530R92023
"NO MIGRATION" VARIANCES TO THE HAZARDOUS WASTE
LAND DISPOSAL PROHIBITIONS:
A GUIDANCE MANUAL FOR PETITIONERS
DRAFT
U.S. Environmental Protection Agency
Office of Solid Waste
Washington, DC
JULY 1992
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TABLE OF CONTENTS
Acknowledgements i
Introduction u
What is a "No Migration" Variance' 1
What are the Land Disposal Prohibitions7 1
Who Can Receive a "No Migration" Variance' 3
What is the Definition of the "Unit Boundary?" 6
How are Levels of Constituents Evaluated' 7
How Long is "As Long As the Wastes Remain Hazardous'" 9
What tsthe Relationship Between Land Treatment Units and
"No Migration"' 9
What is the Relationship between "No Migration" Variances,
RCRA Permits, and Other Federal Laws' 11
Can Generic Petitions be Submitted Covering Several Similar Units
or Facilities' s 12
When Does a Variance Become Effective and How Long Does it Last' 13
Additional Requirements for No Migration Variances 13
What is the Petitioning Procedure for "No Migration" Variances' 15
Pre-Submittal , 15
Petition Submittal 15
Petition Review 17
Decision to Grant or Deny 18
What Information Should be Included in a "No Migration" Petition? 18
Waste Descriptions 19
Waste Types and Sources - 20
Waste Characteristics -- 20
Waste incompatibilities- 20
Waste Transformation Mechanisms - 21
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TABLE OF CONTENTS
Facility Description 22
Site Characterization 23
t
Geology -- 24
Ground-Water Hydrology - 25
Surface-Water Hydrology - 25
Climatology and Meteorology - 26
Background Environmental Quality - 26
Monitoring Plans 26
Waste Mobility Modeling 30
Assessment of Environmental Impacts 33
Prediction of Infrequent Events 34
Quality Assurance and Control , 35
Checklist of Information Needs 37
Where Can i Obtain Additional Information Concerning
"No Migration" Variances' 40
Appendix* Draft Air Pathway Assessment Methodology
for "No Migration" Demonstrations
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What is a "No Migration" Variance?
A "no migration" variance is a formal decision that can be rendered by the EPA to
allow the land disposal at a particular facility of specific, prohibited wastes not
meeting the treatment standards established by EPA. The statutory language
requires anyone pursuing a "no migration" variance to demonstrate "to a
reasonable degree of certainty that there will be "no migration" of hazardous
constituents from the disposal unit or injection zone for as long as the waste remains
hazardous." The EPA codified this language on November 7, 1986 (40 CFR 268.6).
The EPA has interpreted the statutory language to mean that it must be
demonstrated, to a reasonable degree of certainty, that hazardous constituents will
not exceed Agency-approved human health-based levels (or environmentally
protective levels, if they are appropriate) beyond the boundary of the disposal unit.
In most cases, the disposal unit boundary is defined as the outermost limit of
engineered components, but may be defined differently in some site-specific casesi
This definition of "no migration" does not allow fate and transport of hazardous
constituents above acceptable health-based levels outside the boundary of the unit.
What are the Land Disposal Prohibitions?
In 1976, Congress passed the Resource Conservation and Recovery Act (RCRA)
authorizing EPA to establish nationwide standards for the management of
hazardous wastes. Regulations promulgated under RCRA in Title 40 of the Code of
Federal Regulations, Part 261 (40 CFR 261), include lists of designated hazardous
wastes and methods for identifying wastes exhibiting hazardous characteristics.
Under the Hazardous and Solid Waste Amendments of 1984 (HSWA), RCRA Sections
3004 (d), (e), and (g) were to include provisions prohibiting the land disposal of all
such "listed" and "characteristically hazardous" wastes unless they meet
technology-based treatment standards. In order to be land disposed, wastes
included in the EPA's land disposal prohibitions will have to be treated by best
demonstrated available technology (BDAT) to meet the treatment standard
established by the EPA or meet the standard as generated, unless a "no migration"
variance is obtained. Prohibited wastes cannot be stored on the land (unless storage
is in containers or tanks and is for the purpose of accumulating sufficient quantities
to facilitate proper recovery, treatment, or disposal) without a "no migration"
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variance. The land disposal prohibitions become effective on the dates indicated
below.
Novembers, 1986 - Solvents and Dioxins
JulyS, 1987 - California List*
August 8,1988 - At Least One-Third of All Other Listed Wastes
JuneS, 1989 - At Least Two-Thirds of All Other Listed Wastes
May 8,1990 - All Remaining Listed Wastes and All Characteristic
Wastes
A complete schedule of the land disposal prohibitions can be found in 40CFR 268.10
through 268.13. These prohibitions apply to all hazardous wastes identified under
RCRA as of November 8, 1984. For hazardous wastes identified in 40 CFR 261 after
that date, EPA must make prohibition determinations within 6 months of the date of
listing or identification of the new hazardous wastes. Nevertheless, the statute does
not impose an automatic prohibition on land disposal if EPA misses a deadline for
any newly listed or identified waste.
Direct land disposal of an untreated waste that does not meet the BDAT treatment
standard may be allowed nationally by EPA for up to 2 years if treatment capacity is
inadequate. Effective dates have been extended by 2 years for many California List
and First Third wastes. In addition, two 1-year case-by-case extensions of the
effective dates of prohibitions may be granted under certain circumstances. The
applicant must demonstrate that adequate capacity to treat, recover, or dispose
the waste is not available by the effective date and that he has entered into a
binding contractual commitment to provide such capacity. (EPA is developing a
guidance document for case-by-case extensions.) All other RCRA hazardous wastes
that do not meet the BDAT treatment standard will be banned from land disposal
unless a "no migration" variance is received from the EPA.
Based on regulations developed by the California Department of Health Ser-
vices for hazardous waste land disposal restrictions in the State of California.
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Who Can Receive a "No Migration" Variance? {
A "no migration" variance petition can be submitted by anyone who temporarily
stores or disposes of hazardous wastes in or on the land. The petition for a "no
migration" variance can be submitted by any interested hazardous waste facility
owner or operator, either individually or collectively. The petition must clearly
demonstrate that the land-based storage or disposal method to be employed
protects human health and the environment This requires showing, to a reasonable
degree of certainty, that hazardous constituents will not exceed human health-
based levels (or environmentally protective levels, if they are more stringent) beyond
the edge of the disposal unit The petition must also provide long-term assurance
that the "no migration" variance criteria will be met. (Of course, in the case of
petitions for temporary placement, long-term assurances- would not be necessary.)
The variance only becomes effective after EPA reviews the petition, solicits public
comments, and publishes a final determination in the Federal Register In most
cases, the variance will require monitoring to demonstrate continuing compliance
(see substantive and procedural requirements in the Land Disposal Restrictions First
Third Rule, August 17,1988,53 FR 31138)
In the November 7, 1986 Final Rule (51 FR 40572), the Agency identified several
scenarios that may satisfy the "no migration" standard. These scenarios are not the
only situations where "no migration" may be demonstrated successfully The first is
the placement of compatible non-volatile waste in a massive and stable geologic
formation such as a salt dome. In this case, the Agency would expect the "no
migration" demonstration to focus on the stability, extent, and homogeneity of the
host formation, as well as potential for releases during placement
The second scenario is the placement of a waste consisting of fairly immobile
constituents in a monpfill located in an arid area that has no ground-water recharge.
The petitioner would need to demonstrate that hazardous constituents will not
migrate out of the unit above health-based (or environmentally protective) levels.
Such a demonstration may be successful due to the well-defined characteristics of
the waste constituents m a monofill
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In the third scenario, a treatment facility renders the waste nonhazardous through
active chemical, physical, or other processes An example is the neutralization of a
corrosive waste, which does not contain hazardous constituents above health-based
levels, in a surface impoundment This scenario is especially applicable to wastes
that are considered hazardous due only to their tgnitable, reactive, or corrosive
characteristics
In the fourth "no migration" scenario, hazardous waste is stored temporarily on the
land for the purpose of accumulating sufficient quantities of the waste to allow for
proper recovery, treatment, or disposal within the meaning of RCRA Section 3004(j).
The waste is stored in a totally enclosed indoor waste pile with a floor or bottom
liner, where engineered containment systems and air pollution controls are effective
over the period the waste remains in storage Inspections of the building are
performed frequently to ensure that precipitation is not entering the unit. The
waste pile is clean-closed at the end of the storage period. *
Except for temporary storage operations, it should not be assumed that man-made
barriers or engineered systems (e.g., liner systems) alone will meet the "no
migration" standard. Although artificial barriers in conjunction with partial waste
treatment or barriers that are expected to last substantially longer than the
hazardous life of the waste may enhance a petition, artificial barriers alone cannot
be relied upon to provide the long-term assurances required For this reason, "no
migration" variances generally are not envisioned for conventional land disposal
units (e g., landfills and surface impoundments) For temporary land-based storage
purposes only, the containment of hazardous waste within engineered barriers
(meeting minimum technology requirements) will be considered in making the "no
migration" demonstration, provided that wastes are to be removed after a
reasonably short storage period that may be conservatively projected to be well
before the failure of the engineered barrier system
*
An additional "no migration" scenario is the placement of hazardous waste
(particularly that from petroleum refining) in a land treatment unit. Under carefully
controlled conditions, the wastes are biodegraded in the treatment zone with no
releases at concentrations constituting migration to any environmental media,
including- air. The owner/operator manages the land treatment unit so that
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nondegradable hazardous constituents are not allowed to accumulate within the
unit to levels exceeding health-based levels.
in addition, the Agency cautions potential petitioners that the burden of proof m
demonstrating "no migration" will be substantially greater for facilities with a
history of continuing mismanagement of hazardous waste and serious compliance
problems, as evidenced by State or EPA monitoring and inspection reports (Minor
infractions m compliance should not affect EPA's review of a petition.) This does not
mean such facilities will be required to meet a more stringent standard, but that
more information and analysis may be necessary, both in the petition and during
operation under the variance, to confirm to the Agency's satisfaction that migration
is not occurring and will not occur in the future For example, more frequent waste
stream analysis, or even sampling by an independent party could be required under
the terms of the variance
Similarly, for a unit that has experienced releases (migration) in the past, the owner
or operator petitioning for a variance will be under a greater burden of proof to
demonstrate both 1) that the same type of release will not occur m the future, and
2) that past and future releases can be separated. The second item could be
particularly relevant for the ground water medium, for example, where
contamination from the unit that has already been detected m ground water could
continue to appear in monitoring wells after a variance has been granted It would
be difficult to prove whether the contamination was from a past or present release.
Likewise, for a unit located in a waste management area where releases have
occurred from other units, it also could be difficult to differentiate between releases,
particularly if the other units contained the same hazardous constituents as the unit
in question.
In either case, the owner or operator is discouraged from submitting a "no
migration" petition unless he or she can conclusively demonstrate not only that
future migration will not occur, but also that past releases detected through
monitoring either are not from the unit for which a variance is sought, or that they
will not obscure or interfere with the ability of monitoring devices to detect future
releases If there is uncertainty, the assumption will be that the release is from the
unit in question, and the variance likely will be denied or, if already granted,
revoked.
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What is the Definition of the "Unit Boundary?"
For surface impoundments, landfills, and waste piles, the unit boundary (and
consequently, the point of compliance (POC)) generally is defined by the outermost
extent of the engineered barner(s) that contain the waste. For example, in
demonstrating "no migration'* from a unit via ground water or subsurface soil, the
unit boundary would consist of the outer liner present in a surface impoundment,
landfill, or waste pile In demonstrating "no migration" from the unit via surface
water or surface soil, the exterior of any dikes, ditches, or berms present at the edge
of the "hazardous waste management unit" constitute the point of compliance. In
demonstrating "no migration" from the unit via the air pathway, the outer limit of
any engineered barrier over the unit (roof, dome, etc) would constitute the point of
compliance
While engineered barriers form a useful way to delineate the boundary of a
hazardous waste management unit, the Agency recognizes that these engineered
components do not always exist For example, most units are not enclosed to protect
from migration via air In this case, the downwind edge of the unit at a height of 1.5
meters constitutes the point of compliance for demonstrating "no migration" via
air. (A height of 1.5 m corresponds with a typical inhalation height and facilitates
the application of standard modeling and monitoring methods)
In cases where units are unlmed (e.g., a unit obtaining an exemption from liner
requirements under Section 264 221 (b) or (d)), EPA will use best professional
judgment to set the unit boundary. Land treatment units have a subsurface point of
compliance at the base of the maximum treatment zone (not exceeding 5 feet in
depth from the initial soil surface) or immediately outside of any liner that may exist.
Finally, for some miscellaneous units such as those regulated under Subpart X, the
unit boundary should be decided on.a site-specific basis. In the case of geologic
repositories, for example, EPA believes it is appropriate to give some credit for the
encapsulating or confining formation In all cases, however, the Agency will
demarcate the unit boundary and point of compliance for demonstrating "no
migration" via all media in a suitably stringent manner.
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Although engineered barriers frequently are used to define the unit boundary,
engineered barriers such as liners alone are inadequate to prevent migration of
hazardous wastes from a land disposal unit Except for temporary storage units, the
"no migration" demonstration must rely upon other assurances to demonstrate "no
,s
migration" from the unit. Other assurances may include treatment, waste removal
after temporary storage, and characteristics of the waste, unit, or environment.
How are Levels of Constituents Evaluated?
A successful "no migration" demonstration must show that actual or predicted
concentrations of hazardous constituents or emission rates at the edge of the
disposal unit do not exceed Agency-approved health-based levels or
environmentally-based levels for ground water, surface water, soil, and air. If
health-based criteria do not exist for a constituent, the applicant may propose his
own health-based levels using the toxicity testing guidelines contained in 40 CFR
Parts 797 and 798, and the Agency guidelines for assessing health risks (51 FR 33992,
34006, 34014, and 34028). If no health-based level can be determined for a
constituent, that constituent must not exceed analytical detection limits. Use of
analytical detection limits should be based on methodology prescribed in "Test
Methods for Solid Waste, Physical/Chemical Methods" U S EPA Publication No SW-
846, Third Edition, with the lowest possible detection level indicated therein for each
hazardous constituent. If health-based levels are below analytical detection limits
for a constituent, the petitioner must demonstrate, using modeling, that the health-
based levels will be met Nevertheless, in any compliance monitoring required for
the unit where health-based levels are below detection limits, meeting detection
limits would constitute compliance with the demonstration In calculating these
concentrations, the petitioner should use site-specific data to evaluate how the
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hazardous constituents will be apportioned between media, where the constituents
are released into several media When site-specific data are not available, worst-case
assumptions must be used
In reviewing the petition, EPA will compare the calculated concentration of
hazardous constituents to Agency-approved levels For example, the Agency would
compare the constituent concentrations in leachate to the Maximum Contaminant
Levels (MCLs), or Ambient Water Quality Criteria (AWQC). MCLs and AWQCs receive
first priority for use as allowable exposure levels, where they exist. If an MCL or an
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AWQC is not available for a constituent, the appropriate health-based levels would
be the Reference Dose (RfD) for noncarcmogens and the Risk Specific Dose (RSD) for
carcinogenic compounds These health-based criteria have been calculated by
assuming chronic (lifetime) exposure by mgestion or inhalation of contaminated
media For carcinogens the maximum residual risk level is 1x10-6 Class A and B
carcinogenic constituents, and 1x10-5 for Class C carcinogens
For a "no migration" petition, it is necessary to evaluate the concentration of
contaminants in air, surface water, and soil as well as in ground water The Agency
has published health-based levels for soil mgestion and inhalation for a subset of the
hazardous constituents listed in Appendix VIII of 40 CFR 261 The interim draft RCRA
Facility investigation (RFD Guidance (EPA 530/SW-89-031, February, 1989) contains
tables of health-based criteria, both it and the interim draft Surface Impoundment
Clean Closure Guidance. U S EPA, October, 1987 also have explanatory text on the
assumptions used to calculate the numbers. More information on these health^
based numbers ts also available in the Superfund Public Health Evaluation Manual.
U S. EPA, 1986, and the Integrated Risk Information System (IRIS): U.S. EPA, 1988
IRIS is available through various on-line networks such as DIALCOM inc., the Public
Health Network, and the National Library of Medicine's TOXNET Because all health-
based numbers are subject to review and change, EPA recommends that the
petitioner contact EPA's Characterization and Assessment Division in Washington,
D C, at (202) 382-4761 to obtain up-to-date information on health-based levels.
The Agency believes that human health-based exposure levels generally will be
protective of both human health and the environment. Nevertheless, the Agency
may determine that an exposure level for a constituent should be lowered from the
human health-based standard in order to protect against detrimental environmental
effects around the unit (e g., those that may pose a threat to endangered species, or
sensitive ecosystems). EPA will provide the opportunity for notice and comment on
such an exposure level within the petition process.
in addition to comparing individual constituents to the appropriate health-based
level, the Agency may also consider additivity in evaluating the risk posed by
concentrations at the unit boundary For example, if the petition identifies two
constituents that appear at the unit boundary at levels which are below health-
based limits for each of the constituents, the Agency also may consider the potential
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threat posed by adding the two constituents. The Agency intends to consider
additivity only for constituents in the same environmental medium (e g , air) For
more information on the EPA's policy on chemical mixtures, the petitioner should
refer to the Guidelines for the Health Risk Assessment of Chemical Mixtures (51 FR
34014).
