U.S. Environmental Protection Agency
              Office of Solid Waste
                Washington, DC
                  JULY 1992

                           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

                           TABLE OF CONTENTS

         Facility Description                                            22
         Site Characterization                                          23
              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

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"

 variance.  The land disposal prohibitions become effective on the dates indicated

     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

 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.

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

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

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

 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,

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

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.

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
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
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

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

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

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.

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

 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.

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

 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

 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,

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

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.
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


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.

                    Pre-Submittal Meetmg(s)
                          State Allow
                         No Migration
Inform Petitioner
  of Intent to
Draft Fact Sheet
 and PR Notice



                       Internal Review
                      Propose FR Notice
                       Public Comment
                     Evaluate Comment(s)
                        and Revise FR
                       Internal Review
                    Issue Final FR Notice
                          Petition Received
                            at EPA HQ's
                                              Send Acknowledgement
                                                 Letter to Petitioner
                          Technical Review
Request Additional
               "No Migration" Petition Review Process

 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

 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

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

 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

 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 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

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

     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

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
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

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*

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

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

     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.)
Surface-Water Hydrology -

 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

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

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.)
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.

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

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.

     Water content
     Pressure potential
     .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

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

 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

 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
     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

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:
    Species diversity and abundance potentially affected by migration from the

     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.

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
     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

     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

     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.

                         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
      Q    Documentation of unit
      Q    Documentation of unit operation
O    Closure plans
D    Post-closure plans
D    Cover design
Q    Design QA/QC demonstration (testing &
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
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
El    Hand) mg procedures
fj    Waste treatment before, during and after
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
Q    Assessment of immobilization due to
G    Assessment of photodegradati on
D    Assessment of immobilization due to
      hydrolysis      t
Q    Assessment of immobilization due to

Site Characterization

D    Surficial geology and soils (regional and
      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

      P    Geologic cross sections
      G    Degree of bedrock faulting and
      G    Rock characterization
G    Ground-water hydrology (regional and
      G    Water table map
      Q    Seasonal variations in the water
      G    Identification of all aquifers and
      Q    Characterization of all aquifers
      G    Vertical and horizontal hydraulic
      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
Q    Implementation schedule for the
      monitoring program
Q    Equipment used at the moniton ng
Q    Sampling and analytical techniques
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
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

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

      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
      Q    Biosphere alterations

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.

The following is a list of selected documents which may be of value to potential

Permit Applicants' Guidance Manual for  the General Facility Standards  1983.  EPA

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-

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-

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,

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-

Integrated Risk Information System (IRIS) Chemical Files. EPA/600/8-86/032b


                   Prepared for
         U.S. Environmental Protection Agency
               Office of Solid Waste
                 Washington, DC
                   JULY 1992

                       TABLE OF CONTENTS
1.0   INTRODUCTION .              	            1-1

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 	
Gas Phase Emissions - Example Assessment . 	
Fuartive Particulate Matter - Examole Assessment 	
4.0   REFERENCES                                  ...        4-1


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


            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

2.1   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


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

                                            Figure 2-1
                                        NESHAP Compliance
                                        Screening Option''
                                       for Dispersion Modeling
                                        Local Complianoe
                                          as Applicable
Scated-up Modeted
                                                                         Treat Waste/
                                                                       Reduce Emissions

                                     Bam tor Grantbig Variance
                                        Routine Waste/Soil

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

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

2.2   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

      •     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.

                                  Rgure 2-2
Obtain Source
Characterization Information

Step 2
Select Release

Calculate Constituent-Specific
Emission Estimates

Step 4
Calculate Constituent-Specific
Concentration Estimates

Cnnnontratmno ซ**ป•*ป * JซMซ im*4
Data. Scale Uc

as Necessary
Compare Constituent-Specific
Results to Healtf-Based Crttena
(HFI) State/local

Input to
•No-Migration' Petition

       •      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


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

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


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

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)

 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

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

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.

                                      Figure 2-3
                       SURFACES (U.S. EPA, SEPTEMBER 1988a)
50%  -
                    25% -

                         Ratio of Controlled to Uncontrolled Surface Moisture Contents

                                    Figure 2-4
                     MEASUREMENTS (U.S. EPA, MARCH 1989)
       Control 50%
             25%  -
                                                                       -  95%

                        Ratio of O&G Content to Background Soil Moisture Content

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


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

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.

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

                                                      Figure 2-5

                     Emission Rate Data.
                       •   (Step 3)
      Meteorological Data
                   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
                      Determine Maximum
                     Concentration Boundary
                      Point of Compliance
                       Adjust Results for
                         Vertical Wind
  Screening Approach - Based on
  Available Modeling Results for a
Limited Set of Source/Meteorological
     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

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

      •     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.

