilities have adequate funds to implement
closure and post-closure plans are given in Subpart H of Part 265. In
general, the regulations require that the owner or operator have written
estimates of the cost of closing the facility and the annual cost of a post-
closure monitoring and maintenance program. The owner or operator must also
adopt one of the financial instruments provided by the regulations to assure
financial responsibility.
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Additional specific requirements that must be addressed in the closure
plan for a HWLT unit are given in Section 265.280. The goal of closure of a
unit is to control, minimize or eliminate any potential for damage to human
health and the environment (Section 265.111). Closure of the HWLT unit is
therefore concerned with the extent of degradation, transformation, and
immobilization of constituents within a defined treatment zone, and the
control of pathways of migration of hazardous waste and hazardous waste
constituents into the environment, including groundwater, surface water,
atmosphere, and food-chain crops grown on site (Section 265.280(a) (l)-(4)).
The effectiveness of previous treatment of hazardous waste and hazardous waste
constituents in the treatment zone soil (Section 265.280(b)(l),(2),(6) and
(7)) is determined from a site reconnaissance study and from historical
records of waste application and site sampling. Information requirements for
site-characterization are specified in Section 265.280(b)(3),(4) and (5).
The guidance provided in this manual for approaches and criteria for
utilizing appropriate methods for closure and post-closure, including but not
limited to those identified in Section 265.280(c), i.e., (1) soil removal, (2)
cover or cap placement, and/or (3) groundwater monitoring, is based on
site-specific information. This information includes waste type and
constituents, soil type(s), climate, and extent of degradation,
transformation, and immobilization of hazardous waste and hazardous waste
constituents within a defined treatment zone. The information is used to
predict potential pathways of migration of hazardous waste and hazardous waste
constituents into the environment. Closure by soil removal may limit or
eliminate the potential for future migration by eliminating or reducing
contamination at the source, while closure by cover placement may limit or
eliminate direct contact and jnhalation exposure and/or limit or eliminate
leachate production by minimizing infiltration.
Continued in-place treatment of applied hazardous wastes is also a method
recommended for use during the closure period at a HWLT unit. In-place
treatment may consist of a continuation of the operating and management
practices utilized during the active life of the facility, or use of
additional amendments or techniques for enhancing degradation, transformation,
and/or immobilization.
Another approach presented in this guidance combines the use of two or
more of the recommended closure methods to achieve control of migration of
hazardous wastes and hazardous waste constituents from the HWLT unit. For
example, partial removal of more highly contaminated soil may be followed by
covering the unit, or by continued in-place treatment followed by
establishment or placement of a cover.
The closure plan submitted by the owner or operator must include a method
for evaluation of the potential migration of residual waste constituents to
environmental media, including groundwater, surface water, and atmosphere
(Sections 265.111 and 265.280 (b) (2)). An evaluation of potential migration
pathways of concern requires site-specific information concerning waste
residues and site/soil characteristics and may involve the use of laboratory
studies and/or mathematical models for predicting the rate and amount of
migration of constituents into the environment. Levels of constituents in
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leachates or emissions may be determined by the use of soil leaching or
volatilization tests or estimated based on known characteristics of the waste
constituents and soil characteristics (e.g., solubility and partitioning
coefficients). The mathematical model presented in the Permit Guidance Manual
on Hazardous Waste Land Treatment Demonstrations (U.S.EPA 1986a)wa?
developed by Short[1985)specifically for evaluation of degradation and
immobilization of individual organic waste constituents in a land treatment
unit, and for assessment of the potential migration of individual constituents
to groundwater and to atmosphere. The model can be used on IBM-compatible
personal computers (PCs). The model can be used to predict the fate and
relative concentration of hazardous constituents at point(s) of exposure, thus
indicating potential migration pathways of concern that should be controlled.
A detailed description of the model program, including capabilities,
assumptions, and limitations, rationales for selected input criteria, methods,
and information for using the model is given in the Permit Guidance Manual on
Hazardous Waste Land Treatment Demonstrations (U.S. EPA 1986a).A method for
evaluation of the potential for migration of metal constituents to groundwater
for hazardous waste/soil residues using sequential desorption, adsorption, and
column leaching tests is presented in Protection of Groundwater by
Immobilization of Heavy Metals in Industrial Waste Impacted Soil Systems (Sims
and McLean 1986). The geochemical model MINTEQ may also be used to determine
estimates of metals species distributions that can be used to predict
migration potential of metals (Felmy et al. 1984).
The time required for closure will be a function of the method chosen for
closure. If the wastes are left in place for continued treatment, the length
of time required for closure will be related to the time required for the
degradation of hazardous waste and hazardous waste constituents to achievable
levels protective of human health and the environment. While Section
265.113(b) requires that closure be completed within 180 days after receiving
the final known volume of hazardous wastes at the HWLT unit, caution should be
taken not to close a unit" before satisfactory levels are achieved. The
Regional Administrator may approve an extension to the closure period if the
owner or operator demonstrates that closure activities will take longer than
180 days to complete (Section 265.113(b)(l)(i)). Closures by soil removal or
by clay or synthetic capping are expected to require the least time, usually
within the 180 day period given in Section 265.113(b), while closure by
vegetative cover or a combination of approaches requires time periods
dependent upon biological processes and can also be anticipated to be
seasonally dependent. Therefore, closure activities at a HWLT unit may often
be expected to continue longer than 180 days. Also, if a vegetative cover is
used as part of a closure method utilizing continued treatment, sufficient
time must be allowed for degradation and detoxification of soil/waste residues
so that a vegetative cover can be established and maintained. A demonstration
of the ability of the site to support vegetation is also recommended prior to
the completion of closure
Any unit that closes after January 26, 1983 is subject to obtaining a
post-closure permit under Part 264 (Section 270.1 (c)). While the scope of
Section 265.280 requirements is currently limited to hazardous waste and
hazardous waste constituents (i.e., those listed in Appendix VII of Part 261),
the post-closure permit must address hazardous constituents (i.e., those
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listed in Appendix VIII of Part 261) (Section 264.280). Since evaluation of only
hazardous waste and "hazardous waste constituents under Section 265.280 pay allow
significant and potentially harmful levels of hazardous constituents to remain in
HWLT units, it is recommended that owners/operators consider the performance of
analysis and control of these constituents from the viewpoint of protection of
public health and the environment, as required by Section 264.280. If approved
by the permit writer, the hazardous constituents for wastes handled at a facility
that are from an identified process (e.g.,) petroleum refinery processes) for
which analysis is required may include only tiiose hazardous constituents that are
"reasonably expected to be in , or derived from, the wastes to be land treated"
(Section 270.20 (b) (4). A list of Appendix VIII constituents commonly found
in petroleum refinery wastes is included1 in .Appendix A. For facilities other
than petroleum refineries, guidance for determining hazardous constituents for
which a facility should test could follow the guidelines given to facilities
for preparation of petitions to delist hazardous waste (U.S. EPA 1985b). The
permit writer and applicant should agree in writing on the specific subset of
Appendix VIII constituents for which analysis will be required.
The closure performance standard given in Section 265.111 states that post-
closure escape of hazardous waste, hazardous constituents, leachate, contaminated
run-off, or hazardous waste deconposition products must be controlled, minimized
or eliminated. The permit writer should use health-based acceptable concentrations,
as described below, or remove constituents to background levels, or to levels
achievable by the use of selected closure technology at the specific HWLT unit
when Agency approved health-based levels are not available. These criteria should
be used to assess risk due to direct contact with the unit soils (i.e., soil
inqestion), exposure to ground water at the unit boundary, and surface water quality
impacted by ground water discharge or surface runoff.