Petitioners for units in areas where background levels of a hazardous constituent
exist should demonstrate that the incremental contributions of contaminants from
their unit will not, in and of themselves, exceed health-based levels. For example, if
the air inhalation health-based level for Substance X is 10 ppm, and background
levels of that constituent are 5 ppm, "no migration" could be successfully
demonstrated by projecting and monitoring concentrations at the unit boundary
not exceeding 15 ppm The net contribution of Substance X from the unit then
would not exceed the health-based level of 10 ppm In other words, high
background levels of a hazardous constituent will not prevent the granting of a "no
migration" variance; however, neither will they allow releases attributable to the
unit that exceed health-based levels, regardless of how high background levels
might be.
How Long is "As Long As the Wastes Remain Hazardous?"
This is a waste- and site-specific determination For some waste types that degrade
naturally to health-based levels in a relatively short time period, the petitioner may
only have to demonstrate such degradation and show "no migration" from the unit
during the degradation period On the other hand, where nondegradable
constituents such as metals will exist within the unit, the petitioner will potentially
have to make the difficult demonstration that "no migration" will occur for many
thousands of years, unless such constituents are removed at closure or the unit is
capped with clean soil. (Capping will be acceptable only where there is not leaching
potential as determined using a teachability test or modeling procedure that the
Agency determines is valid for the particular types of hazardous constituents
present.) Note that the UIC program considers a demonstration of "no migration"
for 10,000 years to be sufficient, given the nature of wastes that are disposed of
through underground injection.
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What is the Relationship Between Land Treatment Units and "No Migration"?
Land treatment units are subject to all of the general provisions of the land disposal
restrictions program, since they are considered to be disposal units under RCRA
3004(k) Thus, in order to apply prohibited wastes which do not meet the BOAT
performance standards, an owner or operator of a land treatment unit must receive
a "no migration" variance
The petitioner for a land treatment unit must demonstrate that the "no migration"
standard is met for all media The land treatment demonstration (LTD) need not be
complete in order to receive a "no migration" variance The "no migration"
variance will be granted based upon certain basic monitoring and modeling data
However, the variance will be conditioned upon completion of the LTD within a
specified time period (usually two years after the date of granting of the "no
migration" variance), or else the variance will be revoked This requirement is
intended to ensure completion of the Land Treatment Demonstration in a timely
fashion, while nevertheless recognizing that the land treatment unit must operate in
order to generate the relevant information and data. However, it should be clarified
that this provision is not intended to effect any time extension of the requirement to
have an approved "no migration" variance prior to land disposal of restricted
hazardous waste. Land treatment units are required to have an approved "no
migration" variance prior to receipt of restricted hazardous waste, regardless of
whether or not the Land Treatment Demonstration is complete. Furthermore,
petitioners with incomplete Land Treatment Demonstrations also must meet alf of
the same information requirements to fulfill "no migration" petition criteria.
Many wastes that are currently land-treated contain significant amounts of volatile
constituents and/or metals. The petitioner must demonstrate a sufficient level of
degradation and/or immobilization of waste constituents and metals within the
treatment zone to assure that hazardous constituent concentrations will remain
lower than human health-based or environmentally-based standards at the
treatment zone/soil boundary For land treatment units, the "disposal unit" consists
of the treatment zone (plus the liner, if any exists). For volatile constituents, the
applicant must demonstrate that the health-based or environmental levels are not
exceeded at the downwind edge of the unit boundary at a height of 1.5 meters. This
demonstration should be made by using site-verified emission and dispersion
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models, emission monitoring and/or ambient air monitoring. In addition, an
applicant may need to p ret re at a volatile waste (e g., air stripping with appropriate
air pollution controls) in order to successfully demonstrate "no migration" of the
contaminant to the air. (For more information on "no migration" demonstrations
for'the air medium, see the Appendix ) The applicant should attach all relevant parts
of his land treatment demonstration permit application to the "no migration"
petition, including btotoxicity studies, degradation studies, and general site
information regarding ground water, surface water, climate, and soil
If it has been completed, the LTD can be used as a basis upon which to buiid a "no
migration" petition However, the information that is typically provided in the LTD
is largely current sampling and monitoring information The petition must contain
sufficient modeling and theoretical, long-term projections to insure that migration
will not occur to any medium "for as long as the wastes remain hazardous " Because
the LTD does not address the air medium, the air demonstration must also be added!
Finally, if accumulations within the unit of nondegradable hazardous constituents
exceed health-based levels for soil ingestion at the end of the post-closure period, a
teachability test or modeling procedure that the Agency determines is valid for the
particular types of constituents present must be performed to determine their
teachability Such tests may include soil column studies on zone of incorporation
soils, or other methods approved by the Agency Dependent on the results of this
leachability test or procedure, the unit's post-closure plan must require either that
the unit be capped with clean soil at the end of the post-closure care period (if
nondegradable constituents are not teachable above health-based levels), or that
hazardous constituents be removed, at the end of the post-closure care period, to
below health-based levels (if nondegradable constituents are teachable above
health-based levels). If health-based levels have not been achieved a vegetative
cover, as required at Part 264 280{c)(2), must still be maintained during closure and
post-closure, as well as on the clean soil cap It should be noted that land treatment
units (and other land disposal units), that will close with nondegradable hazardous
constituents in place at concentrations above health-based levels must comply with
40 CFR Part 264 119(b) requirements for a deed notice that the site has been used for
hazardous waste management. This provision is intended to prevent future human
intrusion into the site after the post-closure care period has ended.
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What is the Relationship between "No Migration" Variances, RCRA Permits, and
Other Federal Laws?
"No migration" variances may be issued for units functioning under interim status,
units with permits under RCRA, or for new units seeking Part B permits Because
much of the information that must be included in a RCRA Part B application must
also accompany the petition for a "no migration" variance, facility owners and
operators are encouraged to submit petitions with the relevant Part B data
summarized, and copies of critical Part B materials attached as needed
Under 40 CFR 268 6(a)(5), before being issued a "no migration" variance, the
petitioner must provide EPA with sufficient information to assure the Administrator
that land disposal of the prohibited waste(s) will comply with other applicable
Federal laws. These may include the Clean Atr Act, the -Clean Water Act, the Safe
Drinking Water Act, the Endangered Species Act, the National Historic Preservatioh
Act, the Wild and Scenic Rivers Act, the Coastal Zone Management Act, the Fish and
Wildlife Coordination Act, the Atomic Energy Act, and the Marine Protection,
Research and Sanctuary Act. This also includes other provisions of RCRA, such as
regulations under Section 3004(n) limiting volatile organic air emissions from TSDFs.
The operation for which a variance is sought must also be in compliance with
applicable State and local laws and ordinances.
Can Generic Petitions be Submitted Covering Several Similar Units or Facilities?
Yes, but generic petitions are likely to raise practical difficulties, and are discouraged
m most cases. The usefulness of a generic petition is limited since petitions must
include site- and waste-specific data. Accordingly, petitioners would have to
demonstrate that each scenario covered under a generic petition is essentially the
same A demonstration that the hydrogeological characterization of each site
would be essentially the same would require the detailed assessment of each site
addressed in the petition, furthermore, it is unlikely that such a demonstration could
actually be made. As a result, the Agency expects few, if any, generic petitions for
land disposal units An exception may be made for temporary storage units. For
example, several identical indoor waste piles containing identical wastes at the same
clean-up 'site could be covered under one petition Even so, identical units at
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different facilities likely would require different petitions because of variations in
locational and environmental conditions
When Does a Variance Become Effective and How Long Does it Last?
Variances will be effective only after issuance; submittal of a petition will not
exempt a facility from complying with applicable land disposal prohibitions.
Variances will be valid for up to 10 years, but not longer than the term of the
facility's RCRA permit The variance will automatically expire upon termination
or denial of a RCRA permit, or when the volume of waste for which the variance was
issued is reached EPA may revoke a unit's "no migration" variance if the Agency
determines migration has occurred or that such a variance is no longer protective of
human health or the environment Owners and operators desiring to renew expired
variances must re-petttion the Agency Petitions to renew must undergo the same*
notice and comment procedure as did the original petition
Additional Requirements for No Migration Variances
Monitoring Plans for Land Disposal Units
40 CFR Sections 268.6(a)(4) and 268 6(c)(1) require that petitions include plans for
continued monitoring of media of concern to verify compliance with the "no
migration" demonstration. The monitoring plan must be designed to detect
migration "at the earliest practicable time" The Agency intends this to mean at, or
as near as possible to, the unit boundary In certain limited cases the Agency may
determine that monitoring of one or more media at an individual site is unnecessary,
or technically mfeasible or impractical. Monitoring of hazardous waste units and/or
the waste stream going into the unit also may be required, unless unnecessary, or
technically mfeasible or impractical.
Reporting of changes in Operating Conditions From Those Described in the Variance
Application
40 CFR 268 6(e)(1) and (2) require reporting of changes from conditions described in
the variance application, including changes in the type of waste stream received,
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operating practices, unit design and construction, or unusual and significant changes
in the environment such as significant fluctuations in the water table or surface
water flow Where such a change is planned, such as for an operating practice, the
owner or operator must notify the Agency in writing at least 30 days in advance for
approval Where the owner or operator discovers that there has been a significant
and unplanned change from the conditions upon which the variance was granted,
the owner or operator must notify the Agency within 10 days of discovery. EPA then
will determine whether action is necessary, such action may include revocation of
the variance or variance modifications
Detection of Migration of Hazardous Constituents
The Agency has promulgated at 40 CFR 268 6(f) notification requirements if
migration is detected. If an owner or operator discovers migration from the unit
after a variance has been granted, the owner or operator must immediately stop
receipt of the restricted waste and notify EPA within 10 days of discovery EPA will
then decide within 60 days whether the unit can continue to receive prohibited
waste, or whether the variance will be terminated If the Agency determines that
migration is occurring or has occurred from the unit (i e , that a release from the unit
exceeds Agency-approved health-based or environmental-based exposure levels),
the Agency shall revoke the variance This approach is based upon the belief that,
with the exception of the air medium, once even a single incidence of migration has
occurred, the "no migration" demonstration has failed. For the air medium the
Agency holds a slightly different interpretation, however, based upon an annual
average air concentration to demonstrate that "no migration" is occurring from the
unit. EPA interprets migration to the air medium as exceeding the health-based
level for a hazardous constituent on an annual average basis, not on a single event
The Agency believes this approach is consistent with the approaches to long-term
ambient air standards under the Clean Air Act, and that it is also protective, since
health-based levels are based upon long-term exposure assumptions, and are not
appropriate for use in an acute air exposure scenario. Furthermore, air
concentrations are highly dependent upon dispersive and temporal factors, and
therefore differ from the ground water, surface water, and soil media, where these
factors are less significant Furthermore, the Agency will revoke a unit's "no
migration" variance if, on the basis of any information, the Agency at any time
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determines that migration from the unit has occurred, or that such a variance is no
longer protective of human health and the environment
Substantive requirements for variances for waste disposal in deep injection wells
may differ slightly from those described above The reader should refer to the July
26,1988 rule (53 FR 28118) for more detailed information on injection wells.
i
What is the Petitioning Procedure for "No Migration" Variances?
Outlined below is a step-by-step process for the submittal and review of "no
migration" petitions, illustrated in the figure on the following page Until States
have been authorized for the land disposal restrictions and "no migration"
variances, EPA is requiring that applicants submit petitions to the EPA Administrator
Petitioners should note that State programs are free to impose disposal prohibitions
tf such actions are more stringent or broader in scope than Federal programs (RCRA
Section 3009 and 40 CFR 271 1(0). Where States impose bans which contravene an
EPA action,' such as not allowing provisions for granting a "no migration" petition,
the more stringent State standard shall apply and the petition will not be reviewed
by EPA.
It should be noted that the petition submittal and review process discussed in this
guidance manual does not apply to "No Migration" petitions for underground
injection wells
Pre-Submittal
A very important component to the "no migration" process is the pre-submittal
meeting between the petitioner and the EPA This meeting is critical in ensuring
expeditious decisions on petitions. The purpose of the pre-submittal meeting is to
provide the petitioner with an opportunity to identify the hazardous waste,
hazardous constituents, and disposal unit(s) to be included in the petition. The EPA
can provide some historical background on the review of similar petitions, including
a tentative timeframe for the review process The Agency also recommends that
petitioners submit a preliminary outline of their petition for Agency review.
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Pre-Submittal Meetmg(s)
Does
State Allow
No Migration
Petition
Inform Petitioner
of Intent to
Deny/Dismiss
Petitioner
Withdraws
Petition
Yes
Draft Fact Sheet
and PR Notice
-
Ev
Iss
Internal Review
Propose FR Notice
Public Comment
Period
Evaluate Comment(s)
and Revise FR
Internal Review
Issue Final FR Notice
Complete
Petition Received
at EPA HQ's
Send Acknowledgement
Letter to Petitioner
Technical Review
Request Additional
Information
"No Migration" Petition Review Process
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Petition Submittal
As required by Sections 268 6{c) & (d) of the regulations, each petition must be
submitted to the EPA Administrator and include the following statement signed by
the petitioner or an authorized representative.
1 certify under penalty of law that I have personally examined and am familiar
with the information submitted in this petition and all attached documents,
and that, based on my inquiry of those individuals immediately responsible for
obtaining the information, I believe that the submitted information is true,
accurate, and complete I am aware that there are significant penalties for
submitting false information, including the possibility of fine and
imprisonment
Six copies of the petition should be sent to
Chief, Assistance Branch
Off ice of Sol id Waste
U S Environmental Protection Agency
401 M Street, S W (OS-343)
Washington, D C 20460
(When a State becomes authorized for the land disposal restrictions and "no
migration " variances, petitions for units within that State should be sent to the State
for review and determination )
Once the petition has been received by the EPA, a public docket will be established
for the petition and a person from the Assistance Branch (the reviewer) will be
assigned to the petition The reviewer will send a letter to the petitioner
acknowledging receipt of the petition This letter may also contain a tentative
timeframe for the revtew of the petition Copies of this letter will be distributed to
the appropriate EPA Regional Office and State Agency
Petition Review
Petitions will be reviewed by EPA Headquarters with assistance from Regional and
State personnel. The reviewers will perform an initial review of the petition Once
this initial review is completed, EPA will decide if additional information is needed to
make a decision on the petition. If additional information is needed, a letter
requesting the information will be sent to the petitioner. Information to aid in the
17
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review may also be requested from the State contact The request letter to the
petitioner will contain a deadline for the submittal of the additional information
This deadline will be dependent on the type of information being requested
Nevertheless, the deadline will not exceed a period of 180 days from the date of the
request letter. Once the reviewers have obtained all of the necessary information
for the review, a comprehensive, technical review will be performed As part of this
review, the reviewers will work closely with the State contact and will normally
perform a site visit
If the additional information is not received by the deadline, or a request for an
extension of the deadline is not submitted, the reviewers may recommend that the
petition be dismissed The Agency plans to dismiss incomplete petitions by letter. A
dismissal tetter will be sent to the petitioner and to the appropriate State and EPA
regional contacts The effect of a dismissal is to remove the petition from the review
process and close the petition file. The petitioner may at any time re-submit a
complete petition
Decision to Grant or Deny
Once the technical review is complete, EPA will reach a tentative decision to grant or
deny the petition If the tentative decision is to grant the petition, the Agency will
publish a Federal Register notice describing its intent. If the tentative decision is to
deny the petition, the petitioner will be informed by letter of the intent to deny.
This letter will also offer the petitioner the opportunity to withdraw the petition If
the petitioner declines to withdraw the petition, the Agency will publish a Federal
Register notice describing its intent to deny the petition. At this point, with both
petitions intended to deny and to grant, there will be opportunity for public
comment. The final decision subsequently will be published in the Federal Register.
What Information Should be Included in a "No Migration" Petition?
"No migration" petitions will vary considerably. The petition content will be
strongly influenced by the type of facility for which a variance is sought and the
methods chosen to demonstrate that migration will not occur Certain types of units
may have relatively simple information requirements because of the simple nature
of their "no migration" demonstration (e g., some temporary storage units), other
18
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types of units for which complex demonstrations are made will necessarily require
more complex characterization and detail. The petitioner must provide site-specific
information and may, additionally, provide generic and national information for
certain requirements The descriptions of petition content provided on the
following pages are intended to illustrate the nature and complexity of the
information that may be required
This manual should be used as a starting point for identifying the kind of
information that will be required for each element of the petition In some cases,
information identified in this manual may not be necessary; m other cases,
additional information will be required Identification of the specific information
needs for a given unit can best be accomplished in pre-petitton conferences between
the Agency and facility owners and operators
Discussions of each of the principal petition components listed can be found in the
following pages (It should be noted, however, that the information components
described below generally apply to long-term land disposal For temporary
placement, some of the items might not be relevant) A detailed checklist of possible
petition requirements is presented at the end of this manual
Often, much of the information required for a "no migration" petition will already
have been submitted m the petitioner's Part B permit application Such information
need not always be duplicated in the "no migration" petition, but in some cases
simply may be summarized and referenced therein. However, the petitioner is
encouraged to duplicate and include critical components of the petition in order to
expedite its review and processing
Waste Descriptions
"No migration" variances are available only for the disposal of specific wastes at
specific units. Variances are not available for broad categories of wastes; they are
issued only for those wastes for which compliance with the "no migration" standard
is demonstrated in the petition Proper management of wastes for as long as they
remain hazardous requires that potential incompatibilities and waste
transformation mechanisms be assessed
19
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Hazardous and nonhazardous wastes may interact causing changes in their toxicity
and/or mobility Therefore, it is important that the applicant individually
characterize, to the extent possible, each waste to be placed in the unit, including
wastes not subject to the land disposal ban
Waste descriptions should be properly documented and m compliance with
appropriate quality control and quality assurance guidelines The following is a
breakdown of the information that generally should be provided on each petitioned
waste.
