PB89-160006
MIGRATION VARIANCES TO THE HAZARDOUS WASTE LAND DISPOSAL PROHIlgiTIONS
GUIDANCE MANUAL FOR PETITIONERS
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, B.C.
JAN 89
U.S. DEPARTMENT OF COMMERCE
National Technical Information Service
NTIS
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NO MIGRATION" VARIANCES TO THE HAZARDOUS WASTE
LAND DISPOSAL PROHIBITIONS:
A GUIDANCE MANUAL FOR PETITIONERS
DRAFT
DO NOT CITE OR QUOTE
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF SOLID WASTE
WASHINGTON, D.C.
CONTRACT NUMBER 68-01-7310
Prepared by
NUS CORPORATION
910 CLOPPER ROAD
P.O. BOX 6032
GAITHERSBURG, MARYLAND 20877-0962
and
THE EARTH TECHNOLOGY CORPORATION
300 NORTH WASHINGTON STREET
ALEXANDRIA, VIRGINIA 22314
JANUARY 1989
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50272-101
REPORT DOCUMENTATION
PAGE
1. REPORT NO.
EPA/530-SW-89-032
4. Title arid Subtitle
"NO MIGRATE" VARIANCES TO THE HAZARDOUS WASTE LAND DISPOS
A GUIDANCE MANUAL FOR PETITIONERS (DRAFT) (DO NOT CITE OR 01
)
«_ PROHIBITIONS:
3. Recipient s Accession No.
PM9 160006/AS
5. Report Date
JANUARY 1969
JOTEJ i 6.
7. Author(s;
OFFICE OF SOLID WASTE
8. Performing Organization Rept. No
66-01-7310
9. Performing Organization Name and Address
NUS CORPORATION
910 CLOPPER ROAD
PO BOX 6032
6AITHERSBUR6, HP 20S77-Q962
10. Project/Task/Work Unit No.
11. Contract(C) or Brant 16; No.
(C)
(6) 66-01-7310
12. Sponsoring Organization Name and Address
U.S. EPA
OFFICE OF SOLID WASTE
401 M STREET. Sw
WASHINGTON. DC 20460
13. Type of Report Si Period Covered
DRAFT 6UID. MANUAL - 1/89
15. Supplementary Notes
i&. Abstract (Limit: 200 words;
/
A 'no migration1* variance is a formal decision that can be rendered by the EPA to allow the land disposal of specific,
prohiDiteo wastes not meeting the treatment standards estaolisned by EPA at a particular facility.
In 1966. Congress passeo the RCRA authorizing EPA to establish nationwice standards for the management of hazaraous
wastes. Under HSwA, RCRA Sections 3004id), (e), and (g) were to include provisions prohibiting the land disposal of all
sucn "listen* and 'characteristically hazardous' wastes unless they are first treated. Wastes includeo in the EPA's
land disposal prohibitions will have to be treated by best demonstrated technology to aeet the treatment standard estab-
lished bv EFA, unless & ''no migration* variance is obtained. Prohibited wastes cannot be stored on the land (unless.
17. Document Analysis a. Descriptors
b. Identifiers/Open-Ended Teras
c. COSATI Field/Group
18. Availability Statement
RELEASE UNLIMITED
19. Security Class (This Report)
UNCLASSIFIED
20. Security Class (This Page)
UNCLASSIFIED
(See ANSI-Z39.18) ~~ OPT
(For
21. No. of Pages
(04
22. Price
0
ONAL FORM 272 (4-77)
terly NTIS-35)
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Table of Contents
What is a "No Migration" Variance? 1
What are the Land Disposal Prohibitions? 1
Additional Requirements of the Land Disposal Restrictions
First Third Rule 3
Compliance with Other Applicable Laws 3
Monitoring Plans for Land Disposal Units 3
Reporting of Changes in Operating Conditions From
Those Described in the Variance Application 3
Detection of Migration of Hazardous Constituents 3
Who Can Receive a "No Migration" Variance? 4
What is the Definition of the "Unit Boundary?" 5
*
How are Levels of Constituents Evaluated? 6
How Long is "As Long As the Wastes Remain Hazardous?" 7
What is the Relationship Between Land Treatment
Units and "No Migration"? 8
What is the Relation Between "No Migration" Variances,
RCRA Permits, and Other Federal Laws? 9
Can Generic Petitions be Submitted Covering Several
Similar Facilities? 10
When Does a Variance Become Effective and How Long
Does it Last? 10
What is the Petition Procedure for "No Migration" Variances? 11
Pre-Submittal 11
Petition Submittal 11
Petition Review 13
Decision to Grant or Deny 14
What Information Should be Included in a "No Migration"
Petition? 14
Waste Descriptions 15
Waste Types and Sources 15
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Waste Characteristics 16
Waste Incompatibilities 16
Waste Transformation Mechanisms 16
Facility Description 18
Site Characterization 19
Geology 19
Ground-Water Hydrology 20
Surface-Water Hydrology 21
Climatology and Meteorology 21
Background Environmental Quality 22
Monitoring Plans 22
Waste Mobility Modeling 24
Assessment of Environmental Impacts 27
Prediction of Infrequent Events 28
Quality Assurance and Control 29
Checklist of Information Needs 31
Where Can I Obtain Additional Information
Concerning "No Migration" Variances? 34
Appendix: Draft Air Pathway Assessment Methodology
for "No Migration" Demonstrations
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What is a "No Migration" Variance?
A "no migration" variance is a formal decision that can be rendered by the EPA to
allow the land disposal of specific, prohibited wastes not meeting the treatment
standards established by EPA at a particular facility. 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 edge of the disposal unit. In
most cases, the disposal unit is defined as the limit of natural barriers and/or
engineered components, but may be defined differently in some site-specific cases.
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 are first treated.
Wastes included in the EPA's land disposal prohibitions will have to be treated by
best demonstrated available technology (BOAT) to meet the treatment standard
established by the EPA, 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 below.
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Novembers, 1986 - Solvents
JulyS, 1987 - California List*
Augusts, 1988 - At Least One-Third of All Other Listed Wastes
June 8,1989 - At Least Two-Thirds of All Other Listed Wastes
May 8,1990 - All Remaining Listed Wastes and All Characteristic
Wastes
No prohibitions are applicable to contaminated soil and debris from the
Comprehensive Environmental Response, Compensation and Liability Act
(Superfund) sites until November 8, 1988. A complete schedule of the land disposal
prohibitions can be found in 40 CFR 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. However, 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 may be allowed nationally by EPA for up
to 2 years if treatment capacity is inadequate. 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 untreated
RCRA hazardous wastes will be banned from land disposal unless a "no migration"
variance is received from the EPA.
Based on regulations developed by the California Department of Health Ser-
vices for hazardous waste land disposal restrictions in the State of California.
