United States
Environmental Protection
Agency
Office of
Solid Waste and
Emergency Response
Publication: 9347.3- 10FS
April 1991
&EPA
Guide to Obtaining
No Migration Variances for
CERCLA Remedial Actions
Office of Emergency and Remedial Response
Hazardous Site Control Division OS-220W
Quick Reference Fact Sheet
On-site CERCLA remedial response actions must comply with (or justify a waiver of the substantive requirements of the Resource
Conservation and Recovery Act (RCRA) when they are determined to be applicable or relevant and appropriate requirements (ARARs).
RCRA requirements are applicable for CERCLA responses involving the treatment, storage, or disposal of RCRA wastes (or when treatment,
storage, or disposal of the waste being addressed under CERCLA occurred after November 19,1980). A No Migration Variance may be sought
to dispose of untreated hazardous wastes that are otherwise subject to treatment standards under the RCRA land disposal restrictions (LDRs).
Regulatory provisions under 40 CFR 268.6 specify the conditions that must be met in order to qualify for obtaining a No Migration Variance
for a RCRA hazardous waste unit to allow disposal of restricted hazardous waste without treatment. The petition procedures in the RCRA
regulations do not apply to on-site CERCLA actions. Instead, this guide outlines procedures for obtaining a No Migration Variance for RCRA
hazardous wastes as part of a CERCLA response when the LDRs are ARAR. This guide is based on the most current Office of Solid Waste
(OSW) information ("No Migration" Variances to the Hazardous Waste Land Disposal Prohibitions: A Guidance Manual for Petitioners. Draft,
Office of Solid Waste, March 1990). Currently, EPA is developing a proposed rulemaking for obtaining No Migration Variances.
WHEN TO CONSIDER A NO MIGRATION VARIANCE
A "No Migration" Variance allows land disposal of restricted
wastes not meeting the LDR treatment standards in a specific unit
(or engineered subunit within ah area of contamination (AOC)).
To obtain a No Migration Variance, site managers must
demonstrate "to a reasonable degree of certainty that there will be
no migration of hazardous constituents from the disposal unit or
injection zone [for Class I wells] for as long as the waste remains
hazardous" (40 CFR 268.6). This demonstration requires that
actual or predicted concentrations of hazardous constituents or
emission rates at the edge or boundary of the unit do not exceed
health-based levels or environmentally protective levels for ground
water, surface water, soil, and air for as long as the waste remains
hazardous. Site managers also must ensure that monitoring of all
environmental media, including ground water, surface water, soil,
and air (e.g.," compliance with 40 CFR 264 Subpart F, ground-water
monitoring) is or will be in place to demonstrate compliance.
Generally, no migration petitions will be only for on-site
treatment and/or disposal actions. (For example, in a limited
number of cases, the disposal may occur at an off-site, non-
commercial facility.) The Office of Solid Waste (OSW) has
identified several scenarios (see Hazardous Waste Management
System; LDRs Final Rule, 51 FR 40572, November 7,1986) under
which a No Migration Variance may be appropriate. These
scenarios include:
• Placement of compatible non-volatile wastes in a massive and
stable geologic formation, such as a salt dome.
• Placement of a waste consisting of fairly immobile constituents
in a monofill (i.e., a waste unit that contains only one
hazardous waste) located in an arid area that has no ground-
water recharge.
• Placement of a hazardous waste in a land-treatment facility
that through active chemical, physical, biological, or other
processes renders it nonhazardous.
• Temporary storage of a hazardous waste in a totally enclosed
indoor waste pile with a floor or bottom liner for a purpose
other than to accumulate sufficient quantities of the waste to
allow for proper recovery, treatment, or disposal.
No Migration Variances also may be appropriate in
conjunction with CERCLA actions involving the injection of
hazardous wastes into Class I injection wells. (The EPA Office of
Drinking Water has granted variances for several industrial Class I
wells, although not for any involving disposal of Superfund wastes.