Concentration levels for Appendix VIII constituents for each potential route
of exposure are based upon the most appropriate Agenc/-established health-based
levels. The following levels should be used for setting closure target levels
in each medium:
(1) for all routes of exposure involving a drinking water scenario, use
Maximum Contaminant Levels (MCLs) established as drinking water standards under
the Safe Drinking Water Act (3CWA). The Agency is in the process of proposing
and 'finalizino additional MCLs and will continue to do so over the next several
years;
(2) where no VCLs currently exist, however, the closure target levels
involving a drinking water scenario should be based on Reference Doses (Rfi?s)
for threshold contaminants, and Pisk Specific Doses (PSDs) for non-threshold
contaminants, assuming a risk level of 1/1,000,000 for Class A and E carcino-
gens and 1/100,000 for Class C carcinogens;
(3) for routes of exposure involving direct contact with the soil surface
and direct soil ingestion, closure target levels should be based on RfDs and
F5Ds, as described above;
(4) for routes of exposure involving inhalation of chemical contaminants
or particulate natter, the closure target level should be based on National
Ambient Air Quality Standards (^CVAOS) where they exist; where no NAAQS exist,
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target levels based on RfDs and RSDs should be used, assuming an inhalation
route of exposure;
(5) closure target levels for any medium (soil, air, or water) could be
based on adverse effects on environmental systems or species; where such
environmental effects are potentially significant, the closure target levels
should be based on Federally-approved State Water Quality Criteria (for
protection of aquatic species); the assumption is made that a contaminant in
air, soil, or groundwater in addition to surface water could affect aquatic
organisms;
(6) under certain circumstances, the closure target levels based on
Agency-established human health standards (i.e., MCLs, RfDs, RSDs, etc.) may
be lowered. Such circumstances include:
(a) where a mixture of contaminants is present in any one medium
resulting in exposure to multiple contaminants that could cause adverse
effects on the same human organs;
(b) where an unusual exposure scenario or a vulnerable population at
the site requires a more stringent target level;
(c) where levels necessary to protect an aquatic organism or other
environmental species or system are appropriate.
The Agency will prepare additional guidance in the near future to provide a
more precise description of these and other circumstances that would warrant a
lowering of the closure target levels.
If reduction of concentrations of constituents to background levels is
used as a goal to be achieved during closure and post-closure care, these
levels may not be appropriate for conservative metal constituents. If
immobilization of metals is successful in the treatment zone, then background
levels will not be achievable. An alternative approach may be to use the
suggested maximum concentrations of metals that may be added safely to soils
that are given in Tables 6.46 and 6.47 in Hazardous Waste Land Treatment (U.S.
EPA 1983). The concentrations, based on literature and experience, were
developed using microbial and plant toxicity limits, animal health
considerations, and soil chemical properties that reflect the ability the soil
to immobilize metals. Other pathways of exposure such as ingestion, however,
were not considered.
Within 60 days after completion of closure, the owner or operator must
submit to the Regional Administrator a certification that the HWLT unit has
been closed in accordance with the approved closure plan. This certification
must be signed by the owner or operator and by either an independent
registered professional engineer or by an independent qualified soil scientist
(Sections 265.115 and 265.280(e)). Within 60 days after certification of
closure, the owner or operator must also submit to the local zoning authority
or to the authority with jurisdiction over local land use, and to the Regional
Administrator, a record of the type, location, and quantity of hazardous
wastes disposed of at the unit (Section 265.119 (a)). The owner or operator
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must record, in accordance with state law, a notation on the deed to the
facility property, or on some other instrument that is normally examined
during title search, that will notify any potential purchaser of the property
that the land has been used to manage hazardous waste and that its use is
restricted under Subpart G regulations (Section 265.119 (b)).
A post-closure permit will be required for all units that closed after
January 26, 1983, except where a unit satisfies the requirements of Section
264.280 (e),' i.e., no hazardous constituents have migrated beyond the
treatment zone during the active life of the unit, and there are no hazardous
constituents in the treatment zone above background levels at the time of
closure. Certification of completion of post-closure care must be submitted to
the Regional Administrator within 60 days of the completion of the established
post-closure care period, according to the requirements given in Section
265.120.
1.4 GENERAL INFORMATION ON HAZARDOUS WASTE LAND TREATMENT
Land treatment is characterized in 40 CFR Section 265.272 (a) as follows:
"Hazardous waste must not be placed in or on a land treatment facility unless
the waste can be made less hazardous or non-hazardous by degradation,
transformation, or immobilization processes occurring in or on the soil."
Degradation of organic hazardous waste, hazardous waste constituents, and
hazardous constituents as defined in 40 CFR Part 261 (i.e., Appendix VIII
hazardous constituents), describes the loss of parent compounds through
chemical and biological reactions within the soil/waste matrix. The rate of
degradation may be established by measuring the loss of parent compound with
time. Degradation and detoxification represent primary mechanisms for
assimilation of organic waste constituents in a soil system. Transformation
refers to the formation of intermediates during the process of degradation.
Immobil zation refers -~ the extent of retardation of the downward transport,
or leaching potential, and upward transport, or volatilization potential, of
waste constituents. Immobilization is the primary mechanism for treatment of
.hazardous metals in soil- systems. Immobilization of organic waste
constituents allows for time for degradation processes to occur. The mobility
potential for waste constituents to transport from the waste to water, air,
and soil phases is affected by the relative affinity of the constituents for
each phase. The evaluation of soil treatment requires integration of the
results of degradation, transformation, and immobilization processes for waste
constituents of concern.
At a HWLT unit, waste is generally applied to the surface and/or
incorporated into the soil. At some HWLT units, the waste is injected below
the surface using subsurface injection techniques. The zone of incorporation
(ZOI) represents the area and depth over which waste is applied; generally the
ZOI is 15-20 cm (6-8 in.) in depth. The treatment zone includes the ZOI and
the unsaturated soil below the ZOI where treatment is achieved. (In Section
264.271 (c), the maximum depth of the treatment zone is defined as 1.5 m (5
ft.)). Loading rate (amount of waste added per volume of land), and the
frequency of waste application vary for each HWLT unit, and are generally
functions of the waste degradation rate, waste production rate, and climate.
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Unlike other land disposal options , including landfills, surface
impoundments, and waste piles, where wastes are contained or stored
indefinitely or for future disposal, HWLT units are designed to accomplish
simultaneous treatment and ultimate disposal. The objective of HWLT achieves
safe assimilation of wastes by the treatment soil through the processes of
degradation, transformation, and immobilization. Additional information
concerning the objectives, functions, and processes operating within an HWLT
unit are provided in Hazardous Waste Land Treatment (U.S. EPA 1983) and in the
Permit Guidance Manual on Hazardous Waste Land Treatment Demonstrations (U.S.
EPA 1986a).
8
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Chapter 2
FACTORS IN ADDRESSING CLOSURE AND POST-CLOSURE
2.1 INTRODUCTION
To achieve the objectives of closure and post-closure, the owner or
operator must provide information concerning the type and amount of hazardous
wastes applied to the HWLT unit during the active life of the facility,
migration potential of the hazardous wastes and hazardous waste constituents,
environmental site conditions, and waste residue characterization in the
unsaturated zone.
2.2 HISTORY OF WASTE APPLICATION
The owner or operator of a HWLT unit should provide, as required in
Section 265.280 (b) (1), information concerning past waste management
practices. Table 2.1 lists suggested important waste management data and
records. These records include available history of waste application (i.e.,
application rates, timing, and location) and available history of hazardous
waste quality. .
2.3 MOBILITY AND MIGRATION POTENTIAL
An assessment of mobility and migration potential of the hazardous waste
and hazardous waste constituents at the unit into environmental pathways of
exposure is necessary to address the objectives of closure, i.e., control of
migration of constituents (Section 265.280(b)(2)). Assessment of mobility and
migration potential is also necessary in selecting an appropriate closure
method.
The extent of treatment and migration of constituents from wastes that
have been applied to the HWLT unit may be assessed during a site
reconnaissance investigation as part of closure activities. Determination of
the potential for future migration of constituents requires information
concerning the extent of immobilization and rate of degradation of
constituents as affected by site/soil conditions.
Migration potential for organic and inorganic constituents may be
evaluated and predicted using reconnaissance data supplemented as required
with a combination of treatability studies, predictions based on known
characteristics of the soil and waste constituents, and modeling using the
approach presented in the Permit Guidance Manual on Hazardous Waste Land
Treatment Demonstrations (U.S~! EPA 1986a). Refer to the Permit Guidance
Manual on Hazardous Waste Land Treatment Demonstrations (U.S. EPA 1986a) for
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TABLE 2.1 USEFUL WASTE MANAGEMENT DATA AND RECORDS
Category
Item
Specific Information
History of Waste
Application
Years in service
and annual quan-
tity of waste land
treated
Placement of wastes
on land treatment
plots
History of Waste
Quality
Waste Analyses
Records of measured or
estimated annual waste
quantity treated over
the 1ife of the unit.