Waste Types and Sources -
Background information generally should be provided on each waste to be covered
by the variance. Such information includes the applicable waste codes (EPA and
industrial), the waste-generating processes, the hazardous constituents and their
properties, the quantities of waste to be placed in the unit and the rates of
placement, and handling and storage practices
Waste Characteristics -
Physical and chemical characterization is required for each petitioned waste and
other wastes to be placed in the unit. The potential for leachate formation, waste
solubilities, hazardous-constituent vapor pressures, and other factors that could
affect waste mobility should also be assessed Analytical information should include
results of testing for Appendix VIII constituents reasonably expected to be present in
the waste Where release to groundwater is a concern, the petition should provide
teachability study test results to determine the teachability of contaminants,
simulation models of teachability and transport, and field leachate analyses, if
available Acceptable procedures for waste sampling and analysis can be found m
the EPA publication Test Methods for Evaluating Solid Waste
Waste Incompatibilities -
The codisposal of incompatible wastes can result m the generation of heat, the
production of flammable and toxic gases, and the solubilization and mobilization of
hazardous constituents. A comprehensive assessment of waste compatibilities
20
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would include all potential chemical interactions, reaction products, and product
characteristics. The applicant should document, to the extent practicable, any waste
incompatibilities and reaction products.
Waste Transformation Mechanisms ~
To properly demonstrate that wastes can be contained in the unit, the applicant may
be able to show that wastes change over time, resulting in nonhazardous
degradation products In addition, it may be necessary to characterize the
mechanisms by which the wastes change over time Waste transformations may
alter waste mobility and/or toxicity and should be predicted to properly determine
the resulting concentrations of hazardous constituents at the unit boundary In any
case, reaction rates and products should generally be characterized and product
characteristics for each transformation mechanism should be provided The
petitioner may also be called upon to characterize combinations of transformation
mechanisms An assessment of the stability of the waste matrix, matrix
characteristics, and the effect of all transformation mechanisms on the matrix should
be provided The mechanisms that generally should be accounted for in a "no
migration" demonstration are as follows:
Biodegradation. The breakdown of a compound by microbial attack, may be
very important for organic compounds. Degradation rates are dependent on
environmental conditions (pH, salinity, dissolved oxygen, nutrients), the
concentrations of waste and microbes, and the types of microbes.
/
Photodegradation. A chemical change in a compound resulting from
absorption of ultraviolet light, must be considered where appropriate Tests to
determine the photodegradatioa rates should control for pH, light
wavelength, light intensity, competing reactions, temperature, and waste
concentrations. , \
Hydrolysis. The degradation of a chemical compound upon reaction with
water, may be a significant transformation mechanism for some wastes
Oxidation/reduction. The transfer of electrons between molecules, is a
common degradation mechanism
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Volatilization Although technically not a transformation mechanism, is the
conversion of a solid or liquid material into a vapor state. It may represent a
significant waste transport mechanism (i e, from one medium to another).
Determination of environmental factors affecting volatilization rates (eg.,
temperature, pressure, vapor pressure, solubility) may also be required
The likelihood of these and other waste transformation mechanisms should be
described in the petition The methods by which petitioners determine
transformation rates, whether actual waste data or theoretical calculations, also
should be thoroughly described The actual testing of waste transformation
processes or the use of accepted procedures for transformation rate determination
may be required
Facility Description l
The petition should include a description of the hazardous-waste management
facility where the waste will be disposed in sufficient detail to familiarize the
reviewer with its overall operation The facility name, mailing address, and location
should be provided, together with information on a point of contact for
correspondence concerning the petition The nature of the facility's business should
be identified and, for onsite facilities, the processes involved in the generation of
hazardous wastes should be described Operators of facilities accepting waste from
off-site should identify the types of industries serviced
Detailed design, layout, and operating plans should be provided for the unit covered
by the petition. Unit descriptions should focus on waste isolation capabilities of the
unit or environmental setting In many cases, the type of information and level of
detail will be similar to those included in RCRA Part B permit applications. (Detailed
guidance concerning part 8 applications for land disposal units can be found in the
EPA's 1984 Permit Applicants' Guidance Manual for Hazardous Waste Land
Treatment. Storage and Disposal Facilities)
Although man-made barriers and engineered systems alone cannot be relied upon
to provide the long-term "no migration" assurances required, they may play a role in
the facility operation The exception is certain temporary storage facilities that may
22
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rely entirely upon engineered systems to isolate wastes For temporary land-based
storage purposes only, the containment of hazardous waste within engineered
barriers (and meeting Part 264 requirements) will be considered in making the "no
migration" demonstration, provided that wastes are to be removed after a
reasonably short storage period that may be conservatively projected to be weil
before the failure of the engineered barrier system. AM barriers should be
thoroughly described. i
The unit boundaries, which will serve as the compliance point for the variance,
should be defined and thoroughly described In the case where there is no
engineered boundary above the waste to control air emissions, the downwind edge
of the unit at a height of 1 5 meters will be the point of compliance for air emissions
Other aspects of facility design and operation may be considered in evaluating the
petition, including- ' '
Procedures employed to prevent hazards
Contingency plans
Personnel training plans
Closure pians
Post-closure plans
These elements of the facility description are also common to Part B applications.
Any relevant Part B information should be summarized in the petition, or attached
as necessary
V
Site Characterization
A thorough description of each facility's natural environmental setting is crucial to a
"no migration" demonstration in any case where permanent disposal is
contemplated. The site's climatology, meteorology, geology, and hydrology must be
described m sufficient detail to permit assessment of the degree of waste isolation
achievable. Environmental factors and long-term environmental changes that may
impact the waste isolation potential of the unit should be addressed. Moreover,
background ground water, surface water, soil, and air quality must be determined to
property assess any potential impacts of land disposal. The information that may be
23
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required is simitar to the requirements for a Part B permit application and a RCRA
Facility Investigation (RFI) (Detailed guidance concerning RFIs can be found in EPA's
1989 interim final RCRA Facility Investigation Guidance Manual)
Even so, because a "no migration" demonstration does not allow for consideration
of fate and transport of hazardous constituents above acceptable levels outside the
unit boundary, the focus of site characterization should be on the potential impacts
of the site on the waste to be isolated in the unit For example, the potential impacts
of wind, rainfall, and the fluctuation in the ground-water table on the unit and the
waste within it should be addressed Nonetheless, while the demonstration cannot
involve consideration of fate and transport of constituents outside the unit,
locational and environmental factors that are external to the unit may have
significant bearing on the probability of migration from the unit occurring.
Therefore, information on particularly sensitive or vulnerable site characteristics may
be useful in determining the degree of certainty required in a "no migration*
demonstration
Geology -
A geologic description should include regional, local, and site information. A
discussion of regional and local geology should include the following components
and contain maps and other supporting documentation
Structure. Density, distribution, and orientation of.faults, folds, and fractures
Subsurface Geology. Identification, lithologic descriptions, and thicknesses of
all geologic formations underlying the region, available geophysical surveys,
well logs, and boring logs
Geomorphology, Discussion of present surface features, processes that could
affect surface features, and subsurface features that may be implied
Geologic Stability. Potential for earthquakes and degree of resulting ground
motion, faulting, landslides, subsidence, creep, and other types of earth
movement
24
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The discussion of local geology should also include soils and topography Where
relevant, the soils information should encompass soil types (Unified Soil
Classification System), properties, thicknesses, and depths to bedrock In addition,
similar site-specific geologic information should be provided, whenever possible
Ground-Water Hydrology -
The petition should include a comprehensive description of regional, local, and site
ground-water hydrology Ground water is particularly vulnerable to contamination
with hazardous constituents from land disposal units and, in many cases, can provide
an avenue for waste constituent transport to surface waters and municipal and
private wells as well as provide a subsurface migration pathway for gases. In some
instances ground water may migrate into a unit, mobilizing contaminants out of the
unit The following types of information, including maps and supporting
documentation, may be required for a "no migration" petition v
Identity and lateral extent of all aquifers, confining layers, and perched water
tables
Characteristics of all necessary aquifers and confining layers, including
thickness, porosity, permeability, hydraulic conductivity, and storage
Ground-water elevations and seasonal variations thereof
Existence of aquifer interconnections
Ground-water flow rates, directions, and recharge and discharge areas
Locations of all local municipal and private wells and surface water discharge
areas. (For temporary storage in enclosed waste piles, and perhaps other cases
where groundwater is of limited relevance, groundwater information may not
be necessary, orthe level of detail may be less.)
^
ป
Surface-Water Hydrology -
25
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A discussion of surface-water hydrology should include identification of all
watersheds within the region that could potentially affect the facility. Maps of
regional and facility drainage and the effects of facility run-on and run-off controls
should be provided. Floodplam maps incorporating appropriate flood frequency
data should also be provided It must be clearly demonstrated that waste isolation
will not be adversely affected by floods with a reasonable probability of occurrence
during the period in which the wastes are hazardous (e.g., 25-year floods, 100-year
floods, etc)
Climatology and Meteorology --
Meteorological and climatological information should be sufficient to allow for the
assessment of impacts of these factors on the disposal unit and site The climate and
meteorology of the site can have significant impact on the rate of emissions to air,
for example. The following types of information may be required ' x
Site wind roses
Data on precipitation, temperature, and relative humidity data (seasonal
maximum*and mmimums)
Maps of severe storm tracks and statistics on storm occurrence
Data on depth of seasonal freezing
Facilities relying in part on climatic factors to control waste migration (e.g, and
regions with no ground-water recharge) will be required to submit considerably
more meterological and climatic information than facilities that are not significantly
affected by climatic changes
Background Environmental Quality-
The RCRA regulations specifically require that "no migration" petitions contain
analyses of background air, soil, and water quality. The analyses and levels of detail
should be site-specific. Those petitioners with facilities in sensitive environments will
be required to submit considerably more background data than other petitioners
Monitoring Plans
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Monitoring of environmental media at land disposal sites is necessary to confirm
that "no migration" of hazardous constituents beyond the unit boundary occurs
(unless the Agency determines that monitoring of one or more media at a specific
site is unnecessary or technically mfeasible or impracticable ) Accordingly, the Land
Disposal Restrictions First Third Rule [53 FR 31189, August 17,1988] amended 40 CFR
268 6 to require that "no migration" petitions include a plan for monitoring at the
unit boundary, to include the following information*
Media to be monitored
Type of monitoring to be conducted at the unit
Location of the momtortng stations
Frequency of monitoring at each station
The specific hazardous constituents to be monitored
An implementation schedule for the monitoring program
Equipment to be used at the monitoring station ป
Sampling and analytical techniques to be employed
Data recording/reporting procedures
The petitioner should provide sufficient information to justify the design of the
monitoring program and to demonstrate that monitoring stations will be located to
detect migration from the unit at the earliest practicable time.
For existing units that are receiving waste prior to "no migration" petition
submittal, monitoring data for ground water, surface water, soil, and air will be
required as part of the petition. The Agency recognizes, however, that monitoring
data may be difficult or impossible to collect, or may be nonexistent, for new units.
In these cases (as well as for existing units), variance approval will be conditioned
upon Agency review and approval of monitoring data, gathered at regular mtevals
subsequent to unit operation, which confirms "no migration". (Nevertheless, where
any monitoring data are available for a new unit, as a result of field test plots, etc.,
such data may be required as part of a "no migration" petition).
*
In most cases, m addition to initial monitoring to demonstrate "no migration",
detection monitoring to confirm "no migration" for each medium will be required
at regular intervals (for example, semiannually for ground-water monitoring to
coincide with Part 264 Subpart F monitoring). However, for the air medium EPA is
27
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taking a slightly different monitoring approach Except for those units where the
Agency has determined that air monitoring is unnecessary because there is no
realistic probability of migration to the air medium, petitioners generally should
conduct a one-time, reasonable worst-case ambient monitoring program to confirm
that modeling estimates are reasonably accurate for the unit in question
(Monitoring under reasonable worst-case conditions is proposed, because it would
facilitate detection of hazardous constituents, which may be at low concentrations
near detection limits) Subsequent to granting of the variance, however, rather than
performing regular ambient monitoring during the operation of the unit, the owner
or operator should regularly sample the waste stream entering the unit to confirm
that the modeled annual quantity of a hazardous constituent is not exceeded The
Agency believes this approach will be appropriate because ambient air monitoring
performed at the unit boundary may involve too many uncertainties and too much
variability to be reliable in detecting migration. More information on air modeling
and monitoring for the "no migration" demonstration is available in the Appendix
to this guidance document (Where a unit is covered or contained, and monitoring is
at a specific point of release, however, routine monitoring may be appropriate.)
s
Monitoring immediately at the unit boundary may be difficult in certain locations or
under unusual physical conditions at the site Under such circumstances, the
petitioner should propose a monitoring plan to be conducted as near as possible to
the unit boundary without compromising the integrity of the unit One such case
may be hazardous waste repositories in geologic formations that are so extensive
that installation of monitoring wells around the formation itself may not allow
detection of migration at the earliest time, and installation of monitoring wells in
the formation may damage the integrity of the formation. Monitoring of the
repository itself (e.g., pressure monitoring of fluids between well casings in solution-
mined caverns, or leachate sumps and pumps in room-and-pillar mines) may be
suitable in this case After repository closure, however, such monitoring may no
longer be feasible In certain situations, the Agency may determine that
conventional monitoring of one more media at the unit boundary is technically
mfeasible or impractical In most cases of technical mfeasibility or impracticahty,
however, the Agency still will require some type of monitoring or modified
monitoring as near as possible to the unit boundary without compromising the
integrity of the unit.
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In other cases, monitoring of all environmental media at a particular facility may be
unnecessary. In certain limited cases the Agency may determine, based upon waste-
and site- specific characteristics, that monitoring of one or more media is
unnecessary at an individual site, because migration to that medium (those media)
clearly is not a realistic concern An example of this might be monitoring of air
outside a totally enclosed treatment facility In such a case, petitioners should
include information that clearly demonstrates why monitoring of any medium is
unnecessary. The Agency may then determine on a site-specific basis to waive
monitoring requirements for one or more media Petitioners who believe that one
of these situations applies to their units should include in their petitions information
that clearly demonstrates why monitoring of any medium is unnecessary or
technically mfeasible
In addition to monitoring at the unit boundary, the petrtion in some cases should
also include a plan for monitoring the wastes in the unit to detect any changes in
waste composition which could affect the potential for migration of hazardous
constituents over time. Such monitoring might include periodic testing of the waste
in the units or leachate collection systems m surface impoundments, landfills, and
room-and-pillar mines.
A petitioner may be able to incorporate all or part of a monitoring plan designed to
comply with 40 CFR 264 or 265 Subpart F requirements into the "no migration"
monitoring plan. For example, a petitioner may be able to use Subpart F monitoring
wells if they will detect migration at the earliest practicable time, and may only have
to modify the frequency or timing of monitoring. Nevertheless, the petitioner
should be aware that "no migration" monitoring is different from Subpart F
monitoring in that it is to be performed immediately at, or as close as possible to, the
unit boundary. (See the Land Disposal Restrictions First Third Rule promulgated on
August 17. 1988 (53 FR 31138)) Subpart F ground-water monitoring, on the other
hand, does not necessarily occur at the unit boundary, but may instead occur at the
edge of the waste management area. Furthermore, although Subpart F detection
monitoring for indicator parameters may be helpful to demonstrate "no migration",
"no migration" monitoring should be for a set of constituents determined based on
a unit-specific analysis of the waste While indicator parameters may stilt be suitable
for "no migration" monitoring purposes, they may differ from those of Subpart F
monitoring.
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Waste Mobility Modeling
Accurate and representative modeling of waste constituent mobility may be
required for the environment within the unit including unit liners and engineered
barriers. The Agency also may determine m certain limited situations that modeling
of a particular medium is unnecessary or mfeasible (e g , air modeling for a covered
waste pile) However, where an engineered control such as a cover exists which
greatly reduces the likelihood of migration to the air medium, but for which
modeling is mfeasible, the Agency may require the petitioner to assess the
performance of the engineered system in lieu of modeling. Presented below is a
brief overview of information requirements for modeling as well as considerations
relevant to the choice of a representative model
Several types of models may be used to predict waste mobility within the confines of
the unit for which a variance is sought Although hazardous constituents must not
exceed human health-based levels beyond the engineered boundary of the unit,
waste migration within the unit will be acceptable Models may be developed for
predicting leachate and gas generation rates, barrier integrity overtime, and many
other factors that can affect waste mobility All such models and the assumptions
underlying them must be thoroughly explained, and descriptions of the calculations
and codes employed must be provided. Model assumptions and input data should
be conservative and tend toward overestimating rather than underestimating
migration Models, input data, and relevant documentation should be available to
EPA upon request and without restriction.
