[Federal Register Volume 63, Number 95 (Monday, May 18, 1998)]
[Rules and Regulations]
[Pages 27354-27406]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-13100]
[[Page 27353]]
_______________________________________________________________________
Part III
Environmental Protection Agency
_______________________________________________________________________
40 CFR Part 194
Criteria for the Certification and Recertification of the Waste
Isolation Pilot Plant's Compliance With the Disposal Regulations:
Certification Decision; Final Rule
Federal Register / Vol. 63, No. 95 / Monday, May 18, 1998 / Rules and
Regulations
[[Page 27354]]
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 194
[FRL--6014-9]
RIN 2060-AG85
Criteria for the Certification and Recertification of the Waste
Isolation Pilot Plant's Compliance With the Disposal Regulations:
Certification Decision
AGENCY: Environmental Protection Agency.
ACTION: Final rule.
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SUMMARY: The Environmental Protection Agency (``EPA'') is certifying
that the Department of Energy's (``DOE'') Waste Isolation Pilot Plant
(``WIPP'') will comply with the radioactive waste disposal regulations
set forth at Subparts B and C of 40 CFR Part 191 (Environmental
Standards for the Management and Disposal of Spent Nuclear Fuel, High-
Level and Transuranic Radioactive Waste). The EPA is required to
evaluate whether the WIPP will comply with EPA's standards for the
disposal of radioactive waste by the WIPP Land Withdrawal Act (``LWA'')
of 1992, as amended. EPA's certification of compliance allows the
emplacement of radioactive waste in the WIPP to begin, provided that
all other applicable health and safety standards, and other legal
requirements, have been met. The certification constitutes final
approval under the WIPP LWA for shipment of transuranic waste from
specific waste streams from Los Alamos National Laboratory for disposal
at the WIPP. However, the certification is subject to four specific
conditions, most notably that EPA must approve site-specific waste
characterization measures and quality assurance programs before other
waste generator sites may ship waste for disposal at the WIPP. The
Agency is amending the WIPP compliance criteria (40 CFR Part 194) by
adding Appendix A that describes EPA's certification, incorporating the
approval processes for waste generator sites to ship waste for disposal
at the WIPP, and adding a definition for ``Administrator's authorized
representative.'' Finally, EPA is finalizing its decision, also
pursuant to the WIPP LWA, that DOE does not need to acquire existing
oil and gas leases near the WIPP to comply with the disposal
regulations.
EFFECTIVE DATE: This decision is effective June 17, 1998. A petition
for review of this final action must be filed no later than July 17,
1998, pursuant to section 18 of the WIPP Land Withdrawal Act of 1992
(Pub. L. 102-579), as amended by the WIPP LWA Amendments (Pub. L. 104-
201).
FOR FURTHER INFORMATION CONTACT: Betsy Forinash, Scott Monroe, or
Sharon White; telephone number (202) 564-9310; address: Radiation
Protection Division, Center for the Waste Isolation Pilot Plant, Mail
Code 6602-J, U.S. Environmental Protection Agency, 401 M Street S.W.,
Washington, DC 20460. For copies of the Compliance Application Review
Documents supporting today's action, contact Scott Monroe. The Agency
is also publishing a document, accompanying today's action, which
responds in detail to significant public comments that were received on
the proposed certification decision. This document, entitled ``Response
to Comments,'' may be obtained by contacting Sharon White at the above
phone number and address. Copies of these documents are also available
for review in the Agency's Air Docket A-93-02.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. What is the WIPP?
II. What is the purpose of today's action?
III. With which regulations must the WIPP comply?
IV. What is the decision on whether the WIPP complies with EPA's
regulations?
A. Certification Decision
B. Conditions
C. Land Withdrawal Act Section 4(b)(5)(B) Leases
D. EPA's Future Role at the WIPP (recertification, enforcement
of conditions)
V. What information did EPA examine to make its decision?
VI. In making its final decision, how did EPA incorporate public
comments on the proposed rule?
A. Introduction and the Role of Comments in the Rulemaking
Process
B. Significant Changes Made to the Final Rule in Response to
Comments
VII. How did EPA respond to general comments on its proposed
certification decision?
VIII. How did EPA respond to major technical issues raised in
comments?
A. Content of Compliance Certification Application (Sec. 194.14)
1. Site Characterization and Disposal System Design
(a) Shaft Seals
(b) Panel Closure System
2. Results of Assessments, Input Parameters to Performance
Assessments, Assurance Requirements, and Waste Acceptance Criteria
3. Background Radiation, Topographic Maps, Past and Current
Meteorological Conditions
4. Other Information Needed for Demonstration of Compliance
5. Conclusion
B. Performance Assessment: Modeling and Containment Requirements
(Secs. 194.14, 194.23, 194.31 through 194.34)
1. Introduction
2. Human Intrusion Scenarios
(a) Introduction
(b) Spallings
(c) Air Drilling
(d) Fluid Injection
(e) Potash Mining
(f) Carbon Dioxide Injection
(g) Other Drilling Issues
3. Geological Scenarios and Disposal System Characteristics
(a) Introduction
(b) WIPP Geology Overview
(c) Rustler Recharge
(d) Dissolution
(e) Presence of Brine in the Salado
(f) Gas Generation Model
(g) Two-Dimensional Modeling of Brine and Gas Flow
(h) Earthquakes
(i) Conclusion
4. Parameter Values
(a) Introduction
(b) Distribution Coefficient (Kd)
(c) Actinide Solubility
(d) Brine Pockets
(e) Permeability of Borehole Plugs
5. Other Performance Assessment Issues
(a) Sensitivity Analysis
(b) Performance Assessment Verification Test
6. Conclusions
C. General Requirements
1. Quality Assurance (Sec. 194.22)
2. Waste Characterization (Sec. 194.24)
3. Future State Assumptions (Sec. 194.25)
4. Expert Judgment (Sec. 194.26)
5. Peer Review (Sec. 194.27)
D. Assurance Requirements
1. Active Institutional Controls (Sec. 194.41)
2. Monitoring (Sec. 194.42)
3. Passive Institutional Controls (Sec. 194.43)
4. Engineered Barriers (Sec. 194.44)
5. Consideration of the Presence of Resources (Sec. 194.45)
6. Removal of Waste (Sec. 194.46)
E. Individual and Ground-water Protection Requirements
(Secs. 194.51-55)
IX. Does DOE need to buy existing oil and gas leases near the WIPP?
X. Why and how does EPA regulate the WIPP?
A. The WIPP Land Withdrawal Act
B. Limits of EPA's Regulatory Authority at the WIPP
C. Compliance with Other Environmental Laws and Regulations
XI. How has the public been involved in EPA's WIPP activities?
A. Public Involvement Prior to Proposed Rule
B. Proposed Certification Decision
C. Public Hearings on Proposed Rule
D. Additional Public Input on the Proposed Rule
E. Final Certification Decision, Response to Comments Document
F. Dockets
XII. How will the public be involved in EPA's future WIPP
activities?
XIII. Where can I get more information about EPA's WIPP activities?
A. Technical Support Documents
[[Page 27355]]
B. WIPP Information Line, Mailing List, and Internet Homepage
XIV. Regulatory Analysis/Administrative Requirements
A. Executive Order 12866
B. Regulatory Flexibility
C. Paperwork Reduction Act
D. Unfunded Mandates Reform Act
E. Executive Order 12898
F. Small Business Regulatory Enforcement Fairness Act of 1996
G. National Technology Transfer & Advancement Act of 1995
H. Executive Order 13045--Children's Health Protection
I. What is the WIPP?
The Waste Isolation Pilot Plant (``WIPP'') is a potential disposal
system for radioactive waste. Developed by the Department of Energy
(``DOE'' or ``the Department''), the WIPP is located near Carlsbad in
southeastern New Mexico. The DOE intends to bury radioactive waste 2150
feet underground in an ancient layer of salt which will eventually
``creep'' and encapsulate waste containers. The WIPP has a total
capacity of 6.2 million cubic feet of waste.
Congress authorized the development and construction of the WIPP in
1980 ``for the express purpose of providing a research and development
facility to demonstrate the safe disposal of radioactive wastes
resulting from the defense activities and programs of the United
States.'' 1 The waste which may be emplaced in the WIPP is
limited to transuranic (``TRU'') radioactive waste generated by defense
activities associated with nuclear weapons; no high-level waste or
spent nuclear fuel from commercial power plants may be disposed of at
the WIPP. TRU waste is defined as materials containing alpha-emitting
radio-isotopes, with half lives greater than twenty years and atomic
numbers above 92, in concentrations greater than 100 nano-curies per
gram of waste.2
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\1\ Department of Energy National Security and Military
Applications of Nuclear Energy Authorization Act of 1980, Pub. L.
96-164, section 213.
\2\ WIPP Land Withdrawal Act, Pub. L. 102-579, section 2(18), as
amended by the 1996 WIPP LWA Amendments, Pub. L. 104-201.
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Most TRU waste proposed for disposal at the WIPP consists of items
that have become contaminated as a result of activities associated with
the production of nuclear weapons (or with the clean-up of weapons
production facilities), e.g., rags, equipment, tools, protective gear,
and organic or inorganic sludges. Some TRU waste is mixed with
hazardous chemicals. Some of the waste proposed for disposal at the
WIPP is currently stored at Federal facilities across the United
States, including locations in Colorado, Idaho, New Mexico, Nevada,
Ohio, South Carolina, Tennessee, and Washington. Much of the waste
proposed for disposal at the WIPP will be generated in the future.
II. What Is the Purpose of Today's Action?
Before disposal of radioactive waste can begin at the WIPP, the
U.S. Environmental Protection Agency (``EPA,'' or ``the Agency'') must
certify that the WIPP facility will comply with EPA's radioactive waste
disposal regulations (Subparts B and C of 40 CFR Part 191).3
The purpose of today's action is to issue EPA's certification decision.
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\3\ WIPP LWA, section 8(d).
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With today's action, EPA will add to the Code of Federal
Regulations a new Appendix A to 40 CFR Part 194 describing EPA's
certification decision and the conditions that apply to the
certification. The Agency is adding a new section, Sec. 194.8, to the
WIPP compliance criteria (40 CFR Part 194) that describes the processes
EPA will use to approve quality assurance and waste characterization
programs at waste generator sites. The EPA is also adding a definition
of the term ``Administrator's authorized representative'' to the WIPP
compliance criteria. Except for these actions, the certification
decision does not otherwise amend or affect EPA's radioactive waste
disposal regulations or the WIPP compliance criteria.
Today's action also addresses the provision of section 7(b)(2) of
the WIPP Land Withdrawal Act which prohibits DOE from emplacing
transuranic waste underground for disposal at the WIPP until, inter
alia, it acquires specified oil and gas leases, unless EPA determines
that such acquisition is not necessary.
III. With Which Regulations Must the WIPP Comply?
The WIPP must comply with EPA's radioactive waste disposal
regulations, located at Subparts B and C of 40 CFR Part 191. These
regulations limit the amount of radioactive material which may escape
from a disposal facility, and protect individuals and ground water
resources from dangerous levels of radioactive contamination. In
addition, the compliance certification application (``CCA'') and other
information submitted by DOE must meet the requirements of the WIPP
compliance criteria at 40 CFR Part 194. The compliance criteria
implement and interpret the general disposal regulations specifically
for the WIPP, and clarify the basis on which EPA's certification
decision is made.
IV. What Is the Decision on Whether the WIPP Complies With EPA's
Regulations?
A. Certification Decision
The EPA finds that DOE has demonstrated that the WIPP will comply
with EPA's radioactive waste disposal regulations at Subparts B and C
of 40 CFR Part 191. This decision allows the WIPP to begin accepting
transuranic waste for disposal, provided that other applicable
environmental regulations have been met and once a 30-day
Congressionally-required waiting period has elapsed.4 EPA's
decision is based on a thorough review of information submitted by DOE,
independent technical analyses, and public comments. The EPA determined
that DOE met all of the applicable requirements of the WIPP compliance
criteria at 40 CFR Part 194. However, as discussed below, DOE must meet
certain conditions in order to maintain a certification for the WIPP
and before shipping waste for disposal at the WIPP.
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\4\ WIPP LWA, Sec. 7(b).
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B. Conditions
As noted above, EPA determined that DOE met all of the applicable
requirements of the WIPP compliance criteria. In several instances,
however, EPA found that it is necessary for DOE to take additional
steps to ensure that the measures actually implemented at the WIPP (and
thus the circumstances expected to exist there) are consistent with
DOE's compliance certification application (``CCA'') and with the basis
for EPA's compliance certification. Regarding several requirements, DOE
demonstrated compliance with the applicable compliance criteria for
only one category of waste at a single waste generator site. To address
these situations, EPA is amending the WIPP compliance criteria, 40 CFR
Part 194, and appending four explicit conditions to its certification
of compliance for the WIPP.
Condition 1 of the certification relates to the panel closure
system, which is intended over the long term to block brine flow
between waste panels in the WIPP. In its CCA, DOE presented four
options for the design of the panel closure system, but did not specify
which one would be constructed at the WIPP. The EPA based its
certification decision on DOE's use of the most robust design (referred
to in the CCA as ``Option D''). The Agency found the Option D design to
be adequate, but also
[[Page 27356]]
determined that the use of a Salado mass concrete--using brine rather
than fresh water--would produce concrete seal permeabilities in the
repository more consistent with the values used in DOE's performance
assessment. Therefore, Condition 1 of EPA's certification requires DOE
to implement the Option D panel closure system at the WIPP, with Salado
mass concrete replacing fresh water concrete. (For more detail on the
panel closure system, refer to the preamble discussion of Sec. 194.14.)
Conditions 2 and 3 of the final rule relate to activities conducted
at waste generator sites that produce the transuranic waste proposed
for disposal in the WIPP. The WIPP compliance criteria (Secs. 194.22
and 194.24) require DOE to have in place a system of controls to
measure and track important waste components, and to apply quality
assurance (``QA'') programs to waste characterization activities. At
the time of EPA's proposed certification decision, the Los Alamos
National Laboratory (``LANL'') was the only site to demonstrate the
execution of the required QA programs and the implementation of the
required system of controls. Therefore, EPA's certification constitutes
final approval under the WIPP LWA for DOE to ship waste for disposal at
the WIPP only from the LANL, and only for the retrievably stored
(legacy) debris at LANL for which EPA has inspected and approved the
applicable system of controls. Before DOE may ship any mixed (hazardous
and radioactive) waste from the LANL--even if it is encompassed by the
waste streams approved by EPA in this action--DOE must obtain any other
regulatory approvals that may be needed, including approval from the
State of New Mexico under the Resource Conservation and Recovery Act to
dispose of such waste at the WIPP.
As described in the final WIPP certification, before other waste
may be shipped for disposal at the WIPP, EPA must separately approve
the QA programs for other generator sites (Condition 2) and the waste
characterization system of controls for other waste streams (Condition
3). The approval process includes an opportunity for public comment,
and an inspection (of a DOE audit) or audit of the waste generator site
by EPA. The Agency's approval of waste characterization systems of
controls and QA programs will be conveyed in a letter from EPA to DOE.
In response to public comments on these conditions, EPA's approval
processes for waste generator site programs have been incorporated into
the body of the WIPP compliance criteria, in a new section at
Sec. 194.8. (For more information on this change, see the preamble
section entitled, ``Significant Changes to the Final Rule Made in
Response to Public Comments.'' For further discussion of Conditions 2
and 3, refer to the preamble discussions of Sec. 194.22 and
Sec. 194.24, respectively.)
Condition 4 of the certification relates to passive institutional
controls (``PICs''). The WIPP compliance criteria require DOE to use
both records and physical markers to warn future societies about the
location and contents of the disposal system, and thus to deter
inadvertent intrusion into the WIPP. (Sec. 194.43) In its application,
DOE provided a design for a system of PICs, but stated that many
aspects of the design would not be finalized for many years (even up to
100) after closure. The PICs actually constructed and placed in the
future must be consistent with the basis for EPA's certification
decision. Therefore, Condition 4 of the certification requires DOE to
submit a revised schedule showing that markers and other measures will
be implemented as soon as possible after closure of the WIPP. The DOE
also must provide additional documentation showing that it is feasible
to construct markers and place records in archives as described in
DOE's certification application. After closure of the WIPP, DOE will
not be precluded from implementing additional PICs beyond those
described in the application. (See the preamble discussion of
Sec. 194.43 for more information on PICs.)
Although not specified in the certification, it is a condition of
any certification that DOE must submit periodic reports of any planned
or unplanned changes in activities pertaining to the disposal system
that differ significantly from the most recent compliance application.
(Sec. 194.4(b)(3)) The DOE must also report any releases of radioactive
material from the disposal system. (Sec. 194.4(b)(3)(iii), (v))
Finally, EPA may request additional information from DOE at any time.
(Sec. 194.4(b)(2)) These reports and information will allow EPA to
monitor the performance of the disposal system and evaluate whether the
certification must be modified, suspended, or revoked for any reason.
(Modifications, suspensions, recertification, and other activities are
also addressed in the preamble section entitled, ``EPA's Future Role at
the WIPP.'')
C. Land Withdrawal Act Section 4(b)(5)(B) Leases
The EPA finds that DOE does not need to acquire existing oil and
gas leases (Numbers NMNM 02953 and 02953C) (referred to as the
``section 4(b)(5)(B) leases'') in the vicinity of the WIPP in order to
comply with EPA's final disposal regulations at 40 CFR Part 191,
Subparts B and C. The EPA concludes that potential activities at these
existing leases would have an insignificant effect on releases of
radioactive material from the WIPP disposal system and, thus, that they
do not cause the WIPP to violate the disposal regulations.
D. EPA's Future Role at the WIPP (recertification, enforcement of
conditions)
The EPA will continue to have a role at the WIPP after this
certification becomes effective. As discussed above, DOE must submit
periodic reports on any activities or conditions at the WIPP that
differ significantly from the information contained in the most recent
compliance application. The EPA may also, at any time, request
additional information from DOE regarding the WIPP. (Sec. 194.4) The
Agency will review such information as it is received to determine
whether the certification must be modified, suspended, or revoked. Such
action might be warranted if, for example, significant information
contained in the most recent compliance application were no longer to
remain true. The certification could be modified to alter the terms or
conditions of certification--for example, to add a new condition, if
necessary to address new or changed activities at the WIPP.
(Sec. 194.2) The certification could be revoked if it becomes evident
in the future that the WIPP cannot or will not comply with the disposal
regulations. Either modification or revocation must be conducted by
rulemaking, in accordance with the WIPP compliance criteria.
(Secs. 194.65-66) Suspension may be initiated at the Administrator's
discretion, in order to promptly reverse or mitigate a potential threat
to public health. For instance, a suspension would take effect if,
during emplacement of waste, a release from the WIPP occurred in excess
of EPA's containment limits. (See Sec. 194.4(b)(3).)
In addition to reviewing annual reports from DOE regarding
activities at the WIPP, EPA periodically will evaluate the WIPP's
continued compliance with the WIPP compliance criteria and disposal
regulations. As directed by Congress, this ``recertification'' will
occur every five
[[Page 27357]]
years.5 For recertification, DOE must submit to EPA for
review the information described in the WIPP compliance criteria
(although, to the extent that information submitted in previous
certification applications remains valid, it can be summarized and
referenced rather than resubmitted). (Sec. 194.14) In accordance with
the WIPP compliance criteria, documentation of continued compliance
will be made available in EPA's dockets, and the public will be
provided at least a 30-day period in which to submit comments. The
EPA's decision on recertification will be announced in the Federal
Register. (Sec. 194.64)
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\5\ WIPP LWA, Sec. 8(f). Congress also directed that this
periodic recertification ``shall not be subject to rulemaking or
judicial review.''
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In the immediate future, the Agency expects to conduct numerous
inspections at waste generator sites in order to implement Conditions 2
and 3 of the compliance certification. Notices announcing EPA
inspections or audits to evaluate implementation of quality assurance
(``QA'') and waste characterization requirements at generator
facilities will be published in the Federal Register. The public will
have the opportunity to submit written comments on the waste
characterization and QA program plans submitted by DOE. As noted above,
EPA's decisions on whether to approve waste generator QA program plans
and waste characterization systems of controls--and thus, to allow
shipment of specific waste streams for disposal at the WIPP--will be
conveyed by a letter from EPA to DOE. A copy of the letter, as well as
any EPA inspection or audit reports, will be placed in EPA's docket.
(See the preamble sections entitled ``Dockets'' and ``Where can I get
more information about EPA's WIPP activities?'' for more information
regarding EPA's rulemaking docket.) The procedures for EPA's approval
have been incorporated in the compliance criteria at a new section,
Sec. 194.8.
As discussed previously, Condition 1 of the WIPP certification
requires DOE to implement the Option D panel closure system at the
WIPP, with Salado mass concrete being used in place of fresh water
concrete. It will be possible to evaluate the closure system only when
waste panels have been filled and are being sealed. At that time, EPA
intends to confirm compliance with this condition through inspections
under its authority at Sec. 194.21 of the WIPP compliance criteria.
Similarly, EPA will be able to evaluate DOE's compliance with
Condition 4 of the certification only when DOE submits a revised
schedule and additional documentation regarding the feasibility of
implementing passive institutional controls. This documentation must be
provided to EPA no later than the final recertification application.
Once received, the information will be placed in EPA's docket, and the
Agency will evaluate the adequacy of the documentation. If necessary,
EPA may initiate a modification to the certification to address DOE's
revised schedule; any such modification would be undertaken in
accordance with the public participation requirements described in the
WIPP compliance criteria, Secs. 194.65-66. During the operational
period when waste is being emplaced in the WIPP (and before the site
has been sealed and decommissioned), EPA will verify that specific
actions identified by DOE in the CCA and supplementary information (and
in any additional documentation submitted in accordance with Condition
4) are being taken to test and implement passive institutional
controls. For example, DOE stated that it will submit a plan for
soliciting archives and record centers to accept WIPP information in
the fifth recertification application. The Agency can confirm
implementation of such measures by examining documentation and by
conducting inspections under its authority at Sec. 194.21.
Finally, the WIPP compliance criteria provide EPA the authority to
conduct inspections of activities at the WIPP and at all off-site
facilities which provide information included in certification
applications. (Sec. 194.21) The Agency expects to conduct periodic
inspections, both announced and unannounced, to verify the adequacy of
information relevant to certification applications. The Agency may
conduct its own laboratory tests, in parallel with those conducted by
DOE. The Agency also may inspect any relevant records kept by DOE,
including those records required to be generated in accordance with the
compliance criteria. For example, EPA intends to conduct ongoing
inspections or audits at the WIPP and at waste generator sites to
ensure that approved quality assurance programs are being adequately
maintained and documented. The EPA plans to place inspection reports in
its docket for public examination.
V. What Information Did EPA Examine to Make its Decision?
The EPA made its certification decision by comparing relevant
information to the WIPP compliance criteria (40 CFR Part 194) and
ensuring that DOE satisfied the specific requirements of the criteria
in demonstrating compliance with the disposal regulations. The primary
source of information examined by EPA was a compliance certification
application (``CCA'') submitted by DOE on October 29, 1996. (Copies of
the CCA were placed in EPA's Air Docket A-93-02, Category II-G.) The
DOE submitted additional information after that time. On May 22, 1997,
EPA announced that DOE's application was deemed to be complete. (62 FR
27996-27998)
However, as contemplated by Congress, EPA's compliance
certification decision is based on more than the complete application.
The EPA also relied on materials prepared by the Agency or submitted by
DOE in response to EPA requests for specific additional information
necessary to address technical sufficiency concerns. The Agency also
considered public comments on the proposed rule which supported or
refuted technical positions. Thus, EPA's certification decision is
based on the entire record available to the Agency, which is contained
in EPA's Air Docket A-93-02. The record consists of the complete CCA,
supplementary information submitted by DOE in response to EPA requests
for additional information, technical reports generated by EPA and EPA
contractors, EPA audit and inspection reports, and public comments
submitted on EPA's proposed certification decision during the public
comment period.
In response to public comments regarding the precise materials EPA
considered in reaching its certification decision, the Compliance
Application Review Documents (``CARDs'') supporting today's decision
reference the relevant portion(s) of the October 29, 1996, CCA and any
supplementary information that the Agency relied on in reaching a
particular compliance decision. (Docket A-93-02, Item V-B-2) All
materials which informed EPA's proposed and final decisions have been
placed in the WIPP dockets or are otherwise publicly available. A full
list of the supporting documentation for EPA's certification decision
and the DOE compliance documentation considered by the Agency is
located at Docket A-93-02, Item V-B-1. For further information
regarding the availability of information EPA examined, see the section
entitled ``Dockets'' in this preamble.
[[Page 27358]]
VI. In Making its Final Decision, how did EPA Incorporate Public
Comments on the Proposed Rule?
A. Introduction and the Role of Comments in the Rulemaking Process
Congress directed that EPA's certification decision for the WIPP be
conducted by informal (or ``notice-and-comment'') rulemaking pursuant
to Section 4 of the Administrative Procedure Act (``APA'').6
Notice-and-comment rulemaking under the APA requires that regulatory
agencies provide notice of a proposed rulemaking, an opportunity for
the public to comment on the proposed rule, and a general statement of
the basis and purpose of the final rule.7 The notice of
proposed rulemaking required by the APA must ``disclose in detail the
thinking that has animated the form of the proposed rule and the data
upon which the rule is based.'' (Portland Cement Ass'n v. Ruckelshaus,
486 F.2d 375, 392-94 (D.C. Cir. 1973)) The public is thus enabled to
participate in the process by making informed comments on the Agency's
proposal. This provides the Agency the benefit of ``an exchange of
views, information, and criticism between interested persons and the
agency.'' (Id.)
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\6\ WIPP LWA, Sec. 8(d)(2).
\7\ 5 U.S.C. 553
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For the WIPP certification decision, there are two primary
mechanisms by which EPA explains the issues that were raised in public
comments and the Agency's reactions to them. First, broad or major
comments are discussed in the succeeding sections of this preamble.
Second, EPA is publishing a document, accompanying today's action and
entitled ``Response to Comments,'' which contains the Agency's response
to all significant comments received during the comment period on the
proposed certification decision. (The EPA also responded to comments
received on its advance notice of proposed rulemaking (``ANPR''); for
further information on the ANPR, see the preamble section ``Public
Involvement Prior to the Proposed Rule.'') The Response to Comments
document provides more detailed responses to issues which are addressed
in the preamble, and addresses all other significant comments on the
proposal. All comments received by EPA, whether written or oral, were
given equal consideration in developing the final rule.
B. Significant Changes to the Final Rule Made in Response to Public
Comments
Today's action finalizes EPA's proposed decision that the WIPP
facility will comply with the disposal regulations and that DOE does
not need to acquire existing oil and gas leases in the WIPP Land
Withdrawal Area. (For further information, refer to the preamble
section entitled, ``What is the decision on whether the WIPP complies
with EPA's regulations?'') Beyond these broad determinations, EPA's
proposed certification decision also included four conditions related
to the panel closure system, quality assurance at waste generator
sites, waste characterization measures at waste generator sites, and
passive institutional controls. The final rule retains all of these
conditions. However, in response to comments submitted on the proposal,
the Agency has made clarifying changes to Subpart A of 40 CFR Part 194
to provide a clearer explanation of the process for determining
compliance with the conditions related to waste generator sites.
Proposed Conditions 2 and 3 relate to quality assurance (``QA'')
programs and waste characterization programs, respectively, at waste
generator sites intending to ship waste for disposal at the WIPP.