Records of quantity, date,
and location of each waste
application for each land-
treated waste over the
life of the HWLT unit,
including management
practices used
Analyses of each land-
treated hazardous waste
applied during the
operating life of the
unit. (Non-hazardous
waste analyses are also
necessary if these
wastes were land
treated in the same
plots as hazardous
wastes.)
10
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detailed information for determining migration potential. Prediction of the
migration potential of organo-metallic complexes present in waste residues at
closure is a difficult aspect of closure to evaluate at the present time.
This difficulty is directly related to changes in physical, chemical, and
biological properties that occur as a result of the complexation of organic
constituents with metal species. The resulting organo-metal1ic complex may
not have properties that are identified with either the organic fraction or
the metal fraction. It is important to know the structure of the organo-
metal lie complex in order to predict and/or evaluate the degradation and
mobility potential. Changes in either the organic or metal fraction may
result in drastic changes in toxicity, persistence, and/or mobility.
2.4 ENVIRONMENTAL SITE CONDITIONS
Sections 265.280 (b) (3), (4), and (5) require the evaluation of
environmental site conditions of the HWLT unit as they relate to the control
of migration and transport of hazardous waste constituents to groundwater and
surface water and to the control of the release of airborne particulate
contaminants. Specifically, the regulations require that the following
factors must be evaluated:
(1) site location, topography, and surrounding land use;
(2) climate, including amount, frequency, and pH of precipitation;
(3) geological and soil profiles;
(4) surface and subsurface hydrology of the s ,e;
(5) soil characteristics, including cation exchange capacity, total
organic carbon, and pH.
Additional soil properties that are important in waste treatment and
mobility, at HWLT units and. should be assessed include soil texture, soil
mineralogy, bulk density, particle density, available water capacity,
porosity, saturated hydraulic conductivity, aeration status, nutrients,
electrical conductivity, - and buffering capacity. Data concerning any other
soil and site conditions that may be required as input to the mathematical
model for land treatment systems should also be collected if predictive
modelling is used to evaluate migration potential and/or to choose an
appropriate closure method.
Guidance concerning the use of site data for prediction of transport of
hazardous waste constituents from the HWLT unit may be found in Chapter 3 of
Hazardous Waste Land Treatment, (U.S. EPA 1983), in Contaminated Surface Soil
In-Pi ace Treatment Techniques (Sims et al. 1986), in the Permit Guidance
Manual on Hazardous Waste Land Treatment Demonstrations (U.S. EPA 1986a).
2.5 WASTE RESIDUE CHARACTERIZATION IN THE UNSATURATED ZONE
The purpose of waste residue characterization in the unsaturated zone at
the HWLT unit (Section 265.280 (b) (6) and (7)) is to detect and predict
11
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migration of hazardous wastes and hazardous waste constituents in order to
determine the effectiveness of land treatment during the active life of the
facility and to choose and implement appropriate closure methods. Information
from waste residue characterization may also be used in the mathematical model
for land treatment to assess potential migration of residual hazardous wastes
and hazardous waste constituents (Section 265.280 (b) (2)).
Since wastes at the HWLT unit do not exist separately from the
environmental matrix, measurement of waste characteristics must be assessed as
part of the soil matrix, and in the soil pore liquid, groundwater, and surface
runoff. Thus analysis techniques will usually include collection of samples
from the HWLT unit, extraction/digestion procedures to separate constituents
from the environmental matrix, and chemical analyses of the constituents. The
types of waste residue analyses recommended have been categorized into three
groups, as shown in Table 2.2.
The analysis of specific characteristics or constituents to be measured
in the waste residue/soil matrix should provide information concerning the
potential treatability of a hazardous waste in a soil system (e.g., pH,
nutrients, electrical conductivity), and should include analyses that are used
to optimize the performance of other analytical procedures (e.g., oil and
grease content affects the extraction and analysis of samples for specific
organic constituents). These analyses have been designated Type I analyses
(Table 2.2).
Type II and Type III analyses (Table 2.2) are concerned with analysis for
specific hazardous waste constituents (i.e., the waste constituents for which
the waste was listed) and hazardous constituents (i.e., additional Appendix
VIII constituents other than those for which the waste was listed as hazard-
ous) in the waste residue/soil matrix. Since EPA believes "it is necessary to
include all hazardous constituents ... to ensure that all contamination is
adequately addressed at closure" (51 FR 16425), it is recommended that
hazardous constituents be analyzed as well as hazardous waste constituents
(see page 5 of this manual). If approved by the permit writer, EPA may accept
analyses for a subset of Appendix VIII compounds that are "reasonably expected
to be in, or derived from, the wastes to be land treated" (Section 270.20 (b)
(4)), when the wastes handled at a facility are from an identified process. A
list of Appendix VIII constituents commonly found in petroleum wastes is
included in Appendix A. Similar lists may be developed for other industrial
waste processes but should be approved by the permit writer and/or EPA.
Type II analyses are designed to detect and monitor levels of organic
constituents on a routine basis using sample extraction preparation techniques
and gas chromatography (GC) and/or high performance liquid chromatography
(HPLC) for detection of organic constituents. These analyses are used for
known constituents such as those for which a waste was listed as hazardous or
those listed in an approved subset of Appendix VIII constituents for a
specific waste type. The use of Type II analyses allows for the processing of
larger numbers of samples at lower costs than Type III analyses.
12
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TABLE 2.2
SUGGESTED ANALYTICAL INFORMATION
(U.S. EPA 1987)
Typo of
Ana I ys i s
PHI pose
Const ituenta
Media to be Sampled
Soil
Zone of
Incorporat ion
Treatment
Below
Soil- Ground-
Zone Below Treatment Pore
Zone of Zone Liquid*
Incorporation
water
Type I. To provide infor-
I mat ion concerning
th<" Inni! trent-
ab i 1 i ty of a waste
* 2. To optimize other
.inn lyt ica I pro-
cedures
Oil and grease i
Total organic
carbon
Extractable
hydrocarbons* *
Total dissolved
solids or
electrical con-
ductivity (EC)
PH
Nutrients (nitro-
gen, phocphoruA,
potassium)
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X X
X X
X X
-------
TABLE 2.2 CONTINUED
Type o
Analys
Type
H
f Purpose Constituents
is
To detect, monitor, Metals***
and quantify selected
constituents Constituents that
Media to be
Soil
i Zone of Treatment
lucorpornt ion Zone Below
1 Zone of
Incorporat ion
X X
Sampled
Below
Treatment
Zone
X
Soil-
Pore
Liquid *
X
Ground-
wdter*
X
exceed the maximum
concentration listed
in Table 1 of 40 CFR
261.24 that cause a
waste to exhibit EP
toxicity (Required)
Constituents that
caused the wastes to
be listed as a hazard-
ous waste (Required)
Appendix VIII organic
constituents (40 CFR
270.20) that are reason-
ably expected to be in,
or derived from waste
placed in or on the treat-
ment zone of a land treat-
ment unit (Recommended)
-------
TABLE 2.2 CONTINUED
Type of Purpose
An n lysis
Type To identify and
lit quantify Appendix
V 1 [ t organic con-
«t 1 1 uetU s
Const ituents
-
Appendix V[[[
organic con-
st ituents and
intermediate de-
gradation products
Media to be
Soil
Zone of Treatment
Incorporation Zone Below
Zone of
Incorporat ion
X X
Sampled
Below Soil-
Treatment Pore
Zone Liquid
X X
Ground-
water
X
If selected sites have previously installed samplers.
If used as an indicator of amount of wastes applied.
Total concentrations and not EP toxicity data; if food chain crops are grown, analysis of arsenic, cadnum, lead
and mercury required; analysis of all Appendix V11I metals reccrrrrended.
-------
Type II analyses also include the detection of metals in the waste
residue/soil matrix by the use of inductively coupled plasma (ICP) or atomic
absorption (AA).
Type III analyses are designed to identify and quantify organic constitu-
ents using sample clean-up and extraction techniques and gas chromatography/
mass spectrometry (GC/MS) for identification and quantification. These
analyses are usually performed when the identity and levels of hazardous
constituents are not known. They are also used periodically in conjunction
with Type II analyses to confirm the accuracy of Type II techniques.