                                             FIgurt 2-6

                          EXAMPLE SUBDIVISION OF AREA SOURCE
                                           Wind Direction
Point of maximum concentration
             at unit boundary'
Nested subdivisions, as necessary
to yield areas of < 100 m*
         Point of maximum concentration 100 m
                         from unit boundary-

            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
Wind Speed
Height X (m)
Wind Speed Adjustment Factor
[Ratio of Wind Speed (1 5m) to
Wind Speed (Height X)]
- 1.0
Concentration Adjustment
Factor (CAF)
{Ratio of Concentration
(1.5m) to Concentration
(Height X)]
1 5
1 4
1 1
     -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;

      •     Assume an invariant wind direction,                              ••

      *     Adjust concentration estimates to account for the site-specific average wind

      •     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-

    C = ER X DF x UCF X (WDF/1QO) X (10/WS)  x CAF X  SF    (Eq  2-2)

        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
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


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.


                           TABLE 2-2
Unit Area
Dispersion Factors I/
3.9x1 CT3
1 5x1 O*5
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.

                                                      Figure 2-7

                               MONITORING METHODOLOGY - OVERVIEW
                                             Modeling Assessments
                                                     Data Available
                                                   Emisswn/Air Quality
                                      Air Quality
                Direct Emissions
                 Source Testing
                for Point Sources
 Isolation Flux
for Area Sources
Point of Compliance
 Air Monitoring for
   Area Sources
                                 Dispersion Modeling
                                  Dispersion Modeling
                                                        Input to
                                                  Routine Waste and Soil

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


 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

 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

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

      •      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,

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

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


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,

      •     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

      •     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

      •     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


            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.

                                                    Figure  2-8
                                 UTILIZATION OF MEASURED DATA FOR
                                  "NO-MIGRATION" DEMONSTRATIONS
                                                  Define Source and
                                                 Dispersion Conditions
                                                During Monitoring Period
                                                 Conduct Short-Term
                                                Modeling for Monitonng
                                        Compare Maximum Short-Term Estimates for
                                                  Monitoring Penod
                          Rate ซ  [Average background subtracted downwind measured <
                                 [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
                                                                            Pelrtion Dented
                                                         I Yes

                                              Baste for Granting Variance

 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.       ~ ,

                                                    Figure 2-9

                              Routine Waste
                        (Volatiles and Semi-volaflles)
                           Weekly Soil Moisture
                           and/or Oil and Grease
                           Annual Soil Sampling
                              (Trace Metals
                            and Semi-Volatile
                          Additional Sampling as
                           Necessary to Ensure
                          Compliance with 3004(n)
                           NESHAPs and OSHA
                                                                         Define No-Migration
                                                                           Operating Umrts
                                                                          Based on Modeling
                                                                        Assumptions and Results
                                                                        Notify EPA

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

      •     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


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,
      •     Average molecular weight = 282 g/g mol;

            Waste is applied 12 times per year (150 Mg/application) and tilled within 1
            hour  of application,

      •     Annual average wind speed = 10 mph, and

      •     Average Waste Constituents

            Pollutant          ppm
            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

                                               Figure 3-1
                                      Source/Constituent Information
                                           Calculate Emissions from
                                             Waste Application
                                           Calculate Emissions after
                                             Waste Application
                                             &nd bcrfoTB THtirtQi
                                                                Land Treatment Model


Calculate Emissions
after Tiding

                                            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

 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)

        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),


      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)


  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


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

Step 6 - Compare Concentration fud/m3) Results to Health-Based 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

Average Waste Constituents

Pollutant    ppm

Arsenic     3
Chromium   300
Cadmium    5


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)

      e = PM10 emission factor in Ibs/yr;
      k = particle size multiplier = 021 for PM10  and

      s = silt content of the disturbed surface material (%) = 10.

                                                   Figure 3-2

                                         Source/Constituent Information
                                               Calculate Emisstons from
                                                 Waste Application
                        Vehicle Travel on Unpaved
                                                Surface Spreading
Vehicle Travel on Unpaved
                                                Bulldozer Operations
                                               Calculate Emissions from
                                                Waste Incorporation
                                                   and Cutovaton
                                  Initial Waste
Agricultural TWing
                                             Calculate Wind Erosion from
                                               Exposed Surface Areas
                              Crusted Surface
 Uncrueted Surface
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

 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
      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

 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:

 €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

Compare Concentration fuo/m3) Results to Health-Based Criteria


 1 3x1 CT6
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

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.

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