Except for removal of the procedural sections of the proposed
conditions from the appendix (as proposed) to Subpart A of 40 CFR Part
194, to provide for a clearer enunciation of the process for
determining compliance with the conditions, these conditions are
retained with minor clarifications in the final rule. The conditions
restrict DOE from shipping waste to the WIPP from any sites other than
the Los Alamos National Laboratory until EPA separately approves the QA
and waste characterization plans at other waste generator sites. For
both QA and waste characterization programs, the proposed approval
process included: placement in the docket of site-specific
documentation submitted by DOE, publication of a Federal Register
notice by EPA announcing a scheduled inspection or audit, a period of
at least 30 days for the public to comment on information placed in the
docket, and the Agency's written decision regarding the approval of
these programs in the form of a letter from EPA to DOE. The EPA
proposed to approve QA programs on a site-wide basis. However, because
the features of waste streams can vary widely and thus can require
significantly different characterization techniques, EPA proposed to
approve waste characterization measures and controls on the basis of
waste streams or, where multiple waste streams may be characterized by
the same waste characterization processes and techniques, groups of
waste streams.
A number of commenters suggested that in the waste generator site
approval process, EPA should delay the public comment period until
after completion of an inspection or audit, and should make the
Agency's approval decision explicitly subject to judicial review. Other
comments questioned the authority for, and the value of, a separate
site approval process by EPA.
The EPA finds that it is both necessary and within the Agency's
authority to evaluate and approve site-specific QA and waste
characterization programs. The compliance criteria expressly provide
that any certification of compliance ``may include such conditions as
[EPA] finds necessary to support such certification.'' (Sec. 194.4(a))
Before waste is shipped for disposal at the WIPP, EPA must be confident
that the waste will conform to the waste limits and other waste-related
assumptions incorporated in DOE's performance assessment--that is, that
DOE adheres to the fundamental information and assumptions on the waste
on which the certification of compliance is based. Such confidence can
be assured only by confirmation that the required QA and waste
characterization programs are in place (i.e., established, implemented
or executed) at waste generator sites. The EPA believes that an
approval process separate from DOE's internal procedures is beneficial
because DOE's process is not geared solely to confirming that programs
adhere to EPA's compliance criteria, and because DOE's process does not
provide for public participation.
Given the great public interest regarding the WIPP, and waste
characterization in particular, EPA believes it is important that the
public be informed of and have the opportunity to be involved in the
site approval process. To that end, EPA's approval process includes
docketing information relevant to site-specific approvals, and allowing
the public to comment on such information.
The EPA's certification that the WIPP will comply with the 40 CFR
Part 191 radioactive waste disposal regulations is based on the
Agency's determination that the WIPP will comply with the containment
requirements and other requirements of 40 CFR Parts 191 and 194 for the
waste inventory described for purposes of the performance assessment.
In the CCA, DOE purported to demonstrate that the WIPP would meet the
40 CFR Part 191 release limits
[[Page 27359]]
by modeling the WIPP's behavior in its performance assessment. The
performance assessment incorporated certain upper and lower limiting
values of specified waste components, as required by 40 CFR 194.24(c).
The EPA confirmed the results of the performance assessment using the
same upper and lower limiting values in the performance assessment
verification test (``PAVT''). Those upper and lower limiting values
apply to contact-handled, remote-handled, and to-be-generated waste
from numerous generator sites. Thus, in today's action, EPA certifies
that the WIPP will comply with the 40 CFR Part 191 containment
requirements to the extent that emplaced waste falls within the waste
envelope limits that were shown by the performance assessment, and
confirmed by the PAVT, to be compliant with the 40 CFR Part 191
standards. Proposed Conditions 2 and 3 change neither the performance
assessment assumptions nor the terms on which the WIPP is authorized
for disposal, but rather ensure that the assumptions on which the
compliance certification is based are adhered to in practice.
Based on public comments, EPA also finds it necessary to clarify
that the compliance criteria at Sec. 194.22 and Sec. 194.24 were not
intended to require that DOE address their requirements--including QA
measures, and the use of process knowledge--for all waste streams in
the certification application for the initial certification. Clearly,
it would be impossible to do so for the to-be-generated waste. It is
similarly impossible for DOE to demonstrate fully, in the initial
certification application, that the waste emplaced in the disposal
system actually conforms to the waste envelope (i.e., upper and lower
waste limits) upon which the certification is based, since waste cannot
be disposed of at the WIPP before EPA grants an initial certification.
Confusion on these issues arose because the compliance criteria at 40
CFR Part 194 apply to information in compliance recertification
applications as well as the initial certification application.
The fact that it was not EPA's intent to require DOE to have
implemented QA or measurement programs for all waste at every site
prior to initial certification is supported by numerous statements made
by the Agency at the time the compliance criteria were issued. The EPA
had great discretion in setting the waste characterization
requirements, since they were part of the general requirements of the
WIPP compliance criteria and not derived directly from the disposal
regulations. In the Response to Comments for 40 CFR Part 194, EPA
emphasized that compliance with the requirements would be confirmed
through inspections or audits and would not serve to re-open the
certification rulemaking. (Docket A-92-56, Item V-C-1, pp. 6-5, 6-8,
and 6-20) The Agency stated that the certification rulemaking would
address DOE's analysis of waste characteristics and components and
documentation that a system of controls had been established at the
WIPP to track the amount of important waste components emplaced in the
disposal system. (Docket A-92-56, Item V-C-1, p. 6-9) The certification
rulemaking has addressed these issues and found DOE in compliance with
the requisite criteria. The EPA believes that the comprehensive waste
characterization approach described by DOE in the CCA--including the
approach to identification, limitation, and confirmation of waste
components important to containment of waste in the disposal system--is
an appropriate basis for granting an initial certification. The EPA
further believes that confirmation of the QA and system of controls at
waste generator sites (i.e., measuring and tracking important waste
components) can be reasonably obtained by a process of inspections and
audits in accordance with 40 CFR 194.21, 194.22(e), and 194.24(h).
The EPA declines to modify the proposed approval process by
delaying the comment period until after the issuance of EPA's
inspection or audit report. The EPA does not believe it is prudent to
commit to a strict sequence of events that will be adhered to for every
approval. In some cases, the Agency may place records of a completed
inspection or audit in the docket prior to or during the public comment
period. However, in other cases, the Agency believes that the public
comment period may better serve members of the public if it allows them
to provide comments on DOE's documentation prior to EPA's inspection or
audit. In this way, public comments could inform EPA's inspection
criteria and process, or provide information on which EPA may take
action to follow up in the inspection or audit. Therefore, the Agency
does not believe that it is prudent to specify when the comment period
may occur in relation to an inspection or audit. Furthermore, EPA
declines to make any statement regarding whether the approval decisions
are subject to judicial review. Jurisdiction of U.S. Federal Courts is
governed by the enactments of the U.S. Congress.
Nevertheless, in response to comments requesting changes or
clarifications to EPA's waste generator site and waste stream approval
processes, EPA made certain changes to the proposed conditions. In
order to clarify EPA's original intent in the compliance criteria
regarding approval of site-specific activities, EPA is amending the
compliance criteria at 40 CFR Part 194 to include the site-specific
approval process. (See 62 FR 58804, 58815) Thus, the procedures for
demonstrating compliance with the proposed Conditions 2 and 3 are
incorporated in the final rule as a new section at 40 CFR Part 194:
Sec. 194.8, ``Approval Process for Waste Shipment from Waste Generator
Sites for Disposal at the WIPP.'' Also, in response to comments
advocating greater transparency in the approval process, EPA has
clarified that scheduled inspections or audits by EPA for the purpose
of approving quality assurance programs at waste generator sites will
be announced by notice in the Federal Register (Sec. 194.8(a)); this is
consistent with EPA's commitment to do so for inspections and audits of
waste characterization programs at generator sites (Sec. 194.8(b)).
Providing notice of such inspections will alert the public to upcoming
EPA approval activities and allow for more informed public
participation. While public notice will be provided for the scheduled
initial phase of an inspection or audit, should it prove necessary for
EPA to conduct follow-up activities or continuations of inspections and
audits, EPA reserves the right to do so without providing additional
public notice. Such follow-up activities or continuations of audits or
inspections might be necessary to obtain additional information or
ensure that corrective actions are being taken to resolve initial
findings. In no case will EPA decide whether to approve site-specific
quality assurance or waste characterization programs before providing a
minimum 30-day public comment period on documentation of the program
plans, or before conducting an inspection or audit at the relevant
site.
The Agency received some comments related to Conditions 1 and 4 in
the proposed rule. EPA's responses to these comments are discussed in
the preamble sections related to Sec. 194.14 and Sec. 194.43,
respectively. Conditions 1 and 4 were retained without change in the
final rule. The response to comments document accompanying today's
action provides more detailed responses regarding the certification
conditions and all aspects of the final rule.
[[Page 27360]]
The EPA received no significant comments on its proposed actions to
slightly modify the criteria by revising the authority citation and
adding a new definition for Administrator's authorized representative.
Therefore, these actions take effect without change from the proposed
rule.
VII. How Did EPA Respond to General Comments on Its Proposed
Certification Decision?
The EPA received many comments which addressed broad issues related
to the proposed certification decision. Many citizens simply expressed
their strong support for, or opposition to, opening the WIPP. Some
commenters requested that EPA consider certain factors in making its
certification decision. These factors include reviews by organizations
other than EPA, and the political or economic motivations of interested
parties. The EPA's certification decision must be made by comparing the
scope and quality of relevant information to the objective criteria of
40 CFR Part 194. Where relevant, the Agency has considered public
comments which support or refute technical positions taken by DOE.
Emotional pleas and comments on the motives of interested parties are
factors that are not relevant to a determination of whether DOE has
demonstrated compliance with the disposal regulations and the WIPP
compliance criteria, and are therefore outside the scope of this
rulemaking.
A number of commenters suggested that EPA should explore
alternative methods of waste disposal, such as neutralizing radioactive
elements, before proceeding with a certification decision. Others
stated that the WIPP should be opened immediately because underground
burial of radioactive waste is less hazardous than the current strategy
of above-ground storage. Such considerations are all outside the scope
of this rulemaking. Congress did not delegate to EPA the authority to
abandon or delay the WIPP in favor of other disposal methods. Congress
mandated that EPA certify, pursuant to Section 4 of the APA, whether
the WIPP will comply with the radioactive waste disposal
regulations.\8\ Thus, EPA is obligated to determine whether the WIPP
complies with the disposal regulations, regardless of the relative
risks of underground disposal compared to above-ground storage.
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\8\ WIPP Land Withdrawal Act (``WIPP LWA''), Pub. L. 102-579, as
amended by the 1996 WIPP LWA Amendments, Pub. L. 104-201, Section
8(d).
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Many members of the public expressed a desire for EPA to oversee
other aspects of the WIPP's operation. In particular, the public was
concerned with the risks of transporting radioactive materials from
waste generator sites to the WIPP. All transportation requirements for
the WIPP are established and enforced by regulators other than EPA.
(For further discussion on the source and limitations of EPA's
authority to regulate the WIPP, see preamble Section X, ``Why and how
does EPA regulate the WIPP?'') One commenter stated that EPA should
survey electric and magnetic fields at the WIPP. The EPA's disposal
regulations apply only to ionizing radiation. They do not apply to non-
ionizing radiations such as electric and magnetic fields. These issues
are beyond the scope of EPA's authority to regulate waste disposal at
the WIPP and are not addressed in the certification rulemaking.
The EPA received a number of comments suggesting that the Agency
should have provided more or better opportunities for public
participation in its decision making process. Comments suggested, for
example, that EPA should have rescheduled public hearings, responded
more fully to comments submitted prior to the proposed rule, extended
the public comment period, and included the public in all meetings
between EPA and DOE. The EPA provided numerous opportunities for public
participation in the WIPP certification decision, including two comment
periods--one before and one after the proposed decision--of at least
120 days (In fact, EPA accepted comments on its advance notice of
proposed rulemaking announcing receipt of DOE's CCA for over 250
days.), two sets of public hearings in New Mexico, Federal Register
notices, and a number of meetings with various stakeholders. These
measures exceed the basic requirements for notice-and-comment
rulemaking and are in full compliance with the public participation
requirements of both the WIPP compliance criteria and the
Administrative Procedure Act. Further discussion on the measures taken
by EPA to involve the public can be found in the preamble section
entitled, ``How has the public been involved in EPA's WIPP
activities?''
Some members of the public expressed doubt that EPA and its
contractors possessed the necessary technical skills to evaluate DOE's
application or were free from conflicts of interest. Many comments
requested that EPA release the names and qualifications of individual
contractor employees who provided technical support for EPA's
certification rulemaking. The EPA initially denied this request because
such information is typically claimed as confidential business
information by federal government contractors. (The Trade Secrets Act
prohibits EPA from releasing confidential business information, and
imposes criminal liability on federal employees for the unauthorized
disclosure of such confidential information.\9\) However, in response
to the public interest regarding this issue, EPA sought and obtained
from its contractors a limited waiver of confidentiality to release the
names and qualifications of individual employees who provided technical
support related to EPA's certification decision. In January 1998, EPA
provided this contractor information to several stakeholders and also
placed it in the rulemaking docket. (Docket A-93-02, Items IV-C-13 and
IV-C-14) The Agency also sent to stakeholders (and docketed) a
description of the measures EPA has taken to ensure that contractors do
not have any conflict of interest in providing technical support on the
certification rulemaking. While EPA agreed to release the above
information to allay public concerns, such information is not relevant
to EPA's certification decision. Under notice-and-comment rulemaking,
it is the substance and basis for EPA's decision that are at issue.
---------------------------------------------------------------------------
\9\ 18 U.S.C. 1905
---------------------------------------------------------------------------
Finally, several commenters stated that EPA--by initially
certifying the WIPP to receive only certain waste from the Los Alamos
National Laboratory--is granting a piecemeal certification, and that
such an action is illegal under EPA's regulatory authority. The EPA
disagrees with the assertion that its actions constitute a phased
certification. The EPA's certification is based on the Agency's
determination that the WIPP will comply with the disposal regulations
for the inventory described in the performance assessment. Conditions 2
and 3 of the certification (related to waste generator sites) change
neither the performance assessment assumptions nor the terms on which
the WIPP is authorized for disposal, but ensure that DOE adheres to the
assumptions on which compliance is based. The EPA believes this
approach is consistent with Congressional intent (as reflected in the
WIPP LWA) and with the disposal regulations and compliance criteria.
For further discussion of comments related to the proposed conditions
of certification, refer to the preceding preamble section entitled,
``Significant Changes Made to
[[Page 27361]]
the Final Rule in Response to Comments.''
VIII. How Did EPA Respond to Major Technical Issues Raised in
Comments?
A. Content of Compliance Certification Applications (Sec. 194.14)
40 CFR Part 194 sets out those elements which the Agency requires
to be in a complete compliance application. In general, compliance
applications must include information relevant to demonstrating
compliance with each of the individual sections of 40 CFR Part 194 to
determine if the WIPP will comply with the Agency's radioactive waste
disposal regulations at 40 CFR Part 191, Subparts B and C. The Agency
published the ``Compliance Application Guidance for the Waste Isolation
Pilot Plant: A Companion Guide to 40 CFR Part 194'' (``CAG'') which
provided detailed guidance on the submission of a complete compliance
application.\10\
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\10\ Section 194.11 provides that EPA's certification evaluation
would not begin until EPA notified DOE of its receipt of a
``complete'' compliance application. This ensures that the full one-
year period for EPA's review, as provided by the WIPP LWA, shall be
devoted to substantive, meaningful review of the application. (61 FR
5226)
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Any compliance application must include, at a minimum, basic
information about the WIPP site and disposal system design, and must
also address all the provisions of the compliance criteria; these
requirements are embodied in Sec. 194.14. The documentation required in
the compliance criteria is important to enable a rigorous, thorough
assessment of whether the WIPP facility will comply with the disposal
regulations.
The EPA thoroughly reviewed DOE's compliance certification
application (``CCA'') and additional information submitted by DOE, and
proposed that DOE complies with each of the requirements of
Sec. 194.14, conditioned upon DOE's implementation of the most robust
panel closure system design (designated as Option D) with slight
modification. The succeeding sections address public comments related
to Sec. 194.14. (For more detailed discussions, see Docket A-93-02,
Item V-B-2, CARD 14; and Item V-B-3.)
1. Site Characterization and Disposal System Design
The EPA received numerous public comments on issues related to the
requirements of Secs. 194.14(a) and 194.14.(b), primarily related to
the geological features, disposal system design and characteristics of
the WIPP. Since the geology and disposal system characteristics are
directly related to performance assessment modeling and the containment
requirements of 40 CFR Part 191, a discussion of EPA's review of the
substantive comments (except for those relating to shaft seals and
panel closures) can be found in the Performance Assessment section of
this preamble. A discussion of the comments on the engineered features
related to long term performance, specifically on the shaft seal design
and panel closure system, are discussed below.
a. Shaft Seals. In the CCA, DOE described the seals to be used in
each of the four shafts and included the design plans and the material
and construction specifications for the seals. (Docket A-93-02, Item
II-G-1, CCA Chapter 3.3.1, Chapter 8.1.1, and Appendix SEAL) The
purpose of the shaft seal system is to limit fluid flow within the
shafts after the WIPP is decommissioned and to ensure that the shafts
will not become pathways for radionuclide release. The shaft seal
system has 13 elements that fill the shaft with engineered materials
possessing high density and low permeability, including concrete,
asphalt, clay, compacted salt, cementitious grout, and earthen fill.
The compacted salt column component of the system within the Salado is
intended to serve as the primary longterm barrier by limiting fluid
transport along the shaft during the 10,000 year regulatory period. The
EPA proposed that DOE's shaft seal design is adequate because the
system can be built and is expected to function as intended. (Docket A-
93-02, Item V-B-2, CARD 14, Section 14.E; and Item V-B-3)
Commenters expressed concern that dissolution of the salt column
could occur because the overlying Rustler aquifer has karst features
and cannot be relied upon to retard the migration of radionuclides.
(For more information on karst, refer to the preamble sections on
Performance Assessment, Geological Scenarios.) Dissolution of salt
(halite) in the WIPP shafts would require a source of water that is not
saturated with salt, and a sink, i.e., some location for the water to
flow to after it has dissolved the salt in the shafts. Since all of the
ground water from the top of the Salado downward is saturated with salt
(i.e., it is ``brine''), the unsaturated but highly saline water would
probably come down the shaft from the Rustler Formation. In order to
reach the salt component of the shaft seal, that water would have to
pass through or around 490 feet of concrete, asphalt, and bentonite
layers. Then, after flowing through 550 feet of compacted salt column,
the saturated water would have to flow through or around another
concreteasphalt water stop, another 100 feet of bentonite clay, and the
shaft station concrete plug. (Docket A-93-02, Item V-B-2, CARD 14,
Section 14.A)
Even if water were to pass through the salt column, only a small
fraction of the salt column would be removed. Due to the ongoing inward
creep of the Salado Formation, the salt column would still be
consolidated after such a dissolution episode. Finally, DOE's PA
calculations do not include ``credit'' for bentonite swelling, capture
of water by clay, or the adsorption of water into dry halite'all
processes that would tend to reduce water predicted to reach the salt
column'and the PA results are therefore conservative. Therefore, EPA
concludes that dissolution of the salt column is not a concern. (Docket
A-93-02, Item V-B-2, CARD 14, Section 14.E; Item V-B-3, Section F.2)
Commenters questioned the ability of the shaft seals to perform as
expected because the material and construction of the seals have not
been tested. However, EPA found that DOE performed and referenced
numerous tests and experiments to establish the material
characteristics of importance to containment of waste at the WIPP. The
characteristic of primary importance is the material's permeability,
the degree to which fluids can travel through the material. The
permeability of concrete, asphalt, and bentonite clay are well
documented, and DOE performed numerous experiments to demonstrate the
applicability of these characteristics to the WIPP's site specific
conditions (e.g., high brine concentration). The DOE documented many
laboratory and insitu tests of the permeability of compacted crushed
salt including a largescale field test to demonstrate the feasibility
of implementing such a seal measure. (Docket A-93-02, Item II-G-2,
Appendices SEAL, PCS, DEL, and MASS)
The technology planned for constructing the shaft seals has been
tested in the real world. The construction equipment and procedures
necessary to emplace the seal materials are in large part the same as
those used to excavate the WIPP, but used in reverse. Except for salt,
the shaft seal component materials are commonly used in construction.
Salt has been extensively tested to determine its properties and
behavior in the conditions which will exist in the shafts after the
WIPP is closed. The EPA finds that the shaft seal design has undergone
extensive technical review and testing by DOE that shows it is feasible
to construct and is expected to perform as intended. (Docket A-93-02,
Item V-B-
[[Page 27362]]
2, CARD 14, Section 14.E; Item V-B-3, Section F.2)
As commenters pointed out, and EPA agrees, many changes may occur
in knowledge of construction materials and in construction methods and
equipment during the 35 years before the WIPP is expected to be closed.
The DOE provided a final design for the shaft seals which could be
constructed. However, EPA recognizes the fact that technology may
change and expects the shaft seal plans to be periodically reviewed and
revised to take full advantage of new knowledge or construction
equipment in the future. Acknowledgment of this circumstance does not
mean that the existing plans are inadequate, or that major changes in
the design are anticipated. Periodic review of the WIPP
authorization(s) to operate is required by the various statutes and
regulations applicable to the WIPP, including EPA's review of
recertification applications every five years, and the State of New
Mexico's review of the hazardous waste permit at least every ten years.
Shaft seal design changes may be proposed by DOE and perhaps approved
by EPA several times before the end of the WIPP disposal operations
phase. Significant changes in the designs will be required to go
through public noticeandcomment procedures before approval by EPA.
(Sec. 194.65-66)
b. Panel Closure System. Panel closures are needed primarily during
active disposal operations at the WIPP and during preparations for
final closure of the entire facility. Relative to long-term
performance, they can serve to block the flow of brine between panels.
The DOE provided four options for a panel closure system in the
CCA, but did not specify which panel closure option would be used at
WIPP. The EPA reviewed the four panel closure system options proposed
by DOE and considered that the intended purpose of the panel closure
system is to prevent the existing disturbed rock zone (``DRZ'') in the
panel access drifts (tunnels) from increasing in permeability after
panel closure (which could allow greater brine flow). The EPA considers
the panel closure system design identified as ``Option D'' to be the
most robust panel closure design. (Docket A-93-02, Item II-G-1, CCA
Chapter 3 and Appendix PCS; Item V-B-2, CARD 14, Section 14.E; Item V-
B-3, Section F.2) The EPA based its evaluation of compliance for the
proposed rule on the Option D panel seal design and proposed to
establish a certification condition requiring DOE to implement the
Option D design. The EPA believes that the proposed design on which
compliance was based should be actually implemented at the site. The
EPA also proposed to require DOE to use Salado mass concrete (concrete
made with Salado salt) for construction of the concrete barrier
component of the panel closure. This substitution eliminates the
potential for degradation and decomposition of fresh water concrete by
infiltration of brine. The EPA determined that implementation of Option
D is adequate to achieve the long-term performance modeled in the PA,
since DOE shows that the use of a concrete barrier component is capable
of providing resistance to inward deformation of the surrounding salt
and prohibiting growth of the DRZ from its initial state. (Docket A-93-
02, Item V-B-13)
Contrary to public comments, EPA found that the panel closures can
be constructed using currently available and widely used technology.
Mixing and transportation of concrete, using special measures to
prevent segregation of fine and coarse particles (as required in the
Panel Closure System construction specifications), and placement in
confined spaces by pumping, is used routinely in bridge and building
foundations, dams, and in water supply, subway and highway tunnels. The
steel forms in which the concrete will be confined are somewhat unusual
in shape, but the methods of construction are fairly simple and
standardized. The Salado mass concrete mix is specially formulated for
use in the WIPP, but it has been extensively tested to determine its
properties (e.g., strength and resistance to chloride degradation) as
explained in ``Variability in Properties of Salado Mass Concrete.''
(Docket A-93-02, Item II-G-1, Ref. No. 662)
One commenter asked that EPA revise its panel seal design condition
so that DOE may reassess the engineering of panel closures when panels
are to be closed in the future. The EPA proposed a certification
condition (Condition 1) requiring DOE to implement the panel seal
design that it designated as Option D in the CCA. The Option D design
shall be implemented as described in the CCA, except that DOE is
required to use Salado mass concrete rather than fresh water concrete.
Nothing in this condition precludes DOE from reassessing the
engineering of the panel seals at any time. Should DOE determine at any
time that improvements in materials or construction techniques warrant
changes to the panel seal design, DOE must inform EPA. If EPA concurs,
and determines that such changes constitute a significant departure
from the design on which certification is based, the Agency is
authorized under Sec. 194.65 to initiate a rulemaking to appropriately
modify the certification. The EPA has retained the proposed Condition
1, related to the panel closure system, without change in the final
rule. (See also ``Conditions'' and ``Significant Changes to the Final
Rule'' sections of this preamble.)
2. Results of Assessments, Input Parameters to Performance Assessments,
Assurance Requirements, and Waste Acceptance Criteria
Sections 194.14(c) through (f) require DOE to submit the results of
assessments conducted in accordance with 40 CFR Part 194; a description
of the input parameters associated with such assessments and the basis
for selecting such parameters; documentation of measures taken to meet
the assurance requirements of 40 CFR Part 194; and a description of the
waste acceptance criteria and actions taken to assure adherence to such
criteria. The EPA proposed that DOE complied with Secs. 194.14(c)
through (f) based on EPA's finding that DOE submitted the information
required. The EPA received numerous public comments on the results of
assessments, input parameters to the PA, assurance requirements, and
the waste acceptance criteria. A discussion of EPA's responses to
substantive comments can be found in the corresponding sections of the
preamble. Based on these responses, EPA finds that DOE complies with
Secs. 194.14(c) through (f). For further discussion, refer to CARD 14,
Sections 14.C, 14.D, 14.E, 14.F (Docket A-93-02, Item V-B-2) and
Sections H.2, I.2, J.2, and K.2 of the technical support document for
Sec. 194.14 (Docket A-93-02, Item V-B-3).
3. Background Radiation, Topographic Maps, Past and Current
Meteorological Conditions
For the CCA, DOE was required to describe the background radiation
in air, soil and water in the vicinity of the disposal system and the
procedures employed to determine such radiation (Sec. 194.14(g)),
provide topographic maps of the vicinity of the disposal system
(Sec. 194.14(h)), and describe past and current climatic and
meteorological conditions in the vicinity of the disposal system and
how these conditions are expected to change over the regulatory time
frame (Sec. 194.14(i)). The EPA proposed that DOE complied with the
requirements of Secs. 194.14 (g), (h), and (i). The EPA did not receive
substantive comments on these issues, except for dissolution related to
climate change. A
[[Page 27363]]
discussion of EPA's response to the substantive comments on dissolution
can be found in the Performance Assessment, Geological Scenarios and
Disposal System Characteristics section of this preamble. The EPA finds
that DOE complies with Secs. 194.14 (g) through (i). For further
discussion, refer to Sections 14.K, 14.L, and 14.M of CARD 14 (Docket
A-93-02, Item V-B-2) and Sections H.2, L.2, N.2 and N.4 of the
technical support document for Sec. 194.14 (Docket A-93-02, Item V-B-
3).