All procedures used to measure constituents should be those approved by
EPA or should be recognized standard methods. Methods that may be used for
analysis of constituents are described in Test Methods for Evaluating Solid
Waste, Physical/Chemical Methods, SW-846 (U.S. EPA 1987), in the Guidance for
the Analysis of Refinery Wastes (U.S. EPA 1985a), in Standard Methods for the
Examination of Water and Wastewater (APHA 1985), Tri Methods for Organic
Chemical Analysis of Municipal and Industrial Wastewater (U.S. EPA 1979), HT"
Characterization of Hazardous Waste Sites, A Methods Manual. Volume 3:
Available Laboratory Analytical Methods (Plumb 1984),and in Methods of Soil
Analysis, Parts 1 and 2, Second EditTon (Klute 1986, Page 1982~TAdditional
information concerning specifically the analysis of waste constituents at HWLT
units may be found in the Permit Guidance Manual on Hazardous Waste Land
Treatment Demonstrations (U.S. EPA 1986a).
Unsaturated zone monitoring, including sampling of soil core and soil
pore liquid, is used to accomplish waste residue characterization in the soil
system.
Soil core sampling is used to determine the type, concentration, and
depth of migration of hazardous waste constituents in the soil as compared to
background concentrations, as required in Section 265.280 (b)(7). Guidance
concerning soil core sampling, including procedures and equipment, depth of
sampling, area! distribution of sampling, analysis of soil core sampling, and
interpretation of soil core sample data is given in the Guidance Manual on
Unsaturated Zone Monitoring for Hazardous Waste Land Treatment Units (U.S. ETA
1986b),the Permit Guidance Manual on Hazardous Waste Land Treatment
Demonstrations (U.S.EPA 1986a),in Preparation of Soil Sampling Protocol:
Techniques and Strategies (Mason 1983), and in Soil Sampling Qua!ity Assurance
User's Guide (Barth and Mason 1984).
Soil-pore liquid monitoring is intended to detect rapid pulses of
constituents that occur immediately after significant additions of liquids to
the HWLT unit. Therefore, the timing of soil-pore liquid sampling is
essential to the usefulness of this technique (i.e., scheduled sampling cannot
be planned on a preset date, but must be coordinated with precipitation,
irrigation, etc.). The use of several types of soil-pore liquid samplers is
recommended to enhance the likelihood of obtaining samples. Discussions of
soil-pore liquid sampling are presented in the Permit Guidance Manual on
Hazardous Haste Land Treatment Demonstrations (U.S. EPA 1986a) and in Permit
Guidance Manual on Unsaturated Zone Monitoring for Hazardous Waste Land
Treatment Units (U.S. EPA 1986b).
16
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Information collected as required for waste residue characterization
should be representative of the waste residue/soil system. Sampling designs
should provide information of maximum reliability. Statistical plans
including knowledge of the expected variability and confidence limits of both
the analytical methods used and the sampling designs employed should be
incorporated in the closure plan. It is recommended that the owner or
operator secure the services of a statistician familiar with the design of
sampling and monitoring studies to prepare the sampling plan
17
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Chapter 3
METHODS FOR ADDRESSING CLOSURE BASED ON MOBILITY
AND MIGRATION POTENTIAL
3.1 SUGGESTED CLOSURE METHODS
In order to address the goal of closure and post-closure of controlling
the migration of hazardous waste and hazardous waste constituents from the
HWLT unit to the environment (Section 265.280 (a)), Section 265.280 (c)
requires that at least three methods be considered and discussed by the
owner/operator in the closure plan. These approaches include:
(1) removal of contaminated soil from the land treatment unit;
(2) placement of a final cover over the unit, such as a vegetative cover
or a clay or synthetic cap; and
(3) continued groundwater monitoring.
An additional method is also suggested for. use-:..
(4) continued treatment of the waste residue in the soil system, with
the use of treatment amendments and enhancements as required.
A combination of these'methods may also be considered. Examples of such
combinations include:
(a) partial removal of contaminated soil (e.g., the ZOI soil) and
placement of a vegetative cover or a cap of clay or synthetic material;
(b) partial removal of contaminated soil, continuation of treatment,
possibly using amendments to enhance treatment, and placement of a vegetative
cover or cap; or
(c) no soil removal, continuation of treatment, possibly using
amendments, and placement of a vegetative cover.
Additional options not presented here may also be used if the control of
migration of constituents of concern can be achieved.
3.2 FACTORS TO BE CONSIDERED IN THE SELECTION OF A CLOSURE METHOD
The selection of one of the four options presented in this guidance for
use in closure requires the evaluation of several potential sources of
18
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information, including information collected from the reconnaissance
investigation of the unit, environmental site and soil conditions, laboratory
studies, and/or mathematical modeTing to predict potential pathways and
extent of migration. The factors presented for consideration in the following
sections are not meant to be exhaustive but are indicative of the types of
information that may be used in the choice of an appropriate closure method.
3.2.1 Selection of Removal of Contaminated Soil as a Closure Method
The use of soil removal should be considered if information concerning
mobility and migration potential indicates that:
(1) unsatisfactory migration of constituents of concern from the unit
has occurred;
(2) environmental site and soil conditions (e.g., high precipitation,
low evapotranspiration, soils of high permeability and/or low sorptive
capacity, high runoff potential, soil considerations) indicate a high
potential for migration;
(3) the characteristics of residual constituents (e.g., high volatility,
high degree of water solubility, high concentrations) indicate a high
potential for migration;
(4) the degree of hazard presented by the residual constituents suggests
that the contamination should be removed (direct exposure
opportunity/potential effect on post-closure); and/or
(5) the results of the use of the mathematical model for land treatment
indicate a high potential for migration.
P'artval removal" of contaminated soil should be considered if constituents
with higher potential for migration and/or higher toxicity are concentrated in
the upper- soil 1-ayers, e.g., the ZOI. Additional closure activities may be
necessary to stabilize the new soil surface and control migration of remaining
constituents.
3.2.2 Selection of a Cover Over the Unit as a Closure Method
Two types of covers, which act to control migration in different ways,
are suggested for use. In general, factors to be considered in the use of
either type of cover, i.e., vegetative cover or capping, include:
(1) unsatisfactory migration of constituents from the unit has not
occurred;
(2) environmental site and soil conditions (e.g., moderate to low
precipitation and high evapotranspiration, soils with moderate to high
sorptive capacity) indicate a moderate to low potential for migration from the
unit; and
19
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(3) residual waste constituents are at low to medium concentrations,
exhibit moderate potential for transport in percolating water or in air,
and/or are of low residual toxicity;
Specific factors that should also be considered in the selection of
vegetation as a cover include:
(1) a lower potential for migration to groundwater exists such that the
primary purpose of the cover would be to minimize direct contact and
inhalation of residual constituents and to control erosion and run-off; and
(2) there may be potential for continued in-place treatment of waste
residuals in the-soil system during the post-closure period.
The use of capping with clay or synthetic materials should be evaluated
using the following factors:
(1) migration of constituents in percolating water would be minimized or
eliminated if infiltration were controlled;
(2) migration of constituents to the atmosphere would be minimized or
eliminated if a cap were used that reduced vapor transport or particulate
windborne erosion;
(3) the type of constituents present would not present a greater threat
to human health and the environment under the anaerobic conditions that would
likely develop below a clay or synthetic cap (e.g., if cessation of further
treatment, greater mobility, and/or higher toxicity might result, and/or
methane migration might occur); and
(4) waste(s) and waste(s) constituents would be isolated from a direct
contact pathway.
3.2.3 Selection of the Use of Continued Groundwater Monitoring
as a Closure Method
The use of continued monitoring of the HWLT unit as it was operated
during the active life of the facility without additional closure activities
should be considered according to the following factors:
(1) no migration of constituents of concern has occurred from the HWLT
unit;
(2) there is little or no potential for future migration of constituents
from the unit, as indicated by site and soil conditions, residual waste
characteristics, laboratory studies, and/or predictive mathematical modelling;
and
(3) there is no danger from direct contact with waste residuals.
20
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3.2.4 Selection of Continued In-Pi ace Treatment as a Closure Method
Factors that should be considered in the selection of the use of in-place
treatment as a closure method include:
(1) waste residues are capable of further treatment in the soil system;
and
(2) potential migration of waste residuals during the closure period is
low.
3.3 REMOVAL OF CONTAMINATED SOIL AS A CLOSURE METHOD
Complete or partial removal of contaminated soils at the HWLT unit may be
used to eliminate or reduce the source of contamination at the unit.