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Additional Requirements of the Land Disposal Restrictions First Third Rule
In addition to promulgating specific treatment standards and effective dates for
"First Third" wastes, the Land Disposal Restrictions First Third Rule [53 FR 31138,
August 17, 1988] added new procedural and informational requirements at 40 CFR
268.6 for petitioners seeking to demonstrate "no migration" for land disposal units.
Based on inquiries and comments received on the subject of "no migration"
petitions, the Land Disposal Restrictions First Third Rule added the following
requirements.
Compliance with Other Applicable Laws
40 CFR 268.6(a)(5) requires petitioners to include information demonstrating that
units for which they seek a "no migration" variance comply with other applicable
Federal, State, and local laws.
Monitoring Plans for Land Disposal Units
40 CFR Sections 268.6(a)(4) and 268.6(c)(1) require continued monitoring of media
of concern to verify compliance with the "no migration" demonstration.
Monitoring of hazardous waste units is also required unless technically impractical
or infeasible.
Reporting of Changes in Operating Conditions From Those Described in the
Variance Application
40 CFR 268.6(e) requires 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 the water table or surface water flow.
Detection of Migration of Hazardous Constituents
40 CFR 268.6(f) requires immediate suspension of receipt of prohibited waste and
notification of EPA within 10 days if it is determined that there is migration of
hazardous constituents from the unit to any environmental medium.
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Who Can Receive a "No Migration" Variance?
A "no migration" variance petition can be submitted by anyone who generates,
stores, or disposes hazardous wastes. The petition for a "no migration" variance
can be submitted by any interested waste generator or facility owner or operator,
either individually or collectively. The petition must clearly demonstrate that the
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.
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, rather than on the concentration of hazardous constituents in the
waste.
The second scenario is the placement of a waste consisting of fairly immobile
constituents in a monofill 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 in 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
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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 ignitable, reactive, or corrosive
characteristics.
In the fourth "no migration" scenario, hazardous waste is stored temporarily for a
purpose other than to accumulate 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.
Except for temporary storage or treatment operations, it should not be assumed
that man-made barriers or engineered systems (e.g., liner systems, steel tanks) 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 are not envisioned for conventional land
disposal units (e.g., landfills and surface impoundments).
In addition, the EPA will generally deny variances to any disposal facility 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 in compliance should not affect EPA's review of a petition. However, for
a unit located in a waste management area where releases have occurred, the
owner or operator is not encouraged to submit a "no migration" petition unless he
can conclusively demonstrate that the release is not from the unit seeking a
variance.
What is the Definition of the "Unit Boundary?"
The unit boundary (and consequently, the point of compliance (POQ) is defined by
the extent of the natural or engineered barriers that contain the waste. (In
demonstrating "no migration," a strong preference will be shown for units relying
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upon natural barriers to prevent migration.) For land treatment units, the unit
boundary would be the lateral and vertical extent of the treatment zone. The unit
also includes within its boundary any dikes or berms that immediately surround it.
For the air medium, the POC for demonstrating "no migration" is the downwind
boundary of the unit at a height of 1.5 meters.
How are Levels of Constituents Evaluated?
A successful "no migration" demonstration must show that actual or predicted
concentrations of hazardous concentrations 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. 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.
However, 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. When site-specific data are not available,
worst-case assumptions must be used.
In reviewing the petition, EPA will compare the calculated concentrations of
hazardous constituents to Agency-approved levels. For example, the Agency would
compare the constituent concentrations in leachate to the Maximum Concentration
Levels (MCLs). If an MCL is not available for a constituent, the appropriate health-
based levels would be the Reference Dose (RfD) for noncarcinogens and the Risk
Specific Dose (RSD) for carcinogenic compounds. These health-based criteria have
been calculated by assuming chronic (lifetime) exposure by ingestion of
contaminated water. More information on these health-based numbers is 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
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various on-line networks such as DIALCOM Inc., the Public Health Network, and the
National Library of Medicine's TOXNET.
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 ingestion and inhalation for a subset of
the hazardous constituents listed in Appendix VIII of 40 CFR 261. The preliminary
draft RCRA Facility Investigation (RFI) Guidance (EPA 530/SW-87-001. July 1987); and
the preliminary draft Surface Impoundment Clean Closure Guidance. U.S. EPA, 1987
contain tables of health-based criteria, as well as explanatory text on the
assumptions used to calculate the numbers. Because all health- based numbers are
subject to review and change, EPA recommends that the petitioner contact EPA's
Environmental Criteria and Assessment Office in Cincinnati, Ohio at (513) 569-7531
to obtain up-to-date information on health-based levels.
In addition to comparing individual constituents to the appropriate health-based
level, the Agency will 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 will also consider the potential
threat posed by adding the two constituents. In general, the Agency will consider
additivity only for constituents in the same medium (e.g., air). For more
information on the EPA's policy on chemical mixtures, the petitioner should refer to
the Guidelines for the Health Risk Assessment of Chemical Mixtures (51 FR 34014).
Petitioners for units in high background situations must demonstrate that the
incremental contributions of contaminants from their unit will not, in and of
themselves, exceed health-based levels.
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
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have to demonstrate "no migration" forever, unless such constituents are removed
at closure or the unit is capped. (Capping will only be acceptable where there is not
leaching potential as determined using the toxic characteristic leaching procedure
(TCLP) with water.) Note, however, that the UIC program considers a
demonstration of "no migration" for 10,000 years to be sufficient. While this time
frame may be valid for degradation in the injection zone, is not necessarily valid for
other land disposal units.
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 restricted wastes which do not meet the BOAT
performance standards, an owner or operator of a land treatment unit should
consider applying fora "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.
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 pretreat a volatile waste (e.g., air stripping with appropriate
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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 biotoxicity studies, degradation studies, and general site
information regarding ground water, surface water, climate, and soil.
The LTD can be used as a basis upon which to build a "no migration" petition.
However, the information that is typically provided in the LTD is largely current
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, a TCLP
using water (at the pH of ambient rain water) to determine metals leachability must
be performed at closure, and a closure and post-closure plan must be submitted (as
part of the petition) where metals are projected to accumulate above health-based
levels. If metals will exceed health-based levels for ingestion at closure, the unit's
closure plan must require either capping with post-closure monitoring (where
metals are not leachafefe above health-based levels), or clean closure (where metals
are teachable above health-based levels).
What is the Relationship between "No Migration" Variances, RCRA Permits, and
Other Federal Laws?
"No migration" variances may only be issued for facilities functioning under interim
status or facilities with permits under RCRA. 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.