For a Class I variance, petitioners must demonstrate that wastes do
not migrate from the "injection zone.") Site managers may want to
consider this type of No Migration Variance when, for example, a
large volume of restricted RCRA waste requires disposal and it is
feasible, based on the nine selection of remedy criteria, to dispose
of the wastes in an on-site underground injection well.
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In all cases, however, site managers should carefully consider
whether or not to obtain such a variance, considering the extensive
demonstrations (described below) that are required.
NECESSARY FINDINGS
For on-site variance requests (i.e., where waste disposal will
occur in an on-site unit), only substantive requirements of 40 CFR
268.6 must be met (the opportunity for public comment is provided
through the proposed plan and Record of Decision (ROD)
development process); the variance may be granted as part of the
ROD for the site. For off-site responses, both administrative and
substantive requirements must be met. The formal No Migration
Variance petition process (including EPA Headquarters review,
publication of a notice in the Federal Register, and an opportunity
for public comment) must be followed when seeking a No
Migration Variance for wastes or waste residuals to be disposed of
off site. (The variance is granted by OSW and a notice of the
granted variance is published in the Federal Register.) Specific data
needs required to obtain a No Migration Variance follow. The
specific justification required to obtain a No Migration Variance
may differ from site to site, based on the wastes present and
conditions found at the site.
Health-Based Levels
In reviewing the request for a variance, the calculated
concentrations of hazardous constituents will be compared with
health and environmental criteria. The Agency would generally
compare the concentrations of each constituent in leachate. ground
water, and surface water to the non-zero Maximum Contaminant
Level Goals/Maximum Contaminant Levels (MCLGs/MCLs),
Ambient Water Quality Criteria (AWQC), or State Water Quality
Standards (WQS), if they exist, and in air to promulgated emission
standards or reference doses (RfDs) and risk specific doses (RSDs)
based on inhalation.
Per the NCP (55 FR 8745 and 8754-55), if a non-zero
MCLG/MCL, AWQC, or State WQS is not available for a
constituent, the appropriate health-based levels would be the RSD
for carcinogens and the RfD for noncarcinogens (using appropriate
exposure assumptions for each medium). The health-based criteria
would be calculated by assuming chronic (lifetime) exposure by
ingestion or inhalation of contaminated media. For carcinogens,
the maximum residual risk level is set at 1 x 10"* for all constituents.
(More information on these health-based numbers is available in
the Risk Assessment Guidance for Superfund: Human Health
Evaluation Manual. EPA/540/1-89/002, December 1989, the
Integrated Risk Information System (IRIS). US. EPA, 1989, and
the RCRA Facility Investigation Document.)
If health-based criteria do not exist for a constituent, site
managers may propose their own health-based levels using the
tenacity testing guidelines contained in 40 CFR Parts 797 and 798,
and Agency guidelines for assessing health risks (51 FR 33992,
34006, 34014, and 34028). If no health-based level can be
determined for a constituent, the concentration of a constituent
generally must not exceed analytical detection limits for the purpose
of the No Migration demonstration. (Use of analytical detection
limits should be based on methodology prescribed in "Test Methods
for Solid Waste, Physical/Chemical Methods," U.S. EPA Publication
No. SW-846, with the lowest possible detection level indicated
therein for each hazardous constituent.) If health-based levels are
below analytical detection limits for a constituent, site managers
must demonstrate, through the use of modeling (see below), that
the health-based levels will be not be exceeded at the unit
boundary. However, for the purpose of compliance monitoring in
situations where health-based levels are below detection limits,
attaining levels of detection limits usually will constitute compliance.
Models
Existing guidance from OSW (i.e., "No Migration" Variances
to the Hazardous Waste Land Disposal Prohibitions: A Guidance
Manual for Petitioners. Draft, Office of Solid Waste, March 1990)
does not specify the specific types of models that are required to
obtain a No Migration Variance. Therefore, site managers may
select those models that are appropriate to predict that health-
based levels will not be exceeded beyond the unit boundary.
Several of the available models are recommended for use by EPA.