3.3.1 Description of Excavation and Disposal
Excavation is a common technique used in earth-moving projects and is
widely used to move solid and thickened sludge materials. Excavation is
achieved by mechanical means. Typical excavation equipment includes
draglines, backhoes, earthmovers, and bulldozers. The hazardous waste
contaminated soil excavated from an HWLT unit must be disposed of in a
RCRA-approved hazardous waste facility. Arrangements for disposal must be made
as part of the closure plan.
Technical guidance concerning excavation technology and costs associated
with excavation, transportation and disposal are presented in the Handbook for
Remedial Action at~Waste Disposal Sites (U.S. EPA 1982a) and in Liners for
Sanitary Landfills and Chemical and Hazardous Waste Disposal Sites (U.S. EPA
1978).
3.3.2 Advantages and Disadvantages of Excavation and Disposal
to Completely Remove Contaminated Soil
The use of excavation and disposal is not recommended as the sole closure
method for HWLT units unless there is a severe potential for migration of
hazardous waste constituents from the unit or potential for direct exposure to
toxic levels of hazardous waste(s) or constituents following closure. Waste
residues left in the soil at HWLT units may be subject to further treatment in
the soil, however, to render them less or non-hazardous. The availability of
space in another RCRA-approved facility for the large quantities of soils
associated with an HWLT unit may be limited and difficult to locate.
However, an advantage to the use of excavation and disposal as a closure
method is that if the unit has been excavated to such a depth so as to
completely remove the source of contamination, it should therefore present no
threat to human health and the environment, and activities associated with
post-closure care may be limited under Section 265.118 (f). However, a
post-closure permit will be required unless the requirements of Section
264.280 (e) are met.
21
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Partial removal of contaminated soils may reduce the major source of
constituents with a higher potential for migration from the unit and/or a
higher degree of hazard from direct contact. Additional closure methods may
then be implemented to further control expected pathways of migration of
remaining constituents.
3.4 ESTABLISHMENT OF A FINAL COVER AS A CLOSURE METHOD
Two types of covers should be considered: vegetative covers and clay or
synthetic caps. Covers are used to minimize or eliminate infiltration into
the soil and to stabilize the soil surface.
3.4.1 The Use of Vegetation as a Final Cover
The use of vegetation as the final surface cover is highly recommended at
the HWLT unit to prevent water and wind borne erosion and transport of
soil/waste materials, to provide infiltration control into the soil, and to
allow continued treatment of hazardous constituents.
The vegetative cover should be established at such time that the cover
will not impede the treatment of hazardous constituents. Since certain
operating practices to accomplish and enhance treatment, such as tilling,
cannot be performed without damaging or destroying the vegetative cover, the
owner or operator should postpone establishing the vegetative cover until
satisfactory treatment has occurred following the last application of waste.
Results from unsaturated zone monitoring, treatment zone soil analyses, and
run-off monitoring should be used to determine the degree of treatment
achieved^.. Once the cover is established, operating practices that are
inconsistent (e.g., tilling) with establishment and maintenance of the
vegetative cover should be discontinued (U.S. EPA 1983). Long-term vegetative
stabilization generally involves the planting of grasses, legumes, and shrubs.
Technical guidance concerning the establishment of a vegetative cover at
HWLT- units may be found in Hazardous Waste Land Treatment (U.S. EPA 1983),
Handbook for Remedial Action at Waste Disposal Sites (U.S. EPA 1982a), and in
Evaluating Cover Systems for Solid and Hazardous Vlaste (Lutton 1982).
3.4.1.L Description of Vegetative Cover--
In order to establish egetation at an HWLT unit, the following factors
should be addressed in the closure plan (U.S. EPA 1983):
(1) Selection of species adapted for the site
(2) Seedbed preparation
(3) Seeding/planting
(4) Management practices for cover maintenance
22
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3.4.1.1.1 Selection of Species--
The selection of suitable plant species for vegetating a closed HWLT unit
depends on cover soil characteristics and site and plant characteristics, as
shown in Table 3.1.
Perennial grasses such as fescue that have dense root systems that anchor
soil and enhance infiltration provide a quick and lasting ground cover.
Legumes (e.g..., lespedeza, vetch, clover) fix nitrogen from the atmosphere in
their roots, enhancing soil fertility and assisting the growth of grasses.
Shrubs also can provide a dense surface cover. A mixture of plants will
allow more efficient use of soil moisture and nutrients at various depths.
Trees are generally planted in the later stages of revegetation, after legumes
and grasses have established a stable ground cover. They help to provide
long-term protective cover and build up a stable, fertile layer of decaying
leaves/branches.
TABLE 3.1. FACTORS FOR SELECTION OF PLANT SPECIES (U.S. EPA 1982a,
U.S. EPA 1983)
Site/Soil Characteristics
Plant Characteristics
Texture
Organic content
Nutrient and pH levels
Soil water content
Climate
Site hydrology (slope
steepness and drainage
characteristics)
Ease of establishment
Sensitivity to resi-
dual waste constitu-_
ents
Tolerance to soil
characteristics
Ability to control
erosion
Productivity
Ability to withstand
competition with
undesirable
plants
Availability of seed
at reasonable cost
Ease of maintenance
Resistance to dis-
eases and insect
damage
Water tolerance
Suitability for
future land use
Desirable species
(not noxious or
poisonous)
23
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Information concerning the suitability of specific plant species for
revegetation of HWLT units are presented in Table 3.5 in the Handbook for
Remedial Action at Waste Disposal Sites (U.S. EPA 1982a), in Tabie 8.11 in
Hazardous Waste Land Treatment (U.S. EPA 1983), and in Tables 11, 12, and 13
in Evaluating Cover Systems for Solid and Hazardous Waste (Lutton 1982).
Other sources of information are highway cut revegetation standards
available from most state highway departments and recommendations from the
Soil- Conservation Serv-ice, state agricultural extension services, and/or
agronomy departments at universities. In some cases, plant species may be
used in climatic zones other than those recommended if special conditions
unique to the HWLT unit would permit their use, e.g., when the use of
irrigation provides additional moisture.
The use of food-chain crops for vegetating an HWLT requires special
considerations, as given in Section 265.276. These regulations must be
followed if food-chain crops are to be grown. Before growing food chain
crops, the owner or operator must demonstrate, based on field testing, that
any arsenic, lead, mercury, or any constituent that caused the waste to be
listed as a hazardous waste will not be transferred to the food portion of the
crop by plant uptake or direct contact, and will not be ingested by food chain
animals. The owner or operator also must demonstrate that these constituents
will not occur in greater concentrations in crops grown on the HWLT unit than
in the same crops grown on untreated soils under similar conditions in the
same region. If the wastes applied to the HWLT unit contain cadmium, special
requirements concerning annual and cumulative applications of cadmium must be
met, as given in Sections 265.276 (c).
Selection of suitable plant species for HWLT units that have had oily
wastes applied may be difficult because at this time there are little data
available on the revegetation of these sites with perennial plants. Streebin
et al.(1984) prepared a literature review on the effects of oily wastes on the
growth of plants. Problems identified for plant growth include phytotoxic
waste constituents and impaired water, air, and nutrient relations. The
authors recommended that research be conducted to identify and develop plants
that are tolerant to oily wastes.
Because of possible impacts that wastes at an HWLT unit may have on the
growth of vegetation, the use of a demonstration study of selected plant
species or potential species is recommended. The study may be conducted in
field plots at the site, or a greenhouse simulation study may be performed.
Possible protocols for conducting these types of studies are presented in
Field and Laboratory Evaluation of Petroleum Land Treatment System Closure
(Overcash et al. 1985)."~
3.4.1.1.2 Seedbed Preparation--
Seedbed preparation is necessary to create a favorable environment for
the rapid germination and growth of the planted species. The characteristics
of an adequate seedbed include:
(1) appropriate pH level
24
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(2) adequate nutrients
(3) freedom from live vegetation
(4) firm soil below seeding depth
(5) adequate amounts of mulch, plant residues, or chemical stabilizers
on the soil surface
Applications of lime are used to neutralize acidic soils, while
acidifying agents may be added to soils with too high pH levels. Fertilizers
are added to provide essential plant nutrients. The amount of lime or
acidifying agents and fertilizers required should be determined from
site-specific soil tests-.