Before being issued a "no migration" variance, the petitioner must assure the EPA
that land disposal of the prohibited waste(s) will comply with all other applicable
Federal laws. These may include the Clean Air Act, the Clean Water Act, the Safe
Drinking Water Act, the Endangered Species Act, the National Historic Preservation
Act, the Wild and Scenic Rivers Act, the Coastal Zone Management Act, the Fish
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and Wildlife Coordination Act, the Atomic Energy Act, and the Marine Protection,
Research and Sanctuary Act. 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 Facilities?
Yes, but generic petitions should be avoided as a practical matter. 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. For example, a
demonstration that the hydrogeological characterization of each site is essentially
the same would require the detailed assessment of each site addressed in the
petition. As a result, the Agency expects few, if any, generic petitions for surface
land disposal units.
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. In the Land Disposal Restrictions First Third Rule, the Agency has
listed notification requirements if migration is detected. Any significant departure
from the terms or conditions of a variance would require written notification of
EPA, who will determine the appropriate action. Possible actions include
termination of waste acceptance at the unit, termination of the petition, or petition
modifications. The conditions of the variance may require periodic waste analysis
to assure the consistency of waste constituents. If migration from the unit is
discovered after a variance has been granted, the owner or operator must
immediately scop receipt of the restricted waste and notify EPA. EPA will then
decide whether the unit can continue to receive waste, or whether the variance will
be terminated. Substantive requirements for variances for waste disposal in deep
injection wells may differ slightly from those described above. The reader should
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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. As stated in
the preamble to the November 7, 1986 Final Rule, EPA believes that there will be
relatively few petitions. Accordingly, EPA is requiring that applicants submit
petitions to the EPA Administrator. Petitioners should note that authorized State
programs are free to impose disposal prohibitions if such actions are more stringent
or broader in scope than Federal programs (RCRA Section 3009 and 40CFR 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 be denied by EPA.
Pre-Submittal
A very important component to the "no migration" process is pre-submittal
meetings between the petitioner and the EPA. These meetings are 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.
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 follow!ng statement signed by
the petitioner or an authorized representative:
I 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
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Pre-Submittal Meeting(s)
Does
State Allow
"No Migration"
Petition
7
Grant
the
Petition
7
Inform Petitioner
of Intent to
Deny/Dismiss
Yes
Draft Fact Sheet
and FR Notice
Internal Review
Ev
Iss
Propose FR Notice
Public Comment
Period
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
Information
"No Migration" Petition Review Process
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obtaining the information, I believe that the submitted information is true,
accurate, and complete. I am aware that there are significant penalties for
submitting false information, including the possibility of fine and
imprisonment.
The petition should be sent to the following:
The Administrator
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
To facilitate review, a copy of the petition should also be sent to the Assistance
Branch in the Office of Solid Waste. The copy 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
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 review of the petition. Copies of this letter will be distributed to
the appropriate EPA Regional Office and State Agency.
Petition Review
The reviewer will perform an initial review of the petition. Once this initial review is
completed, the reviewer 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 Regional or 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.
However, the deadline will not exceed a period of 180 days from the date of the
request letter. Once the reviewer has obtained all of the necessary information for
the review, a comprehensive, technical review will be performed. As part of this
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review, the reviewer will work closely with the Regional and 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 reviewer may recommend that the
petition be dismissed. The Agency plans to dismiss incomplete petitions by letter. A
dismissal letter 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, the reviewer will recommend a tentative
decision to grant or deny the petition. If the reviewer recommends to grant the
petition, the Agency will publish a draft Federal Register notice describing its intent
to grant the petition. If the reviewer recommends that the petition be denied, 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 draft Federal Register notice
describing its intent to deny the petition.
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 the facility will adequately protect human
health and the environment. 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.
The information in this manual should be used as a starting point for assessing the
level of detail that will be required for each element of the petition. Such
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assessments can best be accomplished in pre-petition 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. A detailed checklist of possible petition requirements is presented
at the end of this manual.
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 essential 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.
All waste descriptions must be properly documented and in compliance with
prescribed quality control and quality assurance guidelines. The following is a
breakdown of the information required on each petitioned waste.
Waste Types and Sources --
Background information must 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.
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Waste Characteristics --
Complete physical and chemical characterization is required for each petitioned
waste and all 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, toxicity characteristic leaching
procedure (TCLP) results to determine the leachability of contaminants, simulation
models of leachability and transport, and field leachate analyses, if available.
Acceptable procedures for waste sampling and analysis can be found in the EPA
publication Test Methods for Evaluating Solid Waste.
Waste Incompatibilities --
The codisposal of incompatible wastes can result in 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 must 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
either case, thorough characterization should be provided for reaction rates,
products, and product characteristics for each transformation mechanism. 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
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should be provided. The mechanisms that must 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 photodegradation rates must 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 (e.g.,
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
must be thoroughly described. The actual testing of waste transformation processes
or the use of accepted procedures for transformation rate determination may be
required.
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Facility Description
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 offsite facilities should identify
the types of industries serviced.
Detailed design, layout, and operating plans should be provided for the unit
covered by the petition. The type of information and level of detail provided should
be similar to those included in RCRA Part B permit applications. (Detailed guidance
concerning Part B 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.) Unit descriptions should focus on waste isolation
capabilities of the unit or environmental setting.
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 and treatment
facilities that may rely entirely upon engineered systems to isolate wastes. All
barriers should be thoroughly described.
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:
Monitoring systems
Procedures employed to prevent hazards
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Contingency plans
Personnel training plans
Closure plans
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. The site's climatology, meteorology, geology, and
hydrology must be described in 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 air, soil, surface water, and ground water quality
must be determined to properly assess any potential impacts of land disposal. The
information that may be required is similar 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 1987 RCRA Facility Investigation Guidance Manual.)
However, since 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 must be addressed. Information on particularly sensitive or
vulnerable site characteristics may be useful in determining the degree of certainty
required in a "no migration" demonstration.
Geology --
A comprehensive 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:
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Structure. Density, distribution, and orientation of faults, folds, and fractures
Subsurface Geology. Identification, lithologic description and thicknesses of
all geologic formations underlying the region, available geophysical surveys,
well logs, and boring logs
Geomorphology. Discussion of present surface features, processes that could
affect surface features, and subsurface features that may be implied
Geologic Stability. Potential for earthquakes and degree of resulting ground
motion, faulting, landslides, subsidence, creep, and other types of earth
movement
The discussion of local geology should also include soils and topography. 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 fora "no migration" petition:
Identity and lateral extent of all aquifers, confining layers, and perched water
tables
Characteristics of all necessary aquifers and confining layers, including
thickness, porosity, permeability, hydraulic conductivity, and storage
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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
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. Floodplain 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 --
Sufficient meteorological and climatological information will need to be provided
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:
Site wind roses
Data on precipitation, temperature, and relative humidity data (seasonal
maximumsand minimums)
Maps of severe storm tracks and statistics on storm occurrence
Data on depth of seasonal freezing
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Facilities relying in part on climatic factors to control waste migration (e.g., arid
regions with no ground-water recharge) will be required to submit considerably
more 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 all environmental media at land disposal sites is necessary to confirm
that "no migration" of hazardous constituents beyond the unit boundary occurs.