4. Other Information Needed for Demonstration of Compliance
The DOE was also required, under Sec. 194.14(j), to provide
additional information, analyses, tests, or records determined by the
Administrator or the Administrator's authorized representative to be
necessary for determining compliance with 40 CFR Part 194. After
receipt of the CCA dated October 29, 1996, EPA formally requested
additional information from DOE in seven letters dated December 19,
1996, and February 18, March 19, April 17, April 25, June 6, and July
2, 1997. (Docket A-93-02, Items II-I-1, II-I-9, II-I-17, II-I-25, II-I-
27, II-I-33, and II-I-37, respectively) The information requested in
these letters was necessary for EPA's completeness determination and
technical review. EPA staff and contractors also reviewed records
maintained by DOE or DOE's contractors (e.g., records kept at the
Sandia National Laboratories Records Center in Albuquerque, New
Mexico). No additional laboratory or field tests were conducted by DOE
at EPA's specific direction; however, DOE did conduct and document
laboratory tests after October 29, 1996, in order to present additional
data to the Conceptual Model Peer Review Panel. (Docket A-93-02, Item
II-A-39)
The EPA proposed that DOE complied with Sec. 194.14(j) because it
responded adequately to EPA's formal requests for additional
information, analyses, and records. The EPA did not formally request
additional information from DOE after publication of the proposed rule.
However, in response to comments, EPA did verbally ask DOE and Sandia
National Laboratory for information and other assistance in
calculations related to the Hartman scenario, drilling into fractured
anhydrite, and the CCDFGF code and quasi-static spreadsheet with regard
to air drilling. (Docket A-93-02, Items IV-E-24, IV-E-25, IV-E-26, and
IV-E-27) In addition, DOE voluntarily submitted information on the
proposed rule that was considered as comments.
All documents sent to EPA regarding certification of the WIPP are
available in EPA Air Docket A-93-02. Additional information relevant to
EPA's certification evaluation that was reviewed by the Agency (e.g.,
DOE data records packages, quality assurance records, and calculations
of actinide solubility for americium, plutonium, thorium and uranium)
is also publicly available. Documentation of peer review panel meetings
conducted after receipt of the CCA has been placed in the EPA docket.
See Docket A-93-02, Item V-B-1 for further information on the location
of all documentation reviewed by EPA.
5. Conclusion
The EPA received numerous public comments on the proposed rule
regarding Sec. 194.14. EPA has thoroughly reviewed the public comments
and addressed all issues raised therein. On the basis of its evaluation
of the CCA and supplementary information, and the issues raised in
public comments, EPA finds that DOE complies with all subsections of 40
CFR 194.14, with the condition that DOE must fulfill the requirements
set forth in Condition 1 of the final rule. For additional information
on EPA's evaluation of compliance for Sec. 194.14, see CARD 14. (Docket
A-93-02, Item V-B-2)
B. Performance Assessment: Modeling and Containment Requirements
(Secs. 194.14, 194.23, 194.31 through 194.34)
1. Introduction
The disposal regulations at 40 CFR Part 191 include requirements
for containment of radionuclides. The containment requirements at 40
CFR 191.13 specify that releases of radionuclides to the accessible
environment must be unlikely to exceed specific limits for 10,000 years
after disposal. At the WIPP, the specific release limits are based on
the amount of waste in the repository at the time of disposal.
(Sec. 194.31) Assessment of the likelihood that the WIPP will meet
these release limits is conducted through the use of a process known as
performance assessment (``PA'').
The WIPP PA process culminates in a series of computer simulations
that attempts to describe the physical attributes of the disposal
system (site characteristics, waste forms and quantities, engineered
features) in a manner that captures the behaviors and interactions
among its various components. The computer simulations require the use
of conceptual models that represent physical attributes of the
repository. The conceptual models are then expressed as mathematical
relationships, which are solved with iterative numerical models, which
are then translated into computer code. (Sec. 194.23) The results of
the simulations are intended to show the potential releases of
radioactive materials from the disposal system to the accessible
environment over the 10,000-year regulatory time frame.
The PA process must consider both natural and man-made processes
and events which have an effect on the disposal system. (Secs. 194.32
and 194.33) It must consider all reasonably probable release mechanisms
from the disposal system and must be structured and conducted in a way
that demonstrates an adequate understanding of the physical conditions
in the disposal system. The PA must evaluate potential releases from
both human-initiated activities (e.g., via drilling intrusions) and
natural processes (e.g., dissolution) that would occur independently of
human activities. The DOE must justify the omissions of events and
processes that could occur but are not included in the final PA
calculations.
The results of the PA are used to demonstrate compliance with the
containment requirements in 40 CFR 191.13. The containment requirements
are expressed in terms of ``normalized releases.'' The results of the
PA are assembled into complementary cumulative distribution functions
(``CCDFs'') which indicate the probability of exceeding various levels
of normalized releases. (Sec. 194.34)
As described above, 40 CFR Part 194 contains several specific
requirements for the performance assessment of WIPP. It is often
difficult to discuss one of the requirements in isolation from the
others. For example, several public comments raised concern about the
CCA's screening of the fluid injection scenario from the PA and EPA's
subsequent analysis. In order for EPA to adequately address the fluid
injection issue, the Agency must discuss multiple requirements related
to geology and other characteristics specific to the WIPP site
(Sec. 194.14), models and computer codes (Sec. 194.23), and the
screening process for both human-initiated releases and releases by
natural processes (Secs. 194.32 and 194.33). Because so many of the PA
issues have similarly overlapping requirements and are often complex,
EPA has chosen to combine the discussions. Therefore, the following
discussions are framed in terms of the PA issues raised in comments,
rather than according to specific PA requirements of the compliance
criteria. The following sections discuss the major PA issues
[[Page 27364]]
that were raised during public hearings and the public comment period.
For more information on performance assessment and related issues,
refer to CARDs 14, 23, 32, and 33. (Docket A-93-02, Item V-B-2)
2. Human Intrusion Scenarios
a. Introduction. Section 194.32 requires DOE to consider, in the
PA, both natural and man-made processes and events which can have an
effect on the disposal system. Of all the features, events, and
processes (``FEPs'') that are considered for the PA calculations, the
human-intrusion scenarios related to drilling have been shown to have
the most significant impact on the disposal system and its ability to
contain waste. (Sec. 194.33)
In preparing the CCA, DOE initially identified 1,200 potential
FEPs, both natural and human-initiated, for the WIPP PA. These FEPs
were reduced in number in the final PA calculations. The DOE may
eliminate FEPs from consideration in the PA for three reasons:
Regulatory--FEPs can be omitted based on regulatory
requirements. For example, drilling activities that occur outside the
Delaware Basin do not have to be considered in the PA, according to
Secs. 194.33(b)(3)(i) and 194.33(b)(4)(i).
Probability--FEPs can be omitted because of the low
probability that the FEP will occur. For example, DOE determined that
the probability of a meteorite landing in the vicinity of the WIPP is
so low that it does not need to be considered in the PA.
(Sec. 194.32(d))
Consequences--FEPS can be omitted because the consequences
resulting from the FEP, even if it does occur, are so small. For
example, there would be no consequences on the repository or the
containment of waste if an archeological excavation took place on the
surface in the vicinity of the WIPP. (Sec. 194.32(a))
The following sections discuss the major public comments on human
intrusion scenarios. Generally, public comments related to whether or
not the scenario was appropriately screened by DOE and to EPA's
subsequent evaluation of this screening. Some comments addressed
whether DOE's modeling of events was appropriate. The human intrusion
scenarios discussed below are: spallings releases, air drilling, fluid
injection, potash mining, and carbon dioxide injection. For more
information on human intrusion scenarios, refer to CARDs 32 and 33.
(Docket A-93-02, Item V-B-2)
b. Spallings. The DOE's models for the PA included five ways in
which radioactive waste could leave the repository and escape to the
accessible environment: cuttings,11 cavings,12
spallings,13 direct brine release, and transport of
dissolved radionuclides through the anhydrite interbeds (i.e., layers
of rock immediately above the repository). The first four of these
potential release pathways involve direct releases of radiation to the
earth's surface in cases where people drill a borehole while searching
for resources.
---------------------------------------------------------------------------
\11\ ``Cuttings'' refers to material, including waste, that is
cut by a drill bit during drilling and is carried to the surface by
the drilling fluid as it is pumped out of the borehole.
\12\ ``Cavings'' refers to material that falls from the walls of
a borehole as a drill bit drills through. Cavings are carried to the
surface by the drilling fluid as it is pumped out of the borehole.
\13\ ``Spallings'' refers to releases of solids pushed up and
out by gas pressure in the repository during a drilling event.
---------------------------------------------------------------------------
The DOE's model for computing releases of radiation due to
spallings was of particular concern to the Conceptual Models Peer
Review Panel which reviewed each of the conceptual models developed for
the purposes of the PA. (See Docket A-93-02, Item V-B-2, CARD 23,
Section 7.) The peer review panel found the spallings conceptual model
inadequate because it did not fully model all potential mechanisms that
may cause pressure-driven solid releases to the accessible environment.
(Docket A-93-02, Item II-G-12, p. 74) The DOE presented additional
experimental evidence and the results of other modeling to the peer
review panel and requested that it consider whether the spallings
volumes predicted by the original inadequate spallings model were
reasonable for use in the PA. (Docket A-93-02, Items II-G-22 and II-G-
23) After considering this additional information, the peer review
panel concluded that the spallings values in the CCA are reasonable for
use in the PA. The panel concluded that, while the spallings model does
not accurately represent the future state of the repository, its
inaccuracies are conservative and, in fact, may overestimate the actual
waste volumes that would be expected to be released by a spallings
event. (Docket A-93-02, Item II-G-22, Section 4, p. 18)
The spallings conceptual model relates to the following
requirements of Sec. 194.23: documentation of conceptual models used in
the PA (Sec. 194.23(a)(1)); consideration and documentation of
alternative conceptual models (Sec. 194.23(a)(2)); and reasonable
representation of future states of the repository in conceptual models
(Sec. 194.23(a)(3)(i)). The EPA proposed that DOE met the requirements
of Sec. 194.24(a)(1) and (a)(2), and, for all conceptual models except
the spallings conceptual model, Sec. 194.24(a)(3)(i). The EPA did not
propose, however, to determine that the spallings model incorporated in
the CCA PA ``reasonably represents possible future states of the
repository,'' as stated in Sec. 194.24(a)(3)(i). The EPA proposed to
accept the spallings model for the purposes of demonstrating compliance
with Sec. 194.23(a)(3)(i) on the basis that it has been determined to
produce conservative overestimates of potential spallings releases. (62
FR 58807) The Agency now concludes that DOE has met the requirements of
Sec. 194.23 in its final rule. (See Docket A-93-02, Item V-B-2, CARD
23, Section 7.4.)
The public commented on four aspects of DOE's spallings modeling
and EPA's evaluation of that modeling: adequacy of DOE's spallings
modeling, purpose and approach of EPA's spallings modeling, use of
DOE's GASOUT code for modeling spallings, and the need to include
additional spallings mechanisms.
Some commenters expressed concern that DOE's conceptual model for
spallings used in the PA did not adequately represent spallings
releases, as stated initially by the Conceptual Model Peer Review
Panel. However, others indicated that DOE had worked on the spallings
model extensively since the peer review panel's review, and that the
spallings model demonstrated that the volume of releases due to
spalling would be small.
The EPA agrees that the spallings conceptual model was inadequate
to represent possible future states of the repository. In response to
the Conceptual Models Peer Review Panel, DOE did substantial additional
work, developed a separate mechanistically-based model and provided
supporting experimental data. The peer review panel concluded that the
spallings model used in the CCA PA calculated release volumes that were
reasonable and probably conservative. (Docket A-93-02, Item II-G-22) On
the basis of this additional work, EPA concludes that the spallings
release volumes calculated by the CCA spallings model are acceptable.
Based upon this work, the Agency also agrees with those commenters who
stated that spallings would result in only a small volume of waste
being released to the accessible environment through spallings.
Commenters asked for clarification of EPA's purpose in producing
its spallings evaluation reports for the proposed rule. (Docket A-93-
02, Items III-B-10 and III-B-11) They also questioned EPA's technical
approach in these reports, particularly the discretization (time and
space intervals).
[[Page 27365]]
Discretization is important because if intervals are too large,
modeling may not calculate or may incorrectly calculate some important
events, and if intervals are too small, modeling will be time-consuming
and inefficient.
The EPA prepared its Spallings Evaluation and Supplemental
Spallings Evaluation for the proposed rule in order to model
simplistically the transport of spallings releases up a borehole during
blowout. The spallings model used in the CCA PA did not examine
transport; rather, DOE's spallings model took the approach that all
waste broken loose and able to move would actually reach the earth's
surface. The Agency used an independent model to investigate if DOE's
spallings conceptual model would give conservative estimates of
spallings releases. The EPA believed this would determine if the
calculated spallings releases were potentially acceptable for use in
PA, despite the flaws in DOE's model. The EPA undertook these studies
early in its own review, and in the Conceptual Models Peer Review
Panel's review of the spallings conceptual model, when both the Panel
and the Agency were concerned about the results of the model.
After EPA completed its own modeling, DOE performed additional
studies using an alternative, mechanistic conceptual model for
spallings. (Hansen et al., Spallings Release Position Paper, Docket A-
93-02, Item II-G-23) DOE's additional studies showed that its original
spallings conceptual model always predicted a greater volume of
releases than the mechanistic spallings conceptual model that used a
more realistic approach to calculate spallings releases. As a result,
both the Conceptual Models Peer Review Panel and EPA concluded that
released volumes estimated using the original CCA spallings conceptual
model were reasonable and conservative. The EPA found DOE's analysis in
the Spallings Release Position Paper to be more conclusive than the
Agency's studies in its Spallings Evaluation and Supplemental Spallings
Evaluation. DOE's analysis was an improvement over EPA's analysis
because it was more thorough, it used much finer discretization
(smaller time and space intervals) which allowed more specific
predictions, and it predicted both volumes and activity of spallings
releases. As described in the proposed rule, EPA examined the Spallings
Release Position Paper and concluded that the spallings release volumes
calculated by the spallings model used in the PA are conservative and,
therefore, acceptable to demonstrate compliance with the waste
containment requirements of 40 CFR 191.13. (62 FR 58807) This
conclusion is based not on the EPA's spallings reports prepared for the
proposed rule, which have been questioned by commenters, but on the
additional spallings analysis performed by DOE, presented to the
Conceptual Models Peer Review Panel, and found by EPA to demonstrate
that the spallings release volumes used in the CCA PA are conservative.
(Docket A-93-02, Item III-B-2; Item V-B-2, CARD 23; and Item V-C-1)
Some commenters expressed concern about the stability of Sandia
National Laboratory's GASOUT computer code that calculates spallings
releases. One individual had used this code to calculate spallings
releases due to air drilling, but other commenters stated that it was
not appropriate to apply the GASOUT code to the air drilling scenario.
(Air drilling refers to the practice of using air or other substances
lighter than mud as a drilling fluid.)
The EPA agrees that the GASOUT code may not be stable under some
conditions. GASOUT was designed to model blowout of waste during the
first few seconds after borehole penetration, where the driller uses
mud in the borehole to reduce friction during drilling. The GASOUT code
was only intended to be used under specific conditions of waste tensile
strength 14 and permeability. (Docket A-93-02, Item II-E-9)
Within its range of applicability, GASOUT produces results that are
consistent with results obtained by other modeling approaches, such as
the quasi-static model and the coupled numerical model. (Docket A-93-
02, Item II-G-23) However, if GASOUT is not used as designed, it may
well be unstable or may calculate invalid results. In particular, EPA
agrees with those commenters stating that it is inappropriate to use
GASOUT to analyze the releases of spallings due to air drilling. The
programmer of the GASOUT code himself has said that this code was not
designed to model drilling using compressible fluids such as air.
(Docket A-93-02, Item II-E-9) For further discussion of the GASOUT
code, see the discussion of air drilling below in this preamble.
---------------------------------------------------------------------------
\14\ Tensile strength is resistance to being pulled apart.
---------------------------------------------------------------------------
Some commenters stated that DOE had erroneously excluded from the
PA the stuck pipe 15 and gas erosion 16 spallings
mechanisms, two additional ways by which high gas pressure conditions
in the repository could result in releases of solid radioactive waste
to the accessible environment. In particular, commenters asserted that
DOE had selected an incorrect value for the threshold waste
permeability, 17 above which the gas erosion and stuck pipe
mechanisms would not occur. They also stated that DOE's assumptions did
not take into consideration the presence of magnesium oxide (MgO)
backfill, which would affect both waste permeability and tensile
strength. These commenters suggested that EPA should do further
analysis, should require DOE to do more analysis, or should reject
DOE's spallings models and mandate new models. Other commenters
countered that stuck pipe and gas erosion would not occur because of
the physical and mechanical properties of the waste.
---------------------------------------------------------------------------
\15\ ``Stuck pipe'' means a situation where high gas pressures
in the repository would break off radioactive waste and press it
against a drill string hard enough to stop or greatly reduce
drilling. In order to continue drilling, a drill operator would
raise and lower the drill string and, in the process, could
transport waste to the surface.
\16\ ``Gas erosion'' means a situation where radioactive waste
breaks off slowly due to high gas pressures in the repository,
enters drilling mud surrounding the drill, and is transported to the
earth's surface in the mud.
\17\ ``Waste permeability'' is the degree to which fluid can
move through the waste.
---------------------------------------------------------------------------
The EPA has analyzed the validity of DOE's decision to exclude
stuck pipe and gas erosion mechanisms from the PA. In order for these
mechanisms to occur, there must be a combination of high gas pressure,
low waste permeability, and low waste strength. First, the gas pressure
in the repository must be sufficiently high to move waste to and up the
borehole. Low waste permeability is necessary to maintain the high
pressure during the drilling event. Finally, low waste tensile strength
is necessary to allow the waste to break off and move toward the
borehole. The DOE has fabricated simulated samples of waste that have
corroded or degraded and have generated gas, as is expected to occur in
the WIPP once waste is emplaced, and has measured the porosity 18
of these samples. Waste porosity and gas pressure are related. This is
because a greater porosity means a greater volume of spaces that gas
can fill. By the ideal gas law, when the same number of gas molecules
fill a larger volume, they will have a lower gas pressure. The waste
porosity also affects waste permeability,
[[Page 27366]]
since more open space in waste means more space where a liquid or gas
can penetrate. Based upon DOE's measurements of the porosity of
surrogate waste samples, EPA found that it is extremely unlikely that
the required conditions of high gas pressure and low waste permeability
will exist in the WIPP. The high pressure necessary to support gas
erosion or stuck pipe mechanisms would expand the WIPP waste, creating
a higher porosity (and higher permeability). Thus, for the
characteristics of the WIPP waste, the permeability would not become
low enough (less than 10-16 square meters) to create a gas
erosion or stuck pipe event. (Docket A-93-02, Item V-B-2, CARD 23,
Section 7.4) If the permeability is not low enough for gas erosion or
stuck pipe, releases may still occur, but the release mechanism will be
a short-lived blowout (spallings) rather than gas erosion or stuck
pipe. Therefore, EPA concludes that DOE correctly modeled only the
``blowout'' process in its spallings model and appropriately excluded
stuck pipe and gas erosion.
---------------------------------------------------------------------------
\18\ ``Porosity'' is the fraction of space present that is open
and can store gases or liquids, as opposed to space filled by solid
matter.
---------------------------------------------------------------------------
c. Air Drilling. Shortly before publication of the proposed
certification decision, and after EPA's cutoff date for addressing ANPR
comments, EPA received a comment containing a technical report stating
that DOE should have included the human intrusion scenario of air
drilling in the PA, rather than screening it out. (Docket A-93-02, Item
IV-D-01) Normally, oil drillers will use mud in the borehole to reduce
friction and to carry away solids that break free as the drill bit
bores into the ground. However, in some cases, drillers might instead
use air, mist, foam, dust, aerated mud or light weight solid additives
as the fluid in the borehole. Public comments noted that the air
drilling 19 scenario was not included by DOE in the CCA, and
raised the following issues:
---------------------------------------------------------------------------
\19\ In this discussion, the term ``air drilling'' refers to all
forms of drilling using drilling substances lighter than mud.
---------------------------------------------------------------------------
Air drilling technology is currently successfully used in
the Delaware Basin.
Air drilling is thought to be a viable drilling technology
under the hydrological and geological conditions at the WIPP site.
Air drilling could result in releases of radionuclides
that are substantially greater than those considered by DOE in the CCA.
In response to these concerns, EPA prepared a study on air drilling
and its likely impact on the WIPP (Docket A-93-02, Item IV-A-1), placed
it in the docket, and allowed for a public comment period of 30 days.
(63 FR 3863; January 27, 1998) The EPA's study examined the frequency
of air drilling near the WIPP, the likelihood that drillers would use
air drilling under the conditions at the WIPP, and the potential volume
of radioactive waste that could be released using air drilling. In the
report, the Agency concluded that air drilling is not a common practice
in the Delaware Basin, and that air drilling through the Salado, the
geologic salt stratum where the WIPP is located, is not presently used
in the Delaware Basin near the WIPP. Because the use of air as a
drilling fluid is not current practice in the Delaware Basin, EPA found
that DOE is not required to include air drilling in the PA.
(Sec. 194.33(c)(1)) Nevertheless, the Agency also modeled potential
releases of radioactive waste during air drilling, and found that any
releases would be within the range calculated in the CCA PA for mud-
based drilling.
The EPA received a number of comments on its air drilling report.
Some members of the public stated that air drilling is a proven
technology and the frequency of its use by the oil and gas industry is
increasing. They suggested that air drilling techniques are not
currently being used more widely because of the limited knowledge of
new developments and the industry's resistance to changing methods. The
commenters implied that if these obstacles are overcome, air drilling
will occur widely in the future. One commenter recommended that the
Agency require DOE to consider air drilling using a frequency of 30% of
all wells, based upon a projected estimate from DOE of the use of air
drilling in the entire U.S. in the year 2005. In contrast, other
commenters stated that air drilling would be less economic than mud
drilling if the driller encountered any interruption in the air
drilling process.
The Agency recognizes that air drilling is a proven technology for
extraction of oil and gas under appropriate conditions. However, EPA
believes that it is inappropriate to use speculative projections of
future practices in the oil and gas industry across the U.S. in the PA
or to guess that a practice will be used more in the future because
some drillers may currently misunderstand the technology. The EPA's
compliance criteria require DOE to assume that future drilling
practices and technology will remain consistent with practices in the
Delaware Basin at the time a compliance application is prepared.
(Sec. 194.33(c)(1)) The EPA included this requirement in the compliance
criteria to prevent endless speculation about future practices, and to
model situations that are representative of the Delaware Basin, rather
than a wider area that is not representative of conditions at the WIPP
site. (61 FR 5234; Docket A-92-56, V-C-1, p. 12-12) The Agency chose to
use current drilling practices for resources exploited in the present
and past as a stand-in for potential future resource drilling
practices. (61 FR 5233) The specific frequency suggested by the
commenter is arbitrary because it applies to the entire U.S. rather
than the Delaware Basin and because the commenter provides no reason
for selecting an estimated frequency of air drilling in 2005 rather
than in some other year. The DOE must abide by the requirement of
Sec. 194.33(c)(1) to assume that future drilling practices remain
consistent with practices in the Delaware Basin at the time the CCA was
prepared (1996). Thus, the pertinent issues are whether air drilling
constitutes current practice in the Delaware Basin and, if so, how it
could affect potential releases from the WIPP.
Some commenters said that air drilling is already occurring in the
Delaware Basin, and thus, should be considered in the PA. One commenter
noted that EPA should look at the frequency of air drilling in the
Texas portion of the Delaware Basin, as well as in the New Mexico
portion of the Delaware Basin, consistent with Sec. 194.33(c)(1).
Commenters also raised a concern that EPA's examination of well files
might underestimate the occurrence of air drilling because information
on the drilling fluid used is not always clear in the records. Another
commenter suggested that air drilling could be left out of the PA only
if it has a probability of less than one chance in ten thousand, under
Sec. 194.32(d).
The EPA agrees that the frequency of air drilling needs to be
examined in the entire Delaware Basin. In response to these public
comments, EPA supplemented the analysis in its initial air drilling
report by conducting a random sample of wells drilled in the New Mexico
and Texas portions of the Delaware Basin and has determined the
frequency of air drilling in the entire Delaware Basin. (The initial
report is located at Docket A-93-02, Item IV-A-1; the supplemented
report is located at Docket A-93-02, Item V-B-29.) The Agency found
that air drilling is not used more frequently in the Delaware Basin as
a whole than in the New Mexico portion of the Basin. At the 95%
statistical confidence level, EPA found that, at most, only 1.65% of
all wells in the Delaware Basin may have been drilled with air. In
those records examined, none of the wells were
[[Page 27367]]
drilled through the salt-bearing geologic formation, as would be
required to penetrate the WIPP. This additional information confirms
the Agency's conclusion (as stated initially in Docket A-93-02, Item
IV-A-1) that air drilling is not a current practice in the Delaware
Basin.
The EPA agrees that the well drilling records examined in its
random sample may not by themselves be conclusive about whether air
drilling was used at specific wells. As an independent confirmation of
the extent of air drilling in the Delaware Basin (and near the WIPP
specifically), EPA also interviewed knowledgeable industry contacts,
many of whom were experienced in air drilling. These individuals
independently confirmed that air drilling is rarely practiced in the
Delaware Basin and that it is virtually nonexistent in the vicinity of
WIPP. (Docket A-93-02, Item V-B-29) The DOE also found similar results
in an exhaustive analysis of 3,349 wells in the Delaware Basin. (Docket
A-93-02, IV-G-7) These independent sources of information further
verify EPA's conclusion that air drilling is not a current practice in
the Delaware Basin. In particular, air drilling through the salt
section (where the waste is present) is not consistent with current
drilling practices in the Delaware Basin.
The EPA disagrees that the frequency of air drilling must be less
than one in ten thousand wells in order for DOE to leave it out of the
PA. Section 194.33(c)(1) requires DOE to look at ``drilling practices
at the time a compliance application is prepared.'' This requirement
refers to typical industry practices in the Delaware Basin at the time
a compliance application is prepared. (See 61 FR 5230; Docket A-92-56,
Item V-C-1, p. 12-18; Docket A-93-02, Item II-B-29, p. 50.) It was not
intended to apply to experimental procedures, emergency procedures, or
conjectured future practices. The Agency finds it unrealistic to
consider a specific deep drilling method to be current practice or
typical of drilling in the Delaware Basin when it is used for only a
small percentage of all wells in the Basin. As indicated in
Sec. 194.32, deep drilling and shallow drilling are events to be
considered in the PA. The Agency believes that DOE has correctly
implemented the requirements of Sec. 194.32(d) by including the general
technique of deep drilling as a scenario in the PA, rather than
separately analyzing the probability of each potential kind of deep
drilling.
One commenter stated that air drilling is a viable technique under
the conditions in the vicinity of the WIPP site. This commenter said
that drilling with air may even become the method of choice in the WIPP
area, since a driller will prefer to use a technology such as air
drilling, which avoids loss of circulation. Another commenter expressed
concern about the conclusions of EPA's Analysis of Air Drilling at WIPP
(Docket A-93-02, Item IV-A-1) that water inflow upon drilling would
prevent air drilling near the WIPP and that air drilling is not an
economically feasible drilling method near the WIPP. This commenter
also stated that EPA's estimates of the water flow rate that can be
tolerated during air drilling were too low.