Modeling of waste and leachate migration in the unsaturated zone may be required
for some units (e.g., the treatment zone of a land treatment unit). Waste
constituent transport within that zone depends on site geology, soils, and
climatology, as well a,s the physical and chemical characteristics of the waste and
leachate The factors affecting flow at or near the land surface are precipitation,
run-off/run-on, evaporation, and transpiration.
Physical properties of the site soils that affect flow in the unit and the unsaturated
zone that should be described in the petition include.
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Water content
Pressure potential
Permeability
.Degree of water saturation
Bulk density
Particle density
Water capacity
Hydraulic conductivity-
Water d iff usivity
The waste or leachate in the unsaturated zone can be affected by various chemical
processes, including ion exchange, adsorption, precipitation, dissolution, and
complex formation Those processes appropriate to the waste and its leachates
should be considered Moreover, certain properties of the soil can be affected by the
waste or leachate its hydraulic conductivity can be changed; its permeability can be1
increased by the removal of organic matter or a change in adsorptive properties;
and others of its properties can be altered by the dewatermg of clays or a change in
pore size. Flow patterns within the soil can also be altered by changes in pore size
due to the dissolution and precipitation of chemical species. The impact of these
factors should be taken into account in the model.
-*
The potential for air emission of hazardous constituents from the waste surface into
the atmosphere must be addressed. Emission rates are influenced by environmental
as well as chemical and physical factors The principal environmental factors
influencing air emissions are temperature, soil characteristics (e.g., pH, moisture,
grain size), and precipitation. The waste or leachate properties that should
generally be modeled include vapor pressure, solubility, chemical activity,
partitioning behavior of the solute (waste) between the atmosphere and water
(Henry's Law), d iff usivity, absorption, and release rate. (In some cases, such as
covered or closed units, actual data on emission rates may be more appropriate than
modeling)
limitations of any air emission release rate and dispersion models should be
documented. The applicant should combine the use of models with ambient air and
emission monitoring to characterize conditions at the1 unit to the greatest extent
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possible. Any models used should be verified at the site (For more information on
the "no migration" demonstration methodology air, see the Appendix)
Appropriate models should be chosen for each of the waste mobility cases discussed
(i e , unsaturated zone, air, etc.). The choice depends on the objectives of the study
and on the sensitivity of the model to various chemical and physical processes. The
model chosen should be sensitive to all of the significant processes and, of the
models considered, should be the most sensitive to those processes of greatest
importance.
Other concerns in choosing a model are how well it represents the field situation,
whether it is appropriate for the available data, and whether it can be confirmed for
accuracy by comparison to actual measurements The most sophisticated models
may be inappropriate for the available data
*
The petitioner should provide the following quality assurance and quality control
information for every model used
s
Model Confirmation and Calibration. Comparing the results of analytical and
numerical models or matching field data to the mode! results is critical to
model confirmation Models should be calibrated at the site.
Justification of assumptions. Proper justification of all assumptions should be
provided. Reasonably conservative assumptions should be chosen
Sensitivity tests. An assessment of the influence of changes in the magnitude
of model parameters should be provided Models should show greatest
. sensitivity to the most influential processes.
Model accuracy assessment. It should be demonstrated that: (1) the model
reasonably represents the actual physical system, (2) there are no
computational errors in the computer code, and (3) there is a high degree of
correlation between the model and measured data
The EPA discourages the use of proprietary models, since the models selected will
have to be closely scrutinized to determine their reasonableness and accuracy. They
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also will be subject to public comment The Agency will give most weight to data
developed under appropriate QA/QC procedures, as described in the facility QA/QC
plan, in the petition review
Assessment of Environmental Impacts
In a "no migration" demonstration the petitioner must show that hazardous
constituents do not exceed human health-based levels at the edge of the disposal
unit If lower levels must be met to protect the environment, then those levels will
be required For example, lower levels may be needed where there is potential
impact to a sensitive environment (e g , an adjacent wetland) or an endangered
species even if human health- based levels are met The petition should identify such
environments or species for which there exists the reasonable probability of impacts
from the unit for which a variance is sought The assessment of environmental
impacts does not mean that migration of hazardous constituents will be measured
(or allowed) beyond the boundary of the unit. Such an assessment should be
undertaken merely to determine if human health-based levels measured at the unit
boundary are sufficient to protect any sensitive environmental receptors.
Environmental assessments should identify any factor which may reasonably be
assumed to require stricter contaminant levels. This will involve defining the,
terrestrial and aquatic species that may be exposed to contaminants and the
exposure pathways through which the species may be sensitive (e.g., inhalation,
direct contact). Where exposure is possible, acute and chronic toxioty and
bioaccumulation factors should be provided for each constituent with respect to the
species involved Effects of transported and transformed air pollutants (e.g.,
ambient ozone or photochemical oxidants) on agricultural crops, forests, or
materials should be considered by the applicant. Field studies and biomomtormg
may be performed in the absence of data, or available data for chemical analogs
may be substituted.
Environmental considerations may include but are not limited to evaluation of:
j
Species diversity and abundance potentially affected by migration from the
unit
33
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Bioaccumulation potential in plants and animals
Fishery and habitat impacts
Endangered species of flora and fauna potentially affected by migration from
the unit
Biological community structure alteration potential
It is important to note that, for many chemicals, exposure levels deemed safe for
humans often have adverse effects upon terrestrial and aquatic Jife In addition,
toxicants present at low levels in the environment may bioaccumulate, presenting
significant health risks to man and animals higher in the food chain.
Prediction of Infrequent Events l
Under 40 CFR 268 6(b}(5) an analysis must be performed to identify and quantify any
aspects of the demonstration that contribute significantly to uncertainty
The petitioner must identify and evaluate the impacts of predictable future events
that could contribute to or result in inadequate waste isolation Natural phenomena
that might require consideration include.
Earthquakes and resulting ground motion
Floods and droughts
Severe storm events
Climatic fluctuations
Geologic activity
The potential for such natural events during the period in which the wastes remain
hazardous should be determined Potential impacts and consequences of events
with a reasonable probability of occurring during that period should then be
estimated with respect to the facility's ability to isolate wastes from the
environment. In addition, likely human-induced events which may affect the
isolation capability of the unit, such as disturbance of the hydrologic regime and
future land uses, should generally be considered.
34
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Analyses of predictable events should take into consideration both the disposal unit
and the surrounding environment For example, ground motion resulting from an
earthquake may cause the breaching of a unit, the fracturing of surrounding rocks,
and surges in the ground-water level Previously unconsidered avenues for
contaminant migration may be created by the earthquake. Impacts of other
geological activity such as sinkhole formation in areas of karst terrane or slope
failure in areas of landslide susceptibility also should considered In analyzing the
potential consequences of predictable phenomena, probable worst-case scenarios
should be used to ensure that any errors occur on the side of safety
Quality Assurance and Control
Under 40 CFR 268 6(b)(4) a QA/QC plan that addresses all aspects of the petition
demonstration must be included m the petition submittal and approved by the
Agency Quality goals and methods to assure that these goals are achieved should
be included for each of the following aspects of the petition demonstration
i
Waste and environmental monitoring, sampling, and analysis activities
Field measurements of the facility setting, such as geophysical exploration,
ground-water monitoring, weather observations, and topographic mapping
\
Validation of computations, codes, models, and methods used in calculating
critical facility parameters
Control of construction activities to ensure compliance with design
specifications, where relevant to the "no migration" demonstration.
Evaluation of the integrity of construction materials, where relevant to the "no
migration" demonstration
The QA/QC plan generally should identify goals for each of the following quality
indicators and describe how they will be achieved:
Data representativeness. The degree to which data accurately and precisely
represent a characteristic of a population, a parameter, variations at a
sampling point, or environmental conditions
35
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Data accuracy. The degree to which data agree with an accepted reference or
true value The measurement of accuracy exposes any bias in a system or
method.
Data precision. A measure of the mutual agreement between comparable
data gathered or developed under similar conditions Precision is best
expressed in terms of a standard deviation
Data completeness. A measure of the amount of valid data obtained against
the amount that was expected
EPA will give most weight to data developed under appropriate QA/QC procedures,
as described in the facility QA/QC plan, in the petition review.
36
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CHECKLIST OF INFORMATION NEEDS
The following checklist is a comprehensive, but not all-inclusive, list of information
needs Individual petitions may require more or less information than that
presented below The level of detail required will depend on site-specific factors
Facility Description
ฃ] Name of facility
Q Address of facility
Q Name of owner/operator
Q Anticipated period of operation
n Status of RCRA permit application
Q Location map
Q Detailed site plan
Q Aenal surveys
n Advantages/disadvantages of location
Q Evaluation of storage/disposal unit
O Design objective
n Design criteria
n Design perform a nee proiecti on
Q Materials specifications
Q Detailed drawings and
specifications
Q Documentation of unit
construction
Q Documentation of unit operation
O Closure plans
D Post-closure plans
D Cover design
Q Design QA/QC demonstration (testing &
inspection)
Q Facility operation QA/QC demonstration
Waste Characteristics
Q Waste type by name
O Process** that produced the waste
O Hazardous properties
Q Physical characteristics
Q Chemical characteristics
Q Biological properties
n Constituents and percentages of
constituents
Q Analytical methods and results
Q Projection of waste volume to be disposed
Q Quantity of banned waste bei ng disposed
Q Frequency of disposal
Q Period of time waste has been and will be
disposed
El Hand) mg procedures
fj Waste treatment before, during and after
disposal
fj Liquid phase mobility information
[~| G as/pa rti cu I ate mobi 11 ty
D Solid phase mobility
Q Dust generation potential
Q Gas-liquid phase interactions
Q Persistence/degradation potential in unit
and environment
D QA/QC demonstration
Waste Transformation and Immobilization *
Q Estimation of quantity and quality of
leachate formation
n Waste/waste compatibility, interaction,
reactio*' products
Q Waste"mer compatibility
D Assessment of biodegradation potential
n Assessment of oxidation/reduction
potential
Q Assessment of immobilization due to
insolubility
G Assessment of photodegradati on
potential
D Assessment of immobilization due to
hydrolysis t
Q Assessment of immobilization due to
adsorptivity
Site Characterization
D Surficial geology and soils (regional and
local)
Q Topography
n Soil types
Q Soil properties
O Depth to bedrock
Q Bedrock geology (regional and local)
O Stratigraphy and lithology
Q Seismic activity of area
Q Assessment of ground motion
potential and degree
37
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P Geologic cross sections
G Degree of bedrock faulting and
fracturing
G Rock characterization
G Ground-water hydrology (regional and
local)
G Water table map
Q Seasonal variations in the water
table
G Identification of all aquifers and
aquitards
Q Characterization of all aquifers
G Vertical and horizontal hydraulic
conductivity
G Aqutfennterconnection
n Description of ground water
monitoring program
G Monitoring QA/QC documentation
Q Surface water hydrology
Q Location of alt watersheds
Q Map of drainage patterns
G Map of floodptam
Q Flood analysis
Q Meteorology/climatology
G Wind rose
Q Precipitation records
Q Temperature records
Q Relative humidity records
Q Maps of storm tracks
Monitoring Plan
Q Media to be monitored
Q Type of monitoring to be conducted at
the unit
O Location of monitoring stations
O frequency of monitoring at each station
Q Specific hazardous constituents to be
monitored
Q Implementation schedule for the
monitoring program
Q Equipment used at the moniton ng
stations
Q Sampling and analytical techniques
employed
O Data recording/reporting procedures
Waste Mobility
Q Unsaturated zone soils
Q Soil sampling
D Soil testing
Q Unsaturated zone physical properties
Q Volumetric water content
Q Degree of water saturation
n Bulk density
Q Pressure potential
n Relative permeability
n Unsaturated hydraulic conductivity
n Water capacity
n Water diffusivity
D Leachate characteristics affecting mobility
Q Leachate characterization
G Leachate interactions
G Secondary leachate evaluation
Q Evaluation of transport mechanisms
Q Evaluation of fate of contaminants m
unsaturated zone
D Vapor concentrator of constituents at
the source
D Vapor pressure of constituents
D Solubility data for constituents
n Activity coefficient
Q Henry s Law constant
n Background measurements for air
O Assessment of volatilization potential
Modeling Evaluation
G Model accounts for all transport
mechen-sms
Q Model appropriate for petitioned was'e
O Data input accurate and verified
Q Model tested under field conditions
O Mode) is accurate over long time periods
D Limitations of model
O Model inputs adequately documented
Q Model outputs appropriate and
reasonable
Assessment of Environmental Risk
O Identification of all exposure pathways
and routes
Q Identification of all potential receptors
D Wildlife'
O Vegetation
Q Identification of sensitive or
endangered species
Q Assessment of bioaccumulation through
the foodcham
Uncertainty Analysis
O Natural Events
Q Climatic fluctuations
Q Glaciation
Q Stream erosion
38
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Q Magmatic activity
Q Epeirogenic displacement
Q Orogenicdiastrophism
Q Di agenesis
Q Static fracturing
Q Dissolution
Q Sedimentation
Q Flooding
Q Undetected features (i e faults,
lava tubes)
n Meteorites
Q Fires
Q Hurricanes
O Tornadoes
Q Earthquakes
D Ground motion
Q Waste/facifity-mduced events
Q Thermal effects
C] Chemical effects
D Mechanical effects
Q Modi fication of hydrologic regime
n Human-induced events
Q Improper design or operation
D Past intrusions
D Future intrusions
Q Intentional intrusion
Q Perturbation of ground-water
system
Q Biosphere alterations
39
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Where Can i Obtain Additional information Concerning "No Migration" Variances?
Additional information on "no migration" variances is available from EPA
Headquarters in Washington, DC Facilities considering submitting a petition are
strongly encouraged to meet with the Agency before preparing the petition to
assess the exact nature of the information required m the "no migration"
demonstration and the level of detail appropriate for the petition Questions
concerning petitions and requests for petition meetings should be directed to
U S Environmental Protection Agency ?
Permits and State Programs Division
401M Street, SW
Washington, D C 20460
Telephone 202/382-4782
Questions concerning these and other RCRA requirements can also be directed to
the RCRA/Superfund Hotline at 800/424-9346 or, m the Washington, D.C.
metropolitan area, 202/382-3000. The Hotline can also provide assistance in
obtaining copies of Federal regulations and other relevant guidance documents.
s
The following is a list of selected documents which may be of value to potential
petitioners.
Permit Applicants' Guidance Manual for the General Facility Standards 1983. EPA
SW-968
Permit Applicants' Guidance Manual for Hazardous Waste Land Treatment, Storage,
and Disposal Facilities. 1984 EPA 530 SW-84-004
HydrologU Simulation at Waste Disposal Sites 1982. EPA SW-868.
Test Methods for Evaluating Solid Wastes, Physical/Chemical Methods Third Edition,
1986 EPASW-846.
A Method for Determining the Compatibility of Hazardous Wastes. EPA 600/2-80-
076.
40
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A Guide for Estimating the Incompatibility of Selected Hazardous Waste Based on
Binary Chemical Mixtures 1986 ASTMP-168
Soil Properties, Classification, and Hydraulic Conductivity Testing 1984. EPA SW-
925
Criteria for Identifying Areas of Vulnerable Hydrogeology Under the Resource
Conservation and Recovery Act. 1986 NTIS 86- 224946
RCRA Facility Investigation Guidance Manual, Interim Final EPA 530/SW-89-031,
February, 1989
Solid Waste Leaching Procedure 1984 EPASW-924
Waste Analysis Plan Guidance Manual 1984 GPO 055-000-00244-4
Construction Quality Assurance for Hazardous Waste Land Disposal Facilities, Draft.
1985. EPA/530 SW-85-021
RCRA Groundwater Monitoring Technical Enforcement Guidance Document, 1986.
Surface Impoundment Clean Closure Guidance Manual, Interim Final October,
1987
\
Superfund Public Health Evaluation Manual. EPA/540-1-86-060.
Guidelines for Carcinogenic Risk Assessment. 51 FR 33992-34003.
Guidelines for the Health Risk Assessment of Chemical Mixtures. 51 FR 34014-
34025.
Integrated Risk Information System (IRIS) Chemical Files. EPA/600/8-86/032b
41
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APPENDIX
AIR PATHWAY ASSESSMENT METHODOLOGY
"NO MIGRATION" VARIANCES TO THE HAZARDOUS WASTE
LAND DISPOSAL PROHIBITIONS:
A GUIDANCE MANUAL FOR PETITIONERS
Prepared for
U.S. Environmental Protection Agency
Office of Solid Waste
Washington, DC
JULY 1992
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TABLE OF CONTENTS
1.0 INTRODUCTION . 1-1
2.0
AIR I
2.1
2.2
2.3
24
EXAI
31
32
PATHWAY ASSESSMENT METHODOLOGY
Overview , . .
Modeling Methodology .... ....
221 Emission Rate Modeling
2 2.2 Dispersion Modeling
Air Monitorina Methodology ... .
2 3 1 Monitoring Approaches
2 3.2 Meteorological Monitoring
2 3.3 Pollutants to be Measured . . .
234 Site Selection
235 Sampling Duration
236 Monitoring Requirements for New Units ....
2.3 7 Documentation of Field Programs ...