Accordingly, the Land Disposal Restrictions First Third Rule [53 FR 31189, August 17,
1988] amended 40CFR 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 monitoring stations
Frequency of monitoring at each station
The specific hazardous constituents to be monitored
An implementation schedule forthe monitoring program
Equipment to be used at the monitoring station
Sampling and analytical techniques to be employed
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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.
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.
In other cases, monitoring of all environmental media at a particular facility may be
unnecessary. 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.
In addition to monitoring at the unit boundary, the petition 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 unit; leachate collection systems in surface impoundments, landfills, and
room-and-pillar mines; and fluid or gas pressure monitoring in well casings above
solution-mined cavities in salt domes.
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
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may only have to increase the frequency of monitoring. However, 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. Subpart F ground-water monitoring, on the other hand, does
not necessarily occur at the unit boundary. 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.
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. 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 natural or 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 over
time, 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.
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 as the physical and chemical characteristics of the waste and
leachate. The factors affecting flow at or near the land surface are precipitation,
run-off/run-on, evaporation, and transpiration.
Physical properties of the site soils that affect flow in the unit and the unsaturated
zone that should be described in the petition include:
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Water content
Pressure potential
Permeability
Degree of water saturation
Bulk density
Particle density
Water capacity
Hydraulic conductivity
Water diffusivity
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
must 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
be increased by the removal of organic matter or a change in adsorptive properties;
and others of its properties can be altered by the dewatering 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 must 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 must be
modeled include vapor pressure, solubility, chemical activity, partitioning behavior
of the solute (waste) between the atmosphere and water (Henry's Law), diffusivity,
absorption, and release rate.
Limitations of any air emission release rate (AERR) and dispersion models must be
documented. The applicant should combine the use of models with ambient air and
emission monitoring to characterize conditions at the unit to the best extent
possible. Any models used must be verified at the site. (For more information on
the "no migration" demonstration methodology for the air medium, see the
Appendix).
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Appropriate models must 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
chosen model should be one that is sensitive to all of the significant processes and
most sensitive to those processes of greatest importance.
Other concerns in choosing a model are how well it represents the field situation,
whether it is appropriate for the available data, and whether it can be verified for
accuracy by comparison to actual measurements. The most sophisticated models
may be inappropriate forthe available data.
The petitioner has the following quality assurance and quality control
responsibilities for every model used:
Model validation. Comparing the results of analytical and numerical models
or matching field data to the model results is critical to model validation. All
models must be validated at the site.
Justification of assumptions. Proper justification of all assumptions should
be provided. In all cases the most 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 must 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 is discouraging the use of proprietary models, since the models selected
will have to be closely scrutinized to determine their reasonableness and accuracy.
Only data developed under appropriate QA/QC procedures as described in the
facility QA/QC plan will be considered in the petition review.
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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 more applicable levels must be met to protect the environment, then those
levels will be required. For example, stricter levels may be needed where there is
potential impact to a sensitive environment or an endangered species even if
human health- based levels are met. The assessment of environmental impacts does
not mean that migration of hazardous constituents will be measured outside 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 require the use of
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). Acute and
chronic toxicity and bioaccumulation factors must be quantified 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 biomonitoring 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
unit
Bioaccumulation potential in plants and animals
Fishery and habitat impacts
Endangered species of flora and fauna potentially affected by migration from
the unit
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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 life. 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
The petitioner must identify and quantify the impacts of events that could
contribute to or result in inadequate waste isolation. Natural phenomena that
should be considered include:
Earthquakes and resulting ground motion
Floods and droughts
Tsunamis (tidal waves)
Hurricanes and tornadoes
Climatic fluctuations
Geologic activity
In addition, human-induced events which may affect the isolation capability of the
unit, such as disturbance of the hydrologic regime and future land uses, must be
considered. The potential for such events during the period in which the wastes
remain hazardous should be determined. Potential impacts 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.
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. 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.
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Quality Assurance and Control
A QA/QC plan that addresses all aspects of the petition demonstration must be
included in the petition submittal. Quality goals and methods to assure that these
goals are achieved must 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
Evaluation of the integrity of construction materials
At a minimum, the QA/QC plan 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
method.
Data precision. A measure of the mutual agreement between comparable
data gathered or developed under similar conditions. Precision is best
expressed in terms of a standard deviation.
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Data completeness. A measure of the amount of valid data obtained against
the amount that was expected.
Only data developed under appropriate QA/QC procedures as described in the
facility QA/QC plan will be considered in the petition review.
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CHECKLIST OF INFORMATION NEEDS
The following checklist is a comprehensive, but not all-inclusive, list of information
needs. Individual petitions may require more or less information than that
presented below. The level of detail required will depend on site-specif ic factors.
Facility Description
P Name of facility
G Address of facility
G Name of owner/operator
D Anticipated period of operation
n Status of RCRA permit application
D Location map
n Detailed site plan
G Aerial surveys
G Advantages/disadvantages of location
G Evaluation of storage/disposal unit
n Design objective.