The EPA examined a report from a commenter that found that water
inflows from the Culebra would not prevent air drilling at the WIPP
site. The report based this premise on the transmissivity in some parts
of the WIPP site. However, EPA disagrees that the transmissivity
threshold mentioned in the report would provide sufficient reason to
conclude that air drilling was currently practical in that area. The
range of transmissivities at the WIPP site shows that air drilling is
definitely not feasible in some parts of the site, and is unsuitable in
other portions of the site. The EPA also found that the possibility of
excessive water inflow was only one of the reasons mentioned by
industry contacts as to why air drilling was not used in the vicinity
of WIPP. Other reasons, cited in EPA's Air Drilling Report, include
sections of unconsolidated rock above the salt section and the
potential for hitting brine pockets in the Castile Formation. (Docket
A-93-02, Item V-B-29) Because of the reasons industry contacts gave for
not conducting air drilling near the WIPP, the Agency disagrees that
air drilling would ever become a preferred method of drilling at the
WIPP site.
Commenters were concerned that there might be greater releases of
waste with air drilling than with mud drilling. This is because air and
foam are less dense than mud, so it would take less pressure inside the
repository to push waste toward the surface as solid waste (spallings)
or as waste dissolved in brine (direct brine release). One individual
calculated spallings releases due to air drilling using DOE's GASOUT
computer code, and found that releases due to air drilling were several
orders of magnitude higher than the releases computed in the CCA PA.
(Docket A-93-02, Item II-D-120) Other commenters countered that the
GASOUT code was not designed to model spallings using air drilling, and
therefore, that the GASOUT code could not be applied in this situation.
Although EPA concluded that there was no need to include air
drilling in the PA, the Agency conducted its own modeling of spallings
due to air drilling to respond to public concerns. (Docket A-93-02,
Item V-B-29, Section 6 and Appendix A) The EPA used the quasi-static
model developed by DOE as a mechanistic model of spallings, an approach
that provides greater modeling flexibility than with the GASOUT code.
The quasi-static model tends to overestimate releases of radioactive
waste because it predicts the total volume of waste that is available
for transport. The total volume available for transport would not all
be released in actuality because pressurized gas would not be able to
lift large, heavy particles up to the earth's surface. Studies have
shown that the quasi-static model generally predicts larger spalled
volumes than the model incorporated in the GASOUT code. (Docket A-93-
02, Item II-G-23, Table 3-3) For air drilling conditions, EPA estimated
volumes of releases to be within the range of spallings values
predicted by the CCA and used in the PAVT evaluation.
The EPA also examined the effects of air drilling on the combined,
complementary cumulative distribution functions (``CCDFs'') used to
show graphically whether the WIPP meets EPA's containment requirements
for radioactive waste. (Docket A-93-02, Item V-B-29, Section 6) The EPA
found that the CCDFs produced by DOE were not significantly different
from those produced in the PAVT. In fact, releases from the WIPP were
still below the containment requirements of Sec. 191.13 by more than an
order of magnitude when air drilling is included as a scenario.
The EPA determines that DOE does not need to include air drilling
in the PA because it is not current practice in the Delaware Basin.
Further analyses, conducted by EPA solely to allay the public's
concerns on this issue, showed that spallings releases calculated in
the CCA and the PAVT encompass the potential impacts of air drilling
(were it to occur) on compliance with the containment requirements.
See CARD 32 for further discussion of the screening of features,
events, and processes. (Docket A-93-02, Item V-B-2)
d. Fluid Injection Commenters stated that DOE should not have
screened out the human intrusion scenario of fluid injection
20 from the final PA
[[Page 27368]]
calculations. Brine could be injected into existing boreholes, enter
the repository, become contaminated and flow to various release points.
In Sec. 194.32(c), EPA's compliance criteria specifically require DOE
to analyze the effects of boreholes or leases that may be used for
fluid injection activities near the disposal system soon after
disposal.
---------------------------------------------------------------------------
\20\ The fluid injection discussed here refers to either (1)
brine disposal from oil activities, (2) maintenance of pressure in
existing oil production, or (3) water flooding to increase oil
recovery. In the Delaware Basin, the fluid would most likely be
brine.
---------------------------------------------------------------------------
The fluid injection scenario has been of particular concern to the
public because of events that occurred in the Rhodes-Yates oil field,
about 40 miles east of WIPP but outside the Delaware Basin in a
different geologic setting. An oil well operator, Mr. Hartman
encountered a brine blowout in an oil development well while drilling
in the Salado Formation in the Rhodes-Yates Field. In subsequent
litigation, the court found that the source of the brine flow was
injection water from a long-term waterflood borehole located more than
a mile away. A fluid injection scenario causing the movement of fluid
under high pressure is referred to as ``the Hartman Scenario'' after
this case.
The DOE initially screened out this activity from the PA because
the Department's modeling of fluid injection indicated that it would
result in brine inflow values within the range calculated in the CCA PA
where there is no human intrusion. (Docket A-93-02, Item II-A-32) Both
EPA and public commenters on the Advance Notice of Proposed Rulemaking
did not believe that DOE had performed sufficient analyses to rule out
the potential effects of fluid injection related to oil production on
the disposal system. Therefore, the Agency required DOE to model fluid
injection using more conservative geologic assumptions about the
ability of Salado anhydrite to transmit fluid. (Docket A-93-02, Item
II-I-17) This more conservative modeling showed that fluid injection
would have little impact on the results of the PA. (Docket A-93-02,
Item II-I-36) Based on this modeling and other information submitted by
DOE on the frequency of fluid injection well failures, EPA proposed
that DOE's screening was sufficient and realistic. (62 FR 58806, 58822)
Thus, EPA concluded that fluid injection could be screened out of the
final PA calculations based on low consequences to the disposal system.
The EPA performed its own independent review of fluid injection,
which showed that the injection analysis must include the nature of
anhydrites, duration of injection activities, and presence of leaking
boreholes. (Docket A-93-02, Item V-B-22) As part of its analysis, the
Agency performed additional modeling of the injection well scenario.
The EPA concluded that, although scenarios can be constructed that move
fluid to the repository via injection, the probability of such an
occurrence, given the necessary combination of natural and human-
induced events, is very low.
Several commenters stated that either EPA or DOE needed to model
the Hartman Scenario. One commenter stated that it should be proven
that DOE's BRAGFLO 21 code can reproduce what is believed to
have happened in the Hartman case. Some members of the public also
referred to modeling performed by Bredehoeft and by Bredehoeft and
Gerstle which found that the Hartman scenario could cause releases in
excess of the disposal regulations (Docket A-93-02, Item II-D-116
Attachment (b)); these commenters stated that neither EPA nor DOE had
satisfactorily modeled the Hartman Scenario.
---------------------------------------------------------------------------
\21\ BRAGFLO predicts gas generation rates, brine and gas flow,
and fracturing within the anhydrite marker beds in order to
calculate the future of the repository.
---------------------------------------------------------------------------
The EPA examined Bredehoeft and Gerstle's modeling of fluid
injection at the WIPP and finds their assumptions highly unrealistic.
In particular, the report assumes that all brine is directly injected
into one anhydrite interbed in the Salado Formation. The anhydrite
interbeds in the Salado are only a few feet thick. Therefore, a driller
would need to plan specifically to deliberately inject brine into the
anhydrite interbeds to have such a situation occur at the WIPP. Also,
well operators using fluid injection for oil or gas recovery would be
attempting to inject brine into formations where petroleum and gas
reserves are found, which are thousands of feet below the Salado. If
flooding due to fluid injection occurred accidentally in the vicinity
of the WIPP, the flow of fluid would not be limited to the narrow band
of one anhydrite interbed in the Salado. Also, Bredehoeft and Gerstle's
report assumes that fractures in the anhydrite will extend for three or
more kilometers and will remain open. This would require extremely high
pressures to be generated by the brine injection process. The EPA
agrees that under very unrealistic conditions, modeling can show fluid
movement toward the WIPP under an injection scenario. However, when
using more realistic but still conservative assumptions in the
modeling, fluid movement sufficient to mobilize radioactive waste in
the disposal system does not occur.
In response to public comments, the Agency tried to reproduce
several of the results obtained with Bredehoeft's model using DOE's
BRAGFLO model. In two cases, EPA's modeling produced flows similar to
those in the March 1997 Bredehoeft report. (Docket A-93-02, Item II-D-
116) However, because the Agency's study looked at flows in multiple
locations and Bredehoeft's study does not specify the location of its
predicted flows, the results are not directly comparable. The EPA also
attempted to replicate Bredehoeft's modeling of high pressure
conditions that would be mostly likely to cause a catastrophic event.
However, the Agency found that critical aspects of Bredehoeft's work
are not documented sufficiently to make meaningful comparisons using
the BRAGFLO computer code. In particular, the grid spacing used in the
model predictions were unclear. This information is necessary in order
to recreate Bredehoeft's simulation. Also, EPA was unable to determine
whether the length to which fractures grow are based on completely
opened or partially opened fractures. The Agency contacted the primary
author of the paper in order to obtain additional critical information.
However, the author was not certain how they had treated these aspects
of modeling and had no further documentation. (Docket A-93-02, Item IV-
E-23) Because of insufficient documentation of vital aspects of
modeling, the Agency could not replicate Bredehoeft's results. In
addition, due to lack of proper documentation it was not clear to EPA
that Bredehoeft's modeling represented the Hartman Scenario. Therefore,
EPA finds that lack of agreement between the Bredehoeft model and
BRAGFLO does not indicate that DOE's modeling is inadequate. (Docket A-
93-02, Item V-B-22)
Several commenters had concerns about EPA's Fluid Injection
Analysis, including its conclusions that the geology and the current
well construction practices near the WIPP are extremely different from
the geology and well construction practices that occurred in the
Hartman case. In contrast, other commenters stated that fluid injection
is unlikely to occur near WIPP and current well construction practices
in the area will prevent injection well leakage. Some commented that
EPA's probability estimates for the chain of events that could lead to
a blowout caused by fluid injection were overly optimistic and that the
probability estimate ignores
[[Page 27369]]
experience with severe water flows in New Mexico.
The EPA concluded that current well construction practice makes it
unlikely that there could be a well failure of the nature of the
``Hartman scenario'' that occurred in the Rhodes-Yates field outside
the Delaware Basin. This is because regulatory requirements for
drilling are much more rigorous near the WIPP than was the case at the
Rhodes-Yates field at the time of the Hartman case. Also, the Agency
reiterates that there are significant differences in the geology near
the WIPP and in the Rhodes-Yates field where the Hartman case occurred,
that should not be ignored. The vertical distance between the formation
where brine would be injected for disposal and the formation where the
repository is located is greater than the vertical distance that fluid
is believed to have traveled in the Hartman case. This distance, and
effects of friction, would make it more difficult for fluids to travel
vertically upward at the WIPP than in the Hartman case. Interbeds near
the WIPP site are more numerous and are likely to be thinner than in
the Hartman case, thereby reducing the likelihood of flow between the
repository and the WIPP boundary. The Agency concludes that the geology
in the WIPP area will play an active role in reducing fluid movement,
or in an extreme case, preventing a massive well blowout. (Docket A-93-
02, Item V-B-22)
While EPA accepted DOE's argument that the fluid injection scenario
can be screened out of the PA on the basis of low consequence, DOE
presented supplemental information that also indicated that the
probability of a catastrophic well failure would be low. The EPA's
Fluid Injection Analysis for the proposed rule also examined the chain
of events necessary to cause catastrophic failure for a well. The EPA
estimated that the probability of this chain of events occurring for a
given well in the vicinity of the WIPP was low'within the range of one
in 56,889 to one in 667 million. (Docket A-93-02, Item III-B-22) These
estimates of probability were intended to illustrate in this
hypothetical failure scenario the chain of events that must all occur
for an injection well to impact the WIPP. The commenters objected to
the lowest probability estimate, but did not state which probabilities
or assumptions in the chain of events that they believed EPA had
incorrectly selected. The EPA notes that this estimate of low
probability was only one of many reasons cited in the technical support
document for EPA's proposed determination that fluid injection could be
screened from the PA. (Docket A-93-02, Item III-B-22) After considering
geologic information, well history and age, construction standards, and
operating practices, the Agency concludes that reported water flows in
the Salado Formation in other areas of New Mexico are not
representative of conditions in the vicinity of the WIPP. (Docket A-93-
02, Item V-B-22) Even if an injection event takes place, the predicted
low consequence is sufficient reason to remove it from consideration in
the PA.
One commenter stated that EPA should require DOE to revise its PA
model to include the Hartman Scenario and perform another PA. In
contrast, another commenter stated that fluid injection events will not
impact repository performance, even with conservative assumptions, so
fluid injection can be excluded from the PA. The Agency finds that:
Commenters' modeling of fluid injection that predicted
potential releases exceeding EPA standards was based upon unrealistic
assumptions that would maximize releases.
The EPA tried to replicate scenarios similar to the
Hartman case using DOE's BRAGFLO model. Some results were similar in
magnitude to modeling results presented by commenters, but not directly
comparable.
Modeling by DOE predicts that fluid injection will cause
low flows that will not significantly impact the results of PA.
Well construction procedures near the WIPP have changed
due to regulatory requirements; therefore, it is unreasonable to assume
that the same well procedures from the Hartman case will occur near the
WIPP.
There are significant geological differences between the
WIPP site and the Rhodes-Yates field in the Hartman case.
For all of these reasons, EPA concludes that it is not necessary to
repeat the PA using the scenario of fluid injection. (Docket A-93-02,
Item V-B-22; Also, see Docket A-93-02, Item V-B-2, CARDs 23 and 32 for
further discussion of fluid injection.)
A related issue raised by commenters was DOE's modeling of
fractures in the anhydrite interbeds directly above the WIPP. Such
fractures could allow injected brine to enter the repository, to
dissolve waste, and to release radioactivity outside the WIPP.
Commenters stated that DOE's model for anhydrite fracturing was
inadequate to describe observed changes at the WIPP and was not based
on sufficient experimental data. Some commenters stated that DOE's
model significantly understates the length of fractures compared to
another modeling technique, Linear Elastic Fracture Mechanics
(``LEFM''). Shorter fractures would mean that contaminated brine does
not travel as easily, which lessens releases.
The Agency disagrees that DOE's modeling of anhydrite fracturing is
inadequate. The independent Conceptual Models Peer Review Panel found
that the ``type of fracture propagation and dilation used in the
conceptual model has been substantiated by in situ tests.'' The Panel
also found that the conceptual model was adequate. (Docket A-93-02,
Item II-G-1, Appendix PEER.1) The EPA finds that the mathematical
``porosity model'' used in the CCA PA adequately implements the
conceptual model for anhydrite fracturing. This mathematical model used
a combination of field test data at lower pressures and the theory of
continuum mechanics at higher pressures.
Some features of LEFM are not appropriate for representing the
anhydrite interbeds. LEFM predicts that a single, long fracture
hundreds of feet long will be created in a homogeneous medium. The
Agency finds that this approach is inappropriate for the anhydrite
interbeds in the Salado at the WIPP, which already contain numerous
small fractures. (Docket A-93-02, Item IV-G-34, Attachment 5; Item V-C-
1, Section 194.23) Field tests found that fractures branched into a
series of fractures following preexisting fractures or weaknesses near
the injection hole, rather than producing a single, long-distance
fracture. In the case of fluid injection, these fractures would store
fluid, which would slow down and shorten further fractures. The pre-
existing fractures will produce a fracture front, such as that modeled
by BRAGFLO, rather than a single fracture radius, as modeled by an
LEFM. Two studies cited by commenters as support for use of LEFM in
fact question the applicability of LEFM to WIPP anhydrites and
recommend that DOE consider alternative conceptual models. (e.g.,
Docket A-93-02, Item IV-G-38) The EPA concludes that BRAGFLO is more
appropriate to use for WIPP than a pure linear elastic fracture
mechanics model because there are pre-existing fractures in the
anhydrite layers that must be accounted for in the conceptual model.
The EPA finds that the conceptual model based on a single fracture is
fundamentally flawed for application in WIPP anhydrites. The Agency
also finds that the model incorporated in the PA is appropriate,
[[Page 27370]]
and that further modeling with revised computer codes is not necessary.
e. Potash Mining. Public comments raised concerns about DOE's
estimates of the potash reserves in the vicinity of the WIPP and DOE's
evaluation of the solution mining scenario. The primary effects that
mining could have on the repository are opening existing fractures in
the geologic formations above the WIPP and increasing hydraulic
conductivity as a result of subsidence. These effects could change the
flow and path of ground water through the Culebra dolomite.
Several commenters stated that DOE underestimated the amount of
potash in the vicinity of the WIPP and therefore underestimated the
impact that extracting the additional potash would have on the
performance of the repository. In the CCA, DOE provided estimates of
the mineable potash reserves both outside and within the WIPP Land
Withdrawal Area. The compliance criteria require DOE to consider
excavation mining of only those mineral resources which are extracted
in the Delaware Basin. (Sec. 194.32(b)) Therefore, potash resources of
a type or quality that are currently not mineable for either
technological or economic reasons need not be addressed in DOE's
analysis. The EPA determined, through an independent analysis, that the
CCA appropriately represents the extent of currently mined resources,
in accordance with the criteria. The EPA also determined that DOE
appropriately considered the impact that such resources and excavation
mining could have on the performance of the repository. (Docket A-93-
02, Item V-B-2, CARD 32)
Additional comments were received on DOE's screening of solution
mining from the PA. The DOE determined that solution mining of potash
is not occurring in the vicinity of the WIPP and can be omitted from
the PA based on the regulatory requirement that only currently
occurring (or near-future) practices be considered in the PA.
(Sec. 194.32(c)) The EPA agrees with DOE that solution mining is not a
current practice and can be omitted from the PA on regulatory grounds.
The DOE submitted supplemental information which related to the
potential effects of solution mining for potash. (Docket A-93-02, Item
II-I-31) The DOE concluded that the impacts of solution mining for
potash would be the same as those for room and pillar mining, and that
the potential subsidence-induced hydraulic effects in the Culebra would
be similar to those for typical mining practices. Some comments
disputed this conclusion, stating that the effects of solution mining
on the repository would be substantially different than those from
conventional mining and could cause the WIPP to exceed the containment
requirements. After examining these comments, EPA concluded that the
scenarios set forth in the comments were not realistic and that the
commenter's conclusion was based on an extreme example of subsidence
from solution mining. The EPA disagrees with the comments and concludes
that subsidence in the vicinity of the WIPP would not vary
significantly with solution mining compared to conventional mining.
The EPA concludes that solution mining for potash is appropriately
omitted from the PA because it is not a current practice, and
therefore, is not an activity expected to occur prior to or soon after
disposal. As added assurance, the Agency also finds that even if
solution mining of potash were to occur in the vicinity of the WIPP,
the potential effects of such mining are consistent with those from
conventional techniques and are therefore already accounted for in the
PA. (Docket A-93-02, Item V-C-1, Section 8)
f. Carbon Dioxide Injection. Public comments raised concerns that
carbon dioxide (CO2) injection is a current drilling
practice in the Delaware Basin that DOE inappropriately omitted from
the PA calculations. Carbon dioxide flooding is the injection of
CO2 into an oil reservoir to improve recovery.
CO2 injection is typically used in tertiary recovery
processes after the economic limits for waterflooding have been
reached. When CO2 is injected and mixing occurs, the
viscosity of the crude oil in the reservoir is reduced. The
CO2 increases the bulk and relative permeability of the oil,
and increases reservoir pressure so that the resulting mixture flows
more readily toward the production wells. When CO2 begins to
appear at the producing well, it is typically recovered, cleaned of
impurities, pressurized and re-injected.
The use of CO2 flooding for enhanced oil recovery in
west Texas and southern New Mexico began in 1972. In this area, most
CO2 injection activity is located on the Central Basin
Platform and on the Northwest Shelf. A limited number of CO2
flooding projects have occurred in the Texas portion of the Delaware
Basin. Economy of scale, oil prices, proximity to CO2 supply
and reservoir heterogeneity are several of the controlling factors that
strongly influence whether this technique is applied at a given well.
(Docket A-93-02, Item V-C-1, Section 8)
In the CCA (Appendix SCR), DOE determined that CO2
injection is not a current drilling practice in the Delaware Basin and
therefore omitted it from consideration in the PA. For the proposed
rule, EPA concurred with DOE that CO2 injection was not a
current practice. However, as a result of the public comments, EPA
reviewed the issue and determined that CO2 injection does
occur in the Texas portion of the Delaware Basin. In responding to
comments, EPA found no evidence of CO2 injection practices
in the New Mexico portion of the Delaware Basin. (Docket A-93-02, Item
V-C-1, Section 8) All CO2 injection projects found in New
Mexico occurred outside the Delaware Basin. The EPA found that
CO2 injection has only limited potential for use around WIPP
because of site-specific concerns related to reservoir size, proximity
to existing pipelines and reservoir heterogeneity. However, because EPA
confirmed that CO2 injection is practiced in the Delaware
Basin, EPA conducted an analysis of the consequences that
CO2 injection could have on the PA calculations.
In order to investigate the potential effect of CO2
injection should it occur in the future, EPA conducted some bounding
calculations. (Docket A-93-02, Item V-C-1, Section 8) Using numerous
conservative assumptions, EPA estimated the rate of CO2 flow
through a hypothetical wellbore annulus into an anhydrite interbed at
the depth of the WIPP repository. For example, grout in the wellbore
annulus is expected to degrade only along portions of the wellbore;
however, EPA assumed that such degradation would occur along the entire
wellbore, thus providing a continuous pathway for CO2
migration. Other conservative assumptions included a long time frame
for injection, constant CO2 pressures at the point of
injection and at the intersection of the interbed with the borehole,
and a high permeability in the interbed. The EPA's calculations also
assumed that CO2 would be injected into the Delaware
Mountain Group below WIPP and readily migrate to Marker Bed 139,
through which CO2 is assumed to flow toward the repository.
These assumptions increase the potential effect of the gas injection
and therefore increase the predicted radionuclide releases that are
calculated for the performance of the WIPP repository.
These simple but conservative calculations for a hypothetical
CO2 flood indicate that, even if it were to occur,
CO2 injection does not pose a threat to WIPP. For the very
conservative assumptions specified in
[[Page 27371]]
this study, even for long periods of time, there is little potential
for injected CO2 to ever reach the repository. In summary,
DOE determined that CO2 injection was not a current drilling
practice in the Delaware Basin and therefore screened it from the PA
based on regulatory requirements. Based on public comments, EPA
identified limited CO2 injection activities in the Delaware
Basin. The EPA conducted an analysis of the effects of CO2
injection on the repository and found that CO2 injection can
be omitted from the PA because of the minimal consequences that would
occur as a result of CO2 injection.
g. Other Drilling Issues. A few public comments raised concerns
about other human intrusion related scenarios. For example, some
comments disagreed with the drilling rates that were set forth in the
CCA. Other comments contended that natural gas storage exists in the
Delaware Basin and should be considered in the PA.
Several public comments stated that the CCA did not provide
drilling rates that are consistent with the extensive drilling
throughout the area. The EPA required DOE to include the effects of
drilling into a WIPP waste panel in the PA. The DOE was required to
separately examine the rate of shallow and deep drilling. Shallow
drilling is defined in Sec. 194.2 as drilling events that do not reach
a depth of 2,150 feet below the surface and therefore do not reach the
depth of the WIPP repository. Deep drilling is defined in Sec. 194.2 as
drilling events that reach or exceed the depth of 2,150 feet and
therefore reach or exceed the depth of the repository. Both types of
drilling events include exploratory and developmental wells. (See
Docket A-93-02, Item V-B-2, CARD 33 for further discussion of drilling
rates.)
The EPA accepted DOE's finding that shallow drilling would not be
of consequence to repository performance and was therefore not included
in the PA. (Docket A-93-02, Item V-B-2, CARD 32, Section 32.G) The
future rate of deep drilling was considered in DOE's PA. The deep
drilling rate set forth in the CCA for the Delaware Basin is 46.775
boreholes per square kilometer per 10,000 years.
Several commenters suggested that DOE should use other, higher deep
drilling rates in the PA. Comments stated that these higher rates,
based on drilling over limited areas near the WIPP or on time periods
shorter than 100 years (such as the last year or the last 50 years),
would be more consistent with current drilling rates. The EPA's
criteria require that the deep drilling rate be based on drilling in
the Delaware Basin over the 100-year period immediately prior to the
time that the compliance application is prepared. (Sec. 194.33(b)(3))
Although the drilling rate dictated by EPA's requirements may be lower
than the current drilling rate, the use of a 100-year drilling rate
more adequately reflects the actual drilling that may be expected to
take place over the long term. (See Response to Comments for 40 CFR
Part 194, Docket A-92-56, Item V-C-1, p. 12-11.) The future rate of
deep drilling in the PA was set equal to the average rate at which that
type of drilling has occurred in the Delaware Basin during the 100-year
period immediately prior to the time that the compliance application
was prepared. Commenters did not suggest that DOE had failed to include
known drilling events or had calculated the rate inconsistently with
EPA's requirements. Therefore, EPA finds that the approach taken by DOE
meets the regulatory requirements set forth in Sec. 194.33(b). (Docket
A-93-02, Item V-B-2, CARD 33)
Natural gas storage facilities, in underground cavities, are known
to exist in the Salado Formation outside the Delaware Basin. However,
neither EPA nor DOE is aware of any natural gas storage in the Salado
Formation of the Delaware Basin. Because there is no known gas storage
in the Delaware Basin, DOE is permitted to omit it from the PA
according to the requirements of Sec. 194.32(c).
In addition to determining that there is no known gas storage in
the Delaware Basin, EPA conducted an analysis of the effects that this
activity would have on the repository. The EPA's analysis, presented in
the response to comments, shows that natural gas storage would not
affect the ability of the WIPP repository to successfully isolate waste
because the migration potential of the gas would be minimal.
3. Geological Scenarios and Disposal System Characteristics
a. Introduction. 40 CFR 194.14(a) requires DOE to describe the
natural and engineered features that may affect the performance of the
disposal system. Among the features specifically required to be
described are potential pathways for transport of waste to the
accessible environment. This information is crucial to the conceptual
models and computer modeling that is done to determine compliance with
the containment requirements and the individual and ground-water
protection requirements. In addition to a general understanding of the
site, EPA required specific information on hydrologic characteristics
with emphasis on brine pockets, anhydrite interbeds, and potential
pathways for transport of waste. The EPA also required DOE to project
how geophysical, hydrogeologic and geochemical conditions of the
disposal system would change due to the presence of waste. Geology also
relates to criteria at Secs. 194.32 and 194.23, which require DOE to
model processes which may affect the disposal system, and to use models
that reasonably represent possible future states of the disposal
system.
The EPA examined the CCA and the supplemental information provided
by DOE and proposed to find that it contained an adequate description
of the WIPP geology, geophysics, hydrogeology, hydrology and
geochemistry of the WIPP disposal system and its vicinity, and how
these conditions change over time. (62 FR 58798-58800) Several
commenters suggested that the WIPP site geology and disposal system
characteristics have been incorrectly assessed or inaccurately modeled.
Commenters expressed concern with the WIPP site regarding Rustler
recharge; dissolution, including karst; presence of brine in the
Salado; use of two dimensional modeling with the BRAGFLO computer code
instead of modeling the disposal system using a three-dimensional
representation (2D/3D BRAGFLO), earthquakes, and the gas generation
conceptual model. The EPA's response to these comments is discussed
below.
b. WIPP Geology Overview. The WIPP is located in the Delaware Basin
of New Mexico and Texas and is approximately 26 miles southeast of
Carlsbad, New Mexico. This area of New Mexico is currently arid, but
potential future precipitation increases were accounted for in the PA.
The Delaware Basin contains thick sedimentary deposits (over 15,000
feet, or 4572 meters, thick) that overlay metamorphic and igneous rock
(1.1 to 1.5 billion years old). The WIPP repository is a mine
constructed approximately 2,150 feet (655 meters) below ground surface
in the Permian age (6200-250 million years old) Salado Formation, which
is composed primarily of salt (halite).