Plowing is the most common method of preparing a seedbed to destroy
existing vegetation and to create a favorable soil density. Mulches or plant
residues are added to the soil to conserve soil moisture, dissipate raindrop
energy, moderate soil temperatures, prevent crusting, increase infiltration,
and control wind and water erosion. Mulches may also be used as a seedbed to
protect seeds from injury from volatile and dissolved constituents during
germination and early growth.
3.4.1.1.3 Seeding/Planting Program--
The development of a successful vegetative stand also depends on an
effective seeding/planting program. Elements of a seeding program include:
(1) seeding/planting method
(2) seeding/planting rate
(3) seeding depth
(4) timing of seeding/planting
Seeding should be performed as soon as possible after seedbed
preparation. The most common methods of seeding are broadcasting and
drilling. Drilling is usually preferred, since seed/soil contact is important
for successful stand establishment. The effectiveness of broadcasting may be
enhanced by following seeding with harrowing or discing to increase seed/soil
contact. Hydroseeders may also be used, which spray seed, fertilizer, mulch,
and lime at one time. However, phytotoxicity of residual waste constituents
may cause difficulty in germination and may require the use of mulches to
protect seeds and developing seedlings from toxic constituents in the
waste/soil matrix.
Hand planting may be required for trees and shrubs. Until trees have
recovered from the initial shock that planting causes their root systems, they
should not be exposed to oil contaminated soils (Streebin et al. 1984). In
order to buffer roots from treated soil and to give trees time to establish
themselves oefore the roots come into contact with contaminated soil, a large
25
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hole about twice the size normally used to plant the tree should be used and
filled in with uncontaminated soil.
The use of a proper seeding rate is also critical to the establishment of
a vegetative stand. The quantity of seed applied depends on the plant
species, the method of seeding, and waste/soil characteristics.
Optimum seeding depth depends on seed size, quantity of stored energy in
the seeds, and texture of the surface soil (U.S. EPA 1983). If seeds are
planted too deep, there may not be enough stored energy to allow developing
seedlings to reach the soil surface. Too shallow seeding may result in
desiccation of the seed. Seed may be planted deeper in lighter-textured soils
than in heavier textured soils.
The optimum time for seeding is dependent on the local climate and the
requirements of the individual plant species. Seeding/planting should be
performed under favorable temperatures and soil moisture conditions. For
perennial species, early fall seeding is usually recommended (U.S. EPA 1982a).
Annuals are usually best seeded in spring and early summer, although they can
be planted whenever soil is damp and warm. In mild climates (e.g.,
southeastern United States) the planting of both summer and winter grasses
will extend the period of time of active growth at the site.
3.4.1.1.4. Management Program--
A management program of periodic maintenance should be established to
ensure the long-term establishment and functioning of the vegetative cover.
Periodic reliming and fertilization may be necessary to maintain optimum
growth. Soils with poor buffering capacity may require frequent liming to
maintain suitable pH levels. Periodic fertilization using appropriate
fertilizer formulations, time of application, and method of application will
also aid in revegetation- efforts. Mowing and the judicious use of selective
herbicides will help control undesirable weed and brush species. Grass
sodding and remulching or planting new shrubs and trees is recommended for
sparsely covered areas.
3.4.1.2 Advantages and Disadvantages of Vegetative Cover—
An advantage of closing the HWLT unit by establishing a vegetative cover
is that the wastes are left in place and continued treatment of any remaining
constituents can occur in the soil system. Vegetation will also help to
reduce the potential for transport of hazardous constituents from the HWLT
unit by control of wind and water erosion and by evapotranspiration, which by
decreasing the amount of percolating water, may decrease the transport of
hazardous constituents to the groundwater.
However, since the wastes are left in place, there exists potential for
migration into the environment. There also exists potential for uptake by
plants and biomagmfication through the food-chain, and for future exposure to
humans by direct contact if treatment to levels below toxic levels is not
successful.
26
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3.4.2 The Use of Capping as a Final Cover
Capping is the process by which an HWLT unit is covered to prevent
surface water infiltration, control erosion, and isolate and contain the
contaminated soil/waste mixtures at the unit. A variety of cover materials
and capping techniques are available for use. The choice of an appropriate
capping material and method of application is dependent on site-specific
factors, including:
(1) local availability and costs of cover materials
(2) desired function of cover material (e.g., control of water
infiltration, water and wind erosion control, crack resistance, settlement
control and waste containment, side slope stability, support of vegetation,
suitability for future site use)
(3) type and properties of waste/soil mixture being covered
(4) local climate and hydrogeology
(5) projected future use of the site
The use of capping at waste disposal sites is discussed in the Handbook
for Remedial Action at Waste Disposal Sites (U.S. EPA 1982a), in Design and
Construction of Covers for Solid Waste Landfills (Lutton et al. 1979}., HI"
Evaluating Cover Systems for Solid and Hazardous Waste (Lutton 1982), and in
the RCRA Guidance Document: Landfill Design, Liner Systems and Final Cover
(Draft) (U.S. EPA 1982b).
3.4.2.1 Description of Capping as a Closure Method--
Soil materials used for capping an HWLT unit must be relatively
impermeable and erosion-resistant. Fine-grained soils such as clays and silty
clays have low permeability but tend to be easily eroded by wind if left
exposed, especially in arid climates. Coarse, heavy grained soil materials
provide more protection from wind erosion, but are highly permeable.
Fine- and large-grained soil materials may be mixed to enhance strength
of the soil cover, minimize wind erosion, and reduce infiltration. Mixing may
be accomplished in situ using a blade or harrow to turn and mix the soil
materials.
Laboratory and field-testing of physical and chemical properties of
potential soil materials may be required to choose an appropriate material for
use as a capping material. Technical guidance concerning interpretation of
test results is given in Lutton et al. (1979).
Other techniques to form a protective cover over an HWLT unit include
adding amendments to the native soil or using synthetic capping materials. If
the unit is to be closed as a hazardous waste landfill, the unit should be
closed in conformance with guidance provided in the RCRA guidance document
(U.S. EPA 1982b).
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Grading techniques are used in conjunction with capping to modify
topography and runoff characteristics to control infiltration and erosion. A
discussion of grading and associated costs are presented in the Handbook for
Remedial Action at Waste Disposal Sites (U.S. EPA 1982a). The cap should also
be vegetated to stabilize the surface of the HWLT unit.
3.4.2.2 Advantages and Disadvantages of Capping--
In general, the-use of capping as a closure method for a HWLT unit is not
recommended. HWLT relies on aerobic soil conditions to degrade applied
hazardous waste constituents. Conditions under a cap are likely to become
anaerobic, thus inhibiting or preventing additional treatment that could occur
during the post-closure period. Anaerobic conditions may also favor the
production of toxic compounds (e.g., methylation of mercury and arsenic) and
the mobilization of toxic metals. The use of capping, however, may be more
appropriate if the unit was operated as a landfill de facto.
In addition, the cap must be graded to reshape the surface to manage
surface water infiltration and runoff and re-vegetated to provide a stabilized
surface. Caps also require long-term maintenance and care. Unsaturated zone
monitoring must also be conducted in such a manner as to ensure the integrity
of the cap.
3.5 CONTINUED GROUNDWATER MONITORING AS A CLOSURE METHOD
Groundwater monitoring provides a means for addressing the objective of
control of migration (265.280 (a)) by the owner/operator of a HWLT unit.
Monitoring data_can_be used to make changes in the closure and/or post-closure
plants). BasecTon results of groundwater monitoring it may also be necessary
to undertake corrective action measurements at the HWLT site. If constituents
are present in groundwater monitoring samples at trigger levels then
corrective action measures may be necessary during the closure or post-
closure period. Therefore, continued groundwater monitoring provides a means
for determining appropriate responses, if any are required, to ensure that the
objective of control of migration is achieved during closure and post-closure.
3.6 IN-PLACE TREATMENT AS A CLOSURE METHOD
In-place treatment technologies may be used as a closure method to
contain the source of contamination (e.g., by immobilization) or to remove it
through treatment (e.g., by degradation). Technical guidance concerning the
selection and implementation of in-place treatment techniques is given in
Review of In-P1ace Treatment Techniques for Contaminated Surface Soils (U.S.
EPA 1984).
3.6.1 Description of In-Place Treatment
In-place treatment techniques may be divided into the following
categories, defined in terms of their primary action on the contaminants in
the soil: immobilization, degradation, and reduction of volatilization (U.S.