238 Pretreatment Issues . ....
239 Presenting Monitoring Results
2310 Use of Measured Data ....
Routine Waste and Soil Sampling
WIPLE APPLICATIONS
Gas Phase Emissions - Example Assessment .
Fuartive Particulate Matter - Examole Assessment
2-1
2-1
2-5
2-7
2-14
2-22
2-25
2-27
2-27
2-28
2-28
2-28
2-28
2-29
2-30
2-30
2-32
3-1
3-1
3-6
3.0
4.0 REFERENCES ... 4-1
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1.0 INTRODUCTION
The Environmental Protection Agency (EPA) promulgated a final rulemaking (51 FR
40572} that established the overall framework for the land disposal restrictions as
mandated by the Hazardous and Solid Waste Amendments (HSWA) of 1984 A major
requirement of HSWA is that all hazardous wastes must meet treatment standards based
on performance of best demonstrated available technology before placement into the
land Otherwise, the owner/operator is prohibited from land disposal of the waste
Sections 3004(d), (e), and (g) also provides an opportunity for generators, owners, and
operators to either individually or collectively petition for a variance from the prohibition
against land disposal of hazardous wastes not meeting Agency standards in order to
receive a variance, a petitioner must successfully demonstrate that there will be "no
migration" of hazardous constituents from the disposal unit or injection zone for as long
as the waste remains hazardous [3004(d)(1)]
A "no-migration" demonstration methodology applicable to. air releases has been
developed This methodology has been based on consideration of the emission and
atmospheric dispersion potential of gaseous and particulate air contaminants from land
disposal units. Typical hazardous waste disposal units such as land treatment, surface
impoundments, and landfills have the potential for air contaminant emissions even with
the application of control technology Local wind conditions will result in the transport of
these air contaminants beyond the unit boundary Therefore, the air pathway assessment
methodology presented in Section 2, which accounts for these emission/dispersion
mechanisms, is recommended for "no-migration" demonstrations Example applications
of this methodology are presented in Section 3
Regulations currently are being developed by EPA under Section 3004(n) of HSWA to
control air emissions from hazardous waste treatment, storage, and disposal facilities.
In addition, the National Emission Standards for Hazardous Air Pollutants (NESHAP)
applicable to benzene were promulgated in March 1990. The Occupational Safety and
Health Administration (OSHA) has promulgated air contaminant standards which address
short-term exposures Compliance with 3004(n) and certification of compliance with
NESHAP and OSHA requirements are necessary prerequisites for approval of a
"no-migration" petition.
3004(n) - Requires air standards for land treatment, landfill, and waste pile
units when obtaining a "no-migration" variance These regulations will be
proposed with the revisions to Section 268.6. Once regulations
implementing Section 3004(n) are promulgated, petitioners will need to
demonstrate volatile organic concentrations in the waste of less than or
equal to 500 ppmw If this is not met, pretreatment or physical controls to
limit emissions will be required
1-1
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Benzene NESHAP - 40 CFR Part 61 sub-part FF was promulgated March
7,1990,55 FR 45 It requires certain facilities that manage >10 Mg/year of
total annual benzene in the waste to control certain waste streams, normally
ones with > 10 ppmw benzene in waste Facilities subject to the benzene
NESHAP control requirements must treat the benzene in the waste to below
10 ppmw prior to land disposal in an open unit
OSHA - 29 CFR Part 1910 was promulgated June 7, 1988, 53 FR 109. It
requires facilities to meet concentration limits for 8-hour time-weighted
averages (TWA), and short term exposure limits (STELS), which generally
are 15-mmute time-weighted average exposures
2.0 AIR PATHWAY ASSESSMENT METHODOLOGY
2.1 Overview
The intent of a "no-migration" petition is to demonstrate that there will be no transport of
constituents at hazardous concentrations from the disposal unit. For air pathway
assessments, "no-migration" is defined as constituent-specific (gaseous and particulate)
air concentrations which are protective of human health and the environment This
approach involves the application of standard emission and dispersion models to esti-
mate air concentrations at or beyond the point of compliance for comparison to available
inhalation health criteria. The point of compliance is the outermost extent of the berm that
contains the LTU. Concentrations at or beyond the point of compliance must to be
shown to be less than all applicable health criteria to demonstrate "no-migration"
A height of 1 5m should be used for "no-migration" air pathway assessments to evaluate
air concentrations relative to health criteria Although dispersion models can be applied
to a ground-level measurement height, this would not be appropriate for "no-migration"
because of the need to compare ambient air quality monitoring and dispersion modeling
Monitoring at a height less than 1.5m is not appropriate for a land treatment unit because
surface effects would pose a major complication for collecting representative air quality
samples For example, particulate samples with inlet heights significantly less than the
inhalation height of 1 5m would have the potential to collect non-suspendable participates
from the surface This could bias the measured data set, and adversely affect long-term
comparisons of modeled and measured concentrations The 1 5m height is a
compromise, which is unlikely to show significantly lower concentrations than surface
concentrations because the composite LTU area source is generally large relative to the
difference in height of 0 to 1 5m at the LTU boundary1
Only during stable conditions is there likely to be strong enough vertical gradients to
potentially show significant differences in concentration within the range of 0 to 1.5m above ground
level.
2-1
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A combination of modeling and monitoring approaches can be used to estimate the
maximum air concentration at 1 5m at or beyond the point of compliance An overview
of the recommended air pathway assessment methodology for "no-migration"
demonstrations is illustrated in Figure 2-1 This methodology consists of the following
major components'
Conduct an emission rate/dispersion modeling assessment prior to
submittal of a "no-migration" petition.
Conduct a worst-case air quality monitoring assessment and optional
emission rate monitoring prior to submittal of a "no-migration" petition
Scale-up modeled concentrations within a pollutant class if measured data
show that modeling underestimates the pollutant class
Conduct a routine waste and soil sampling after a "no-migration" variance
has been granted
A waste-based analysis is needed to evaluate compliance with section 3004 (n) and the
benzene NESHAP Dispersion modeling is the basis to evaluate compliance with the RFI
Health Criteria (EPA, May 1989a). A dispersion modeling assessment initially should be
conducted to characterize the air emission potential for the disposal unit and to estimate
maximum air concentrations at the unit boundary The primary modeling approach,
which must be done for all sources and Skinner List pollutants, is to use refined emission
rate and dispersion models An alternative (optional) approach involves the application
of conservative screening models The screening approach is generally useful to obtain
preliminary conservative modeling results. But the refined modeling approach will still be
required as the primary basis for evaluation of a "no-migration" petition. If modeling
results indicate compliance, then a monrtonng assessment should be conducted
Non-compliance results indicate that waste treatment and/or additional measures to
reduce emissions would be needed. Based on these control measures, a revised
modeling assessment should be conducted If waste treatment/ control measures are
not adequate for compliance, the "no-migration" petition will be denied The
recommended methodology for the conduct of modeling assessments is presented in
Section 2 2
A monitoring assessment also should be conducted (e.g, this may involve a
demonstration plot for a new land treatment unrt) to evaluate modeling estimates, and the
results should be submitted with the "no-migration" petition. All pollutants with ratios of
modeled concentrations divided by applicable health criteria greater than 0.10 for any
health criteria should be included in the monitoring program unless there is not a
2-2
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Figure 2-1
AIR PATHWAY ASSESSMENT METHODOLOGY FOR
"NO-MIGRATION PETITION" DEMONSTRATION
Evaluate
3004(n)and
NESHAP Compliance
Screening Option''
for Dispersion Modeling
No-Migrabon
Compliance
(RFI
State/
Local Complianoe
as Applicable
No-Migration
Compliance
(RF
Scated-up Modeted
ixjfxsornra
aana
Treat Waste/
Reduce Emissions
Yw
Bam tor Grantbig Variance
Routine Waste/Soil
Sampbng
2-3
S12074-1
-------
validated method suitable for use in the ambient air The emission and air monitoring
program should be conducted during a period representative of worst-case emission/
dispersion conditions. Worst-case conditions, considering waste application rates,
emission conditions, and meteorological conditions, provide the best potential to obtain
conclusive monitoring results because of the higher concentrations expected relative to
analytical detection limits
Measured air quality concentrations are then compared with matched modeled
concentrations. If modeled-concentrations are less than measured values based on
selected indicative pollutants, the modeled concentrations are scaled up to the magnitude
of the measured values A scale-up factor is determined separately for each pollutant
class (volatile organics, semi-volatile organics, and metals) Comparisons between
scaled-up concentrations and all applicable health criteria must be made for all pollutants
and applicable averaging periods Compliance based on this evaluation will be a
prerequisite for granting a "no-migration" variance, while non-compliance will constitute
a basis for petition denial The recommended methodologies for the conduct of
monitoring assessments for "no-migration" demonstrations are presented in Section 2 3
In existing units, air modeling and monitoring data for appropriate constituents must be
submitted as part of the "no-migration" petition for units currently managing hazardous
wastes. Petitions will be considered incomplete if these data are not submitted The only
exemption to this requirement is for petitions submitted prior to January 1,1990. These
petitions will be considered complete for "initial review" purposes if they lack only
modeling and monitoring data for particulates This exception was necessary to allow
those early petitioners reasonable time to implement the additional requirements of the
"Air Pathway Assessment Methodology" Particulate modeling and monitoring data,
however, must still be submitted to EPA before a "no-migration" determination can be
made.
Subsequent routine waste and soil sampling and analyses will be required to determine
compliance with modeling assumptions and results used for the "no-migration" petition.
The modeling analyses should establish a Mg/year application limit and constituent
concentration limits, neither of which should be exceeded. The recommended
methodologies for the conduct of routine sampling assessments after a "no-migration"
vanance has been granted are presented in Section 2 4
2-4
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2.2 Modeling Methodology
The air pathway assessment modeling methodology for "no-migration" demonstrations
involves applying emission rate and dispersion models These modeling results are used
to estimate the maximum air concentrations at the unit boundary for comparison to
health-based criteria The methodology consists of five steps as follows (see Figure 2-2)
Step 1 - Obtain Source Characterization Information. This information (e.g ,
unit size, waste quantity, etc) is needed to define the emission potential of
a disposal unit. The specific source data needed will be a function of the
input requirements of the emission and dispersion models selected
Step 2 - Select Release Constituents Unit and waste- specific information
should be used to identify potential release constituents for modeling
purposes
Step 3 - Calculate Emission Estimates' Unit-specific emission models
should be used based on source conditions identified in Step 1 for
constituents identified in
Step 2. These modeling results will provide constituent-specific emission
rate estimates, which are input to Step 4.
Step 4 - Calculate Concentration Estimates Emission rates from Step 3
should be used to calculate concentration estimates at and beyond the unit
boundary Standard dispersion models (see Section 2.2.2) should be used
to obtain these concentration estimates
Step 5 - Compare Modeled Concentrations with Matched Measured Data:
The measured and modeled data are matched in space and time. Average
concentrations measured across the monitonng program are compared
with corresponding modeled data for indicative pollutants after subtracting
background concentrations from the measured data Modeled
concentrations should be scaled-uo as necessary Modeled concentrations
are never reduced on this basis.
2-5
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Rgure 2-2
MODELING METHODOLOGY OVERVIEW
Stepl
Obtain Source
Characterization Information
1
Step 2
Select Release
Constituents
i
SteoS
Calculate Constituent-Specific
Emission Estimates
i
Step 4
Calculate Constituent-Specific
Concentration Estimates
i
SteoS
Cnnnontratmno ซ**ป*ป * JซMซ im*4
Data. Scale Uc
j
as Necessary
t
Stepfi
Compare Constituent-Specific
Results to Healtf-Based Crttena
(HFI) State/local
i
Input to
No-Migration' Petition
2-6
SI2074-2
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Step 6 - Compare Concentration Results to Health-Based Criteria (RFI and
State and Local Criteria) Concentration results from Step 5 should be
compared with constituent specific, health-based criteria presented in the
interim final RCRA Facility Investigation fRFI) Guidance (U.S.EPA, May
1989a) Chronic exposures for carcinogens and toxicants should be
evaluated by comparison of the estimated maximum annual (1-year) con-
centration directly to the annual average concentrations (based on RFI
health criteria and assuming a 70- year exposure) Therefore, the health
criteria concentrations should not be exceeded during any calendar year.
Furthermore, credit should not be taken for reduced 70-year average
concentrations if the unit will not be operational for the full 70-year period
Interpretation of the ambient concentration estimates should account for the
uncertainties associated with the source/waste characterization data, as well
as modeling inaccuracies
Hard copies of modeling input and output files and supporting calculations should be
submitted with the "no-migration" petition Submrttal of modeling files on floppy disk is
recommended to help facilitate review of the air pathway assessment by the U.S. EPA
Wind direction (wind rose) plots also should be submitted with the petition for each
modeling period
Recommended emission rate methods and dispersion modeling methods as they apply
to "no-migration" demonstrations are presented in Section 2 21 and 2.2.2, respectively.
2.2.1 Emission Rate Modeling
All air emissions sources (both direct and indirect) within the unit boundary should be
evaluated in the petition to demonstrate compliance with the "no-migration" criteria for the
air pathway at the point of compliance (based on modeling and monitoring) Emissions
sources outside of the unit boundary are excluded from the "no-migration" evaluation,
although it might be desirable to account for such background levels so that air
emissions attributable to the unit alone may be evaluated The only exceptions are
surface impoundment emissions if the impoundment(s) is covered in the "no-migration"
demonstration These emissions would be included in the "no-migration" demonstration
Air emission models can be used to estimate constituent-specific emission rates based
on waste/unit input data for many types of waste management units (An emission rate
is defined as the source release rate for the air pathway in terms of mass per unit time)
The models applicable to land disposal units are based on theoretical considerations and
have been evaluated against pilot-scale and field test results. Often these models are
empirically correlated. However, because the models attempt to predict complex physical
and chemical phenomena, they should be used carefully. These models are generally
considered accurate within an order of magnitude (assuming representative input data)
for short-term emission rate estimates. Accuracies for long-term estimates are more
2-7
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favorable and are also limited by mass balance considerations (i.e, the emission rate
cannot exceed the waste' input to the disposal unit)
The potential variability of the waste and unit input data should be accounted for in the
modeling assessment Therefore, a sensitivity analysis of this variability relevant to
emission rate estimates should be conducted to determine the level of confidence
associated with the emission modeling results
Emission rate estimation methods for gaseous emissions should be based primarily on
CHEMDAT7 (or alternatively LAND7 (US EPA, 1990)), which are computer models
applicable to land treatment units Emission factors should be used to estimate fugitive
emissions of particulate matter
ซป
Gaseous Emissions
The modeling methodology for "no-migration" demonstrations to estimate gaseous
emissions is based on trie application of CHEMDAT7 air emission models developed by
EPA's Office of Air Quality Planning and Standards (U.S. EPA, March 1989) and is
available from NTIS. These models are applicable to volatile as well as semi-volatile
constituents that enter the air pathway via volatilization CHEMDAT7 includes air emission
rate models for the following land disposal units
Land treatment
Oil film surface
Land treatment soil
Disposal impoundment
Landfills
Open landfills
Closed landfills
Comprehensive technical information regarding these CHEMDAT7 models is presented
in the Hazardous Waste Treatment. Storage and Disposal Facilities (TSDR Air Emission
Models (U.S. EPA, March 1989) This reference also presents air emission rate models
for many other sources
For some applications, Step 4 - Calculate Concentration Estimates, wilt not warrant the
use of emission models because it can be assumed that all of the volatile wastes handled
will eventually be emitted to the air. This assumption is generally appropriate for highly
volatile organic compounds placed in a disposal unit like a surface impoundment In
these cases, mass balance calculations can be used since the air emission rate can be
assumed to be equivalent to the disposal rate, and an emission rate model may not be
2-8
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required. This assumption is .valid because of the long-term residence time of wastes in
the disposal units. In open units like surface impoundments, a substantial portion of the
volatile constituents will frequently be released to the atmosphere within several days But
the use of the mass balance approach is only applicable if waste transformation and
degradation processes do not produce significant quantities of the constituents being
evaluated
For more complex situations (e.g, land treatment units and landfills), air emission models
can be used to obtain a more refined release rate If subsurface injection is the
application method, the depth of injection should be considered in the analysis of peak
emission rates Whenever subsurface injection is not the application method, the
petitioner should consider using the oil film model, or the landfill model for limited
seepage depth, not the full depth of tilling, when estimating maximum" emission rates
Inappropriate characterization of the depth of initial application can be a major oversight
that leads to underestimating concentrations
To calculate the oil loading rate and the concentration of constituents in the oil, the
following equations apply
ฃ = oil loading = [(W)x(0r)] / [(A)x(D)] - grains oil/cm* (Eg. 2-1)
where.
W = total mass of waste applied (g)
Or = grams of oil per gram of waste
A = area of plot (cm2)
D = tilling depth (cm)
C, = concentration of pollutant in oil, not waste
C, = [(ppmw pollutant in waste) / (Or)] x 10"6
2-9
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Fugitive Particulate Matter
Trace metal and semi-volatile constituents of fugitive particulate emissions are of concern
for "no-mjgration" demonstrations Emission factors should be used to estimate these
fugitive particulate air emissions Emission rate estimates should be based on standard
methodologies developed by the U.S. EPA in the following documents:
Hazardous Waste TSDF - Fugitive Particutate Matter Air Emissions Guidance
Document. (EPA-450/3-89-019), U.S. EPA, March 1989
Control of Open Fugitive Dust Sources. U.S EPA, September 1988a.