n Design criteria
Q Design performance projection
Q Materials specifications
G Detailed drawings and
specifications
G Documentation of unit
construction
G Documentation of unit operation
n Closure plans
n Post-closure plans
n Cover design
G Design QA/QC demonstration (testing &
inspection)
n Facility operation QA/QC demonstration
Waste Characteristics
G Waste type by name
G Processes that produced the waste
G Hazardous properties
G Physical characteristics
G Chemical characteristics
G Biological properties
G Constituents and percentages of
constituents
G Analytical methods and results
G Projection of waste volume to be
disposed
G Quantity of banned waste being disposed
G Frequency of disposal
G Period of time waste has been and will be
disposed
G Handling procedures
G Waste treatment before, during and after
disposal
G Liquid phase mobility information
G Gas/particulate mobility
G Solid phase mobility
G Dust generation potential
G Gas-liquid phase interactions
Q Persistence/degradation potential in unit
and environment
G QA/QC demonstration
Waste Transformation and Immobilization
G Estimation of quantity and quality of
leachate formation
G Waste/waste compatibility, interaction,
reaction products
G Waste/liner compatibility
G Assessment of biodegradation potential
G Assessment of oxidation/reduction
potential
G Assessment of immobilization due to
insolubility
G Assessment of photodegradation
potential
G Assessment of immobilization due to
hydrolysis
G Assessment of immobilization due to
adsorptivity
Site Characterization
G Surficial geology and soils (regional and
local)
G Topography
G Soil types
G Soil properties
G Depth to bed rock
G Bedrock geology (regional and local)
G Stratigraphy and lithology
G Seismic activity of area
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n Assessment of ground motion
potential and degree
n G eol og i c c ross secti ons
n Degree of bedrock faulting and
fracturing
Q Rock characterization
n Ground-water hydrology (regional and
local)
L"3 Water table map
n Seasonal variations in the water
table
n Identification of all aquifers and
aquitards
n Characterization of all aquifers
n Vertical and horizontal hydraulic
conductivity
[] Aquifer interconnection
n Description of ground-water
monitoring program
n Monitoring QA/QC documentation
[3 Surface water hydrology
[3 Location of all watersheds
[3 Map of drainage patterns
[3 Map of floodplain
Q Flood analysis
n Meteorology/climatology
Q Wind rose
n Precipitation records
n Temperature records
n Relative humidity records
n Maps of storm tracks
Monitoring Plan
n Media to be monitored
Q Type of monitoring to be conducted at
the unit
n Location of monitoring stations
Q Frequency of monitoring at each station
n Specific hazardous constituents to be
monitored
fj Implementation schedule for the
monitoring program
n Equipment used at the monitoring
stations
[] Sampling and analytical techniques
employed
n Data record i ng/reporti ng proced u res
Waste Mobility
[J Unsaturated zone soils
Q Soil sampling
n Soil testing
D Unsaturated zone physical properties
n Volumetric water content
n Degree of water saturation
n Bulk density
n Pressure potential
fj Relative permeability
n Unsaturated hydraulic conductivity
fj Water capacity
n Water diffusivity
[H Leachate characteristics affecting
mobility
fj Leachate characterization
n Leachate interactions
Q Secondary leachate evaluation
n Evaluation of transport mechanisms
n Evaluation of fate of contaminants in
unsaturated zone
n Vapor concentration of constituents at
the source
n Vapor pressure of constituents
n Solubility data for constituents
n Activity coefficient
n Henry's Law constant
n. Background measurements for air
n Assessment of volatilization potential
Modeling Evaluation
n Model accounts for all transport
mechanisms
Q Model appropriate for petitioned waste
n Data input accurate and verified
n Model tested under field conditions
n Model is accurate over long time periods
Q Limitations of model
Q Model inputs adequately documented
n Model outputs appropriate and
reasonable
Assessment of Environmental Risk
Q Identification of all exposure pathways
and routes
C] Identification of all potential receptors
n Wildlife
D Vegetation
n Identification of sensitive or
endangered species
n Assessment of bioaccumulation through
the foodchain
Uncertainty Analysis
[] Natural Events
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D Climatic fluctuations
D Glaciation
D Stream erosion
D Magmatic activity
D Epeirogenic displacement
D Orogenicdiastrophism
G Oiagenesis
D Static fracturing
D Dissolution
D Sedimentation
D Flooding
D Undetected features (i.e. faults,
lava tubes)
n Meteorites
D Fires
n Hurricanes
Q Tornadoes
D Earthquakes
[3 Ground motion
Waste/facility-induced events
n Thermal effects
n Chemical effects
n Mechanical effects
n Modif ication of hydrologic regime
Human-induced events
Q Improper design or operation
n Past intrusions
n Future intrusions
n Intentional intrusion
n Perturbation of ground-water
system
n Biosphere alterations
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Where can I Obtain Additional Information Concerning "No Migration" Variances?
Additional information on "no migration" variances is available from EPA
Headquarters in Washington, D.C. 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 in 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
401 M Street, S.W.
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, in 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
petitioners:
Permit Applicants' Guidance Manual for the General Facility Standards. 1983. EPA
SW-968.
Permit Applicants' Guidance Manual for Hazardous Waste Land Treatment,
Storage, and Disposal Facilities. 1984. EPA 530 SW- 84-004.
Hydrologic Simulation at Waste Disposal Sites. 1982. EPASW-868.
Test Methods for Evaluating Solid Wastes, Third Edition. EPA SW-846.
A Method for Determining the Compatibility of Hazardous Wastes. EPA 600/2-80-
076.
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A Guide for Estimating the Incompatibility of Selected Hazardous Waste Based on
Binary Chemical Mixtures. 1986. ASTMP-168.
Soil Properties, Classification, and Hydraulic Conductivity Testing. 1984. EPA SW-
925.
Criteria for Identifying Areas of Vulnerable Hydrogeology Under the Resource
Conservation and Recovery Act. 1986. NTIS 86-224946.
RCRA Facility Investigation Guidance Manual, Draft Final. May 1987.
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, Draft Final. September,
1987.
Superfund Public Health Evaluation Manual. EPA/540-1-86-060.
Guidelines for Carcinogenic Risk Assessment. 51 FR 33992-34003.
Guidelines for the Health Risk Assessment of Chemical Mixtures. 51 FR 34014-
34025.
Integrated Risk Information System (IRIS) Chemical Files. EPA/600/8-86/032b.
35
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APPENDIX
DRAFT AIR PATHWAY ASSESSMENT
METHODOLOGY FOR
'NO MIGRATION" DEMONSTRATIONS
OCTOBER 1988
-------
TABLE OF CONTENTS
Section Title Page
1.0 Introduction 1-1
2.0 Air Pathway Assessment Methodology 2-1
2.1 Overview 2-1
2.2 Modeling Methodology 2-3
2.2.1 Emission Rate Modeling 2-5
2.2.2 Dispersion Modeling 2-6
2.3 Monitoring Methodology 2-14
3.0 Example Application 3-1
4.0 References 4-1
-------
LIST OF TABLES
Title Page
2-1 Example Adjustment Factors to Account for 2-11
the Vertical Wind Speed Profile
2-2 Example Unit Boundary Dispersion Factor 2-13
Values
LIST OF FIGURES
Title Pace
2-1 Air Pathway Assessment Methodology for 2-2
No-Migration Demonstrations
2-2 Modeling Methodology Overview 2-4
2-3 Step4-CalculateConcentration Estimates 2-8
2-4 Example Subdivision of Area Source 2-10
2-5 Monitoring Methodology-Overview 2-15
3-1 Emission Rate Modeling - Land Treatment 3-2
Units
-------
1.0 INTRODUCTION
Tht Environmental Protection Agency 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 19W. A major requirement of the HSWA is that all
hazardous wastes must be treated using best demonstrated available technology before placement
into the land. Otherwise, the owner/operator is prohibited from land disposal of the waste. Section
3004(d), (e). and (f) 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 treated according to 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)(l)l.
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 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. An example application of this methodology is
presented in Section 3.