The DOE considered the primary geologic units of concern to be
(from below the repository to the surface): (1) the Castile Formation
(``Castile''), consisting of anhydrite and halite with pressurized
brine pockets found locally throughout the vicinity of the WIPP site;
(2) the Salado Formation (``Salado''), consisting primarily of halite
with some anhydrite interbeds and accessory minerals and approximately
2,000 feet (600 meters) thick; (3) the Rustler Formation (``Rustler''),
containing salt,
[[Page 27372]]
anhydrite, clastics, and carbonates (primarily dolomite), with the
Culebra dolomite member of the Rustler as the unit of most interest;
and (4) the Dewey Lake Red Beds Formation (``Dewey Lake''), consisting
of sandstone, siltstone and silty claystone. The geologic formations
below these were included in the screening of features, events, and
processes, but were not included in the PA calculations because they
did not affect the performance of the disposal system. See CARD 32,
Sections 32.A and 32.F, for a detailed discussion of screening of
features, events, and processes. (Docket A-93-02, Item V-B-2)
c. Rustler Recharge. Numerous comments on the proposed rule were
related to whether the Rustler Formation, primarily the Culebra
dolomite member, would be recharged; that is, whether water will
infiltrate through the soil and underlying rock and into the Culebra.
Commenters linked high infiltration to the potential dissolution of the
Culebra and other members of the Rustler, concluding that karst has
been formed and contributes to ground water flow. Commenters claimed
that the presence of karst features would render DOE's ground water
flow models invalid. Site characterization data and DOE's ground water
modeling indicate that infiltration is very low and limited, if any,
dissolution is ongoing, contrary to commenters statements.
The DOE indicated that the units above the Salado (i.e., the
Rustler, the Dewey Lake and the Santa Rosa) are classified as a single
hydrostratigraphic unit (i.e., equivalent to a geologic unit but for
ground water flow) for conceptual and computer modeling. The Rustler is
of particular importance for WIPP because it contains the most
transmissive units above the repository (i.e., has the highest
potential rate of ground water flow). In particular, the Culebra
dolomite member of the Rustler Formation is considered to be the
primary ground water pathway for radionuclides because it has the
fastest ground water flow in the Rustler Formation. The Culebra
dolomite is conceptualized as a confined aquifer in which the water
flowing in the Culebra is distinct from rock units above or below it
and interacts very slowly with other rock units. In general, fluid flow
in the Rustler is characterized by DOE as exhibiting very slow vertical
leakage through confining layers and faster lateral flow in conductive
units. (Docket A-93-02, Item V-B-2, CARD 14, Sections 14.B.4 and
14.B.5) The DOE stated that the Culebra member conceptually acts as a
``drain'' for the units around it, but that it takes up to thousands of
years for the Culebra to respond to changes in the environment. DOE's
modeling indicates that the Culebra ground water is still responding to
changes in precipitation from the latest ice age. DOE's explanation for
the ground water flow in the units above the Salado is embodied in the
ground water basin model which was introduced in Chapter 2 of the CCA.
The EPA did not consider treatment of this issue in the CCA to be
adequate and requested additional information. (Docket A-93-02, Item
II-I-17) The DOE provided additional information in response to this
request. (Docket A-93-02, Item II-I-31)
The ground water basin model, which simulates recharge passing
slowly through the overlying strata before reaching the portion of the
Culebra within the boundaries of the WIPP site recognizes the
possibility of localized infiltration. (Docket A-93-02, Item V-B-2,
CARD 23) The DOE included ground water recharge in its ground water
basin modeling for the Culebra Member of the Rustler formation. The DOE
also acknowledged the water-bearing capabilities of the Dewey Lake and
considered this possibility in the PA evaluations. The DOE assumed that
the water table would rise in response to increased recharge caused by
up to twice the current site precipitation.
Essentially, DOE's conceptual model of flow in the Culebra assumes
that the Culebra is a confined aquifer in which the flow slowly changes
directions over time, depending on climatic conditions. The ground
water basin model also accounts for the current ground water chemistry.
Current geochemical conditions are the result of past climatic regimes
and ground water responses to those changes; because the ground water
chemistry is still adjusting to the current conditions, it does not
reflect the current ground water flow direction in the Culebra. This
new interpretation allows for limited but very slow vertical
infiltration to the Culebra through overlying beds, although the
primary source of ground water will be lateral flow from the north of
the site. The EPA reviewed DOE's conceptualization of ground water flow
and recharge, and believes that it provides a realistic representation
of site conditions because it plausibly accounts for the
inconsistencies in the current ground water flow directions and the
geochemistry. The EPA examined this treatment of recharge in the PA
modeling and determined it to be an appropriate approach that
reasonably bounds and accounts for the impact of potential future
recharge. (See Docket A-93-02, Item V-B-2, CARD 14, Sections 14.B.4 and
14.B.5; CARD 23, Section 2.4; and CARD 32, Section 32.F.4 for detailed
discussions of hydrogeology.)
Commenters also stated that DOE's estimate of the age of ground
water is based on an unreliable methodology and that the stable
isotopic compositions of most samples of ground water from the Rustler
Formation were found to be similar to the composition of other,
verifiably young, ground water in the area. The age of the ground water
is important because the ground water basin model is based on the
assumption that the Rustler water is ``fossil'' water, having been
recharged under climatic conditions significantly different from the
present. Because the isotopic data can be interpreted differently, EPA
examined the entire spectrum of data that could be used to assess
infiltration rates, including DOE's ground water basin model, Carbon-14
data, and tritium data. Based on these data, EPA concluded that the
ground water basin model provides a plausible description of ground
water conditions in the Culebra. The EPA also points out that recent
Carbon-14 data indicate that a minimum age of 13,000 years is
appropriate for Culebra waters. Further, different geochemical zones in
the WIPP are explained by differences in regional recharge and long
residence time. (Docket A-93-02, Item II-I-31) The EPA examined all
data pertaining to ground water flow in the Rustler, and believes the
DOE's total conceptualization adequately described system behavior for
the purposes of the PA.
d. Dissolution. In the CCA, DOE indicated that the major geologic
process in the vicinity of the WIPP is dissolution. The DOE proposed
that three principal dissolution mechanisms may occur in the Delaware
Basin: lateral, deep and shallow. (Docket A-93-02, Item V-B-2, CARD 14,
section 14.B.4) Deep dissolution refers to that at the base of or
within the salt section along the Bell Canyon Castile Formation;
lateral dissolution occurs within the geological units above the Salado
(progressing eastward from Nash Draw); and shallow dissolution,
including the development of karst and dissolution of fracture fill in
Salado marker beds and the Rustler, would occur from surface-down
infiltration of undersaturated water. Lateral, strata-bound dissolution
can occur without shallow dissolution from above.
To the west, the slight dip in the beds has exposed the Salado to
near-surface dissolution processes; however, DOE estimated that the
dissolution front will not reach the WIPP site for hundreds of
[[Page 27373]]
thousands of years. Near-surface dissolution of evaporitic rocks (e.g.,
gypsum) has created karst topography west of the WIPP site, but DOE
contended that karst processes do not appear to have affected the rocks
within the WIPP site itself. The DOE indicated that while deep
dissolution has occurred in the Delaware Basin, the process of deep
dissolution would not occur at such a rate near the WIPP that it would
impact the waste containment capabilities of the WIPP during the
regulatory time period. The DOE concluded that the potential for
significant fluid migration to occur through most of these pathways is
low. However, DOE also concluded that fluid migration could occur
within the Rustler and Salado anhydrite marker beds and included this
possibility in PA calculations. In the proposed rule, EPA concluded
that deep, lateral, and shallow dissolution (including karst features
and breccia pipes) will not serve as significant potential radionuclide
pathways and that the potential for significant fracture-fill
dissolution during the regulatory time period is low. (Docket A-93-02,
Item V-B-2, CARD 14, Section 14.B.5; Item V-B-3, Section B.3.t)
Comments on the proposed rule stated that shallow dissolution and
karst features occur at WIPP and will affect its containment
capabilities. The EPA does not agree with DOE's assertion that the
distribution of salt in the Rustler is solely a depositional feature
because Rustler transmissivity (which is related to fracture occurrence
in the Rustler) corresponds somewhat to the occurrence of salt in the
Rustler. This implies that some post-Rustler dissolution has occurred
which impacts the fracturing in Rustler rocks. However, the evidence
observed by EPA indicate many Rustler features were formed millions of
years ago (e.g., the breccia zone in the exhaust shaft, or at WIPP-18,
where anhydrite/clay-rich strata may be halite dissolution residues).
Other Rustler features (e.g., salt distribution in the Rustler) could
have occurred sometime after the Rustler was deposited, but there is no
evidence to indicate that ongoing dissolution of soluble material in
the Rustler or at the Rustler-Salado contact will modify the existing
transmissivity to the extent that the results of PA will be affected.
(Docket A-93-02, Item V-B-2, CARD 14, Section 14.B.5)
The EPA concurs that the presence of fractures and related fracture
fill that could be attributed to dissolution or precipitation could
significantly impact ground water transport in the Rustler. The DOE
modeled the presence of fractures using a dual porosity model, and has
accounted for permeability variability by developing transmissivity
fields based upon measured field data which reflect the varying
transmissivity values. This dual porosity conceptual model recognizes
that fluid may flow through both the rock matrix and fractures at the
site. The use of dual porosity assumes ground water flows through
fractures, but allows solutes to diffuse into the matrix. The EPA
concludes that while fractures are present in Rustler Formation units
and slow vertical infiltration does occur, there is no evidence that
indicates fractures are conduits for immediate dissolution of Rustler
or Salado salts, or that pervasive infiltration and subsequent
dissolution of the Salado Formation or Rustler is a rapid, ongoing
occurrence at the WIPP site. Further, ground water quality differences
between the more permeable units of the Rustler Formation support
relative hydrologic isolation (i.e., the water in the Magenta member
interacts very little with the water in the Culebra member), or at
least they support very slow vertical infiltration that has not allowed
for extensive geochemical mixing of ground waters in these units.
Many commenters suggested that WIPP cannot contain radionuclides
because WIPP is in a region of karst (topography created by the
dissolution of rock). Karst terrain typically exhibits cavernous flow,
blind streams, and potential for channel development that would enhance
fluid and contaminant migration. Numerous geologic investigations have
been conducted in the vicinity and across the WIPP site to assess the
occurrence of dissolution (karst) and the presence of dissolution-
related features. The EPA reviewed information and comments submitted
by DOE, stakeholders, and other members of the public regarding the
occurrence and development of karst at the WIPP. (Docket A-93-02, Item
V-B-2, CARD 14, section 14.B.5) The EPA acknowledges that karst terrain
is present in the vicinity of the WIPP site boundary near the surface.
Near-surface dissolution of evaporitic rocks (e.g., gypsum) have
created karst topography west of the WIPP site. Nash Draw, which (at
its closest to WIPP) is approximately one mile west of the WIPP site,
is attributed to shallow dissolution and contains karst features.
(Docket A-93-02, Item V-B-3, Section B.3.t) The EPA also recognizes the
potential importance of karst development on fluid migration.
The EPA agrees that karst features occur in the WIPP area but
concluded that karst features are not pervasive over the disposal
system itself. The EPA examined hydrogeologic data (e.g.,
transmissivity and tracer tests) from DOE's wells at and near the WIPP
site and found no evidence of cavernous ground water flow typical of
karst terrain at the WIPP site. Similarly, a field investigation
conducted by EPA during the summer of 1990 to assess the occurrence of
karst features showed no evidence of significant karst features, such
as large channels, dolines, sinkholes, or collapsed breccias (other
than those at, for example, at WIPP-33 and Nash Draw) in the immediate
WIPP vicinity. (55 FR 47714) Available data suggest that dissolution-
related features occur in the immediate WIPP area (e.g., WIPP-33 west
of the WIPP site), but these features are not pervasive and are not
associated with any identified preferential ground water flow paths or
anomalies at the WIPP site. (Docket A-93-02, Item V-B-2, CARD 14,
Section 14.B.5) Therefore, the groundwater modeling in the PA is
adequate.
Several commenters stated that poor Rustler Formation core recovery
at WIPP indicates the presence of karst. The commenters state that
fragmented core samples containing dissolution residues are a clear
indication of unconsolidated or cavernous zones capable of transmitting
water with little resistance. However, core recovery is related to rock
strength, and does not necessarily have an association with local
hydrologic conditions. In the case of WIPP, cores that were attempted
through fractured material, including the Culebra, exhibited poor
recoveries. The EPA agrees that fractured Rustler is 'present at test
well H-3. However, EPA does not believe that the presence of fractured
material in the Rustler indicates that karst processes are active. In
fact, the development of fractures can occur for various reasons
unrelated to dissolution (e.g., removal of overlying rock due to
erosion). The DOE recognized the presence of fractures within the
Culebra, and included this dual porosity system in the PA modeling. In
addition, core loss is a common occurrence in the drilling of all kinds
of rocks, sometimes associated with fracture and other causes related
to drilling technology, as well as the occurrence of soft or
incompetent rock. The EPA concludes that to interpret all zones of lost
core as zones of karst is inappropriate, as other rock features
contribute to core loss which have nothing to do with cavernous
porosity.
The EPA reviewed information pertinent to the potential development
of karst in the WIPP area and believes that the near continuous
presence of the more than half-million year old
[[Page 27374]]
Mescalero Caliche over the WIPP site is a critical indicator that
recharge from the ground surface to the bedrock hydrologic regime has
not been sufficient to dissolve the caliche at the site. If active
dissolution of the evaporites in the subsurface were occurring in the
WIPP area, it would be expected that collapse features would be evident
in the Mescalero above the area where the dissolution is, or has
occurred. As noted above, EPA has found no evidence of direct
precipitation-related flow increases typical of karst terrain, and no
field evidence of large channels or other karst features. The relative
pervasiveness of the Mescalero Caliche over a long period of time is
also an indication that there has been an arid climate and very low
recharge conditions over a long period of time at the WIPP site. This,
combined with DOE's near-future precipitation assumptions, led EPA to
conclude that karst feature development will neither be pervasive nor
impact the containment capabilities of the WIPP during the 10,000 year
regulatory period. (Docket A-93-02, Item V-B-2, CARD 14, Section
14.B.5; Item V-B-3, Section 3.B.t)
The EPA concludes that dissolution has occurred in the WIPP area
outside of the WIPP site, as evidenced by karst features like Nash
Draw. It is possible that dissolution has occurred at the WIPP site
sometime in the distant past (i.e., millions of years ago for strata-
bound features) associated with a geologic setting other than that
currently present at WIPP; however dissolution in the Culebra is not an
ongoing process at the WIPP site. Thus EPA finds that DOE's modeling
(which assumes no karst within the WIPP site boundary) is consistent
with existing borehole data and other geologic information.
e. Presence of Brine in the Salado. Numerous commenters stated the
Salado Formation will be wet and that brine is weeping into the
repository at a slow but significant rate, leading to a wet repository
which will corrode the waste containers. This, the commenters stated,
would invalidate the basic premises of the WIPP that dry salt beds
would creep and encapsulate the waste canisters.
The EPA agrees that brine will enter the repository from the Salado
Formation via anhydrite marker beds. The EPA also notes that the
presence of brine within the Salado is a key element of the PA
modeling; brine inflow is assumed to occur and the impact of brine
inflow on gas generation is assessed. Brine is necessary for both of
the processes that may cause gas generation: either drum corrosion or
microbial respiration. If there is no inflow of brine into the
repository, neither corrosion of iron drums nor survival of microbes
would occur, so gas generation would not occur. Therefore, although the
commenters correctly noted that initial WIPP studies did assume the
salt to be ``dry,'' the presence of interstitial brine has long been
recognized and is accounted for in the PA. (Docket A-93-02, Item V-B-2,
CARD 14, Section 14.E.5; Item V-B-3, Section F.2)
In the CCA discussion of the gas generation conceptual model, DOE
indicates that brine is expected to be present in the repository due to
a natural inflow of brine. Corrosion of the waste containers,
generation of gases resulting from waste corrosion and microbial
degradation, and the effects of these processes on the disposal system
components have been addressed in the DOE PA and the EPA-mandated PAVT.
(Docket A-93-02, Item V-B-2, CARD 14, Section 14.D; Item V-B-2, CARD
23, Section 2.4; Item V-B-3, Section E.2) The DOE also considered that
additional brine could be introduced to the waste area if a drilling
event passed through the waste and subsequently hit a brine pocket. The
presence of a pressurized brine pocket beneath WIPP was addressed in
the PA under the Human Intrusion Scenarios whereby the reservoir is
penetrated by a borehole and brine is subsequently released into and
mixed with the waste and eventually discharged either into the Culebra
or at the ground surface. The EPA concludes that DOE adequately
considered the presence of brine in PA modeling because it included the
possibility of encountering a brine pocket in its intrusion scenarios,
and because the potential effects of brine on corrosion rates and gas
generation were incorporated in PA models. For more information on
brine pocket parameter values, see the subsequent discussion of
Parameter Values in the Performance Assessment sections of this
preamble.
f. Gas Generation Model. Some chemical reactions could occur in the
WIPP because metal containers holding waste may corrode and waste made
from organic materials such as rubber may decompose if water is
available and if other conditions are conducive to such decomposition.
The corrosion reaction would create hydrogen gas (H2). The
decomposition of organic waste would create carbon dioxide
(2) and methane (CH4). These gases would build up
in the repository after it is sealed, increasing pressure inside the
waste rooms.
The DOE developed a gas generation conceptual model to describe
this situation. The Department's gas generation conceptual model
incorporates the following basic premises:
Gas is generated primarily by metal corrosion and
microbial processes;
Gas generation is closely linked to other processes;
Gas generation from microbial processes will not always
occur;
High gas pressures in the repository can cause the Salado
anhydrite interbeds to fracture; and
High gas pressure is necessary before spalling and direct
brine releases can begin.
The DOE performed experiments on gas generation rates for the 1992
PA and updated these experiments more recently. (Telander, M.R. and
R.E. Westerman, 1997. ``Hydrogen Generation by Metal Corrosion in
Simulated Waste Isolation Pilot Plant Environments,'' SAND96-2538; see
Docket A-93-02, Item V-B-1.) The gas generation rates are important in
The PA because build-up of high gas pressures increases the chance for
releases if a drill bores into the repository.
During the public comment period, commenters questioned the gas
generation rates used in the gas generation conceptual model. One
commenter stated that calculated corrosion rates were too low because
they are based upon long-term tests that show lower rates than short-
term tests, they assume a high pH, and they include a minimum rate of
zero, perhaps by assuming that salt crystallization will prevent
corrosion. The commenter also stated that corrosion rates used in the
model should account for the fact that direct contact with salt and
backfill increases the rate. The commenter further stated that DOE
seemed to use the observed data to set the upper limit of a
distribution of corrosion rates, rather than the midpoint of such a
distribution, which would systematically understate the corrosion rate
because most values would be less than the values taken from DOE's
observed data. Finally, the commenter stated that aluminum corrosion is
as significant as corrosion of steel, and that it is likely to take
place in the repository because CO2 and iron will be present
and will enhance aluminum corrosion.
The EPA examined DOE's studies on gas generation rates. The EPA
disagrees that the assumptions of long-term rates, pH, and minimum
corrosion rate are not well-founded. Since the results of the corrosion
testing are used to develop a long-term hydrogen gas generation rate
for the repository that applies over
[[Page 27375]]
hundreds of years, it is appropriate that DOE developed the rate based
on hydrogen generation over a longer time (12 to 24 months) rather than
for a shorter time. Data indicate that during the first few months of
the test, the corrosion reaction had not yet stabilized at equilibrium,
producing more hydrogen gas than would have been expected at
equilibrium for the amount of iron present. (Docket A-93-02, Item II-G-
1, CCA Reference #622) Therefore, the higher rate of gas generation
observed in the short-term is unlikely to represent what happens in the
repository over hundreds of years.
The DOE's assumption of high pH (about 10) is consistent with data
on the use of magnesium oxide (MgO) backfill. Because DOE has committed
to using MgO backfill in the repository in the CCA, EPA finds it
reasonable to assume this pH in the repository. (See the preamble
section ``Engineered Barriers'' for further discussion of MgO
backfill.) Furthermore, even if the MgO were not fully effective and
the pH were to drop from near 10 to between 7 and 8, the enhanced
corrosion rate expected at that lower pH is already reflected in the
probability distribution for the corrosion rate parameter. DOE's
experimental data show that MgO backfill will function as assumed in
the CCA. Therefore, EPA concludes that DOE considered the issue of pH
and realistically incorporated it into the model.
The DOE took its minimum corrosion rate of zero from studies on
steel corrosion rates when the steel is in a humid environment and also
when steel is submerged in brine. The DOE found that virtually no
corrosion occurred and no hydrogen gas was generated under humid
conditions. Also, the studies show that the steel has an extremely low
corrosion rate when it is submerged in brine at the higher pH expected
in the WIPP. Some DOE studies also found that salt films may prevent
corrosion, as the commenter mentioned. (Docket A-93-02, Item II-G-1,
CCA Appendix MASS, Attachment MASS 8-2) Based on all these studies, EPA
concludes that DOE's minimum corrosion rate is supported and
appropriate.
The DOE assumed that the corrosion rates of steel submerged in
brine were uniformly distributed from zero to 0.5 micrometers per year.
The EPA believes that the bases for the parameter assumptions are
adequately documented and the use of the particular parameter
distribution is consistent with demonstrating the concept of reasonable
expectation for the H2 gas generation rates used in the CCA.
However, EPA was concerned that the maximum corrosion rate value
selected by DOE did not fully reflect other uncertainties. These
uncertainties included the accelerated corrosion of steel in reactions
with other materials such as backfill and aluminum. Data from DOE tests
indicated that corrosion rates might be twice as high as those used in
the PA. (Docket A-93-02, Item V-B-14) Thus, in the PAVT, EPA required
DOE to double the maximum corrosion rate to assure that these other
uncertainties were more fully reflected. (Docket A-93-02, Item II-G-28)
(Doubling the corrosion rate would be expected to cause the gas
generation rate to rise but not necessarily double, since other factors
such as microbial degradation also influence gas generation.) This and
other changes made in the PAVT showed that the repository remained in
compliance with the standards.
The commenter correctly notes that the corrosion data from DOE's
studies were used to set the upper limit of a uniform distribution of
corrosion, rather than a mid-point. (Telander, M.R. and R.E. Westerman,
1997. See Docket A-93-02, Item V-B-1.) However, EPA does not agree that
this practice would systematically understate the corrosion rate under
the conditions expected to occur in the repository. The experimental
rate was obtained under pH conditions substantially lower than those
expected in the repository (i.e., 7.4 to 8.4 versus 9.2 to 9.9). The
corrosion rate is expected to be at least an order of magnitude lower
at the higher pH than at the pH expected in the repository in the
presence of MgO. (Docket A-93-02, Item V-B-14) Therefore, the higher
corrosion values (i.e., those based on the study) represent extreme
conditions, rather than those expected in the repository, and the
parameter range would account for all values that are likely to occur.
In addition, as noted above, EPA required that the maximum corrosion
rate be doubled in the PAVT to account for uncertainties in this
parameter. The Agency believes that this addresses the concerns raised
by the commenter.
The commenter notes that CO2 and iron will enhance the
corrosion of aluminum. Although EPA agrees this is true, the Agency
believes it does not affect the results of the PA. Carbon dioxide
reacts with MgO, so CO2 will not be available to reduce the
brine pH and to enhance corrosion. Second, accelerated corrosion of
aluminum is not a significant factor in the WIPP's performance, since
brine will be consumed in corrosion reactions and will lead to smaller
direct brine releases. (This is also discussed in the following
preamble section concerning two dimensional modeling of brine and gas
flow.) The results of DOE's modeling show that iron is consistently
left over after reacting with all available brine. (Docket A-93-02,
Item II-G-7, Fig. 2.2.9) Based upon data on these reactions, the Agency
concludes that enhanced corrosion of aluminum due to CO2 and
iron will not increase releases of radioactivity because brine will not
be left over to go to the surface as direct brine releases. (Docket A-
93-02, Item V-C-1)
g. Two-Dimensional Modeling of Brine and Gas Flow. The DOE modeled
the flow of brine and gases within the repository in the BRAGFLO
computer code. The DOE simplified this model by representing the
repository as a space in two dimensions rather than in three
dimensions, as it is in reality. The Department made this
simplification in order to speed up computer calculations
significantly. The DOE performed a screening analysis titled S1:
Verification of 2D-Radial Flaring Using 3D Geometry to see if the two-
dimensional BRAGFLO model would predict similar results to a three-
dimensional model. (WPO #30840) In Appendix MASS, Attachment 4-1 of the
CCA, DOE explained that the results of the screening analysis showed
that a three-dimensional model would not give significantly different
results from the two-dimensional model used in the PA. The EPA examined
DOE's documentation to determine if the CCA complied with EPA's
requirements for documentation of conceptual models and consideration
of alternative conceptual models under Secs. 194.23(a)(1) and (a)(2).
The EPA reviewed the screening analysis and concluded in the proposal
that DOE sufficiently documented its rationale and approach behind
using a two-dimensional model for brine and gas flow in the repository.
(62 FR 58808)
One commenter stated that DOE's screening analysis suggested that
the two-dimensional (``2D'') BRAGFLO model might underestimate releases
of radionuclides to the surface under higher gas pressures. The
commenter stated that several three-dimensional (``3D'') BRAGFLO
simulations of the repository should be performed using parameter
values from the CCA PA. The recommended analysis would include
calculations of direct brine releases (releases of brine contaminated
with radioactive waste) and spallings (releases of solid waste pushed
out of the repository under high pressure), and an assessment of how
much brine would be consumed by chemical reactions. Another commenter
stated that the screening analysis had been
[[Page 27376]]
misinterpreted because details of the assumptions used in the original
screening analysis had not been considered. This commenter also stated
that results of additional analysis submitted by DOE as comments showed
that the two-dimensional BRAGFLO code used in the CCA PA results in a
conservative estimate of the releases when compared to results from a
three-dimensional code.
The EPA examined the screening analysis mentioned by the
commenters. The Agency found that the divergence between the results of
the two-dimensional and three-dimensional versions of BRAGFLO occurred
only at very high (lithostatic 22) pressures that would
occur seldom if ever in the repository. (Docket A-93-02, Item V-C-1,
Section 5) For simulations at the gas generation rates used in the CCA
PA, the two-dimensional BRAGFLO code predicted greater brine inflows
than the three-dimensional code. (Greater brine inflows could
potentially lead to greater direct brine releases.)
---------------------------------------------------------------------------
\22\ Lithostatic pressure is the pressure exerted by overlying
rock layers.
---------------------------------------------------------------------------
The EPA also considered how much brine would be consumed in
chemical reactions. One of DOE's studies showed that brine is consumed
by corroding steel barrels and leaves behind at least 20 percent of the
original steel at the end of 10,000 years for 99 percent of the sets of
simulated conditions tested in the CCA PA. (Docket A-93-02, Item II-G-
7, p. 2-12) Based on this study, EPA concluded that even if the 3D
model predicted additional brine inflow (beyond that predicted in the
current 2D model), this brine will simply be consumed in chemical
reactions (i.e., corrosion of metal drums), and will not go to the
surface as direct brine releases. In addition, the Agency looked at
results of additional simulations that DOE conducted to compare BRAGFLO
2D and 3D results. (Docket A-93-02, Item IV-G-34, Attachment 1 and
February 25, 1998, memorandum) DOE's results show that the use of a two
dimensional representation does not result in an underestimate of
direct brine release during human intrusion. In all cases investigated,
the two dimensional simulations consistently predict either the same or
higher repository pressures and brine saturations than their
corresponding three-dimensional simulations, leading to larger
releases. The Agency, therefore, concludes that the two-dimensional
BRAGFLO code results in conservative estimates of releases from the
repository compared to results from a three-dimensional model.