The Vadose Interactive Processes (VIP) model, for example,
predicts the degradation and mobility of organics in soil; the
Industrial Source Complex (ISC) Long Term or Short Term model
calculates waste dispersion rates into the air at the unit boundary,
and the Chemdat 6 model predicts the emission rates of wastes into
the air (more information on these models may be obtained from
OSWs Waste Management Division). EPA discourages the use of
proprietary models, because all models, the assumptions underlying
them, and their relevance for use at a site seeking a No Migration
Variance must be explained, and descriptions of their calculations
and codes must be available for review. Models, input data, and
relevant documentation should be included in the detailed
justification for a No Migration Variance.
DEMONSTRATING COMPLIANCE
The demonstration that there will be no migration of the
wastes for "as long as the wastes remain hazardous" is a waste- and
site-specific determination. For example, if hazardous waste is to
be placed in a salt dome under a No Migration Variance, the site
manager must consider the degradation and transformation
potential of the waste as well as the containment properties of the
salt dome (e.g., geologic stability, depth, thickness, and permeability
of the formation, and the properties of the salt as an encapsulating
medium).
For some waste types that degrade naturally to health-based
and/or environmentally protective levels in a relatively short time
period, site managers may only have to demonstrate that such
degradation occurs and show that "no migration" from the unit of
the waste or any toxic byproducts occurs during or after the
degradation period.
After a variance has been granted, all environmental media
must be monitored to 'confirm that no migration of hazardous
constituents occurs beyond the unit boundary. For air, a one-time
confirmatory ambient monitoring should also be performed to
confirm modeling estimates. The emission and air monitoring
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should be conducted during a period representative of worst-case
emission/dispersion conditions. After that, regular waste
sampling/monitoring must be performed to confirm modeling inputs
(e.g., routine waste sampling, weekly soil moisture, annual soil
sampling (for organics)). Site managers 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 practical time. (See Air
Pathway Assessment Methodology for "No-Migration"
Demonstrations. Interim Final, July 1989 for more information.)
If migration is detected during the monitoring period, the site
manager, in conjuncion with the Office of Regional Counsel, must
decide whether to issue an Explanation of Significant Differences
(ESD) or ROD Amendment announcing termination of waste
acceptance at the unit, termination of the variance, or changes in
the conditions of the variance. (Conditions of the variance that are
likely to be changed will cease migration. The variance must still be
maintained.) Where the receiving unit is not located on site (and
a petition has been filed under RCRA), if migration is detected, site
managers should contact the Permits and State Programs Division.
DOCUMENTING A NO MIGRATION VARIANCE FOR
REMEDIAL ACTIONS
RI/FS Report
The substantive requirements for demonstrating no migration
of the restricted RCRA hazardous waste should be documented in
the RI/FS Report. In the Detailed Analysis of Alternatives chapter
of the FS Report, a general discussion of why a No Migration
Variance is attempted should be included in the description of each
alternative for which a variance is contemplated. (The more
specific and detailed information, such as relevant waste analysis
Highlight 1 - DOCUMENTATION RECOMMENDED IN RI/FS REPORT FOR NO MIGRATION VARIANCES (DEVELOPMENT
OF ALTERNATIVES SECTION)
ON-SITE:
• Waste Descriptions
EPA Hazardous Waste Numbers) (if appropriate)
Estimated quantity of waste to be placed in unit
Physical and chemical characteristics
Waste incompatibilities (if any)
Waste transformation and immobilization mechanisms (e.g., biodegradation, photodegradation, hydrolysis, oxidation/reduction, volatilization)
Relevant sampling and testing information1 (e.g., TCLP test results)
• Site Characterization (e.g., climatology, meteorology, geology, hydrology)
• Monitoring Plans (e.g., type of monitoring for all media, frequency, location, equipment, reporting procedures)
• Waste Mobility Modeling
Leachate and gas generations
Barrier integrity over time
Potential for air emission of wastes
Physical properties of site soils affecting flow (e.g., water content, pressure potential, permeability, degree of water saturation)
Description of calculations and assumptions
Demonstration of appropriate QA/QC procedures
• Assessment of Environmental Impacts (e.g., species diversity, fishery and habitat impacts)
• Prediction of Infrequent Events (e.g., earthquakes, floods)
• QA/QC of all data and information
OFF-SITE:
For off-site No Migration Variances, the documentation requirements listed for on-site actions should be extracted from the RI/FS report and
combined with the following information found below. The information should be incorporated with the on-site information into a formal petition under