1-1
-------
2.0 AIR PATHWAY ASSESSMENT METHODOLOGY
2.1 Overview
The intent of a no-migration petition is to demonstrate that there will be no transport of hazardous
constituents from the disposal unit. Therefore, the point(s) of compliance for air pathway
assessments should be evaluated at the location(s) of the maximum air concentration on the unit
boundary. This approach involves the application of standard emission and dispersion models to
estimate air concentrations for comparison to available inhalation health criteria.
A standard exposure height of 1.5m should be used for no-migration air pathway assessments. This
value corresponds with a typical inhalation height and facilitates the application of standard
modeling/monitoring methods. The vertical profile of air concentrations may be quite significant
but highly variable within 1m of the surface due to various microscale atmospheric effects. It is
frequently difficult to obtain reoresentative air concentration samples or to accurately characterize
dispersion conditions at exposure heights of less than 0.1m on or at the edge of area sources such as
land treatment areas, surface impoundments, and landfills.
A combination of modeling and monitoring approaches can be used to estimate the maximum air
concentration at 1.5m on the unit boundary. An overview of a recommended air pathway
assessment methodology for no-migration demonstrations is illustrated in Figure 2-1. This
methodology consists of the following major components:
Conduct of an emission rate/dispersion modeling assessment
Conduct of a confirmatory emission rate/air monitoring assessment.
A modeling assessment should initially be conducted to characterize the air emission potential for
the disposal unit and to estimate maximum air concentrations at the unit boundary. The
recommended methodology for the conduct of modeling assessments is presented in Section 2.2.
A monitoring assessment should also be conducted to confirm modeling estimates. Monitoring
should be conducted at existing units in order to provide additional information for EPA
decisionmaking. Monitoring data from similar units, as available, should be submitted for no-
migration demonstrations involving new land disposal units. In addition, the EPA may require
confirmatory monitoring as part of the permit conditions for a unit. The recommended
2-1
-------
FIGURE 2-1
AIR PATHWAY ASSESSMENT METHODOLOGY FOR
NO-MIGRATION DEMONSTRATIONS
Conduct
Emission Rate/Dispersion
Modeling Assessment
(See Section 2.2)
.Conduct Confirmatory
Emission Rate/Air
Monitoring Assessment
(See Section 2.3)
Input
to
No-Migration Petition
2-2
-------
methodology for the conduct of monitoring assessments fot no-migration demonstrations is
presented in Seaion 2.3.
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
rate and dispersion models selected.
Step 2 Select Release Constituent/Surrogates: Unit and waste-specific information
should be used to identify potential release constituents for modeling purposes. A
limited set of surrogates can be selected to represent a wide range of potential release
constituents. This approach significantly simplifies the modeling process.
Step 3 Calculate Emission Estimates: Unit-specific emission models should be used
based on source conditions identified in Step 1 for constituents identified in Steo 2.
These modeling results will provide emission rate estimates.
Step 4 - Calculate Concentration Estimates: Emission rates from Step 3 should be used
to calculate concentration estimates at the unit boundary. Standard dispersion models
should be used to obtain these concentration estimates.
Step 5 Compare Concentration Results to Health-Based Criteria: Concentration results
from Step 4 should be compared to constituent-specific, health-based criteria presented
in the RCRA Facility Investigation Guidance (U.S. EPA, 1988). Chronic exposures for
carcinogens should be evaluated by comparison of the estimated maximum annual (1-
year) concentration directly to the annual average concentrations (based on health
criteria and assuming a 70-year exposure). Interpretation of the ambient concentration
estimates should account for the uncertainties associated with the source/waste
2-3
-------
FIGURE 2-2
MODELING METHODOLOGY OVERVIEW
Stepl
Obtain Source
Characterization Information
Step 2
Select Release
Constituents/Surrogates
Step 3
Calculate Emission
Estimates
Step 4
Calculate Concentration
Estimates
StepS
Compare Results to
Health-Based Criteria
1
Input to
No-Migration Petition
2-4
-------
characterization data, and modeling inaccuracies. It is also necessary to consider
background concentrations and contributions from other sources.
An expanded discussion of this five-step process is available in the Air Release Screening Assessment
Methodology. (U.S. EPA, 1988).
Recommended emission rate methods and dispersion modeling methods as they apply to no-
migration demonstrations are presented in Section 2.2.1 and 2.2.2, respectively.
2.2.1 Emission Rate Modeling
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 upon 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 modeling methodology for no-migration demonstrations is based on the application of
CHEMOAT6 air emission models (applicable to releases of volatile organics) developed by EPA's
Office of Air Quality Planning and Standards and available from NTIS. (U.S. EPA, December 1987).
CHEMDAT6 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
2-5
-------
Comprehensive technical information regarding these CHEMDAT6 models is presented in the
Hazardous Waste Treatment. Storage and Disposal Facilities (TSDP) Air Emission Models. (U.S. EPA,
December 1987). This reference also presents air emission rate models for many other units.
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.
For some applications, Step 4 - Calculate Concentration Estimates will not warrant the use of
emission models because it can be assumed that all 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, the air emission rate can be
assumed to be equivalent to the disposal rate, so that 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. However, for more complex situations
(e.g., land treatment units and tandfills), air emission models can be used to obtain a more refined
release rate.
2.2.2 Dispersion Modeling
Emission rate values from Step 3 should be used as modeling input to calculate concentration
estimates at the unit boundary. 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 within a factor of two to three for'flat terrain
sites (inaccuracy can be a factor of 10 m complex terrains). However, validation studies have been
2-6
-------
quit* 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. Therefore, the use of dispersion models is recommended for no-
migration demonstrations.
The use of the Industrial Source Complex (ISC) model is recommended as a prime candidate 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 model
can be used for both flat and rolling terrain. 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, 1987).
Additional guidance on dispersion model selection and application is available in the Guideline on
Air Quality Models (Revised). U.S. EPA, July 1986).
Meteorological data (i.e., wind and atmospheric stability summaries) are necessary dispersion
modeling input. Data from a representative National Weather Service station can be used as
available. Alternatively, onsite meteorological data can be used. Guidance on the conduct of
meteorological programs is presented in Qn-Site Meteorological Program Guidance for Regulatory
Modeling Applications. (U.S. EPA. June 1987).
Two alternative dispersion modeling approaches are available for no-migration demonstrations, as
illustrated in Figure 2-3. The primary approach involves the direct application of the ISC dispersion
model based on site-specific and unit-specific input data. The alternative (screening) approach
involves the application of modeling results available for a limited set of source and meteorological
conditions. 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
recommended approach for no-migration demonstrations. This refined modeling approach involves
the direct use of the ISC dispersion model to provide direct estimates of concentrations. This involves
the following tasks, as indicated in Figure 2-3:
Determine the point of the maximum concentration 100m from the source.