EPA 1984). These techniques include using the naturally occurring capacities
of the soil to accomplish treatment, supplemented as required with amendments
28
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or management and operational practices to accomplish the desired degree of
treatment.
Immobilization techniques are designed to retain waste constituents
within the contaminated soil, reducing the rate of migration of the
constituents to groundwater, surface water, or atmosphere exposure pathways.
Soil systems have inherent capacities for immobilization of both organic and
inorganic constituents, but if additional capacity is required, amendments may
be added to alter soil-properties that improve the immobilization capacity.
Immobilization includes sorption, ion exchange, and precipitation.
Sorption processes are important in the immobilization of both organic and
inorganic constituents. Organic matter, both naturally occurring in soils and
added in the form of manures and other agricultural by-products, may be used
for sorption of waste constituents. Activated carbon may also be used as a
sorbent, especially for organics.
Ion exchange is a process in which minerals and resins in contact with a
solution release ions in preference for ions of another type in the solution.
In soils, clays and organic matter participate in ion exchange reactions.
Synthetic resins and zeolites as well as clay minerals and organic matter may
be added to enhance the natural capacity of the soil to remove constituents by
ion exchange. Soil ptt is also important in the exchange capacity of a soil.
Ion exchange is important in immobilizing hazardous metals, but also may be
applicable to organic constituents.
Precipitation is a process in which inorganic constituents that are
initially soluble react and form compounds of very low solubility, and are
thereby retained in the soil instead of being removed by percolating water.
Precipitating agents can be added directly t the soil or generated in-place
by a chemical or biochemical reaction.
Degradation techniques are used to convert waste constituents into
innocuous or less toxic compound or compounds and are generally applicable
primarily to organic constituents.
Biological degradation utilizes the action of micro-organisms. Naturally
occurring micro-organisms found in nearly every soil system can often degrade
organic constituents. Promotion of biological degradation can be accomplished
by altering selected soil properties, such as moisture and pH, aerating the
soil, or adding nutrients. Addition of selectively adapted or genetically
engineered organisms may enhance degradation of some wastes.
Chemical degradation processes include oxidation reactions, reduction
reactions, and polymerization reactions. Naturally occurring reactions can be
enhanced by adding additional reagents to the soil system or by modifying
selected soil properties such as soil moisture.
Photodegradation of organic constituents can occur by the action of
incident solar radiation. The organics must be present or brought to the
surface of the soil (e.g., by volatilization or mechanical mixing of the soil)
for this process to be effective. Enhanced photodegradation may be
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accomplished through the addition of various proton donors to the contaminated
soils.
Volatilization of constituents from the HWLT unit may require control to
reduce air emissions or to retain constituents within the soil system to allow
for other in-place treatment processes to occur. Reduction of volatilization
may be accomplished by reduction of soil vapor volume, use of
physical/chemical barriers, and soil cooling.
Design and implementation of an in-place treatment process requires
information on characteristics of the soil/waste system. In general, these
types of processes are most applicable to soils contaminated to shallow depths
and are only applicable to waste constituents treatable by the specific
process. Treatability studies of a specific process using the waste
constituents of concern and the soils present at the HWLT unit are recommended
to determine the natural capacity of the soil system as well as the capacity
of the amended or modified soil system to achieve a satisfactory level of
treatment.
After closure using in-place treatment technology has been completed, the
soil surface must be stabilized to prevent water and windborne erosion and
runoff.
3.6.2 Advantages and Disadvantages of In-Place Treatment Techniques
In-place treatment techniques allow for continued treatment of waste
residues in the soil system, thus reducing the potential for migration of
these constituents to the environment. Many of the techniques are easily
implemented and relatively inexpensive.
However, because the wastes are left in place, there does exist potential
for migration of, as well as direct contact with, the waste residues.
Long-term stability of many types if immobilized constituents has not yet been
well-defined, especially under changing environmental conditions. Degradation
processes may result in intermediate products equally or more hazardous than
the parent compounds.
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Chapter 4
MANAGEMENT DURING CLOSURE
4.1 INTRODUCTION
In addition to the requirements given in Subpart G, Part 265, which
includes the continuation of groundwater monitoring to ensure that closure
performance standards are met (Section 265.112 (b) (5)), the owner or operator
of an HWLT~ unit must continue unsaturated zone monitoring, maintain run-on
control and runoff management, and control wind dispersal of particulate
matter during the closure period (Section 265.280 (d) (1), (2), (3), and (4)).
4.2 UNSATURATED ZONE MONITORING
The owner or operator must continue unsaturated zone monitoring,
including soil pore liquid and soil core sampling during the closure period.
The purpose of the monitoring is to detect vertical migration of hazardous
waste and hazardous waste constituents under the active portion of the HWLT
unit and to provide information on the background concentration of the
hazardous waste and hazardous waste constituents in similar but untreated
soils.
Results of monitoring may be used to assess the effectiveness of the
selected method of closure as it is being implemented. Monitoring below the
treatment zone will indicate whether constituents are migrating out of the
treatment zone. Monitoring through depth within the treatment zone allows the
owner or operator to determine the extent of degradation and immobilization of
constituents.
Soil-pore liquid monitoring detects rapidly moving waste constituents, so
movement of these constituents should occur soon after the last application of
waste, depending on the input of moisture to the site (i.e., precipitation or
irrigation at the site). Therefore, soil pore liquid monitoring may be
terminated 90 days after the last application of waste to the treatment zone
(Section 265.280(d)(l)). However, it is recommended that soil pore liquid
monitoring continue until three consecutive samples are free of statistically
significant increases of hazardous constituents over background (U.S. EPA
1983).
The soil pore and soil core liquid monitoring system used during the
active life of the facility should be continued to be used during the closure
period. Technical guidance concerning unsaturated zone monitoring may be
found in the Guidance Manual on Unsaturated Zone Monitoring for Hazardous
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Waste Land Treatment Units (U.S. EPA 19865), and in The Permit Guidance Manual
on Hazardous Waste Land Treatment Demonstrations (U.S. EPA 1986b).
4.3 RUN-ON AND RUN-OFF CONTROL
Water control is required during the closure period of an HWLT unit (Part
265.280(d)(2) and (3)), since water may be the primary means of transport of
hazardous constituents to off-site land surfaces, surface waters, or
groundwater. Hazardous constituents may either be transported as dissolved
substances or suspended in the water. Water management is used to limit the
amount of water contacting treated areas and to minimize precipitation run-off
from treated areas. Any precipitation run-off is collected for storage and
disposal.
A HWLT unit undergoing closure under Part 265 should already have in
place an operating run-on control system as required under Part 265.272(b) and
a precipitation run-off management system as required under Part 265.272(c).
Guidance concerning the design and operation of precipitation run-on and
run-off control management systems may be found in Chapter 8 of Hazardous
Waste Land Treatment (U.S. EPA 1983), and in J. Skinner Memorandum, November
4, 1984, Management of Precipitation Runoff from Land Treatment Units.
4.4 CONTROL OF DISPERSAL OF PARTICULATES
Many hazardous constituents can be tightly bound to soil materials. .Soil
particles from an HWLT unit can be entrained into the air and transported
off-site by wind,resulting in human exposure by direct inhalation. Indirect
exposure can result if these particulates are deposited in-agr-icul tural
fields, pastures, or waterways and thereby enter the food-chain (U.S. EPA
1985).
Control of wind erosion may be accomplished by reducing windspeed on the
soil surface or by forming a new, less erodible soil surface. Technical
guidance design and management of wind erosion control systems may be found in
Dust Control at Hazardous Waste Sites (Rosbury 1985) and in Hazardous Waste
Land Treatment (U.S. EPA 1983).
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Chapter 5
MANAGEMENT DURING POST-CLOSURE
5.1 POST-CLOSURE REQUIREMENTS
The owner or operator of the HWLT unit must develop a post-closure plan
that will identify activities that will be carried on after closure to comply
with the requirements of Section 265.117, including groundwater monitoring
requirements (Subpart F of Part 265) and specific requirements for HWLT units
in Subpart M, Section 265.280 (f). During the post-closure care period, which
may extend for 30 years after the date of completion of closure (unless
shortened according to Section 265.117 (a) (2) (i)), the following activities
must be performed:
(1) ground water monitoring must be continued in accordance with Subpart
F of Part 265;
(2) soil core monitoring must be continued;
(2) access to the-unit must be restricted as appropriate for its
post-closure use (Section 265.117 (c)). Guidance concerning site security is
presented in Hazardous Waste Land Treatment (U.S.EPA 1983);
(3) growth of food chain crops must comply with the guidance given in
Section 265.276; and
(4) wind dispersal of hazardous wastes must be controlled.