Compilation of Air Pollutant Emission Factors (AP-42), U.S. EPA, 1985,
Supplement B, September 1988b, and Supplement C, 1990)
Emission estimates should be representative of inhalable particles (le, particles 10
microns or less in diameter) Soil concentration estimates (representative of inhalable size
particles) from the surface of the unit should be used as modeling input to determine
constituent-specific emission rates These soil concentration estimates should be used
to define the upper limit for unit operating conditions and, therefore, should account for
the potential accumulations of the constituents being evaluated In other words, trace
metal analysis generally must consider worst-case annual impacts on soil metal
concentrations expected during the last year of operation Guidance on developing
particulate emission estimates is provided in Hazardous Waste TSDF - Fugitive Particulate
Matter Air Emissions Guidance Document (U S EPA, March 1989).
Potential fugitive particulate emissions due to mechanical disturbances, wind erosion, and
fugitive gaseous emissions from the application process, waste handling/transfer, and
waste storage within the LTU all should be quantitatively evaluated and presented in the
"no-migration" demonstration Particulate and gaseous emissions should be estimated
from tank loading, unloading, vacuum truck loading/unloading, vehicular-induced fugitive
dust, pumps, valves, flanges, etc, for all releases within the LTU The potential for
reduced fugitive particulate emissions as a function of moisture or oil and grease content
of exposed soil surfaces should be based on Figures 2-3 or 2-4, respectively. However,
the applicant must commit to maintain these soil conditions on a long-term basis in order
to obtain credit for these mitigative control conditions
Control performance should be estimated in the "no-migration" petition, it should be
confirmed that no sources are inappropriately dismissed because the petitioner assumed
100 percent efficiency for controls, eg watering plots/roads
2-10
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Routine (weekly) soil moisture and/or oil and grease content sampling from the unit and
background conditions is recommended to confirm initial emission modeling/control
assumptions, it should also include daily observations and documentation of visible dust
emissions (especially during unit disturbance periods and high wind speed events)
Appropriate soil sampling and analysis methods for this application are presented in the
following references
* Hazardous Waste TSDF-Fugitive Particulate Matter Air Emissions Document.
(Appendix D - Sampling and Analysis Procedures) U S. EPA, March 1989
(and subsequent versions as available)
RCRA Facility Investigation Guidance. Section 7 - Waste and Unit
Characterization, and Section 9 - Soil, U S EPA, May 1989a.
Test Methods for Evaluating Solid Waste. U S EPA, November 1986.
2-11
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Figure 2-3
WATERING CONTROL EFFECTIVENESS FOR UNPAVED TRAVEL
SURFACES (U.S. EPA, SEPTEMBER 1988a)
100%
75%
Instantaneous
PM-10
Control
Efficiency
50% -
25% -
95%
12345
Ratio of Controlled to Uncontrolled Surface Moisture Contents
2-12
512074-5
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Figure 2-4
PROCEDURE FOR ESTIMATING CONTROL EFFICIENCY WITH OIL
AND GREASE (O&G) CONTENT AND MOISTURE CONTENT
MEASUREMENTS (U.S. EPA, MARCH 1989)
100%
75%
Instantaneous
Control 50%
Efficiency
25% -
- 95%
2345
Ratio of O&G Content to Background Soil Moisture Content
6
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S12074-6
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Vehicle travel from the land treatment unit to other locations of the facility could result in
the "trackout" of contaminated soil This potential ^can be reduced by proper
management of soil moisture conditions (in general, muddy soil conditions are not condu-
cive to effective land treatment operations) Trackout can also be reduced by use of
vehicles which are committed exclusively to the land treatment unit and by the use of
routine washing of vehicles before they leave the unit "No-migration" demonstrations
should address unit-specific preventive controls for potential trackout of contaminated soil
and should estimate trackout rates
Wind erosion potential can be reduced by the revegetation of fallow areas and use of
berms or shelter belts around the perimeter of the unit "No-migration" demonstrations
should take appropriate credit for preventive wind erosion and soil erosion controls. Soil
and wind erosion rates for "no-migration" demonstrations should include emission rate
estimates with and without preventative emission controls
2.2.2 Dispersion Modeling
Emission rate values from Step 3 should be used as modeling input to calculate
concentration estimates at or beyond the point of compliance. Two alternative types of
models (i.e, flux models and dispersion models) are candidates for this application.
Flux models can be used to evaluate concentrations at and in the vicinity of an area
source (Most disposal units such as land treatment areas, surface impoundments, and
landfills can be classified as area sources) Although these models can be technically
sophisticated, they generally lack extensive validation
Standard dispersion models used by EPA for regulatory applications are based on the
assumption that the downwind concentration of air contaminants can be characterized
by a statistical (Gaussian) distribution Validation efforts have confirmed the performance
of this class of models Atmospheric dispersion models are typically accurate on a long-
term basis within a factor of two to three for flat terrain sites (inaccuracy can be a factor
of 10 or more in complex terrains) However, validation studies have been quite limited
in regard to receptors near an area source boundary. However, dispersion model
predictions for such situations are still considered more dependable than the use of flux
models which have little, if any, validation
The use of the Industrial Source Complex (ISC) model is recommended as tine preferred
model for "no-migration" demonstrations The ISCLT version of the model can be used
to calculate long-term concentrations for exposure periods ranging from 24 hours to
annual average estimates. The ISCST model is generally used to estimate concentrations
for averaging periods of 24-hours or less Selection of the ISCLT versus ISCST version
of the model should be based on matching the averaging time for dispersion modeling
with the specific exposure period for the applicable health criteria, including annual
averages. The model can be used for both flat and rolling terrain, and for urban or rural
2-14
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conditions Petitioners that use urban dispersion coefficients need to provide
documentation to support the use of this option, since the rural treatment will generally
show higher concentrations. The ISC model software is available from NTIS and the
user's guide is presented in Industrial Source Complex (ISC) Model User's Guide. (U S.
EPA, December 1987b) Additional guidance on dispersion model selection and
application is available in the Guideline on Air Quality Models (Revised). U.S. EPA, July
1986)
Meteorological data (i e., wind and atmospheric stability summaries) are necessary
dispersion modeling input. Data from a representative National Weather Service station
can be used as available but must be justified in terms of terrain, land/water interface, and
other relevant factors It is preferable to evaluate five years of meteorological data and
base "no-migration" estimates on the one-year period associated with the highest
predicted concentration, as opposed to a five-year composite model run Alternatively,
onsite meteorological data can be used If less than five years of meteorological data are
available (as is frequently the case for on-site data) the available data should be
compared to long-term offsite data to evaluate the representativeness of the data selected
for modeling to estimate air concentrations during the worst-case year Guidance on the
conduct of meteorological programs is presented in On-Srte Meteorological Program
Guidance for Regulatory Modeling Applications (US EPA, 1987)
Land treatment units can be seasonal operations, especially for northern sites The
modeling analyses should account for the seasonal variations in emission rates when
there are substantial differences in application rates on a seasonal basis Since wastes
are generally applied during the daytime, there ts a diurnal factor, which also can be
addressed Facilities where a waste stream (s) is applied once or several times a year
need special consideration There is a major complication: (1) annual average
concentrations could be heavily weighted by the specific conditions during the day of
application Petitioners that model extreme emission rates will need to estimate annual
average concentrations for a range of potential meteorological conditions that could occur
during the day(s) of applications If restrictive meteorological conditions could result in
exceedance of chronic health criteria, the maximum daily application rates may need to
be reduced or conditions for application restricted.
Two alternative dispersion modeling approaches are available for "no-migration"
demonstrations, as illustrated in Figure 2-5 The primary (required) approach involves the
direct application of the ISC dispersion model based on site-specific and unit-specific
input data. The alternative (optional) screening approach involves tine application of
modeling results available for a limited set of source and meteorological conditions This
screening approach can be used to obtain preliminary, conservative modeling estimates
Based on these results, the applicant may decide whether to consider waste treatment
or proceed to refined modeling. The "no-migration" demonstrations, however, must be
based on ISC. Following is a description of each of these approaches.
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Primary Approach
The conduct of a dispersion modeling study based on site/unit-specific model input data
is the required approach for "no-migration" demonstrations The air modeling analyses
should be conducted separately for each land treatment unit to account for variations in
unit size, configuration, and waste/operating conditions, however, modeled concentrations
should consider contributions from all units at each modeled receptor. This refined
modeling approach involves the direct use of the ISC dispersion model to provide
estimates of concentrations The following tasks are required, as indicated in Figure 2-5:
Determine-the point of maximum concentration up to 100m beyond
(outside) the point of compliance,
Subdivide the source area into multiple smaller source areas,
Determine the maximum concentration at or beyond the point of
compliance (generally the maximum concentration will be at the unit,
boundary), and
Adjust modeling results, as necessary, to account for the vertical wind
profile.
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Figure 2-5
STEP 4 - CALCULATE CONCENTRATION ESTIMATES
Emission Rate Data.
(Step 3)
Required
Meteorological Data
Optional
Primary Approach - Conduct
Srte/Unrt-Specific Modeling
Based on ISCST
and ISCLT
Determine Maximum
Concentration Point 100m
from Source
Subdivide Source into
Multiple Smaller Source
Areas
Determine Maximum
Concentration Boundary
Point of Compliance
Adjust Results for
Vertical Wind
Profile
Screening Approach - Based on
Available Modeling Results for a
Limited Set of Source/Meteorological
Conditions
Calculate Concentrations
Based on Available
Dispersion Factors
Adjust Concentrations
Based on Prevailing
Wind Direction Frequency
Adjust Concentration
Estimates Based on Site-Specific
Average Wind Speed
Adjust Concentration
Estimates Based on Vertical
Wind Speed Profile
Input to Step S - Compare Results to Health-Based Criteria
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S11074-3
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Dispersion modeling estimates should be obtained that are representative of each land
treatment unit A specialized modeling approach is generally needed for standard
dispersion models, such as ISC, in order to obtain concentration estimates near the
boundary of a large area source. This approach consists of the following tasks,
assuming a ground-level area source,
Determine the point of maximum concentration up to 100m outside the
point of compliance using standard dispersion modeling methods.
Concentration estimates should be obtained based on receptors placed in
each of 16 sectors of 22.5 degrees each (a finer resolution is acceptable)
in order to select the point of maximum concentration. A polar coordinate
system should not be used These results will provide the basis to identify
the sector associated with the maximum concentration.
Refine the area source grid to provide enhanced resolution near the area
of maximum concentrations The goal is to confirm that the size of each
area source is smaller than the distance from each area source to the
closest model receptor (See Figure 2-6) Computational restraints of ISC
require that area sources must be represented as a square or multiple
squares. (The ISC user's guide should be consulted for the approach to
use for irregularly shaped area sources) For "no-migration"
demonstrations, it is recommended that the land disposal area should be
represented initially by at least 25 squares of equal area
Using the refined area sources, estimate the concentrations from the point
of compliance out to at least 100m Contributions from all sources should
be included (For modeling purposes, a downwind distance of
approximately 1 m from the point of compliance can be used for the closest
receptors, as necessary) In most cases, the maximum concentrations and
the point of compliance are at the LTD boundary, but not always Periods
with minimal dispersion (stable conditions) can act to restrict plume growth
to the extent that maximum concentrations at the reference height of 1 5m
above ground level occur past the LTU boundary For this reason, the
dispersion modeling approach requires modeling out to 100m past the site
boundary
Concentration estimates for "no-migration" demonstrations should be
representative of the 1 5m inhalation height Meteorological data available
for modeling studies often are based on a 10m tower height. Air
concentrations are inversely proportional to wind speed. Near the surface,
the mean wind speed has been found to increase in proportion to the
logarithm of the height Therefore, wind speed values or modeling results
should be adjusted, as necessary, to account for the vertical wind profile.
2-18
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FIgurt 2-6
EXAMPLE SUBDIVISION OF AREA SOURCE
Wind Direction
Point of maximum concentration
at unit boundary'
j
Nested subdivisions, as necessary
to yield areas of < 100 m*
Point of maximum concentration 100 m
from unit boundary-
2-19
S1Z074-7
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Many standard dispersion models, such as ISC, extrapolate input wind data
to a height of 10m for ground level sources. However, 1.5m winds are
more representative for this application Example wind profile adjustment
factors for "no-migration" demonstrations are presented in Table 2-1 based
on the logarithmic wind profile law (U S EPA, 1974).
TABLE 2-1
T^XAMPLE ADJUSTMENT FACTORS TO ACCOUNT
^ - FOR THE VERTICAL WIND SPEED PROFILE
Wind Speed
Measurement
Height X (m)
200
15.0
10.0
5.0
20
1.5
Wind Speed Adjustment Factor
[Ratio of Wind Speed (1 5m) to
Wind Speed (Height X)]
07
0.7
07
0.8
09
- 1.0
Concentration Adjustment
Factor (CAF)
{Ratio of Concentration
(1.5m) to Concentration
(Height X)]
1 5
1.4
1 4
1.2
1 1
1.0
-Assuming neutral stability and uniform roughness
Screening Approach
Screening dispersion modeling is an optional approach to obtain preliminary, conservative
estimates of air concentrations The screening approach involves the manual calculation
of concentration estimates based on adjusting dispersion modeling results available for
a limited set of source/meteorological conditions Since these results may be less
representative than those based on the refined modeling approach, conservative
assumptions should be used. The following tasks are required for the screening
modeling, as indicated in Figure 2-5
Calculate concentration estimates at the unit boundary based on available
dispersion factors;
2-20
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Assume an invariant wind direction,
* Adjust concentration estimates to account for the site-specific average wind
speed,
Adjust concentration estimates to account for the vertical wind profile; and
Apply a safety factor to account for input data and modeling uncertainties.
This process can be summarized by the following equation-
M
C = ER X DF x UCF X (WDF/1QO) X (10/WS) x CAF X SF (Eq 2-2)
where
C = annual average concentration at unit boundary
ER = emission rate (106 g/yr = Mg/yr),
DF = dispersion factor for appropriate source area (sec/m3),
UCF = unit conversion factor (3 17 x 104),
WDF = frequency of occurrence of the prevailing wind direction (assumed
to be invariant for screening application, i.e, WDF = 100 percent);
WS = average wind speed 1 5m above ground (mph),
CAF = concentration adjustment factor to account for the vertical wind
profile (dimensionless), and
SF = Safety factor of 10 0 (to account for input and modeling
uncertainties)
The product of ER times DF times UCF yields an initial concentration estimate The
emission rate estimates from Step 3 should be used as ER values Dispersion factor (DF)
values can be obtained from Table 2-2 as a function of source area. These DF values
are based on ISCLT dispersion equations for a receptor on the downwind unit edge
2-21
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assuming a square area source configuration (with no subdivisions of the area), neutral
stability, 10 mph winds at a measurement height of 10m and an invariant wind direction
(i e, the receptor point for calculation purposes is directly downwind of the source 100
percent of the time).
This initial concentration estimate should be adjusted (using the parameters WS and CAF)
to account for site-specific wind conditions Representative National Weather Service or
onsite meteorological data should be used as the basis for these adjustments,
The modeling results presented in Table 2-2 are based on a 10 mph wmd speed "Tne
average wind speed (WS) at the site should, therefore, be used to adjustthese mullein ig
results Similarly, a concentration adjustment factor (CAF) should be usetttoaccountfor
the vertical wind speed profile. Values of CAF are presented in
Table 2-1 for a range of wind measurement heights to facilitate scaling concentration
modeling results to represent a 1 5m inhalation exposure
An example application of this approach is illustrated in
Section 3
2.3 Air Monitoring Methodology
For most "no-migration" variances, a monitoring program must be conducted to confirm
that modeled concentrations conservatively represent LTU impacts, i.e. modeled
concentrations should overestimate, not underestimate, actual concentrations (see Figure
2-7) The main objective of the ambient air quality monitoring program is to confirm that
the modeling analysis is conservative, not to calibrate the model to site conditions. The
monitoring program for the air pathway involves air quality monitoring (and optional
emissions monitoring) conducted pnor to the submission of the "no-migration" petition.
(This may involve monitoring demonstration plots for new land treatment unite.) The
applicant is encouraged to submit a detailed monitoring plan prior to the execution of the
field program to facilitate the completion of "no-migration" The air pathway assessment
requirements are also applicable to petitions that include "no-migration" xtemcwstratons
for multiple units at the facility
Separate air monitoring programs for each unit are generally necessary. However, there
is an exception to this requirement If the petition can demonstrate that a representative
monitoring program can apply to other units having similar characteristics such as
waste/soil, meteorological, topographic, air flow, and operating conditions, then only one
representative program would be necessary
/
Prior to implementing an air monitoring program, a sensitivity analyse should be done
that considers ranges in meteorological conditions and emissions for volatites,
semi-volatiles, and metals as a function of seasonal and operational factors.
2-22
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TABLE 2-2
EXAMPLE UNIT BOUNDARY DISPERSION FACTOR VALUES
Unit Area
(Hectares)
001
004
025
100
400
2500
10000
40000
Dispersion Factors I/
(sec/m3)
3.9x1 CT3
26X10"3
89x10^
28X10"4
79x1Q-5
1 5x1 O*5
4:3x10"ฎ
1 4x1 0"6
I/ Based on ISCLT results with the following assumptions
/
Ground-level area source (square configuration).