Subdivide the source area into multiple smaller source areas.
2-7
-------
FIGURE 2-3
STEP 4 - CALCULATE CONCENTRATION ESTIMATES
Emission Rate Data
(Step 3)
Meteorological Data
Primary approach conduct
site/unit-specific modeling
based on ISC
Screening approach based on
available modeling results for a
limited set of source/meteorological
conditions
Determine maximum
concentration point 100m
from source
Calculate concentrations
based on available
dispersion factors
Subdivide source into
multiple smaller source
areas
Adjust concentrations
based on prevailing
wind direction frequency
Determine maximum
concentration at unit
boundary
Adjust concentration
estimates based on site-
specific average wind speed
I
Adjust results for
vertical wind
profile
Adjust concentration
estimates based on vertical
wind speed profile
Input to Step 5-
Compare Results to Health-Based Criteria
2-8
-------
Determine the maximum concentration at the unit boundary.
Adjust modeling results, as necessary, to account for the vertical wind profile.
Dispersion modeling estimates should be obtained which are representative of unit boundary
conditions. 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 at approximately 100m from the unit
boundary using standard dispersion modeling methods. This is a standard
computational distance for the ISC model. Concentration estimates should be obtained
for 16 sectors of 22.5 degrees each in order to select the point of maximum
concentration. These results will provide the basis to identify the 22.5 degree sector
associated with the maximum concentration.
Estimate the concentration at the unit boundary for the 22.5 degree sector associated
with the maximum concentration point located 100m from the boundary. (For
modeling purposes, a downwind distance of approximately 1m from the unit boundary
can be used for this estimate as necessary.) Contributions to the receptor from all 16
sectors should be accounted for.
The concentration at 1m from the unit boundary can be obtained from ISC results by subdividing the
source area into multiple smaller areas (see Figure 2-4). Computational restraints of ISC require that
area sources must be represented as a square or multiple squares. (The ISC user's guide should be
onsulted 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 by 25 squares
of equal area.
The square along the edge of the unit boundary nearest to the point of maximum concentration
should be further subdivided if the side of this square is greater than 10m. This approach will ensure
a representative concentration estimate at the unit boundary (i.e., 1m downwind).
Concentration estimates for no-migration demonstrations should be representative of a 1.5m
inhalation height. Meteorological data available for most modeling studies 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 m proportion to the logarithm of the height.
2-9
-------
FIGURE 2-4
EXAMPLE SUBDIVISION OF AREA SOURCE
Wind Direction
Point of maximum
concentration at unit
boundary
Nested subdivisions, as
necessary to yield areas
of <100m*
Point of maximum
concentration 100m
from unit boundary
2-10
-------
Therefore, wind speed values or modeling results should be adjusted, as necessary, to account for the
vertical wind profile. Example wind profile adjustment factors are presented in Table 2-1 based on
the logarithmic wind profile law. (U.S. EPA, 1974).
Table 2-1
EXAMPLE ADJUSTMENT FACTORS TO ACCOUNT FOR THE VERTICAL WIND SPEED PROFILE*
Wind Speed Measurement
Height X (m)
20.0
15.0
10.0
5.0
2.0
1.5
Wind Speed Adjustment
Factor (Ratio of Wind Speed
(1.5m) to Wind Speed
(Height X)]
0.7
0.7
0.7
0.8
0.9
1.0
Concentration Adjustment
Factor (CAP) [Ratio of
Concentration (1 .5m) to
Concentration (Height X)]
1.5
1.4
1.4
1.2
1.1
1.0
* Assuming neutral stability and uniform surface roughness.
Screening Approach
Screening dispersion modeling is an alternative to the refined modeling approach. 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. Following are the tasks involved in the conduct of screening modeling
as indicated in Figure 2-3:
e Calculate concentration estimates at the unit boundary based on available dispersion
factors
Adjust concentration estimates to account for the frequency of the prevailing wind
direction
Adjust concentration estimates to account for the site-specific average wind speed
2-11
-------
Adjust concentration estimates to account for the vertical wind profile.
This process can be summarized by the following equation:
WDF 10
C = ERxDFxUCFx x x CAP Equation 2-1
100 WS
Where
C = concentration at unit boundary (ug/m3)
ER = emission rate (106g/yr = Mg/yr)
OF = dispersion factor for appropriate source area (sec/m3)
UCF = unit conversion factor (317)
WDF = frequency of occurrence of the prevailing wind direction (percent)
WS = average wind speed 1.5 (mph)
CAP = concentration adjustment factor to account for the vertical wind profile.
(dimensionless)
The product of ER times OF 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 WDF, WS and CAP) to
account for site-specific wind conditions. Representative National Weather Service or onsite
meteorological data should be used as the basis for these adjustments.
2-12
-------
TABLE 2-2
EXAMPLE UNIT BOUNDARY DISPERSION FACTOR VALUES
Unit Area
(Hectares)
0.01
0.04
0.25
1.00
4.00
25.00
100.00
400.00
Dispersion Factors*
(sec/m3)
3.9 x 10-3
2.6x10-3
8.9 x 10-*
2.8 x 10-»
7.9x 10-5
1.5x 10-5
43x10-6
1.4x 10-6
a Based on ISCLT results with the following assumptions:
Ground-level area source (square configuration)
Average wind speed of 10mph 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
The receptor should be assumed to be within the 22.5 degree sector associated with the prevailing
wind direction (i.e., the direction with the highest frequency of occurrence). Therefore, the WDF
parameter should be used to account for this condition.
The modeling results presented in Table 2-2 are based on a 10 mph wind speed. The average wind
speed (WS) at the site should, therefore, be used to adjust these modeling results. Similarly, a
concentration adjustment factor (CAP) should be used to account for the vertical wind speed profile.
Values of CAP are presented in Table 2-1 for a range of wind measurements heights to facilitate
scaling concentration modeling results to represent a 1.5m inhalation exposure.
An example application of this approach is illustrated m Section 3.
2-13
-------
2.3 Monitoring Methodology
A monitoring program may also be appropriate to confirm modeling estimates. This may involve
emission rate monitoring and/or air concentration monitoring as illustrated in Figure 2-5.
Recommendations for the conduct of an acceptable monitoring program are presented in the RCRA
Facility Investigation Guidance. (U.S. EPA, 1988).
Emission rate monitoring can be used in conjunction with dispersion modeling to estimate
concentrations at the unit boundary. (An appropriate dispersion modeling methodology has been
discussed in Section 2.2.) Direct emission sampling should be used for point sources (e.g., vents at
closed landfills). An isolation flux chamber may be used for area source emission measurements
(e.g., land treatment areas). Multiple sampling locations are required to adequately characterize the
spatial variability of emission conditions over an area source. Further guidance on the application of
isolation flux chambers is provided in Measurement of Gaseous Emission Rates from Land Surfaces
Using an Emission isolation Flux Chamber: User's Guide. (U.S. EPA, 1986).