In addition, EPA found that DOE sufficiently documented its
development of conceptual models and scenarios, including alternative
conceptual models considered, in the CCA and additional documentation
submitted to the Agency. Therefore, EPA finds DOE in compliance with
the requirements of Secs. 194.23(a)(1) and (a)(2) with respect to
modeling of brine and gas flow.
h. Earthquakes. Several public comments raised concerns about the
effect that earthquakes could have on the repository and the
containment of waste. Several commenters refer to a recent (January 4,
1998) earthquake in New Mexico, over 100 miles from the WIPP site, as
an indication of the weakness of the WIPP site for disposal purposes.
In the CCA, DOE examined seismicity as part of its features,
events, and processes, analyses, and concluded earthquakes could be
excluded from the PA calculations based on low consequences. This
conclusion is drawn from a wealth of knowledge about the seismic
activity and processes in the region, but is based primarily on the
fact that the intensity of ground shaking (the primary cause of
destruction from an earthquake) is significantly less underground than
at the surface. In addition, the ductile nature of a salt deposit makes
it deform differently than typical hard rocks, so the displacement due
to rupture (if any) will be less. The EPA reviewed DOE's earthquake
(seismic) scenario in the Technical Support Document for 194.14:
Content of Compliance Application, Section IV.B.4.f. (Docket A-93-02,
Item V-B-3) The EPA concurs with DOE's analysis, that the probability
of a release of radionuclides from the repository due to the opening of
fracture pathways caused by an earthquake is very small.
Many years of seismological monitoring, microseismal studies and
geologic study demonstrate that there are no probable sources of large
earthquakes at or near the WIPP site. (Docket A-93-02, Item II-G-1,
Chapter 2.6) The only sources of significant earthquakes in the region
lie far to the west of the site along the Rio Grande rift or to the
south along major plate tectonic features in Mexico, although
measurable earthquakes have occurred closer to the WIPP. (Docket A-93-
02, Item II-G-1, Chapter 2 and Appendix SCR) Micro-earthquakes
(magnitude 3.0 or smaller on the Richter scale), most of which are too
small to be felt, or small, shallow teleseismal ground motion related
to distant earthquakes are the only seismicity expected at the WIPP
site during the very short period that the repository will persist as
an underground opening. The EPA notes that the site of the January 4,
1998, earthquake is located in the Rio Grande Rift--over 100 miles east
of WIPP--and seismic activity in that area, including the January 4,
1998 earthquake, was too small to have an impact at WIPP. Therefore,
EPA finds that the effects of earthquakes need not be considered in
performance assessments. (See Docket A-93-02, Item V-B-2, CARD 32,
Section G)
i. Conclusion. The EPA finds that DOE adequately assessed the site
characteristics for the purposes of the PA and use in comparison with
EPA's radioactive waste disposal standards and WIPP compliance
criteria. The results of EPA's review of the CCA and additional
information provided by DOE is provided in CARDs 14, 23, 32 and 33.
(Docket A-93-02, Item V-B-2)
4. Parameter Values
a. Introduction. Parameters are numerical values or ranges of
numerical values used in the PA to describe different physical and
chemical aspects of the repository, the geology and geometry of the
area surrounding the WIPP, and possible scenarios for human intrusion.
Some parameter values are well-established physical constants, such as
the Universal Gas Constant or atomic masses of radionuclides.
Parameters also can be physical, chemical or geologic characteristics
that DOE established by experimentation. The DOE has also assigned
parameters to aspects of human intrusion scenarios, such as the
diameter of a drill bit used to drill a borehole that might penetrate
the repository.
Section 194.23(c)(4) requires detailed descriptions of data
collection procedures, data reduction and analysis, and code input
parameter development. Section 194.14(d) requires DOE to describe the
input parameters to the PA and to discuss the basis for their
selection. Section 194.14(a) requires DOE to describe the
characteristics of the WIPP site, including the natural and engineered
features that may affect the performance of the disposal system, which
is part of the process of parameter development.
The Agency reviewed the CCA, parameter documentation, and record
packages for approximately 1,600 parameters used as input values to the
CCA PA calculations. The EPA further reviewed parameters record
packages and documentation in detail for 465 parameters important to
performance of the disposal system. The Agency selected parameters to
review in depth based on the following criteria:
[[Page 27377]]
Parameters that were likely to contribute significantly to
releases or seemed to be poorly justified;
Parameters that control various functions of the CCA PA
computer codes that were likely to be important to calculations of
releases and important to compliance with the containment requirements
of Sec. 191.13; and
Other parameters EPA used to evaluate the overall quality
of Sandia National Laboratory's (``SNL'') documentation traceability.
After its initial review, EPA found that DOE had a great deal of
documentation available in the SNL Records Center supporting most of
the parameters used in the CCA PA. However, EPA had some concerns about
the completeness of the list of CCA PA parameters in the CCA and the
SNL Records Center, the description and justification to support the
development of some code input parameters, and the traceability of data
reduction and analysis of parameter-related records. The Agency did not
agree with the technical justification of some parameter values and
probability distributions.
The Agency later required DOE to perform additional calculations in
a Performance Assessment Verification Test (``PAVT'') in order to
verify that the cumulative impact of all required and other corrections
to input parameters, conceptual models, and computer codes used in the
PA was not significant enough to necessitate a new PA. The EPA directed
DOE to incorporate modified values or distributions for twenty-four
parameters in the PAVT. (Docket A-93-02, Item II-I-27) The PAVT showed
that the calculated releases may increase by up to three times from
those in the original CCA PA, but that the WIPP is still an order of
magnitude below the containment requirements in Sec. 191.13. The DOE
satisfied EPA's concerns about the parameters by incorporating EPA's
changes to the parameter values and parameter distributions in the
PAVT.
During the public comment period on the proposed rule, members of
the public expressed concern about a few specific parameters used in
the PAVT: distribution coefficients (Kd), the permeability
of borehole plugs, the characteristics of a potential brine pocket, and
the solubility of different actinide ions in brine. Commenters stated
these particular parameters could have an especially great impact on
releases, and therefore, on the results of the PA.
b. Distribution Coefficient (Kd). As the primary
radionuclide pathway during an intrusion, the Culebra was the subject
of many public comments, especially related to distribution
coefficients 23 (Kd values). In DOE's conceptual
model the Culebra is characterized as a fractured dolomite that has
dual-porosity and acts to physically retard movement of contaminants.
In a dual-porosity rock unit, ground water is believed to flow through
the fractures, but water and contaminants can access the pore space
within the rock matrix away from the fractures. Movement of water and
contaminants into the pore space slows (retards) their respective
forward movement. This physical retardation is necessary in order to
have chemical retardation. In the process of chemical retardation,
contaminants diffuse from the fractures into the pore space where they
can adsorb onto the rock mass. This adsorption is described by
distribution coefficients, or Kd values.
---------------------------------------------------------------------------
\23\ Dissolved waste migrating out of the disposal site would
migrate as atoms with a positive electrical charge, or cations;
these could be cation species such as Pu+4 or
U+6. When liquid such as brine carries the cations
through sediment or rock, some of the cations become attached to the
surface of these solids. Therefore, the cations travel more slowly
than the liquid as a whole. The rate of advance of the cation as the
liquid migrates can be described with a number called a retardation
factor. Distribution coefficients, or Kd's, are used in
calculating the retardation factor.
---------------------------------------------------------------------------
The CCA indicated that there were no contributions to total
releases from the ground water pathway. (Docket A-93-02, Item II-G-1,
Chapter 2) This was due to the limited amount of contaminated brine
predicted to reach the Culebra and the fact that radionuclides adsorbed
into the Culebra dolomite did not move with the ground water flow. That
is, the movement of the radionuclides were retarded with respect to the
ground water flow. The estimate of the extent of the retardation (i.e.,
the Kd value) was based on laboratory tests using crushed
rocks and small columns of rock. (CCA, Docket A-93-02, Item II-G-1,
Chapter 6)
The EPA reviewed DOE's Kd values in detail. (Docket A-
93-02, Item V-B-4) Based upon the review of DOE's data, methodologies,
and conclusions, EPA proposed that the Kd ranges suggested
by DOE were sufficient for the PA. (62 FR 58799) The EPA also concluded
that the laboratory tests were conducted appropriately and that the
Kd values DOE derived from this testing are reasonable,
given the experimental evidence, and sufficient for PA purposes.
(Docket A-93-02, Item V-B-2, CARD 14, Section 14.B.5)
Commenters stated that DOE's experiments did not produce
Kd values that are representative of conditions in the
Culebra. The DOE data on actinide Kd values are derived
directly from the results of a number of experiments (e.g., crushed
rock, column tests) conducted with brine solutions that are
representative of brines in the disposal system. The DOE used samples
of the Culebra Dolomite and brine solutions that are considered to be
representative of the field situation. These data were supplemented by
experiments with other natural dolomites and column experiments, in
which the effects of a field-realistic solid to solution ratio could be
investigated. The laboratory-derived Kd values are expected
to overestimate the mobilities of the actinides, making them reflective
of upper bounds for predicting the maximum possible rates of actinide
migration in the PA calculations. Therefore, it is reasonable to expect
that the range of actinide Kd values obtained from the DOE
experiments are inclusive of any scale-effects that might produce a
different average Kd value than the experimental average in
either the greater or lesser directions. Docket A-93-02, Item V-B-4,
Section 4.4 presents EPA's analysis of field Kd testing.
The DOE's experimental results show that each of the actinides
tested is adsorbed to the rock matrix to varying extents; hence, they
will not migrate as fast as the overall rate of horizontal water flow
(i.e., the actinides will be attenuated). These results are consistent
with general theories of the adsorptive behavior of cationic solutes
under alkaline pH conditions.
The EPA reviewed DOE's actinide Kd values and concluded
that the population of Kd values determined in DOE
experiments was not well-represented by a uniform distribution. The
Agency recommended that a loguniform distribution be used in the PA
calculations. In the PAVT, loguniform distributions for the actinide
Kd values were used. (WPO# 47258; Docket No A-93-02, Item
II-G-39) The results of PAVT still resulted in compliance with
regulatory release limits. Therefore, EPA determined that the CCA PA
was adequate for the purpose of determining compliance. (Docket A-93-
02, Item V-B-4)
The DOE also performed bounding calculations using the minimum
Kd values necessary to achieve compliance with EPA limits.
The bounding estimates were obtained for plutonium (239Pu)
and americium (241Am), which are critical actinides with
respect to releases to the accessible environment. Results of DOE's
bounding assumptions (whereby all other factors are set to the least
favorable value) indicate that a Kd of 3 milliliter per gram
(ml/g) is sufficient for compliance for 239Pu and
[[Page 27378]]
241Am. Estimates based on typical CCA sample sets indicate
that Kd values greater than 1 ml/g are sufficient for
compliance. (A higher Kd value indicates greater
retardation--or less movement--of radionuclides.) The Kd
ranges determined from DOE column experiments, conducted since
submission of the CCA, for 239Pu and 241Am are
typically greater than 100 ml/g, thus inferring that Kd
values used in the PA are more than sufficient to ensure compliance
with EPA limits with respect to accessible environment release through
the Culebra. For these reasons, the actinide Kd values
developed by DOE are considered to be adequate for representing
actinide mobilities in the PA calculations. (Docket A-93-02, Item V-B-
2, CARD 14, Section 14.G.5)
The EPA reviewed and responded to the public comments on
Kd values and finds the Kd values used in the PA
are sufficient. Refer to EPA Technical Support Document for Section
194.14: Assessment of Kd Values Used in the CCA for EPA's
detailed review. (Docket A-93-02, Item V-B-4)
c. Actinide Solubility. Actinide solubilities are used in the
computer codes to calculate the actinide concentrations released from
the repository. They are important because as radionuclides dissolve in
brine, they are more easily released from the disposal system through
direct brine release mechanisms. Commenters questioned the analysis of
certain chemical conditions in the disposal system relating to
backfill, ligands, uncertainty, and oxidation state analogy.
An important factor influencing actinide solubility is the
magnesium oxide (MgO) backfill DOE proposed to emplace in the WIPP. The
DOE indicated that MgO backfill emplaced with transuranic waste would
mitigate the solubility-enhancing effects of carbon dioxide from waste
degradation. The DOE proposed to emplace a large amount of MgO in and
around waste drums in order to provide an additional factor of safety
and thus account for uncertainties in the geochemical conditions that
would affect CO2 generation and MgO reactions.
Commenters stated that DOE has not shown the predicted MgO chemical
processes will take place. The DOE provided documentation in the CCA
and supplementary information that MgO can effectively reduce actinide
solubility in the disposal system. While the conceptual model peer
review panel initially rejected DOE's conceptualization of the Chemical
Conditions Model, DOE provided additional information on MgO processes
and the peer review panel later concluded that MgO processes will
indeed take place as initially postulated by DOE. The EPA concluded
that DOE's qualitative justification was sufficient to show that the
emplacement of MgO backfill in the repository will help prevent or
substantially delay the movement of radionuclides toward the accessible
environment by helping to maintain alkaline conditions in the
repository, which in turn favors lower actinide solubilities.
Furthermore, DOE's bounding of pH levels to a narrow range greatly
reduces the uncertainty associated with pH and actinide solubility in
the PA. Refer to CARD 24, Section 24.B.6, and CARD 44 for further
discussion of the effects of MgO. (Docket A-93-02, Item V-B-2)
The EPA received numerous comments regarding DOE's lack of a
sensitivity analysis on the effects of organic ligands and that organic
ligands other than ethylene diaminetetraacetic acid (``EDTA'') should
have been considered. Organic ligands are important since they can
increase more mobile fractions, i.e., can make more radionuclides
available for transport. Organic chemicals are expected to be part of
the waste, especially because many were used in the separation of
actinides during chemical processing of nuclear materials. DOE's
bounding calculations and incorporation of uncertainty ranges to
represent actinide concentrations in the PA calculations indicate that
organic ligands will have only a minor effect on the solubilities of
actinide solids under the expected repository conditions. The EPA
found, through independent calculations, that there is no substantive
information that could be gained by conducting a sensitivity analysis
on the effects of organic ligands or conducting the calculations with
citrate rather than EDTA, since EDTA provides a conservative assessment
of the effects of ligands on solubility of actinide solids. (Docket A-
93-02, Item V-B-2, CARD 24, Section 24.E.5) The EPA agrees with the
conclusions of the Waste Characterization Independent Review Panel
``that under the conditions of MgO backfill, chelating agents (e.g.,
organic ligands) will have a negligible effect on repository
performance. The Panel notes that, even at the basic pH in the
repository, the availability of transition metals may be enhanced due
to the formation of soluble halo complexes, making an even stronger
case that base metals control ligand chemistry.''
Commenters also expressed concern about the solubility uncertainty
range used in the PA computer codes. The DOE determined that the
available experimental data for the oxidation state +IV actinides
(i.e., plutonium, uranium, and neptunium) were insufficient for making
such comparisons. However, the experimental procedures for determining
the solubilities of +IV actinide solids are not substantially different
from those used to determine the solubilities of +III and +V actinide
solids. Therefore, EPA concluded that the uncertainties determined for
the +III and +V actinide solids would be inclusive of those that would
be obtained for +IV actinide solids, which are based on experimental
measurements of thorium oxide. This expectation is based on the fact
that DOE used the outermost limits of the differences between model
results and experimental results for all data examined to define the
breadth of the uncertainty limits. This procedure greatly expands the
size of the uncertainty bounds beyond what might be calculated from
statistical treatment of the distribution of the differences. (Docket
A-93-02, Item V-B-2, CARD 24, Section 24.B.6; and Item V-B-17) The EPA
therefore finds that the uncertainty bounds on actinide solubility are
adequate for use in the PA.
Finally, commenters raised issues regarding the limitations of the
oxidation state analogy in the Actinide Source Term Dissolved Species
Model. In short, the actinide oxidation analogy means that actinides of
the same oxidation state tend to have similar chemical properties under
similar conditions. The oxidation state analogy is based on standard
inorganic chemistry principles. This generalization can be made because
chemical reactions involving ionic species are related primarily to the
charge densities of the reacting species. Actinides with the same
oxidation state have the same core electronic structure; hence they
have similar ionic radii and charge densities, which in turn leads to
analogous chemical behavior in solubility and aqueous speciation
reactions. In addition to the theoretical basis, DOE conducted
experimental studies that confirmed the validity of the oxidation state
analogy, and subsequently employed it in its representation of the
solubilities of actinides. The EPA finds that the actinide oxidation
state is adequate for use in the PA. (Docket A-93-02, Item V-B-2, CARD
24, Section 2.B.6)
For details regarding chemical reactions of MgO, see CARD 24 (Waste
Characterization) and CARD 44 (Engineered Barriers). For further
[[Page 27379]]
information regarding the PA modeling of solubility and chemical
conditions in the repository, see CARD 23 (Models and Computer Codes).
CARDs can be found in Docket A-93-02, Item V-B-2.
d. Brine Pockets. The Castile Formation lies underneath the Salado
Formation, where the WIPP is located. This stratum contains pockets of
brine under pressure. One of the parameters in the PA that commenters
believed to be important is the probability that a driller will hit a
brine pocket in the Castile. The CCA PA models the possibility that a
drill bit could penetrate a brine pocket in the Castile Formation,
allowing brine to rise up the borehole and into the repository. The
brine could then dissolve radioactive waste and could carry it to the
earth's surface if another driller bored a hole into the repository.
This could increase the amount of radioactive waste reaching the
accessible environment.
Some commenters expressed concern that brine from brine pockets in
the Castile Formation could travel up to the level of the repository,
or even to the earth's surface. The EPA believes that this is not a
problem unless the repository is disturbed by human intrusion. Because
it is difficult for water to travel in the Salado and Castile
formations (i.e., they have low permeability), there is no natural
connection between a Castile brine pocket and the waste panel area
under undisturbed conditions. These brines are also either saturated or
nearly saturated with soluble minerals such as salt (halite), and thus,
the brine in pockets will not dissolve the surrounding material.
(Docket A-93-02, Item II-G-1, CCA Chapter 2, Table 2-5) However, in the
case of a deep drilling intrusion that goes through a waste panel and
into the Castile, it is possible that the driller will intercept brine
in the Castile and create a pathway for Castile brine to flow into the
repository and interact with the waste. The probability of human
intrusion through the WIPP repository to an underlying Castile brine
pocket is a key component of the PA.
The 1992 draft PA considered the probability of a driller hitting a
brine pocket under the waste area with a range of 25 percent to 62
percent, based on geophysical work that suggested brine may be present.
(Docket A-93-02, Item II-G-1, Reference #563) In the CCA PA, DOE
assigned a probability of hitting a brine pocket of 8 percent, based
upon a geostatistical analysis of oil and gas wells in the vicinity of
WIPP. The Agency believed that the assigned probability was low, based
upon data from one particular DOE study using the Time Domain
Electromagnetic (``TDEM'') method. In addition, EPA found there was
considerable uncertainty in this parameter. Therefore, in the PAVT the
Agency required DOE to change the constant value of this parameter to a
uniform probability distribution from 1 percent to 60 percent, based
upon data in the TDEM study. (Docket A-93-02, Item II-I-27)
Many commenters questioned the use of a uniform distribution from 1
percent to 60 percent as the range for the probability of hitting a
brine pocket that EPA specified be used in the PAVT. Some believed that
EPA should require DOE to examine a probability of 100 percent for
hitting a brine pocket, based upon data from DOE's WIPP-12 borehole,
which suggested that a large reservoir of brine might lie in the
Castile Formation under the WIPP Land Withdrawal Area. Others
recommended that EPA require DOE to repeat the PA assuming a constant
probability of 60 percent.
The EPA carefully evaluated the potential occurrence of brine
pockets below the WIPP. The EPA agrees that there is significant
uncertainty concerning the existence of a brine pocket beneath the
repository. For this reason, EPA required DOE to reevaluate the
probability of hitting a brine pocket in the PAVT using a probability
distribution rather than a constant value.
The EPA also considered the possibility that the brine pocket
indicated by WIPP-12 data may underlie 100 percent of the repository.
Based on reservoir volume and thickness data from WIPP-12, commenters
found that a cylindrically-shaped reservoir could underlie the entire
repository. However, EPA considers this unlikely because brine in the
Castile does not reside in homogeneous and well-defined reservoirs.
Instead, it is believed to reside in vertical or subvertical fracture
systems, which may be extensive and contain significant volumes of
brine. (Docket A-93-02, Item II-G-1, Appendix MASS, Attachment 18-6)
Although EPA agrees that part of the WIPP-12 reservoir may underlie
part of the repository, the time-domain electromagnetic (``TDEM'')
survey data do not support speculation of a 100% probability of an
encounter. (Docket A-93-02, Item II-G-1, Chapter 2.2.1.2.2, Item V-B-3,
section IV; Item V-B-14, Sections 4.1, 4.4, and 4.5) In addition, as
pointed out by one of the commenters recommending a probability of 60
percent, some boreholes adjacent to brine-producing boreholes near the
WIPP site are known to be dry. In view of the lack of support from the
TDEM data and the other concerns expressed above, EPA concludes that
available data do not support a 100 percent probability of hitting a
brine pocket.
The EPA established its 1 percent to 60 percent range of
probability for hitting a brine pocket based upon data from the TDEM
survey. The Agency examined the data and found that the probability
distributions for encountering brine under the WIPP varied widely,
depending on whether or not one assumed that brine pockets exist below
the bottom of the Anhydrite III layer near the top of the Castile
Formation. Using the base of the anhydrite layer as the cutoff, EPA's
simulations showed that the fraction of the excavated area of the
repository underlain by brine varies from 1 to 6 percent of the
excavated area. Using the base of the Castile as the cutoff, the
fraction of the excavated area of the repository underlain by brine
would range from about 35 to 58 percent. According to the 1992 WIPP PA,
Castile Formation brines are generally found in the uppermost anhydrite
layer (usually Anhydrite III), rather than all the way through the
Castile. (Docket A-92-03, Item II-G-1, CCA Reference #563, Vol. 3, p.
5-4) If brine is confined to the upper (Anhydrite III) layer, which is
the more probable case based on geologic information, the maximum
fraction of the repository area underlain by brine is 6 percent.
However, in order to examine the possible effects of the more
conservative case, EPA chose to assume an equal probability that a
driller would hit a brine pocket in either the upper Anhydrite III
layer or the base of the Castile. Therefore, EPA used a probability
range in the PAVT with a low value of 1 percent based on the upper
anhydrite layer and the high value of 60 percent derived by rounding up
the highest value from the TDEM survey. The EPA believes that existing
information supports the range used in the PAVT as valid, and probably
conservative, values for the probability of hitting a brine pocket.
The Agency also notes that a sensitivity analysis of the PA
parameters submitted in comments showed that the final results of the
PA were not significantly affected by increasing the probability of
hitting a brine pocket. Even when the Castile brine encounter
probability was increased to 100 percent'the highest possible
probability'there was no significant difference between the resulting
mean CCDF and the mean CCDF in the CCA, which was based upon a brine
encounter probability of 8 percent.
[[Page 27380]]
(Docket A-93-02, Item IV-G-43) The EPA believes that 100 percent is an
unrealistically high probability. The results of this study confirm
that examining such a probability in more detail would provide little
added information about the performance of the WIPP.
Commenters stated that the range of the compressibility of rock
surrounding a Castile brine pocket used in the CCA PA was too wide.
They also believed that the brine pocket volume values used in the PA
were too small. Castile rock compressibility is one of several
parameters that affects the volume of brine pockets in the Castile.
This is important because a drill bit would be more likely to hit a
large brine pocket than a small one.
The EPA agrees with commenters that DOE's parameters for rock
compressibility in the Castile and representation of brine pocket size/
volume in the CCA PA were not consistent with available information.
The EPA also believes that the parameters of the Castile brine pockets
are highly uncertain. In order to capture this uncertainty, the Agency
believed it would be appropriate to sample from a range of parameter
values, rather than to use a single estimate, as DOE did in the CCA PA.
In the PAVT, EPA required DOE to use a range of possible brine pocket
volumes. (WPO#41887. See Docket A-93-02, Item V-B-1. See also Docket A-
93-02, Item V-B-14.) Changing the rock compressibility of the Castile
and the Castile porosity effectively modified the sampled brine pocket
volume to include, more representatively, the possibility of larger
brine pocket volumes like those expected based on data from the WIPP-12
borehole. The EPA found that modification of these parameters in the
PAVT did not result in releases that exceed EPA's containment
standards. Based on these results, EPA has concluded that the CCA PA
was adequate for the purpose of demonstrating compliance.
e. Permeability of Borehole Plugs. In the PA modeling, DOE assumed
that people drilling for resources would follow standard practice and
plug the boreholes left behind. As long as these borehole plugs remain
intact, the pressure of gases generated from the waste will build up
inside the repository. The more permeable the borehole plugs are, the
more gas will be capable of escaping from the repository. This would
reduce pressure in the repository and therefore would reduce the
potential for releases of radioactivity through spallings or direct
brine release from a future drilling event. In the CCA PA, DOE modeled
a situation in which borehole plugs between the Castile and Bell Canyon
Formations would remain impermeable, and most borehole plugs closer to
the earth's surface would disintegrate after two hundred years and
would become more permeable.
One commenter stated that the CCA does not model the gas buildup
which would result from impermeable plugs. The EPA does not agree that
the CCA does not model gas buildup. In the CCA PA and PAVT, gas
pressure is allowed to build up in the undisturbed repository. Pressure
would be released if a borehole is drilled into the repository. In some
of the PA simulations, pressure builds up again, although not to
undisturbed levels, after it is released during a borehole intrusion.
(Docket A-93-02, Item II-G-7, Figure 3.3.1) However, EPA was concerned
about DOE's assumption that a relatively small number of borehole plugs
would have low permeability. In the CCA PA, DOE assumed that 98 percent
of the boreholes would be plugged with either two or three plugs, where
the top plug would degrade and become more permeable, and 2 percent of
the boreholes were plugged with a single low permeability plug. The EPA
was concerned that an assumption that only 2 percent of the boreholes
had low permeability might not be conservative. Therefore, EPA required
that the permeability range for borehole plugs in the PAVT be broadened
to include lower values (at which gas will not escape at a significant
rate). This parameter change ensured that the PAVT would more
frequently incorporate low borehole permeability and gas pressure
buildup for more simulations than in the CCA PA, providing a more
conservative result.
Other commenters expressed concern that the borehole plug
permeabilities used in the CCA PA and the PAVT were too high, and might
underestimate releases of radioactive material from the WIPP. One
commenter pointed out that EPA retained the permeability used by DOE as
a high value and then added a range of permeabilities extending to
lower values after the Agency rejected DOE's initial value as too high.