Average wind speed of 10 mph at a measurement height of 10m
(dispersion factors do not account for the expected lower wind
speeds at 1 5m exposure height
Invariant wind direction
Dispersion factors are the maximum value at the unit boundary.
2-23
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Figure 2-7
MONITORING METHODOLOGY - OVERVIEW
Modeling Assessments
Representative
Meteorological
Data Available
Conduct
Meteorological
Monitoring
Conduct
Emisswn/Air Quality
Monitoring
Emission
Monrtonng
Air Quality
Monitoring
Direct Emissions
Source Testing
for Point Sources
Isolation Flux
Chamber
for Area Sources
Point of Compliance
Air Monitoring for
Area Sources
Conduct
Dispersion Modeling
Conduct
Dispersion Modeling
Input to
No-Mtgraton'
Pdtilion
Conduct
Routine Waste and Soil
Sampling
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S12074.ll
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These results, therefore, provide the basis for selection of the target season, preferred
wind and temperature conditions,- as well as optimal operating conditions (i e conditions
to obtain worst-case concentrations) for conduct of the air monitoring program. Each
pollutant class needs to be considered separately Criteria should be established based
on sensitivity analyses to select specific periods that represent worst case conditions for
each pollutant class Conditions that may be difficult to monitor or model and are not
conducive to worst-case air concentrations (eg, snow cover, frozen ground or
precipitation conditions at LTUs) do not support viable monitoring periods.
2.3.1 Monitoring Approaches
There are two major areas of uncertainty in modeling air quality emission rates and
transport/dispersion Two monitoring strategies can be used to assess uncertainty in
these areas: ambient air quality monitoring and emission flux monitoring. Ambient air
quality monitoring is required in this methodology because it evaluates the overall
adequacy of the modeled ambient concentrations, i e, the endpoint of analysis Ambient
monitoring, therefore, can be used to evaluate the combined adequacy of emissions and
dispersion/ transport
Emission Monitoring - Emission flux monitoring and direct emission sampling are
suggested as options to enhance the comparison of modeled (an appropriate dispersion
modeling methodology was presented in Section 2 2) and measured air quality data
Direct emission sampling should be used for point sources, (e g, vents at covered waste
piles) Source testing via emission flux measurements can isolate the emission term To'-
be effective, this option requires detailed planning and interpretation.
An isolation flux chamber may be used for gas-phase area source emission
measurements (e g., land treatment areas). Multiple sampling locations are required to
adequately characterize the spatial and temporal variability of emission conditions over
an area source The spatial and temporal coverage recommended in U S EPA, February
1986, however, is not directly suited to the highly variable nature of emissions from land
treatment, which are often characterized by high emission rates immediately after waste
application, and then rapid decrease in emissions Alternative emission rate monitoring
approaches may need to be considered for waste spreading operations. The petitioner
needs to propose a sampling strategy that adapts this method to effectively estimate
average emission rates within the LTU for the 24-hour periods of the monitoring program
The spatial and temporal resolution in the emission flux monitoring needs to be sufficiently
compatible with key emission terms in the dispersion modeling analysis in order to
support model performance evaluation
The petitioner also should describe in the monitoring plan how the emission flux data will
be interpreted to evaluate the performance of emission and dispersion modeling. A
significant limitation of emission flux monitoring is that these techniques cannot be applied
during spreading and tilling operations, which are conditions when peak concentrations
2-25
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often occur. Further guidance on the application of isolation flux chambers and the
quality control procedures to be followed are provided in Measurement of Gaseous
Emission Rates from Land Surfaces Using an Emission Isolation Flux Chamber' User's
Guide. {U.S. EPA, February 1986)
A concept similar to flux monitoring is using a portable wind tunnel deployed in the field
to estimate potential participate emission rates due to wind erosion. But, either way,
.emission rate monitoring still requires the use of dispersion modeling to estimate air
concentrations. However, emission rate monitoring in conjunction wrth air monitoring at
the unit .boundary may provide an enhanced basis to interpret modeling results In most
cases, the preterrea approach would be to conduct a representative ambient air quality
monitoring program,
Ambient Monitoring - Air monitoring at the area of maximum concentration at or beyond
point of compliance is the preferred approach for confirming modeled concentrations.
This facilitates the direct comparison of measured and modeled air concentrations at or
beyond the point of compliance However, for air modeling and monitoring purposes,
EPA on a site-specific basis, may choose to modify the definition of the outer edge of the
unit boundary where there is an inordinate distance separating the outer most point of
waste placement and the outer edge of perimeter dikes or berms In other words, buffer
zones will not be,allowed to expand the unit boundary and the resultant point of
compliance
The sampling approach for inhalable particulates, which is generally applicable to many
trace metal constituent analyses, is well documented in the PM-10 regulations (40 CFR
Part 50 - Appendix J and 40 CFR Part 58 - Appendix E) This approach is based on the
use of a high-volume sampler. However, the potential for sample loss due to volatilization
should be evaluated.on a constituent-specific basis The inlet height for this sampler
should be 1.5m above the ground surface. Analytical methods for trace metals in
.paniculate samples generally include the application of Atomic Absorption,
Inductively-Coupled Argon Plasmography, and Graphite Furnace Atomic Absorption.
Additional information concerning the sampling and analysis of airborne trace metals is
summarized m the following document
Toxic Trace Elements Associated With Airborne Particulate Matter A Review".
(Schroeder, eta!., 1987).
Volatile organics are generally measured using EPA Method TO-14 (canister sampling
and GC/MS analysis). Semi-volatiles are generally measured using EPA Method TO-13,
i e PUF sampler. The EPA Compendium of Methods (U S EPA, April 1984, U.S EPA,
September 1986; U.S EPA, June 1988) should be consulted for specific monitoring
recommendations
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2.3.2 Meteorological Monitoring
Representative meteorological data (preferably onsite) will be necessary to interpret air
monitoring results and needs to be justified. Precipitation data that are representative of
the site should be provided for seven days before air monitoring is conducted and for the
duration of the ambient air quality monitoring program. After a precipitation event, air
monitoring should not be conducted for at least 48 hours unless justified on a site-specific
basis. The following documentation should be shown in the petition for onsite field
programs
Representative hourly averages are needed for wind speed, wind direction,
stability, and ambient temperature,
* Calibration procedures need to be shown,
The representativeness of meteorological data collected during the air
quality field program need to be compared to long-term averages using
offsrte data sources, and
The method used to estimate stability needs to be described
Recommendations on the conduct of meteorological programs are presented in On-Site
Meteorological Program Guidance for Regulatory Modeling Applications (U S - EPA,
1987)
Representative (preferably onsite) meteorological data also should be available as
dispersion modeling input to calculate concentration estimates based on emission rate
mentoring results
2.3.3 Pollutants to be Measured
Petitions do not have to include air monitoring data for those constituents that are
modeled to have concentrations that are ten times less than the applicable health criteria.
With the exception of benzene, the Agency intends to exclude constituents which are
considered insignificant for the "no-migration" demonstration This exclusion does not
apply to benzene because it is considered a critical constituent of "no-migration"
demonstrations for the land application o* refinery wastes The exclusion of benzene from
the ambient air quality monitoring program will be considered on a case-by-case basis
Monitoring results for at least one indicator constituent for volatile organics, semi-volatiles
and trace metals, should be used to confirm modeling results Monitoring results that are
below the analytical detection limit for an indicator constituent should be considered as
2-27
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acceptable if appropriate standard sampling and analytical methods are properly used
Long-term modeling results should not be adjusted for these situations.
2.3.4 Site Selection
The selection of appropriate monitoring locations is critical to ensure the measurement
of maximum concentrations. There should be upwind (at least 1) and downwind (at least
2} coverage, and the monitoring program duration must tie adequate to facilitate
comparison of monitoring and modeling results for at least five days, with 24-hour sample
duration for each. Additional recommendations for the conduct, of air monitoring
programs for gas phase and paniculate constituents are presented 'm the interim final
RCRA Facility Investigation Guidance (U.S EPA, May 1989a)
2.3.5 Sampling Duration
Monitoring should be conducted during a minimum of five sampling days of 24 tiours
each, which include worst-case emission/dispersion conditions Worst-case conditions
provide the best potential to obtain conclusive monitoring results because of the higher
concentrations expected relative to analytical detection limits The five days selected for
monitoring do not have to be a sequential five-day block This approach provides greater
flexibility for a petitioner to obtain air monitoring data during actual worst-case air
concentration conditions. Petitioners have the option to use more than five monitoring
days to compare monitoring versus modeling results for a larger data set The petitioner
also can develop alternative approaches to use monitoring data to confirm modeling
estimates in order to demonstrate "no-migration". If an alternative approach is*used,~lhe
burden of proof is on the petitioner to present a comprehensive technical defense of the
approach selected ^
2.3.6 Monitoring Requirements for New Units
The same submittal requirements discussed for existing units are applicable to new units.
However, for new units, an air monitoring plan can be submitted in lieu of monitoring
data "No-migration" variances for these new units will be granted on a conditional basis
and subsequent performances of one-time monitoring program must confirm the
modeling results presented in the petition to demonstrate "no-migration". The air
monitoring program must be implemented within one year of initiation of new unit
operations. The air monitoring program for new LTUs can be done concurrent with the
land treatment demonstration if this option is selected, the LTD monitoring data must
be submitted with the "nq-migration" petition
2.3.7 Documentation of Field Programs
The description of Chain of Custody Procedures needs to indicate ttow_sarnptes are
handled, stored, and transported. Furthermore, a detailed air quality monitoring program
2-28
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is of little value unless site conditions during the monitoring program are clearly
described. The following is needed to adequately interpret the measured data set
ป A site map is needed showing the locations of all active areas during each
day of the field program (where waste is applied, stored, and transferred,
etc);
All activities should be shown for each day of the monitoring program,
including application, disking, tilling, storage, vehicular-induced dust along
access roads, etc. Activities should be described as a function of time and
day;
Waste application amounts and waste constituents, including physical
characteristics, and soil characterization need to be described specific to
the field test period, and
Surface meteorological data (onsite or representative offsite data) needs to
be submitted for a seven-day period preceding each monitoring day, and
for the full monitoring period (wind speed/wind direction, precipitation,
stability, relative humidity or dew point temperature).
2.3.8 Pretreatrnent Issues
Petitioners for LTUs that receive (or will receive) waste pretreated to lower volatile organic
concentrations must adhere to the same submrttal requirements (including providing air
monitoring data) as discussed. Facilities that pretreat waste may have relatively low
ambient concentrations associated with these waste streams This could lead to difficulty
in quantifying ambient concentrations during an air quality monitoring program. It is
especially important for these facilities that the following be considered in the monitoring
program:
Care should be taken to select sampling days that are conducive to high
constituent concentrations, in order to improve the detectabilrty in the
ambient air of the constituents of the pretreated waste streams;
The preferred approach is to follow routine operating procedures as closely
as possible during the air monitoring program. The petitioner would have
the option, however, to apply waste streams (that are routinely pretreated)
without any treatment for the monitoring test periods, as necessary, to
improve detectabilrty in the ambient air. As part of this approach, credit for
pretreatment to lower volatile organic constituent waste concentrations
would need to be taken as an input parameter to support the "no-migration"
demonstration. If this option is used, it would be essential for the
differences in physical characteristics and pollutant concentrations in the
2-29
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treated and untreated waste to be clearly documented This would ensure
that the credit for pretreatment is accurately computed, and
Emission flux monitoring may be helpful to confirm emission rates for cases
where ambient concentrations are below detection limits.
The option to apply untreated wastes and to scale modeling for documented treatment
efficiency also would apply to facilities that currently apply untreated waste, but plan to
treat waste in the future There would be no need to delay the implementation of an
ambient air quality field program until treated wastes are routinely applied In all cases,
however, routine waste stream sampling must be sufficient to demonstrate consistent and
acceptable pretreatment efficiency
2.3.9 Presenting Monitoring Results
Monitoring results and quality control data should be submitted with the "no-migration"
petition. For each sampling medium, a minimum of five sampling days of 24-hours each
should be evaluated which include worst-case emission/dispersion events. Worst-case
emission/dispersion events for paniculate emissions may not necessarily coincide with
worst-case conditions for gaseous emissions For example, worst-case LTD conditions
for volatile organic constituent emissions will generally occur during the summer months
(especially hot and dry conditions) at the time of application and spreading of the waste
For this example the monitoring period should include at least one day of waste
application/ spreading It would be preferable to monitor during several of these waste
application/spreading events But the monitoring period should not include 24-hour
samples beyond the fourth day after the last waste incorporation For particulate
emissions, worst-case LTU conditions generally will occur during tilling operations
subsequent to initial waste incorporation, and during dry and high wind-speed conditions
which are conducive to wind erosion The monitoring period" for particulates should
include five days each with a high potential for particulate emissions.
2.3.10 Use of Measured Data
The use of monrtonng data for "no-migration" demonstrations is summarized in Figure 2-8.
The emissions and air monitoring data representative of worst-case, short-term conditions
should be used to evaluate the accuracy of the modeling estimates developed to support
the "no-migration" petition This should be accomplished by comparing short-term
modeling and monitoring results for the same source and dispersion conditions that
occurred during the monrtonng period. This comparison should be the basis for
developing a scale-up factor to adjust, as necessary, previous modeling estimates used
to demonstrate "no-migration" compliance. Short-term versions of the emission and
dispersion models should be used, as available, for these comparisons.
2-30
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Figure 2-8
UTILIZATION OF MEASURED DATA FOR
"NO-MIGRATION" DEMONSTRATIONS
1
Conduct
Short-Term
Monitoring
(Worst-Case)
Define Source and
Dispersion Conditions
During Monitoring Period
Conduct Short-Term
Modeling for Monitonng
T
Compare Maximum Short-Term Estimates for
Monitoring Penod
Rate ซ [Average background subtracted downwind measured <
ntrationsl/
[Modeling estimate (for same receptors and source/dispersion conditions}]
MQ Correction to
" No Migration*
Modeling Estimates
Adjust Short-Term Peak
and Annual Average
Modeled Corn
No-Mlgraton
Compliance
(RFI)
Pelrtion Dented
I Yes
Baste for Granting Variance
2-31
S12074-4
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A ratio of the maximum monitoring estimates divided by the modeling estimates (which
correspond to the same maximum monitoring locations and source/dispersion conditions)
should be computed Constituent-specific ratios should be determined as feasible.
Comparisons should be made for both emission rate monitoring (as available) and air
monitoring results. If the average ratio, based on indicative pollutants in a class, is
greater than 1, the maximum "no-migration" modeling estimates should be multiplied by
the ratio to account for modeling under-predictions This would apply to either the
emission flux or ambient air quality data The computed scale-up factors apply to all
pollutants and averaging periods in the applicable pollutant class If the ratio is less than
or equal to 1, the maximum "no-migraton" results should not be adjusted. The revised
^modeling estimates should -beDevaluated for compliance with the "no-migration" criteria
It should be noted that although worst-case monitoring conditions are used, exceedance
..of health based criteria during monitoring is not grounds for denial.
2.4 . Routine Waste and Soil Sampling
Ambient air monrtonng generally needs to be performed only once (i e. prior to submittal
of the "no-migration" petition) to confirm air modeling results. Routine compliance
monitoring for the air medium will typically consist of waste stream and soil sampling
during operation of the unit to confirm that the constituent concentrations specified as
operating limits in the petition are not being exceeded A plan for routine waste and soil
sampling should be submitted with each "no-migration" petition. This plan should be
implemented to determine on a continuing basis, compliance with "no-migration"
conditions .presented in the petition. A summary of this routine sampling process is
presented in Figure 2-9. ~ ,
2-32
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Figure 2-9
ROUTINE WASTE AND SOIL SAMPLING PROGRAM
Routine Waste
Sampling
(Volatiles and Semi-volaflles)
Weekly Soil Moisture
and/or Oil and Grease
Content
Annual Soil Sampling
(Trace Metals
and Semi-Volatile
Parbculates)
Additional Sampling as
Necessary to Ensure
Compliance with 3004(n)
NESHAPs and OSHA
Sampling
Plan
Define No-Migration
Operating Umrts
Based on Modeling
Assumptions and Results
Notify EPA
SU074-8
2-33
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The sampling plan should define specific "no-migration" operating limits. These operating
limits should be based on the modeling analyses (assumptions and results) presented
in the petition and should ensure compliance with all "no-migration" requirements and
applicable 3004(n). These operating limits should include, at a minimum, the following
factors
Concentrations in zone of incorporation,
Annual throughput quantity by volatile and semi-volatile constituents to
ensure compliance with chronic health criteria for gaseous emissions;
Weekly soil surface moisture and/or oil and grease content to ensure
implementation of fugitive dust emission mitigative controls as assumed m
the "no-migration" petition,
Annual soil sampling (based on composite results for the zone of
incorporation) to determine compliance with upper limit concentration
assumptions for particulate trace metals and semi-volatiles;
Daily documentation of visible dust emissions;
Waste concentration limits, and
* Additional criteria as necessary to ensure compliance with 3004(n).