Air monitoring at the unit boundary is an alternative approach for characterizing area source
emissions. This facilitates the direct measurement of air concentrations at the point of compliance.
However, the selection of appropriate monitoring locations is critical to ensure the measurement of
the maximum concentration. Also, the monitoring program duration must be adequate to
determine maximum concentrations for averaging periods commensurate with health criteria.
Additional recommendations for the conduct of air monitoring programs are presented in RCRA
Facility Investigation Guidance. (U.S. EPA, 1988).
Representative meteorological data should be available as dispersion modeling input to calculate
concentration estimates based on emission rate monitoring results. Meteorological data will also be
necessary to interpret air monitoring results. Recommendations on the conduct of meteorological
programs are presented in On-Site Meteorological Program Guidance for Regulatory Modeling
Applications. (U.S. EPA, June 1987).
Monitoring results should be compared to health criteria as discussed in Step 5 of the modeling
methodology (see Section 2.1).
2-14
-------
FIGURE 2-5
MONITORING METHODOLOGY OVERVIEW
Modeling Assessments
Emission
Monitoring
Direct Emissions
Source Testing
for Point Sources
t
Representative
Meteorological
ata Available,
No
\
1
/
ves
r
Conduct
Monitoring
Conduct
Meteorological
Monitoring
Air
Monitoring
Emission Monitoring
Isolation Flux
Chamber
for Area Sources
Unit Boundary
Air
Monitoring for
Area Sources
I
Conduct
Dispersion Modeling
Input to No-Migration Petition
2-15
-------
3.0 EXAMPLE APPLICATION
The following cast study has been selected to demonstrate the recommended air pathway
assessment methodology for no-migration demonstrations. This case study also includes an example
application of the screening dispersion modeling approach.
The case study involves a no-migration petition for a new land treatment unit at a site which also has
similar existing units. Following is a synopsis of the modeling assessment for the new unit.
Step 1 Obtain Source Characterization Information
The following information describes the proposed land treatment unit:
Land area = 2.5 hectares
Annual waste throughput = 1,800Mg
Oil content of waste = 10 percent by weight
Tilling depth = 20cm
Soil air porosity = 0.5
Soil total porosity = 0.61
Average molecular weight' = 282 g/g mol
£teo 2 Select Release Constituents/Surrogates
An evaluation of the expected waste constituents indicated that benzene was the constituent with
the greatest potential volatility and most restrictive health criteria. Therefore, benzene was selected
to represent the total volatile organic concentration (2,000 ppm by weight) of the oil content of the
waste. Therefore, the benzene concentration was conservatively assumed to be 2,000 ppm by
weight of the oil.
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 tiling). The appropriate emission rate models are also a function of the type of
waste application (i.e., surface or subsurface injection) as well as the fate of the oil prior to tilling
(i.e., formation of a surface oil film, oil seepage through a layer of the soil, or the waste is
immediately
3-1
-------
FIGURE 3-1
EMISSION RATE MODELING LAND TREATMENT UNITS
Sourca/Constituant Information
| Calculate Emissions from Wast* Application I
I
Surfaca
Application / Wasta
Application
Moda
Subsurfaca
Injaction
j Wasta Application Modal* \
1
Nagligibla Emiiiions |
Calculata Emissions aftar Wasta Application
and Bafora Tilling
Surfaca
Oil Film
Saapaga
Layar
Immtdiata
Tilling
CHEMOATC
Oil Film Modal
I
Nagligibla
Emissions
CHEMOATC
Land Traatmant
Modal
Calculata Emissions aftar Tilling
CHEMOATC
Land Traatmant
Moc'al
Input to Oisparsion Modal
* Equations prasantad in Hazardous Wasta Traatmant. Storaaa. and Disposal Facilitias-Air
EmiisionsModalsfU.S. EPA, Dacamb«r 1917)
3-2
-------
tilled into the soil). For this case study, it has been assumed that the unit will use subsurface injection
followed by immediate tilling. Modeling results are summarized below for benzene:
Emission Source Model Emission Rate
Subsurface injection Not applicable Negligible
Immediate tilling Not applicable Negligible
Soil after til I ing CHEMDAT6 land treatment 0.33 Mg/yr
model
Step 4 Calculate Concentration Estimates
The screening dispersion modeling approach was selected for this case study. Representative wind
data were available from the National Weather Service. The frequency of the prevailing wind
direction is 10 percent and the average wind speed is 8 mph (at a measurement height of 10m).
A maximum concentration at the unit boundary was estimated as follows:
C s ERxOFxUCFx x xCAF Equation 3-1
Where
C = benzene concentration at unit boundary (ug/m*)
ER = benzene emission rate (0.33 Mg/yr)
DP » dispersion factor for source area of 2.5 hectares based on Table 2-2 (interpolated
value of 1.2x10"*sec/m3)
UCF a unit conversion factor (317)
WDF = frequency of occurrence of the prevailing wind direction (10 percent)
WS = average measured wind speed (8 mph)
= 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)
3-3
-------
Therefore:
C = (0.33) x(1.2x10-4) x (317) x x x 1.4 Equation3-2
100 8 ^
= 0.002 ug/m3
Step 5 Compare Concentration Results to Health-Based Criteria
A carcinogenic risk-specific dose of 0.12 yg/m3 for benzene is presented in the RCRA Facility
Investigation Guidance. (U.S. EPA, 1988). The estimated unit boundary concentration from Step 4
(0.002 ug/m3) is lower than this health-based criteria. Background concentrations of benzene at this
site due to emissions from existing units should also be accounted for.
A monitoring program was conducted at the site to confirm modeling estimates. A combination of
emission rate measurements and air monitoring data at the boundary of an existing land treatment
unit during worst case emission/dispersion conditions as well as at locations representative of
background air concentrations was obtained. These monitoring data confirmed that benzene
concentrations at the unit boundary (including background conditions) do not exceed health
criteria.
3-4
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4.0 REFERENCES
U.S. EPA. 1988. RCRA Facility Investigation Guidance. EPA.53Q/SW.a7.om Office of Solid Wast*.
Washington, O.C 20460.
U.S. EPA. 1988. Air Release Screening Assessment Methodology. Office of Solid Wast* Washington,
D.C. 20460.
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, IMC 27711.
U.S. EPA. December 1987. 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 1987. Industrial Source Complex (ISO 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. 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. Las 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.
U.S. EPA. 1974. Development of Emission Factors for Fugitive Dust Sources. Office of Air Quality
Planning and Standards. Research Triangle Park, NC 27711.
4-1
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