In the PAVT, EPA required that two changes be made regarding the
permeability of the borehole plugs. First, the Agency required that the
permeability of the intact plugs during the first two hundred years of
the plug lifetime be treated as a variable or probability distribution
rather than as a fixed parameter, with a range bounded by values found
in the literature. The range of values included borehole plug
permeabilities both higher and lower than the constant permeability
used in the CCA. In addition, EPA required DOE to use a range of
permeability values to represent the permeability of borehole plugs
that have started to degrade. The upper end of the new range was the
same permeability as that used in the CCA, but the lower end of the
range was reduced by three orders of magnitude and the median was
reduced by an order of magnitude. The Agency believed that the upper
end of the range chosen by DOE, based upon the permeability of silty
sand, was reasonable because an abandoned borehole plug could degrade
to this type of debris over long periods of time. Since the
permeability of the actual borehole fill material at some time well
into the future is unknowable, the Agency believes that the use of data
based on natural materials is a reasonable approach. However, the
Agency was not satisfied with the rationale for the lower end of the
range originally chosen by DOE. The EPA believes that there is some
probability that the concrete borehole plugs will not degrade as
assumed in the CCA PA. Consequently, in the PAVT, EPA set the lower end
of the range at a permeability value consistent with intact concrete.
One commenter stated that DOE had not sufficiently accounted for
uncertainty in the lifetime of a borehole plug before it degrades. (A
borehole plug with a longer lifetime would take longer to become more
permeable and would allow more gas to build up in the repository.) This
commenter stated that DOE should perform additional calculations to
investigate how borehole plug lifetimes could influence repository
conditions and compliance with the containment requirements.
The EPA also initially had concerns that uncertainty about the
lifetime of borehole plugs had not been sufficiently represented in the
CCA PA. In order to reflect this uncertainty, the Agency required DOE
to use a probability distribution of borehole plug permeabilities for
intact plugs during the first two hundred years of their lifetime in
the PAVT, rather than a constant value. The sampled range of
permeabilities includes values representing the permeability of both
intact (newer) plugs and disintegrating (older) plugs. Therefore, EPA
believes that this change made in the PAVT adequately addresses the
effects of uncertainty in borehole plug life.
5. Other Performance Assessment Issues
The EPA used many methods to analyze specific scenarios or
characteristics that DOE included in the PA. Commenters had concerns
about
[[Page 27381]]
these methods, since the soundness of EPA's conclusions would depend
upon the soundness of the methods used to reach those conclusions.
Commenters disagreed with aspects of a few types of analyses in
particular: sensitivity analysis, and the PA verification test
(``PAVT''). Sensitivity analysis is a computer modeling technique that
examines whether results of computer modeling will change significantly
if a particular parameter value is changed. The EPA's approach to
sensitivity analysis is documented in EPA's Technical Support Document
for Section 194.23: Sensitivity Analysis. (Docket A-93-02, V-B-13) The
PAVT was a set of 300 simulations of additional performance assessment
calculations required by EPA. The PAVT implemented DOE's PA modeling
using the same sampling methods as the CCA PA, but incorporating
parameter values that were selected by EPA. Because some commenters
disagreed with DOE's approach to the PA and EPA's approach to its
analysis, they recommended that the Agency require DOE to repeat the PA
using different scenarios or characteristics of the WIPP and its
surroundings; these issues are discussed in preceding sections of this
preamble related to the PA.
a. Sensitivity Analysis. Computer modelers perform a sensitivity
analysis for a parameter in a model to find out if results of modeling
are sensitive to (significantly affected by) that parameter. If the
results of modeling are not sensitive to the parameter, then the exact
value of the parameter is not important to the results of modeling.
The compliance criteria require DOE to document the development of
input parameters for the PA under Secs. 194.14(d), 194.23(c)(4), and
194.34(b). As part of its parameter development, DOE conducted a
sensitivity analysis of parameters used in the CCA PA. (Docket A-93-02,
Item II-G-1, Appendix SA, Volume XVI) The EPA reviewed this and
supplementary information that documents DOE sensitivity analysis of
the parameters sampled in the PA. (Docket A-93-02, Item II-G-7) As the
Agency continued in its review of the CCA and supporting documentation,
EPA found that there were three categories of parameters not fully
documented in the CCA documents or in the Sandia National Laboratory
WIPP Records Center. These categories were: (1) parameters lacking
supporting evidence; (2) parameters having data records that support
values other than those selected by DOE; and (3) parameters that are
not explicitly supported by the relevant data or information. The EPA
expressed concern about 58 parameters of the 465 parameters that EPA
reviewed in detail. (Docket A-93-02, Item II-I-17) For these 58
parameters, EPA evaluated whether changing the parameter values would
have a significant impact on the results of computer modeling,
primarily through the use of a sensitivity analysis. (Docket A-93-02,
Item V-B-13) (Distribution coefficients, or Kd values, were examined in
separate calculations and analyses conducted by EPA. (Docket A-93-02,
Items V-B-4, V-B-7, and V-B-8)) In its sensitivity analysis, the Agency
examined changes in output from the PA models' major submodels that
calculate releases and solubility of actinides: BRAGFLO 24,
BRAGFLO--DBR 25, CUTTINGS--S 26, SOURCE TERM
27, and CCDFGF 28. The EPA found that 27 of the
58 parameters have a significant impact on the results of modeling and
that 31 of the 58 parameters did not have a significant impact. Some of
these parameters (both significant and insignificant to results) were
subsequently determined to be adequately supported based on additional
documentation provided by DOE or Sandia National Laboratory. (Docket A-
93-02, Items II-I-25 and II-I-27) For parameters that might have an
impact on the results of the PA and were found not to be adequately
supported, EPA required DOE to perform a Performance Assessment
Verification Test with revisions to the significant parameters.
---------------------------------------------------------------------------
\24\ BRAGFLO predicts gas generation rates, brine and gas flow,
and fracturing within the anhydrite marker beds in order to predict
the future state of the repository.
\25\ BRAGFLO--DBR calculates the amount of waste that dissolves
in brine and travels in the contaminated brine as a direct brine
release.
\26\ CUTTINGS--S predicts the volume of solid waste released
from the repository because of human intrusion drilling. This
includes releases from cavings (material that falls from the walls
as a drill bit drills through), cuttings (material that is actually
cut by a drill bit during drilling, including any waste), and
spallings (releases of solids pushed up and out by gas pressure in
the repository).
\27\ SOURCE TERM calculates actinide solubilities within the
repository. The solubility values are then used in the NUTS and
PANEL codes to calculate the actinide concentrations in brine
released from the repository.
\28\ CCDFGF calculates the complementary, cumulative
distribution functions (``CCDFs'') used to show compliance with
EPA's containment requirements.
---------------------------------------------------------------------------
Commenters stated that they had concerns about the submodel
approach used in EPA's sensitivity analysis. One commenter stated that
EPA had not justified this approach, beyond stating that it was ``a
more sensitive method'' than examining the final results of the
complete PA model. Another commenter stated that EPA had not shown that
the submodel approach for testing sensitivity related in any particular
way to the compliance demonstration with the containment requirements.
This commenter also stated that EPA had not explained or justified why
the analysis used the average of changes in the outputs of the
submodels, and that averaging output changes might disguise the
significance of a parameter value change if some outputs change in
direct response and others change inversely.
The DOE's PA model uses almost 1600 parameters. Even an important
parameter may change the final results of the PA by a relatively small
percentage because so many parameters contribute to the final results.
The different submodels contain far fewer parameters than the complete
PA. Therefore, a change in any one parameter will cause a greater
percentage change in the output from a submodel than in the final
result of the entire PA modeling. It is for this reason that EPA chose
to use submodels. This approach provided intermediate results that
would be a more sensitive measure of reactions of a model to changes in
input parameters than the resultant complementary cumulative
distribution functions (``CCDFs'') used to determine compliance.
The submodel outputs that EPA analyzed for sensitivity included the
outputs most closely linked with radionuclide release and the ability
of the WIPP to meet EPA's containment requirements. Examples of
submodel outputs are gas pressure in the repository; cumulative brine
release into the Culebra dolomite; cumulative cavings release and
cumulative spallings release to the earth's surface; and brine flow
into the anhydrite interbeds away from the repository. If a parameter
changes the submodel outputs significantly, it may have a significant
impact on the final results of the PA; however, if a parameter does not
change the submodel output significantly, then it cannot change the
final results of the PA significantly. In addition, EPA notes that the
nature of the testing--which included three model runs at low, average,
and high parameter values--means that it is not practical to develop
mean CCDFs. It would be necessary to run all of the PA codes for each
parameter change a hundred times to create a single CCDF. Therefore,
except for those parameters included in the CCDFGF code, it would have
been extremely cumbersome and time-consuming to perform a sensitivity
analysis on the final results of the PA.
The Agency disagrees that averaging the submodel outputs disguises
the significance of a parameter value change
[[Page 27382]]
if some outputs change in direct response and others change inversely.
The EPA used absolute values 29 of the percent changes in
computing the average percent changes. If two parameters had inverse
relationships, those relationships would not cancel each other out
because the final results would be an average of the absolute values.
Averaging of the percent changes in the key submodel outputs was a
significant step only for the parameters in the BRAGFLO code, where
average changes to output were developed based on 11 model outputs. The
EPA averaged the results of these eleven outputs in order to give equal
weight to each in determining the sensitivity of BRAGFLO parameters.
---------------------------------------------------------------------------
\29\ Absolute value is the magnitude of a number, without a
positive or negative sign. For example, positive three and negative
three both have an absolute value of three.
---------------------------------------------------------------------------
Several members of the public commented that most of the
sensitivity analyses varied only one parameter, rather than varying
several parameters at a time, which potentially could show a
significant combined result. The EPA varied single parameters in most
of the analyses to identify those parameters that were most important
to the PA results. One of the problems with varying multiple parameters
simultaneously is that it is difficult to determine which parameter (or
parameters) led to the observed result. Analysis of groups of
parameters requires the Agency to find that the entire group of
parameters is sensitive or not sensitive. In addition, if some
parameters in a group increase releases while others reduce releases, a
group analysis may not detect actual sensitivity for individual
parameters. This is because the sensitivity analysis typically looks at
low, high, and average values for all parameters in the group
simultaneously. Without examining the sensitivity of individual
parameters, the analyst would not always know enough about the
parameters to be able to predict the most extreme situation with the
greatest consequences of releases. The ability to determine the
significance of individual parameters is important because this allows
one to improve the model's predictive capability by focusing resources
on those parameters that are most sensitive and have the greatest
impact on results. It is true that EPA did not perform a separate
sensitivity analysis run on groups of parameters that it determined
were insensitive through individual parameter tests. The Agency
believes that this is not necessary because the cumulative calculated
sensitivity of these insensitive parameters is so small compared to the
sensitive parameters. For example, the sum of the percent changes for
all 33 insensitive parameters in BRAGFLO together was 47 percent
(ranging from 0 percent to 10 percent each), while the percent change
for the individual sensitive parameters ranged from 101 percent to
103,611 percent each. (Docket A-93-02, Item V-B-13, Table 3.1-1)
Therefore, EPA concluded that those parameters it found insensitive
through analysis of individual parameters will not have a significant
effect on results of the PA and do not need to be re-analyzed in
groups.
In addition to performing its own sensitivity analysis on
parameters, the Agency required DOE to complete a comprehensive
recalculation of the entire PA in the Performance Assessment
Verification Test (``PAVT''). The purpose of the PAVT was to perform a
complete evaluation of the synergistic effects of changing important
and questionable parameters on the outcome of the PA calculations. The
results of the PAVT indicate that the calculated releases would
increase when changes are made to the sensitive parameters identified
by the Agency, but the revised results of the PA with these more
conservative parameter values would still be an order of magnitude less
than the containment requirements of 40 CFR 191.13.
A commenter stated that EPA's sensitivity analysis did not vary
conceptual models. The Agency agrees that this is true. The objective
of EPA's sensitivity analysis was to determine the importance of
selected individual parameters and groups of parameters to the PA
results. The purpose of a sensitivity analysis on conceptual models
would be to determine if model results would change significantly using
different assumptions or using alternative conceptual models. The EPA
examined the conceptual models and alternatives, under
Secs. 194.23(a)(1) and (a)(2). As a result of this review, EPA required
DOE to conduct a sensitivity analysis on Culebra transmissivity and to
examine the assumption that the Culebra acts as a fully confined system
as it pertains to hydrogeochemistry of the Culebra. (Docket A-93-02,
Item II-I-17) The EPA found that the sensitivity analysis results
supported DOE's treatment of Culebra transmissivity and treatment of
the Culebra as a confined system because of the minimal impact on
results when changing assumptions. (Docket A-93-02, Item II-I-31) In
addition, the Conceptual Models Peer Review Panel reviewed the
conceptual models, as required by Secs. 194.27 and 194.23(a)(3)(v). The
Agency finds that it is not necessary to perform further sensitivity
analysis on conceptual models because both the Agency's and the Panel's
reviews accomplished the purpose of evaluating the impact of using
different assumptions or using alternative conceptual models. These
reviews found all the conceptual models except the spallings model to
be adequate for use in the PA, and concluded that the spallings values
used in the CCA PA are reasonable for use in the PA. (Docket A-93-02,
Item V-B-2, CARD 23, Section 7)
The EPA determined that DOE adequately provided a detailed listing
of the code input parameters; listed sampled input parameters; provided
a description of parameters and the codes in which they are used;
discussed parameters important to releases; described data collection
procedures, sources of data, data reduction and analysis; and described
code input parameter development, including an explanation of quality
assurance activities. The DOE also documented the probability
distribution of these parameters, as required by Sec. 194.34(b). The
Agency analyzed parameter values used in the CCA, including DOE's
documentation of the values and EPA's sensitivity analysis. The EPA
also required DOE to change these parameter values in the PAVT and
found that the WIPP is still an order of magnitude below the
containment requirements in Sec. 191.13. (For further discussion of
values for several specific parameters, refer to the preceding preamble
discussion, ``Parameter values.'' See also Docket A-93-02, Item V-B-2,
CARD 23, Sections 8 and 9.) Therefore, the Agency determines that the
CCA complies with Secs. 194.14(d), 194.23(c)(4) and 194.34(b).
b. Performance Assessment Verification Test. The containment
requirements at Sec. 191.13 indicate that a disposal system is to be
tested through a PA that predicts the likelihood of occurrence of all
significant processes and events that may disturb the disposal system
and affect its performance, and that predicts the ability of the
disposal system to contain radionuclides. Section 191.13 requires that
a disposal system be designed so that there is reasonable expectation
that cumulative releases (1) have a probability of less than one in ten
(0.1) of exceeding the calculated release limits, and (2) have no more
than a one in one thousand (0.001) chance of exceeding ten times the
calculated release limits.
In the process of reviewing the CCA, the Agency found problems with
some computer codes and with documentation of parameter
[[Page 27383]]
development. Commenters also voiced concerns about some parameters used
in the CCA PA during the public comment period for the Advanced Notice
of Proposed Rulemaking. The Conceptual Models Peer Review Panel
initially found that one of the conceptual models used for the PA, the
spallings conceptual model, was not adequate. The DOE itself found some
problems with some of its codes, particularly concerning code
stability. Because of these many concerns, the Agency required DOE to
perform additional calculations in a Performance Assessment
Verification Test (``PAVT'') in order to verify that the cumulative
impact of all changes to input parameters, conceptual models, and
computer codes used in the PA was not significant enough to necessitate
a new PA. (PAVT, Docket A-93-02, Items II-G-26 and II-G-28) The PAVT
used modified parameter values and ranges, selected by EPA, in DOE's PA
model. Many of these parameter values were suggested by public
comments. The PAVT results showed releases that were higher, on
average, than DOE's original calculations in the CCA. However, the PAVT
results were still well within the EPA release limits stated in 40 CFR
191.13.
During the public comment period on EPA's proposed certification
decision for the WIPP, commenters raised several issues about the PAVT
and about the PA in general. Some commenters stated that the PAVT
incorporated extremely conservative ranges for 24 critical parameters,
and that the PA in general was done in a conservative fashion. Other
commenters stated that specific parameter values needed to be changed
in order to make more conservative assumptions. In particular, the
public mentioned parameters for actinide solubility, distribution
coefficients (Kd), the probability of hitting a brine
pocket, and the permeability of borehole plugs. (These parameters are
discussed above.) Commenters also said that DOE needed to investigate
possible human intrusion scenarios more thoroughly. Among the human
intrusion scenarios commenters identified for further study were air
drilling, fluid injection, CO2 injection, and potash mining.
Members of the public commented that DOE had incorrectly assessed
geology of the WIPP site and the future state of the waste to go into
the WIPP. They stated concerns about the potential for dissolution, for
the recharge of ground water in the Rustler Formation with contaminated
brine, for earthquakes, and for water entering the Salado layer and the
modeling of gas generation and flow of brine and gas in the repository.
Many commenters stated that the Agency should require DOE to run
another PA using different assumptions about these topics.
The EPA initially had many of the same concerns as those mentioned
by the public, particularly concerning parameters and human intrusion
scenarios. As discussed in the above preamble sections on the PA, EPA
questioned the values and distributions of many values of the
parameters. The Agency even required DOE to revise some parameter
values for the PAVT. The EPA also asked DOE to investigate fluid
injection further. After receiving public comments, the Agency did
independent work on the possible impacts of fluid injection and air
drilling, as well as analysis of the likelihood of air drilling and
CO2 injection in the Delaware Basin. (Docket A-93-02, Item
V-C-1, Sections 5 and 8) After reviewing the information available, the
Agency concludes that DOE's PA incorporates the appropriate human
intrusion scenarios and geologic and disposal system characteristics.
The PAVT and additional analyses of intrusion scenarios by both DOE and
EPA have adequately addressed concerns raised by commenters.
Based upon results of the CCA PA (as confirmed by the PAVT), EPA
finds that the WIPP complies with the containment requirements by a
comfortable margin, even when using more conservative parameter values
that were changed significantly from those in the CCA PA. This modeling
shows that the WIPP will contain waste safely under realistic
scenarios, and even in many extreme cases. The EPA found that the
scenarios and parameter changes suggested by commenters either had
already been adequately addressed by DOE, were inappropriate for the
Delaware Basin, would impact neither releases nor the results of the PA
sufficiently to justify further analysis, or were not realistic.
Therefore, the Agency concludes that no further PA is required to
determine if the WIPP is safe or to make its certification decision.
Many comments were based on a philosophy that DOE should use an
unrealistically conservative approach to the PA. For example, a
commenter stated that air drilling should be incorporated in the PA at
the most conservative rate predicted by DOE in the near future for the
entire U.S., even if air drilling is not currently a standard practice
in the Delaware Basin. Another commenter suggested using the most
conservative value from the PAVT for the probability of hitting a brine
pocket, even after the commenter's own sensitivity analysis showed that
this parameter did not have a significant impact on WIPP compliance at
still higher values. A different commenter stated that DOE and EPA
should analyze actinide solubilities as if DOE were not adding MgO to
reduce those solubilities, even though the Department has committed to
adding MgO. The Agency found all of these suggestions to be
inappropriate, either because they were unrealistic or because they
required additional analysis when the change had already been
demonstrated to have little or no impact on the PA results. The Agency
believes that the PA should be a reasonable assessment with some
conservative assumptions built in, rather than an assessment comprised
entirely of unrealistic assumptions and worst-case scenarios. The
disposal regulations at 40 CFR Part 191 require the PA to show there is
a reasonable expectation that cumulative releases will meet the
containment requirements. This philosophy is reflected elsewhere in
EPA's requirements, such as in the requirement for the mean CCDF to
comply with the containment requirement, rather than for every CCDF to
comply. If unrealistically conservative assumptions were used in the
PA, then results of the PA would not reflect reality and would not be a
reasonable measure of the WIPP's capability to contain waste.
6. Conclusions
Section 194.23 sets forth specific requirements for the models and
computer codes used to calculate the results of performance assessments
(``PA'') and compliance assessments. In order for these calculations to
be reliable, DOE must properly design and implement the computer codes
used in the PA. To that end, Sec. 194.23 requires DOE to provide
documentation and descriptions of the PA models, progressing from
conceptual models through development to mathematical and numerical
models, and finally to their implementation in computer codes.
The CCA and supporting documents contain a complete and accurate
description of each of the conceptual models used and the scenario
construction methods used. The scenario construction descriptions
include sufficient detail to understand the basis for selecting some
scenarios and rejecting others and are adequate for use in the CCA PA
calculations. Based on information provided in the CCA, together with
supplementary information provided by DOE in response to specific EPA
requests, EPA
[[Page 27384]]
concluded that DOE provided an adequate and complete description of
alternative conceptual models seriously considered but not used in the
CCA. The information on peer review in the CCA and in supplementary
information demonstrates that all conceptual models have undergone peer
review consistent with the requirements of Sec. 194.27. Related issues
discussed above in today's preamble include spallings, fluid injection,
air drilling, CO2 injection, and the gas generation
conceptual model. The Agency determines that the DOE has demonstrated
compliance with the requirements of Secs. 194.23 (a)(1), (a)(2) and
(a)(3)(v).
The Conceptual Models Peer Review Panel found all the conceptual
models to reasonably represent possible future states of the repository
and to be adequate for use in the PA except the spallings conceptual
model. However, as discussed above in this preamble, additional
modeling conducted by DOE, and additional data presented by DOE,
provide a substantial basis for EPA to conclude that the results of the
spallings model are adequate and useful for the purpose for which
conceptual models are intended, i.e., to aid in the determination of
whether the WIPP will comply with the disposal regulations during the
regulatory time period. Public comments received on this issue are
discussed above in the preamble section on spallings. Because the
spallings model produces reasonable and conservative results, and
because the Peer Review Panel found that all other conceptual models
reasonably represent possible future states of the repository, EPA
finds DOE in compliance with Sec. 194.23(a)(3)(i).
Based on information contained in the CCA and supporting
documentation for each code, EPA concludes that the mathematical models
used to describe the conceptual models incorporate equations and
boundary conditions which reasonably represent the mathematical
formulation of the conceptual models. Some of the specific issues
related to this criterion are in the section of the preamble entitled,
``Two-dimensional modeling of brine and gas flow.'' Based on the CCA
and supplementary information provided by DOE, the Agency determines
that DOE provided sufficient technical information to document the
numerical models used in the CCA. Based on verification testing, EPA
also determined that the computer codes accurately implement the
numerical models and that the computer codes are free of coding errors
and produce stable solutions. The DOE resolved coding error problems
and stability problems identified in numerical models by completing
code revisions and supplementary testing requested by the Agency.
Therefore, the Agency concludes that DOE has demonstrated compliance
with Secs. 194.23(a)(3) (ii), (iii) and (iv).
Based on EPA audits and CCA review, EPA found that code
documentation meets the quality assurance requirements of ASME NQA-2a-
1990 addenda, part 2.7, to ASME NQA-2-1989 edition. Thus, the Agency
finds that DOE complies with Sec. 194.23(b).
Based on DOE's documentation for each code and supplementary
information requested by EPA, the Agency found that DOE provided
adequate documentation so that individuals knowledgeable in the subject
matter have sufficient information to judge whether the codes are
formulated on a sound theoretical foundation, and whether the code has
been used properly in the PA. The EPA found that the CCA and
supplementary information included an adequate description of each
model used in the calculations; a description of limits of
applicability of each model; detailed instructions for executing the
computer codes; hardware and software requirements to run these codes;
input and output formats with explanations of each input and output
variable and parameter; listings of input and output files from sample
computer runs; and reports of code verification, bench marking,
validation, and QA procedures. The EPA also found that DOE adequately
provided a detailed description of the structure of the computer codes
and supplied a complete listing of the computer source code in
supplementary documentation to the CCA. The documentation of computer
codes describes the structure of computer codes with sufficient detail
to allow EPA to understand how software subroutines are linked. The
code structure documentation shows how the codes operate to provide
accurate solutions of the conceptual models. The EPA finds that DOE did
not use any software requiring licenses. Therefore, EPA determines that
DOE has complied with the requirements of Secs. 194.23(c) (1),(2),(3)
and (5).
The EPA determined that DOE, after additional work and improvement
of records in the SNL Record Center, adequately provided a detailed
listing of the code input parameters; listed sampled input parameters;
provided a description of parameters and the codes in which they are
used; discussed parameters important to releases; described data
collection procedures, sources of data, data reduction and analysis;
and described code input parameter development, including an
explanation of QA activities. The EPA determined that the CCA and
supplementary information adequately discussed how the effects of
parameter correlation are incorporated, explained the mathematical
functions that describe these relationships, and described the
potential impacts on the sampling of uncertain parameters. The CCA also
adequately documented the effects of parameter correlation for both
conceptual models and the formulation of computer codes, and
appropriately incorporated these correlations in the PA. Public
comments regarding parameters are discussed above in the preamble in
the section titled ``Parameter Values.'' The Agency finds that DOE has
demonstrated compliance with the requirements of Sec. 194.23(c) (4) and
(6).
Because DOE provided EPA with ready access to the necessary tools
to permit EPA to perform independent simulations using computer
software and hardware employed in the CCA, EPA finds DOE in compliance
with Sec. 194.23(d).
Section 194.31 of the compliance criteria requires DOE to calculate
release limits for radionuclides in the WIPP in accordance with 40 CFR
Part 191, Appendix A. Release limits are to be calculated using the
activity, in curies, from radioactive waste that will exist in the WIPP
at the time of disposal. The CCA PA and the PAVT were calculated using
release limits calculated according to Appendix A of 40 CFR Part 191
using DOE's projected inventory of waste radioactivity at the time of
disposal. Therefore, EPA concludes that DOE has met the requirements of
Sec. 194.31.
Section 194.32 requires DOE to consider, in the PA, both natural
and man-made processes and events which can have an effect on the
disposal system. The EPA expected DOE to consider all features, events
and processes (``FEPs'') that may have an effect on the disposal
system, including both natural and human-initiated processes. The
Department is not required to consider FEPs that have less than one
change in 10,000 of occurring over 10,000 years.
The EPA concluded that the initial FEP list assembled by DOE was
sufficiently comprehensive, in accordance with Secs. 194.32(a) and
(e)(1). Based on quantitative and qualitative assessments provided in
the CCA and supporting documents, EPA concluded that DOE appropriately
rejected those FEPs that exhibit low probability of occurrence during
the regulatory period,
[[Page 27385]]
in accordance with Sec. 194.32(d). In addition, EPA found DOE's
inclusion of various scenarios in the PA to be reasonable and
justified, and meets the requirement of Sec. 194.32(e)(2). The DOE
provided documentation and justification for eliminating those FEPs
that were not included in the PA. In some cases (e.g., fluid injection,
CO2 injection, potash mining and dissolution), the CCA did
not initially provide adequate justification or convincing arguments to
eliminate FEPs from consideration in the PA. However, DOE provided
supplemental information and analyses, which EPA determined was
sufficient to demonstrate compliance with Sec. 194.32(e)(3).
The EPA verified, through review of the CCA and supporting
documents, that DOE included, in the PA, appropriate changes in the
hydraulic conductivity values for the areas affected by mining. The
area considered to be mined for potash in the controlled area is
consistent with the requirement of Sec. 194.32(b), that the mined area
be based on mineral deposits of those resources currently extracted
from the Delaware Basin. Thus, EPA finds that DOE complies with
Sec. 194.32(b).
In accordance with Sec. 194.32(c), DOE considered the possibility
of fluid injection, identified oil and gas exploration and
exploitation, and water and potash exploration as the only near future
human-initiated activities that need to be considered in the PA. The
EPA's review of the CCA and supporting documents referenced in the CCA
with respect to Sec. 194.32(c), indicated that DOE adequately analyzed
the possible effects of current and future potential activities on the
disposal system. In response to concerns expressed by EPA and
stakeholders, DOE conducted additional analyses and submitted follow-up
information. In addition, EPA has performed its own analysis of fluid
injection. Public comments concerning human intrusion FEPs are
discussed in the preamble sections above titled, ``Fluid injection,''
``Potash mining,'' and ``CO2 injection.'' The collected
information provided by DOE was adequate. Therefore, EPA concludes that
DOE's analysis meets the requirements of Sec. 194.32(c).