40 CFR 268.6 and a.copy of the petition should be referenced and attached to the RI/FS report.
Petitioner's name and address
Identification of on-site contact person, if different from above
Description and location of site
Statement of the petitioner's interest in the proposed action
Source: "No Migration" Variances to the Hazardous Waste Land Disposal Prohibitions: A Guidance Manual for Petitioners. Draft, Office of Solid
Waste, March 1990.
1 Appropriate sampling information may be contained in the Superfund Quality Assurance Project Plan (QAPP) and, therefore, not specifically repeated
in the RI/FS Report
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data from sampling, should be placed in an appendix to the report.)
Under the "Compliance with ARARs Criterion," site managers
should identify those wastes or waste residuals to be granted a No
Migration Variance, and state that those wastes or waste residuals
would achieve compliance with the LDRs through the No
Migration Variance.
The specific information that should be included in an RI/FS
report for on-site and off-site CERCLA remedial actions is
presented in Highlight 1.
Proposed Plan
The intent to seek a No Migration Variance should be stated
clearly in the Description of Alternatives section of the Proposed
Plan. Because the Proposed Plan solicits public comment on all of
the remedial alternatives, the intent to seek a No Migration
Variance should be identified for all alternatives for which such an
action is contemplated. This opportunity for public comment on
the Proposed Plan fulfills the requirements for public notice and
comment on No Migration Variances required under 40 CFR
260.20 when wastes are transported off-site. Highlight 2 provides
sample language for the Proposed Plan.
Highlight 2 - SAMPLE LANGUAGE FOR THE
PROPOSED PLAN
Description of Alternatives section:
Under this alternative, compliance with RCRA land
disposal restrictions would be achieved by obtaining a
No Migration Variance under which hazardous wastes
would not be allowed to migrate from the unit above
health-based levels.
Evaluation of Alternatives section, under
"Compliance with ARARs":
A No Migration Variance would be granted for [Enter
number] of [Enter total number of alternatives] to
comply with the RCRA land disposal restrictions.
Community's Role in Selection Process section:
The Proposed Plan also seeks comment on granting a
No Migration Variance for each alternative for which
a No Migration Variance is proposed, [Alternatives #1,
#2, etc.].
Record of Decision (ROD")
The documentation provided in the ROD for a No Migration
Variance should be a brief synopsis of the information provided in
the FS report. In the Description of Alternatives section, as part
of the discussion of major ARARs associated with each remedial
alternative, site managers should include a statement that explains
why a No Migration Variance is justified. Sample language for the
Description of Alternatives section of the ROD is presented in
Highlight 3.
In the Statutory Determination section, under "Compliance
with ARARs," site managers should indicate that wastes receiving
a No Migration Variance will achieve compliance with the LDRs
through a No Migration Variance.
Highlight 3 - SAMPLE LANGUAGE FOR THE RECORD
OF DECISION
Description of Alternatives section:
Because existing and available data demonstrate that
there will be no migration of hazardous constituents
from the unit as long as the waste remains hazardous,
a No Migration Variance has accordingly been granted
as part of this ROD. Accordingly, the residuals placed
in this unit do not have to meet the RCRA LDR
treatment standards. The [landfill/clean] closure
requirements will, however, be met.
NOTICE: The policies set out in this memorandum are intended solely as guidance. They are not intended, nor can they be relied
upon, to create any rights enforceable by any party in litigation with the United States. EPA officials may decide to follow the guidance
provided in this memorandum, or to act at variance with the guidance, based on an analysis of specific site circumstances. The Agency
also reserves the right to change this guidance any time without public notice.
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