The comparison of modeled emissions and concentrations data should be used to
establish peak short-term and average application rates. Peak and annual average
application rates need to be presented based on limits set from the air qualify analysis
used for the "no-migrahon" demonstration
Appropriate sampling procedures are presented in the following refi
Hazardous Waste TSDF - Fugitive Particulate Matter Air Emissions
Document. (Appendix D - Sampling and Analysis Procedures), U.S-EPA,
March 1989 (and subsequent versions as available),
RCRA Facility Investigation Guidance. (Section 7 - Waste and Unit
Characterization and Section 9 - Soil), U S EPA, May 1989a; and
Test Methods for Evaluating Solid Waste. US EPA, November 1986.
The unit owner/operator should notify EPA on a timely basis of non-compliance with
"no-migration" operating limits
2-34
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3.0 EXAMPLE APPLICATIONS
The following case studies have been selected to demonstrate the recommended air
pathway assessment methodology for "no-migration" demonstrations These case studies
present example modeling results and do not represent the example content of a
"no-migration" petition for the air pathway (which should contain a much more detailed
documentation of the analyses) Although not discussed in these examples, each case
study would require the conduct of a monitoring program to evaluate modeling results
(and to adjust for modeling under-prediction, as necessary) Routine waste and soil
sampling during unit operations would also be necessary to assure compliance with
"no-migratron" criteria Two examples, a gas phase and particle phase example are
presented in the following sections
3.1 Gas Phase Emissions - Example Assessment
The case study involves a "no-migration" petition for an existing land treatment unit and
includes an example application of the six-step air pathway assessment process The
following ts a synopsis of the modeling assessment for the new unit.
Step 1 - Obtain Source Characterization Information
The following input information describes the proposed land treatment unit:
Land area = 2.5 hectares (6 2 acres),
Annual waste throughput = 1,800 Mg,
Oil content of waste = 10 percent by weight;
Silt content = 10 percent,
Subsurface injection depth = 5 cm,
"filling depth = 20 cm,
Soil air porosity = 05,
Soil total porosity = 061,
i
Average molecular weight = 282 g/g mol;
Waste is applied 12 times per year (150 Mg/application) and tilled within 1
hour of application,
3-1
-------
Annual average wind speed = 10 mph, and
Average Waste Constituents
Pollutant ppm
j
Benzene 200
Toluene 750
Ethylbenzene 1500
Xylene 600
Step 2 - Select Release Constituents
Each of the four pollutants were covered by applicable health criteria Since the oi!
content is 10 percent of the waste, the constituent concentration in the oil is calculated
as follows*
Pollutant Concentration Concentration
in waste (ppm) in oil (ppm)
Benzene 200 2,000
Toluene 750 7,500
Ethylbenzene 1500 15,000
Xylene 600 6,000
Step 3 - Calculate Emission Estimates
The emission rate modeling process for land treatment units is summarized in Figure 3-1.
Air emissions can occur during three stages (i e, during waste application, after waste
application prior to tilling, and after tilling) The appropriate emission rate models are also
a function of the type of waste application (ie., surface application or subsurface
injection) as well as the fate of the oil for surface application operations prior to waste
incorporation into the soil (i e , formation of a surface oil film, oil seepage through a layer
of the soil, or the waste is immediately tilled into the soil). For this case study, it has been
assumed that the unit will use subsurface injection (thus the emission rates during
application are negligible) and tilling occurs immediately after injection Modeling results
based on CHEMDAT7 for untreated waste are summarized oelow for the applicable
pollutants For the annual estimates, the full 20 cm tilling depth was used
3-2
-------
Figure 3-1
GASEOUS EMISSION RATE MODELING - LAND TREATMENT UNITS
Source/Constituent Information
Calculate Emissions from
Waste Application
Calculate Emissions after
Waste Application
&nd bcrfoTB THtirtQi
CHEMOAT7
Land Treatment Model
\
Calculate Emissions
after Tiding
I
CHEMOATE7
Land Treatment Modal
Input to Dispersion Model
Equatons presented in tjaza
(US EPA December 1987)
me Waota Tmatmont Rtnrana and Dlsrrafll Paeiltties-Arr Emissions MacMs
3-3
S1Z074-9
-------
Pollutant Annual Emission Rate (Mg/yr)
Benzene C '25
Toluene C 56
Ethylbenzene 1.931
Xylene 0.346
These results indicated that waste pretreatment was necessary in order to reduce the
volatile organic constituent content necessary to comply with the RFI criteria for benzene.
Tne revised emission rates -based on 99 9 percent efficient treatment are as follows:
Pollutant Annual Emission Rate (mg/yr)
Benzene 3.3 x KT4
Toluene 67X10"4
Ethylbenzene 1.9 x 10"3
Xylene ' 3.5 xlO"4
Step 4 -'Calculate Concentration Estimates
The screening dispersion modeling approach was selected for this case study Actual
petitions would also need to show the refined modeling analysis. Representative wind
speed data were available from the National Weather Service The average wind speed
is 10 mph (at a measurement height of 10m)
A maximum concentration representative of chronic exposure at the unit boundary was
estimated as follows.
.C- ERxDFxTJCFx (JH2F/100) x (10/WS) x CAP x SF (Eq. 3-1)
where:
C = Annual average benzene concentration at the point of compliance
R ->-= -benzene annual average emission rate (computed to be
3 3 x 10"4 Mg/yr after waste treatment),
" DF - dispersion factor for source area of 2 5 hectares based on Table 2-2
(interpolated value of 1.2 x 10"4 sec/m3);
-UCF unit conversion factor (317 x 104),
3-4
-------
WDF = frequency of occurrence of the wind direction (100 percent);
WS = annual average measured wind speed (10 mph),
SF = safety factor of 10.0; and
CAF= concentration adjustment factor from Table 2-1 to account for the
lower wind speeds at the 1.5m receptor height compared to 10m
wind measurement height (1.4)
Therefore
C = (0 00033) x (1 2x10"*) x (3 17x104) x 100/100 x 10/10 x 1 4 x 10
= 0 02 jig/m3 benzene,
C = (0 00067) x (1 2x10"*) x (3 17x104) x 100/100 x 10/10 x 1.4 x 10
= 0 04 jig/rn3 toluene,
C = (0 00193) x (1.2x10^) x (3 17x104) x 100/100 x 10/10 x 1 4 x 10
= 0.10 /zg/m3 ethyl benzene, and
C = (0 00035) x (1 2X10"4) x (317x104) x 100/100 x 10/10 x 1 4 x 10
= 0.02 jig/m3 xylene.
CONCENTRATIONS jig/m3
POLLUTANT ANNUAL AVERAGE
Benzene 0 02
Toluene 0 04
Ethyl benzene 010
Xylene 0 02
Step 5 - Compare Matched Modeled Concentrations with Measure Data
This step would have been included had there been measured data provided in this
example
3-5
-------
Step 6 - Compare Concentration fud/m3) Results to Health-Based Criteria
POLLUTANT RFI CRITERIA
CARCINOGENS SYSTEMIC AVE. MODELED
TOXICANTS CONCENTRATION
Benzene 012 - ~D.02
Toluene - ? *~G.O4~-
Ethyl benzene - - 010
Xylene - - : 0.02
For this example, pretreatment resulted in all criteria being met If the criteria had not
been met, either the magnitude of waste would need to be reduced-during each
application, or conditions for application be restricted to meet all applicable critena based
on this pretreatment efficiency.
[Note that in the No Migration proposed rule published in August 1992,~EPA proposes
that it will not routinely consider additive effects for either carcinogens or systemic
toxicants, within a single medium or across two or more media. The Agency is soliciting
comments on this approach. An earlier draft of this Air Pathway Assessment
Methodology provided one approach to addressing possible addrtive effects of
hazardous constituents within the air medium However, in this draft EPA has deleted
consideration of possible additivity to be consistent with the Agency's current policy as
proposed in the rule EPA nonetheless welcomes comments on the issue of additivity in
decisions on individual no migration petitions and will give those comments careful
consideration ]
3.2 Fugitive Partlculate Matter Example Assessment
Fugitive particulate matter emissions were also characterized for the Hand freatment unit
described in the example presented in Section 31. The following additional data are
needed
Average Waste Constituents
Pollutant ppm
Arsenic 3
Chromium 300
Cadmium 5
3-6
-------
For the purpose of this example, assume that the preceding pollutant concentrations
apply to all soil within the LIU.
Potential sources of particulate emissions from land treatment units include the following
(see Figure 3-2)
Waste application operations,
Waste incorporation and cultivation operations,
Wind erosion of exposed surface areas, and
Track-out from vehicles
For this example, we will further assume that the petition shows that an efficient wash
station is in place near the boundary of the LTU In this example, emission estimates are
shown only for incorporation/cultivation operations, and vehicular travel on the LTU.
Actual petitions would need to estimate emissions .from waste application,
incorporation/cultivation, wind erosion, and trackout, and then sum the predicted
incremental impacts
The emission factors for incorporation and cultivation is as follows-
S f
e - Jc(4.80) (s)ฐ-6 Ib/acre (Eq. 3-2)
where:
e = PM10 emission factor in Ibs/yr;
j
k = particle size multiplier = 021 for PM10 and
s = silt content of the disturbed surface material (%) = 10.
3-7
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Figure 3-2
PARTICULATE EMISSION RATE MODELING - LAND TREATMENT UNITS*
Source/Constituent Information
i
Calculate Emisstons from
Waste Application
Vehicle Travel on Unpaved
Surfaces
Surface Spreading
Vehicle Travel on Unpaved
Surfaces
Bulldozer Operations
Calculate Emissions from
Waste Incorporation
and Cutovaton
Initial Waste
Incorporation
Subsequent
1
t
Agricultural TWing
Calculate Wind Erosion from
Exposed Surface Areas
Crusted Surface
Uncrueted Surface
1
r
Limited Wind Eroson
Input to Dispersion Model
* Emission factors are presented In Corrimt of Open Fugitive Dust Sources (U S EPA. September 1988)
Equipment track-out of partculates should also be evaluated
** Emissions generally negligible
3-8
S12074-10
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Further assume that application takes 1 hour and cultivation/tilling takes 1 hour per
application Thus.
e = (021)(4.8)(10)0'6 = (401 lbs/acres)(62 acres) = 249 ibs/yr
The following additional data are needed when using the equation for delivery vehicle
travel within the LTU:
i N&) (ir ' (f
where
e = PM10 emission factor in Ibs/acre,
s = silt content of road surface material, % = 10;
S - mean vehicle speed, mi/hr = 5,
W = mean vehicle weight, ton = 8,
w -mean number of wheels (dimensionless) = 10,
p = number of days with precipitation greater than or equal
to 0.01,
For this example, the term (365 - p/365) is dropped out because of the
assumption that there was no application occurring during wet conditions.
VMT = vehicle miles traveled, the annual source extent = 100
For PM10:
e = 2.1(10/12)(5/30)(8/3)07(10/4)05(100 miles) = 91.6 Ibs
3-9
-------
To calculate the arsenic emissions associated with the waste application/multiply the
concentration of arsenic m the soil, i.e., 3 ppm, by the results of the two equations and
sum as follows:
ฃte ป {3/1 0^(24.9) -+ (3/1 06)^ ฃ) ~= 3.5x1 0"4 IDS of arsenic
. ECr = -(300/10)(24.9) H- (300/1 0*)(91.flt) = 3.5x10'2 Ibs of chromium
Assuming the ratio of oil and grease content/background soil moisture = 4, -the control
efficiency is estimated to be 85% .based on Figure 2-4 Therefore, multiply -total emissions
by 0.15:
:EAsx0.15=
Cr x 0.15 = * 5.2>x lO^3 Ibs/yr = 24x10^ Mg/yr
E^-x 015^ -8.7x40'* Ibs/yr = 4 0 x 10"8 Mg/yr
Using "Equation 3-1 , the concentrations tor these metals are eslmialbiU db follows:
C = (2 4x10"^ x (1^x10^*) x (3.17X104) x 100/100 x 10/10 x 1.4 x 10
C * ^4x10^ X (1J2X10"4) x (3.17X1D4) x 100/100 x 10/10 x 1,4 x 10
/m3 dnuuiium
C = (4.0X10'8) x (12x10^) x (3.17X104) x 100/100 x 10/10 x 1.4 x 10
ซ 2.1X10"6 i/m3 cadmium
3-10
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Compare Concentration fuo/m3) Results to Health-Based Criteria
METAL
RFI CRITERIA
Arsenic
Chronnum
Cadmium
CARCINOGEN
TOXICANTS
23x10^
4.5x10"4
8.5x10"5
SYSTEMIC
AVE MODELED
CONCENTRATION
1 3x1 CT6
1.3X1CT4
2.1X1CT6
In this example, chromium is approaching the RFI criteria for cancer On this basis, the
routine sampling plan would need to confirm the assumed control efficiency of 85%
[Note that in the No Migration proposed rule published in August 1992, EPA proposes
that it will not routinely consider additive effects for either carcinogens or systemic
toxicants, within a single medium or across two or more media The Agency is soliciting
comments on this approach An earlier draft of this Air Pathway Assessment
Methodology provided one approach to addressing possible additive effects of
hazardous constituents within the air medium However, in this draft EPA has deleted
consideration of possible additivity to be consistent with the Agency's current policy as
proposed in the rule EPA nonetheless welcomes comments on the issue of additivity in
decisions on individual no migration petitions and will'give those comments careful
consideration.]
3-11
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4.0 REFERENCES
Davis, C, etal December 1987. "A Review of Sampling Methods for Polyaromatic
Hydrocarbons in Air" The International Journal of the Air Pollution Control and
Hazardous Waste Management, Vol 37, No. 12, Pittsburgh, PA , 15230.
Schroeder, W, et al, November 1987 'Toxic Trace Elements Associated with Airborne
Participate Matter' A Review" The International Journal of the Air Pollution Control and
Hazardous Waste Management, Vol. 37, No 11, Pittsburgh, PA , 15230.
U.S EPA 1990. Supplement C Compilation of Air Pollutant Emission Factors, (AP-42).
Office of Air Quality Planning and Standards Research Triangle Park, NC. --
U.S EPA. July, 1990 User's Guide for land Treatment Compound Property Processor
and Air Emissions Estimator (LAND7) U S Environmental Protectipn Agency, Chemical
and Petroleum Branch, OAQPS, Research Triangle Park, NC
U.S EPA. May 1989a. RCRA Facility Investigation Guidance, (intenm final)
EPA-530/SW-89-031 Office of Solid Waste Washington, D C 20460.
U.S EPA May 1989b Air Release Screening Assessment Methodology, Office of Solid
Waste Washington, D C 20460
U.S. EPA March 1989 Hazardous Waste TSDF - Fugitive Paniculate Matter Air
Emissions Guidance Document (Review Draft) EPA-450/3-89-019. Office of Air Quality
Planning and Standards Research Triangle Park NC
U S EPA. September 1988a Control of Open Fugitive Dust Sources, EPA 450/3-88-008.
Office of Air Quality Planning and Standards Research Triangle Park, NC 27711.
US EPA September 1988b Supplements Compilation of Air Pollutant Emission
Factors, (AP-42). PB89-128631 Office of Air Quality Planning and Standards Research
Triangle Park, NC.
US EPA June 1988. Second Supplement to Compendium of Methods for the
Determination of Toxic Organic Compounds in Ambient Air Office of Research and
Development, Research Tiiangle Park, NC.
U.S. EPA. 1987 On-Site Meteorological Program Guidance for Regulatory Modeling
Applications. EPA-450/4-87-013 Office of Air Quality Planning and Standards. Research
Triangle Park, NC 27711.
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US EPA. December 1987a. Hazardous Waste Treatment Storage and Disposal Facilities
(TSDF) Air Emission Models) EPA-450/3-87- 026 Office of Air Quality Planning and
Standards Research Triangle Park, NC 27711.
U.S. EPA. December 1987b Industrial Source Complex (ISC) Model User's
Guide-Second Edition. EPA-450/4-88-002a and b Office of Air Quality Planning and
Standards Research Triangle Park, NC 27711
U S EPA November 1986 Test Methods for Evaluating Solid Waste (SW-846), Office
of Solid Waste, Washington, DC 20460
US EPA September 1986 First Supplement to Compendium of Methods for the
Determination of Toxic Organic Compounds in Ambient Air. EPA-600/4-87-006 Office
of Research and Development Research Triangle Park, NC
U S EPA February 1986 Measurement of Gaseous Emission Rates from Land Surfaces
Using an Emission Isolation Flux Chamber User's Guide EPA/600/8-86/008. NTIS PB
86-223161 Environmental Monitoring Systems Laboratory. J_as Vegas, NV 89114
U S. EPA July 1986 Guideline on Air Quality Models (Revised). EPA-450/2-78 027R.
NTIS PB 86-245248 Office of Air Quality Planning and Standards Research Triangle
Park, NC 27711.
US EPA. September 1985 Compilation of Air Pollutant Emission Factors, (AP-42)
Office of Air Quality Planning and Standards Research Triangle Park, NC.
U.S EPA. April 1984 Compendium of Methods for the Determination of Toxic Organic
Compounds in Ambient Air EPA-600/4-84-041. Office of Research and Development
Research Triangle Park, NC.
U S EPA 1974 Development of Emission Factors for Fugitive Dust Sources Office of
Air Quality Planning and Standards Research Triangle Park, NC 27711
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