Post-closure use of property on or in which hazardous wastes remain after
closure must never be allowed to disturb the integrity of the final cover or
any other components of the containment system or the function of the
monitoring systems (Section 265.117 (c)).
5.2 DURATION OF POST-CLOSURE CARE
The Regional Administrator may reduce the post-closure care period
specified in the post-closure plan if there is evidence that the secure nature
of the facility indicates that post-closure care requirements may be reduced
or eliminated (Section 265.117 (a) (2) (i)). Such evidence might include
leachate or groundwater monitoring results. The Regional Administrator may
also extend the post-closure care period if necessary to prevent threats to
human health and the environment (Section 265.118 (a) (2) (i)).
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Additional reasons for reducing the post-closure care period might
include site conditions where threats to human health and the environment from
the applied waste are very low, i.e., there is low potential for migration
from the site. Such a site could include the following characteristics: deep
groundwater (e.g., greater than 200 feet), low precipitation and high
evaporation (e.g., desert environment), no surface water body nearby, soil
conditions that are suitable for easy establishment of volunteer vegetation,
little wind action to prevent dispersal of airborne contaminants, and no
observation of soil movement (e.g^,- soil creep) during the closure period.
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REFERENCES
APHA. 1985. Standard methods for the examination of water and wastewater.
Sixteenth edition. American Public Health Association, Washington, DC.
Barth, 0. S., and 8. J. Mason. 1984. Soil sampling quality assurance user's
guide. EPA-600/4-84-043, Environmental Monitoring Systems Laboratory,
U.S. Environmental Protection Agency, Las Vegas, NV.
Felmy, A. R., D. C. Girvin, and E. A. Jeanne. 1984. MINTEQ-A computer
program for calculating geochemical equilibria. EPA-600/3-84-032, Athens
Environmental Research Laboratory, U.S. Environmental Protection Agency,
Athens, GA.
Klute, A. 1986. Methods of soil analysis. Part 2: Physical and mineralogical
properties. Monograph No. 9, Soil Science Society of America and
American Society of Agronomy, Madison, WI.
Lutton, R. 1982. Evaluating cover systems for solid and hazardous waste.
SW-867, Office of Solid Waste and Emergency Response, U.S. Environmental
Protection Agency, Washington, DC.
Lutton, R., G. Regan, and L. Jones. 1979. Design and construction of covers
for solid waste landfills. EPA-600/2-79-165, U.S. Environmental
Protection Agency, Cincinnati, OH,
Mason, 8. J. 1983. Preparation of soil sampling protocol: Techniques and
strategies. EPA-600/4-83-020, Environmental Monitoring Systems
Laboratory, U.S. Environmental Protection Agency, Las Vegas, NV.
Overcash, M. R., W. L. Nutter, R. L. Kendall, and J. R. Wallace. 1985. Field
and laboratory evaluation of petroleum land treatment system closure.
EPA-600/2-85-134, Robert S. Kerr Environmental Research Laboratory, U.S.
Environmental Protection Agency, Ada, OK.
Page, A. L. (Ed.). *jQ2. Methods of soil analysis. Part 2: Chemical and
microbiological properties. Monograph No. 9, Soil Science Society of
America and American Society of Agronomy, Madison, WI.
Plumb, R. H., Jr. 1984. Characterization of hazardous waste sites - a methods
manual: Volume III. Available laboratory analytical methods.
EPA-600/4-84-038, Environmental Monitoring Systems Laboratory, U.S.
Environmental Protection Agency, Las Vegas, NV.
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Rosbury, K. 0., 1985. Handbook: Dust control at hazardous waste sites.
EPA-540/2-85-003, Hazardous Waste Engineering Research Laboratory, U.S.
Environmental Protection Agency, Cincinnati, OH.
Sims, R. C., and J. E. McLean. 1986. Protection of Groundwater by
Immobilization of Heavy Metals in Industrial Waste Impacted Soil Systems.
Grant No. 14-08-0001-G-939-06, U.S. Geological Survey, Washington, DC.
Sims, R., D. Sorensen, J. Sims, J. McLean, R. Mahmood, R. Oupont, and J.
Jurinak. 1986. Contaminated Surface Soils In-Place Treatment
Techniques. Noyes Publications, Park Ridge, NJ.
Streebin, L. E,, J. M. Robertson, A. B. Callender, L. Doty, and K.
Bagawandoss. ' 1984. Closure evaluation for petroleum residue land
treatment. EPA-600/2-84-162, Robert S. Kerr Environmental Research
Laboratory, U.S. Environmental Protection Agency, Ada, OK.
U.S. EPA. 1979. Methods for chemical analysis of water and wastes.
EPA-600/4-79-020. Environmental Monitoring and Support Laboratory, U.S.
Environmental Protection Agency, Cincinnati, OH.
U.S. EPA. 1982a. Handbook for remedial action at waste disposal sites.
EPA-625/6-82-006, Municipal Environmental Research Laboratory, U.S.
Environmental Protection Agency, Cincinnati, OH.
U.S. EPA. 1982c. Test methods for evaluating solid waste: Physical/chemical
methods. Second Edition. SW-846, Office of Solid Waste and Emergency
Response, U.S. Environmental Protection Agency, Washington, DC.
U.S. EPA. 1983. Hazardous waste land treatment. Revised Edition. SW-874,
Office of Solid Waste and Emergency Response, U.S. Environmental
Protection Agency, Washington, DC.
U.S. EPA. 1984. Review of In-Place Treatment Techniques for Contaminated
Surface Soils. Volumes 1 and 2. EPA-540/2-84-003a and b, Municipal
Environmental Research-Laboratory, U.S. Environmental Protection Agency,
Cincinnati, OH.
U.S. EPA. 1985a. Guidance for the analysis of refinery wastes. Office of
Solid Waste and Emergency Response, U.S. Environmental Protection Agency,
Washington, DC.
U.S. EPA. 1985b. Petitions to delist hazardous wastes: A guidance manual.
Office of Solid Waste and Emergency Response, U.S. Environmental
Protection Agency, Washington, DC.
U.S. EPA. 1986a. Permit guidance manual on hazardous waste land treatment
demonstrations. EPA/530-SW-86-032, Office of Solid Waste and Emergency
Response, U.S. Environmental Protection Agency, Washington, DC.
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U.S. EPA. 1986b. Permit guidance manual on unsaturated zone monitoring for
hazardous waste land treatment units. EPA-530/SW-86-040, Office of Solid
Waste and Emergency Response U.S. Environmental Protection Agency,
Washington, DC.
U.S. EPA. 1987. RCRA guidance document: Landfill design, liner systems and
final cover (Draft). Office of Solid Waste and Emergency Response, U.S.
Environmental Protection Agency, Washington, DC.
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APPENDIX A
TABLE A.I. CONSTITUENTS OF PETROLEUM REFINING WASTES
1. Metals
• " Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Lead
Mercury
- 'Nickel
Selen i urn
Vanadium
2. Volatiles
Benzene
Carbon disulfide
Chlorobenzene
Chloroform
1,2-Oichloroethane
1,4-Dioxane--
Ethyl benzene
Ethylene dibromide
Methyl ethyl ketone
Styrene
Toluene
Xylene
3. Semi volatile Base/Neutral
E'x tract able Compounds
Anthracene
Benzo(a)anthracene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Benzo(a)pyrene
Bis(2-ethylhexyl) phthalate
Butyl benzyl phthalate
Chrysene
Dibenz(a,h)acridine
Dibenz(a,h)anthracene
Dichlorobenzenes
Diethyl phthalate
7,12-Dimethylbenz(a)anthracene
Dimethyl phthalate
Di(n)butyl phthalate
Di(n)octyl phthalate
Fluoranthene
Indene
Methyl chrysene
1-Methyl naphthalene
Naphthalene
Phenanthrene
Pyrene
Pyridine
Quinoline
4. Semivolatile Acid-Extractable
Compound?
Benzenethiol
Cresols
2,4-Dimethylphenol
2,4-Dinitrophenol
4-Nitrophenol
Phenol
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