Section 194.33 requires DOE to make specific assumptions about
future deep and shallow drilling in the Delaware Basin. The EPA found
that the documentation in the CCA demonstrated that DOE thoroughly
considered deep and shallow drilling activities and rates within the
Delaware Basin in accordance with Sec. 194.33 (a) and (b). The EPA
found that DOE appropriately screened out shallow drilling from
consideration in the PA. The EPA also found that DOE appropriately
incorporated the assumptions and calculations for drilling into the PA
as stipulated in Secs. 194.33 (b) and (c). In accordance with
Sec. 194.33(c), DOE evaluated the consequences of drilling events
assuming that drilling practices and technology remain consistent with
practices in the Delaware Basin at the time the certification
application was prepared. Public comments concerning this issue are
discussed in the preamble section above titled, ``Air drilling.'' The
EPA determined that the PA models did not incorporate the effects of
techniques used for resource recovery, as allowed by Sec. 194.33(d).
The EPA further concludes that the drilling information in the CCA is
consistent with available data. Therefore, the Agency finds DOE in
compliance with the requirements of Sec. 194.33.
Section 194.34 of the compliance criteria provides specific
requirements for presenting the results of the PA for the WIPP. Section
194.34 requires DOE to use complementary cumulative distribution
functions (``CCDFs'') to express the results of the PA. The Department
also must document the development of probability distributions, and
the computational techniques used for drawing random samples from these
probability distributions, for any uncertain parameters used in the PA.
The PA must include a statistically sufficient number of CCDFs. The CCA
must display the full range of CCDFs generated. Finally, the CCA must
demonstrate that the mean of the population of CCDFs meets the
containment requirements of Sec. 191.13 with at least a 95 percent
level of statistical confidence.
The CCA presented the results of the PA in the form of CCDFs. The
PA used Latin Hypercube Sampling to sample values randomly from
probability distributions of uncertain parameters. Parameter values and
their distributions were documented in the CCA and in Sandia National
Laboratory's Records Center. The CCA presented the full range of the
300 CCDFs generated in the PA, as well as mean CCDF curves. The CCDFs
showed that the mean CCDF curve met the containment requirements of
Sec. 191.13. Less than one percent of CCDF curves in the CCA PA
exceeded one times the release limit, and no CCDF curves exceeded ten
times the release limit. Based on these results, DOE concluded that the
WIPP met EPA's requirements.
The EPA also examined the results of the PAVT in light of the
requirements of Sec. 194.34. The PAVT presented the results of the PA
in CCDFs, and presented the complement of 300 CCDFs. DOE's
documentation and EPA's separate analysis demonstrated that 300 CCDFs
are sufficient, statistically speaking. The PAVT used the same random
sampling technique of Latin Hypercube Sampling that the PA model used
for the CCA PA. The DOE used parameter values assigned by EPA, as well
as other parameter values and their distributions documented earlier
for the CCA PA. The mean CCDF curve for the PAVT showed that releases
were roughly three times those calculated in the CCA PA, but releases
still met the containment requirements of Sec. 191.13 by more than an
order of magnitude at the required statistical confidence level. Less
than ten percent of CCDF curves in the PAVT exceeded one times the
release limit, and no CCDF curves exceeded ten times the release limit.
The PAVT confirmed that the CCA PA was adequate for determining
compliance. Therefore, EPA concludes that the CCA PA meets EPA's
containment requirements and that DOE complies with the requirements of
Sec. 194.34.
C. General Requirements
1. Quality Assurance (Sec. 194.22)
Section 194.22 establishes quality assurance (``QA'') requirements
for the WIPP. QA is a process for enhancing the reliability of
technical data and analyses underlying DOE's CCA. Section 194.22
requires DOE to (a) establish and execute a QA program for all items
and activities important to the containment of waste in the disposal
system, (b) qualify data that were collected prior to implementation of
the required QA program, (c) assess data for their quality
characteristics, to the extent practicable, (d) demonstrate how data
are qualified for their use, and (e) allow verification of the above
measures through EPA inspections/audits. The DOE's QA program must
adhere to specific Nuclear Quality Assurance (``NQA'') standards issued
by the American Society of Mechanical Engineers (``ASME'').
The EPA assessed compliance with the QA requirements in two ways.
First, EPA reviewed general QA information submitted by DOE in the CCA
and reference documents. The EPA's second level of review consisted of
visits to the WIPP site, as well as WIPP-related facilities, to perform
independent audits and inspections to verify DOE's compliance with the
QA requirements. The proper establishment and execution of a QA program
is verified strictly by way of inspections and audits.
[[Page 27386]]
Therefore, EPA conducted audits to verify the proper execution of the
QA program at DOE's Carlsbad Area Office (``CAO''), Sandia National
Laboratories (``SNL''), and Westinghouse's Waste Isolation Division
(``WID'') at the WIPP facility. The EPA auditors observed WIPP QA
activities, interviewed WIPP personnel, and reviewed voluminous records
required by the NQA standards, but not required to be submitted as part
of the CCA.
Section 194.22(a)(1) requires DOE to adhere to a QA program that
implements the requirements of the following: (1) ASME NQA-1-1989
edition; (2) ASME NQA-2a-1990 addenda, part 2.7, to ASME NQA-2-1989
edition; and (3) ASME NQA-3-1989 edition (excluding Section 2.1 (b) and
(c), and Section 17.1). The EPA verified that DOE established these
requirements in the Quality Assurance Program Document (``QAPD'')
contained in the CCA. The QAPD is the documented QA program plan for
the WIPP project, as a whole, to comply with the NQA requirements. The
QAPD is implemented by DOE's CAO, which has the authority to audit all
other organizations associated with waste disposal at the WIPP (such as
WID, SNL and waste generator sites) to ensure that their lower-tier QA
programs establish and implement the applicable requirements of the
QAPD. The EPA audited DOE's QA program at CAO and determined that DOE
properly adhered to a QA program that implements the NQA standards.
Therefore, EPA finds DOE in compliance with Sec. 194.22(a)(1).
Section 194.22(a)(2) requires DOE to include information in the CCA
that demonstrates that the requisite QA program has been ``established
and executed'' for a number of specific activities. Section
194.22(a)(2)(i) requires DOE to include information which demonstrates
that the QA program has been established and executed for waste
characterization activities and assumptions. In the CCA, DOE provided
the QAPD, which is DOE's central QA document program plan that then
must be incorporated into site-specific QA program plans. The DOE
generator sites will prepare site certification Quality Assurance Plans
(``QAPs'') that, together with Quality Assurance Project Plans
(``QAPjPs''), will constitute site-specific QA program
plans.30 The EPA finds that the QAPD, as it applies to waste
characterization, is in conformance with the NQA requirements and that
DOE's QA organization can properly perform audits to internally check
the QA programs of the waste generator sites. However, as discussed
below, the Agency will verify the establishment and execution of site-
specific QA programs.
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\30\ NQA-1 (Element II-2) requires that organizations
responsible for activities affecting quality (in the case of the
WIPP, affecting the containment of waste in the disposal system)
must have documented QA programs in accordance with the applicable
NQA requirements. The documentation for such programs is commonly
referred to as a ``quality assurance program plan,'' or ``QAPP.''
For WIPP waste generator sites, the role of the QAPP is fulfilled by
documents with other titles, such as the QAP and the QAPjP. The
``TRU QAPP'' referenced by DOE in the CCA is not a QAPP as described
by the NQA standards; rather, it is a technical document that
describes the quality control requirements and performance standards
for characterization of TRU waste coming to the WIPP facility. The
TRU QAPP is addressed more specifically in the preamble discussion
of Sec. 194.24, Waste Characterization.
---------------------------------------------------------------------------
The compliance criteria require that QA programs be established and
executed specifically with respect to the use of process knowledge and
a system of controls for waste characterization. (Secs. 194.22(a)(2)(i)
and 194.24(c)(3) through (5)) To accomplish this, waste generator site-
specific QA programs and plans must be individually examined and
approved by EPA to ensure adequate QA programs are in place before EPA
allows individual waste generator sites to transport waste for disposal
at the WIPP. Since waste characterization activities have not begun for
most TRU waste generator sites and storage facilities, EPA has not yet
evaluated the compliance of many site-specific QA plans and programs.
To date, one WIPP waste generator site, Los Alamos National
Laboratory (``LANL''), has been approved by EPA to have established an
adequate QA program plan and to have properly executed its QA program
in accordance with the plan. Prior to approval of LANL's site-specific
QA program, EPA conducted an audit of DOE's overall WIPP QA program and
approved its capability to perform audits in accordance with the
requirements of NQA-1. The EPA then inspected three DOE audits of
LANL's QA program. Based on the results of the inspections, the EPA
inspectors determined that the QA program had been properly executed at
LANL.31 Therefore, EPA finds that the requirements of
Sec. 194.22(a)(2)(i) have been met for waste characterization
activities at LANL.
---------------------------------------------------------------------------
\31\ The terms ``audits'' and ``inspections'' are not
synonymous. At waste generator sites, EPA may either conduct its own
audits or inspect audits conducted by DOE. (The DOE-CAO conducts
audits to evaluate waste characterization programs at waste
generator sites.) The difference is that for an inspection, EPA's
role is to review DOE's QA checks, and not actually conduct all of
the checks itself.
---------------------------------------------------------------------------
With respect to other waste generator sites, EPA will verify
compliance with Sec. 194.22(a)(2)(i) conditioned on separate,
subsequent approvals from EPA that site-specific QA programs for waste
characterization activities and assumptions have been established and
executed in accordance with applicable NQA requirements at each waste
generator site.
As waste generator facilities establish QA programs after LANL, EPA
will assess their compliance with NQA requirements. The approval
process for site-specific QA programs includes a Federal Register
notice, public comment period, and on-site EPA audits or inspections to
evaluate implementation. For further information on EPA's approval
process, see Condition 2 and Sec. 194.8. For further discussion of
waste characterization programs and approval of the processes used to
characterize waste streams from generator sites, see the discussion of
Sec. 194.24 below in this preamble.
Section 194.22(a)(2)(ii) requires DOE to include information which
demonstrates that the QA program has been established and executed for
environmental monitoring, monitoring of performance of the disposal
system and sampling and analysis activities. Westinghouse's WID was
responsible for establishing this requirement under the WID QAPD
described in the CCA. The EPA conducted an audit of the WID and found
that the requisite QA program had been established and executed for
environmental monitoring, sampling and analysis activities. The EPA
also finds that Chapter 5 of the CCA and referenced documents contain a
satisfactory description of compliance with this section. Therefore,
EPA finds the WIPP in compliance with Sec. 194.22(a)(2)(ii).
Section 194.22(a)(2)(iii) requires DOE to include information which
demonstrates that the QA program has been established and executed for
field measurements of geologic factors, ground water, meteorologic, and
topographic characteristics. WID is responsible for conducting field
measurements of geologic factors, ground water, meteorologic and
topographic characteristics. The EPA conducted an audit of the WID QA
program and found it to be properly established and executed in
accordance with the applicable NQA requirements. The EPA also finds
that Chapter 5 of the CCA and referenced documents contain a
satisfactory description of compliance with this section. Therefore,
EPA finds DOE in compliance with Sec. 194.22(a)(2)(iii).
[[Page 27387]]
Section 194.22(a)(2)(iv) requires DOE to include information to
demonstrate that the QA program has been established and executed for
computations, computer codes, models and methods used to demonstrate
compliance with the disposal regulations. SNL and WID are responsible
for computations and software items. The EPA reviewed information in
the CCA and conducted audits of both SNL and WID QA programs. The
Agency found that computer codes were documented in a manner that
complies with the applicable NQA requirements, and that software QA
procedures were implemented in accordance with ASME NQA-2a, part 2.7.
The EPA also finds that Chapter 5 of the CCA and referenced documents
contain a satisfactory description of compliance with this section. The
EPA therefore finds that DOE complies with Sec. 194.22(a)(2)(iv).
Section 194.22(a)(2)(v) requires DOE to include information which
demonstrates that the QA program has been established and executed for
procedures for implementation of expert judgment elicitation. CAO and
CAO's Technical Assistance Contractor were responsible for developing
the procedures for the expert elicitation that was conducted (after the
publication of the CCA). The EPA found that the requirements of this
regulation were met by the development and implementation of CAO Team
Procedure 10.6 (Revision 0), CAO Team Plan for Expert Panel Elicitation
(Revision 2), and CAO Technical Assistance Contractor Experimental
Programs Desktop Instruction No.1 (Revision 1). The EPA finds DOE in
compliance with Sec. 194.22(a)(2)(v). The process of expert judgment
elicitation is discussed in further detail in the section of this
preamble related to Sec. 194.26 of the compliance criteria.
Section 194.22(a)(2)(vi) requires DOE to include information which
demonstrates that the QA program has been established and executed for
design of the disposal system and actions taken to ensure compliance
with the design specifications. Most of the WIPP's design was conducted
before the EPA required a QA program. Design work for the repository
sealing system was conducted under the SNL QA program. The QA
procedures established and implemented by SNL and WID address the
requirements of the NQA standards; design verification was accomplished
by a combination of NQA-1 Supplement 3S-1 methods. The EPA audits of
SNL and WID showed that the QA programs are properly established and
executed. The EPA also finds that Chapter 5 of the CCA and referenced
documents contain an adequate description of compliance with this
section. Therefore, EPA finds DOE in compliance with
Sec. 194.22(a)(2)(vi).
Section 194.22(a)(2)(vii) requires DOE to include information which
demonstrates that the QA program has been established and executed for
the collection of data and information used to support compliance
applications. SNL was responsible for this activity. SNL adequately
addressed these requirements by implementing numerous QA procedures to
ensure the quality of data and information collected in support of the
WIPP. The EPA's audit of SNL concluded that the QA program is properly
established and executed. Therefore, EPA finds DOE in compliance with
Sec. 194.22(a)(2)(vii).
Section 194.22(a)(2)(viii) requires DOE to include information
which demonstrates that the QA program has been established for any
other item or activity not listed above that is important to the
containment of waste in the disposal system. The DOE has not identified
any other item or activity important to waste isolation in the disposal
system that require QA controls to be applied as described in the CAO
QAPD. To date, the EPA has also not identified any other items or
activities which require controls. The EPA audits determined that the
QA organizations of CAO, WID, and SNL have sufficient authority, access
to work areas, and organizational freedom to identify other items and
activities affecting the quality of waste isolation. Therefore, EPA
finds DOE in compliance with Sec. 194.22(a)(2)(viii).
Section 194.22(b) requires DOE to include information which
demonstrates that data and information collected prior to the
implementation of the QA program required by Sec. 194.22(a)(1) have
been qualified in accordance with an alternate methodology, approved by
the Administrator or the Administrator's authorized representative,
that employs one or more of the following methods: peer review;
corroborating data; confirmatory testing; or a QA program that is
equivalent in effect to Sec. 194.22(a)(1) ASME documents.
The EPA conducted two audits that traced new and existing data to
their qualifying sources. The two audits found that equivalent QA
programs and peer review had been properly applied to qualify existing
data used in the PA. The EPA also concluded that the use of existing
data from peer-reviewed technical journals was appropriate, since the
level of such reviews was equivalent to NUREG-1297 peer reviews
conducted by DOE. Therefore, EPA finds DOE in compliance with
Sec. 194.22(b). Furthermore, the Agency is approving the use of any one
of the following three methods for qualification of existing data: (1)
peer review, conducted in a manner that is compatible with NUREG-1297;
(2) a QA program that is equivalent in effect to ASME NQA-1-1989
edition, ASME NQA-2a-1990 addenda, part 2.7, to ASME NQA-2-1989
edition, and ASME NQA-3-1989 edition (excluding Section 2.1(b) and (c)
and Section 17.1); or (3) use of data from a peer-reviewed technical
journal.
Sections 194.22(c)(1) through (5) require DOE to provide
information which describes how all data used to support the compliance
application have been assessed, to the extent practicable, for specific
data quality characteristics (``DQCs''). In the CCA, DOE stated that in
most cases it was not practicable to document DQCs for performance
assessments, but asserted that the intent of DQCs was fulfilled by
other QA programs and quality control measures.
The Agency agrees with DOE that it is not appropriate to apply DQCs
retroactively to all of the parameters and existing data used in the
PA, but believes that they can and should be applied to measured data
(i.e., field monitoring and laboratory experiments) as they are
developed and used. The EPA found that, because DOE deemed it
impractical to apply DQCs in some instances, the CCA and supplementary
information did not systematically or adequately address DOE's
consideration of DQCs for measured data related to the PA. Therefore,
EPA reviewed parameter records to determine whether DOE could in fact
show that various data quality characteristics had been considered for
measured data. The Agency reviewed additional materials, primarily data
record packages at the SNL records center, to independently determine
whether DQCs had been assessed for data used in the PA. The EPA found
that for recent data (five to ten years old), DOE's experimental
program plans in the data record packages generally addressed data
quality in measured data, including accuracy, precision,
representativeness, completeness, and comparability during measurement
and collection.
For older existing data, EPA found less documentation of assessment
of DQCs. However, laboratory notebooks'which provide first-hand
documentation of measurement procedures and results'supporting data
[[Page 27388]]
record packages provided some information related to the quality of
measurements (e.g., how well DOE's measured values compared with values
found in peer-reviewed publications). Many existing data were also
subject to peer review in order to qualify them for use in the CCA; EPA
concluded that the peer review panels considered the use of DQCs in
determining that such data were adequate. The EPA also agreed with
DOE's argument in supplementary information that for most of the
existing data, collection under a program equivalent to the NQA
standards in Sec. 194.22(a)(1) provided adequate evidence that the
quality of data had been evaluated and controlled. Finally, EPA
concurred with DOE's conclusion that the uncertainties in measured data
reflected in DQCs have a small effect on compliance certainty, compared
to other uncertainties in the PA (such as extrapolation of processes
over 10,000 years).
The EPA found that data quality received considerable attention
from peer reviewers and Independent Review Teams assembled by DOE, and
was subject to NQA requirements as specified in the Quality Assurance
Program Document (``QAPD''). Section Sec. 194.22(a) requires DOE to
implement NQA-3-1989 in its quality assurance program. NQA-3-1989
states, ``Planning shall establish provisions for data quality
evaluation to assure data generated are valid, comparable, complete,
representative, and of known precision and accuracy.'' This requirement
was satisfactorily incorporated in the QAPD, which is the quality
assurance ``master'' document that establishes QA requirements for all
activities overseen by the DOE Carlsbad Area Office. The EPA determined
by means of audits that DOE adequately implemented the requirements of
the QAPD, and also determined that DOE adequately qualified existing
data in accordance with Section Sec. 194.22(b). (See Docket A-93-02,
Item V-B-2, CARD 22, Sections 22.A.6 and 22.J.5.) Therefore, EPA finds
that DOE's data qualification was sufficiently rigorous to account for
the DQCs identified in the WIPP compliance criteria.
Based on its review of data record packages and the QAPD, the
Agency finds that DOE has assessed DQCs, to the extent practicable, for
data used in the CCA. The EPA thus finds that DOE complies with
Sec. 194.22(c). The Agency expects that DOE will assess DQCs for future
waste characterization and monitoring activities.
Section 194.22(d) requires DOE to provide information which
describes how all data are qualified for use. SNL generated a table
providing information of how all data in the PA were qualified. The EPA
audited the existing QA programs and determined that the data were
qualified for use by independent and qualified personnel in accordance
with NQA requirements. On this basis, EPA finds DOE in compliance with
Sec. 194.22(d).
Section 194.22(e) allows EPA to verify execution of QA programs
through inspections, record reviews, and other measures. As discussed
above, EPA has conducted numerous audits of DOE facilities, and intends
to conduct future inspections of waste generator site-specific QA plans
under its authority. The Agency also intends to conduct inspections or
audits to confirmed DOE's continued adherence to QA requirements for
which EPA is certifying compliance.
In summary, EPA finds DOE in compliance with the requirements of
Sec. 194.22 subject to the condition that EPA separately approve the
establishment and execution of site-specific QA programs for waste
characterization activities at waste generator sites. (See Condition 2
of the proposed Appendix A to 40 CFR Part 194.)
The EPA received many public comments on Sec. 194.22, but the most
significant issue identified by commenters was the lack of objective
evidence in the CCA to justify meeting the requirements at
Sec. 194.22(a)(2). The comments posed the fundamental question of
whether or not EPA could certify, based solely on information provided
by DOE in the CCA, that DOE established and executed a QA program for
the eight areas considered important to the containment of waste in the
disposal system. In response to such concerns, EPA believes it is
necessary to explain and clarify the verification of these QA
requirements.
The CCA does not alone provide all the documentation to verify
compliance with the requirement of Sec. 194.22(a)(2). Section
Sec. 194.22(e) requires EPA to verify that DOE has established and
executed a QA program for the areas indicated in Sec. 194.22(a)(2). The
``objective evidence'' for determining whether or not a QA program has
been established and executed exists at the WIPP-related facilities and
generator sites, and is gathered in the field audits and inspections.
The function of the audits and inspections is to gather objective
evidence to determine compliance of the QA programs with the applicable
NQA standards.
Several WIPP organizations are responsible for establishing and
executing the activities and items listed in the eight areas of
Sec. 194.22(a)(2). The CCA states that DOE provides the overall QA
program requirements for WIPP via the CAO QAPD. The CAO QAPD
requirements are further supported and amplified by the next tier of QA
program documents, which includes the SNL quality assurance procedures
(SNL QAPs), the WID Quality Assurance Program Description, and the
individual site quality assurance program plans (e.g., QAPjPs). More
documentation is found in DOE, WID and SNL implementing procedures and
QA records. For example, ``Corrective Action Reports'' and ``Audit
Reports'' provide objective evidence of implementation of certain NQA
elements. Therefore, EPA finds that sufficient information for
compliance with Sec. 194.22(a)(2)(ii)-(viii), and for QA program
implementation for waste characterization activities at LANL
(Sec. 194.22(a)(2)(i)) was provided in the CCA and supporting documents
to the extent practical.
The EPA verified that QA programs were established in accordance
with Sec. 194.22 through the CAO QAPD and supporting documents. The EPA
expected to find objective evidence of compliance or noncompliance with
the QA requirements within the QA records and activities of the WIPP
organizations, including CAO, SNL, and WID. In accordance with
Sec. 194.22(e), the Agency conducted audits of these WIPP organizations
to verify the appropriate execution of QA programs. (Docket A-93-02;
Items II-A-43, II-A-44, II-A-45, II-A-46, II-A-47, II-A-48, and II-A-
49) Documentation of evidence of audits that verified the execution of
the QA programs is found in EPA's audit reports. The EPA's audits of
CAO, SNL, and WID covered all aspects of the programs including, but
not limited to: the adoption of the requirements of Sec. 194.22 through
the CAO QAPD, quality assurance procedures (``QAPs''), reports from
previous audits, surveillance reports, and corrective action reports
(``CARs''). The audits assessed the adequacy and implementation of the
SNL and WID quality assurance programs in accordance with the
requirements of Sec. 194.22(a)(1). For example, for
Sec. 194.22(a)(2)(iv), the ``computations, computer codes, models and
methods used to demonstrate compliance with the disposal regulations,''
EPA conducted audits of the SNL and WID quality assurance programs for
computations, computer codes, methods and models. For all of the other
areas in Sec. 194.22(a)(2), CARD 22 (Section 22.B) should be consulted
for information and
[[Page 27389]]
citations to audit reports. (Docket A-93-02, Item V-B-2)
In summary, EPA certifies compliance with the eight areas in
Sec. 194.22(a)(2) through inspections and audits. Most of the evidence
demonstrating compliance is found at the WIPP-related facilities and
generator sites. Such evidence was unreasonable to include in the CCA
due to the voluminous nature of the information.
2. Waste Characterization (Sec. 194.24)
Section 194.24, waste characterization, generally requires DOE to
identify, quantify, and track the chemical, radiological and physical
components of the waste destined for disposal at the WIPP that can
influence disposal system performance.
Section 194.24(a) requires DOE to describe the chemical,
radiological and physical composition of all existing and to-be-
generated waste, including a list of waste components and their
approximate quantities in the waste. The DOE provided the required
information on existing waste (35% of the total WIPP inventory) by
combining similar waste streams into waste stream profiles. The waste
stream profiles contain information on the waste material parameters,
or components, that could affect repository performance. For to-be-
generated waste (65% of the total WIPP inventory), DOE extrapolated
information from the existing waste streams to determine the future
amount of waste. The EPA reviewed this information and determined that
DOE's waste stream profiles contained the appropriate specific
information on the components and their approximate quantities in the
waste. Therefore, EPA finds DOE in compliance with Sec. 194.24(a).
Section 194.24(b) requires DOE to analyze waste characteristics and
waste components for their impact on disposal system performance. Waste
components affect waste characteristics and are integral to disposal
system performance. The DOE identified waste-related elements pertinent
to the WIPP as part of its screening for features, events, and
processes. The features, events, and processes used in the performance
assessment (``PA'') served as the basis from which characteristics and
associated components were identified and further analyzed. (For
further information on features, events, and processes, see Docket A-
93-02, Item V-B-2, CARD 32; and the above preamble sections related to
the PA.)
The DOE concluded that six characteristics were expected to have a
significant effect on disposal system performance and were used in the
PA as parameters or in conceptual models: solubility, formation of
colloidal suspensions containing radionuclides, gas generation, shear
strength of waste, radioactivity of specific isotopes, and transuranic
(``TRU'') activity at disposal. The DOE identified eight waste
components influencing the six significant waste characteristics:
ferrous metals, cellulose, radionuclide identification, radioactivity
of isotopes, TRU activity of waste, solid waste components, sulfates,
and nitrates. Finally, DOE provided a list of waste characteristics and
components assessed, but determined not to be significant for various
reasons such as negligible impact on the PA. The EPA found that DOE
used a reasonable methodology to identify and assess waste
characteristics and components. The analysis appropriately accounted
for uncertainty and the quality of available information. Therefore,
EPA finds DOE in compliance with requirements in Sec. 194.24(b).
Section 194.24(c)(1) requires DOE to specify numeric limits on
significant waste components and demonstrate that, for those component
limits, the WIPP complies with the numeric requirements of Secs. 194.34
and 194.55. Either upper or lower limits were established for
components that must be controlled to ensure that the PA results comply
with the containment requirements. The DOE explicitly included numeric
limits, identified as fixed values with no associated uncertainty, for
four waste components. Lower limits were established for (1) ferrous
and (2) non-ferrous metals (not included in DOE's original list of
components, but added later due to its binding effect on organic
ligands); upper limits were established for (3) cellulosics and (4)
free water (not included in DOE's original list of components, but
added later due to its inclusion in the Waste Acceptance Criteria).
The three components related to radioactivity (radionuclide
identification, radioactivity of isotopes, TRU activity of waste) were
effectively limited by the inventory estimates used in the PA and the
WIPP LWA fixed-value limits. Both the PA inventory estimates and the
WIPP LWA fixed-value limits were included in the PA calculations
through parameters closely related to these components, and the results
demonstrated compliance with EPA's standards.
Explicit limits were not identified for solid waste, sulfates, and
nitrates, even though DOE identified these as components significant to
performance. For solid waste, EPA determined that in the PA, DOE took
no credit for the potential gas-reducing effects of solid waste (i.e.,
assumed a lower limit of zero) and demonstrated that the WIPP would
still comply. For nitrates and sulfates, EPA determined that these
components would not significantly affect the behavior of the disposal
system as long as cellulosics were limited. Thus, EPA concurred that it
is unnecessary to specify limits for nitrates, sulfates, and solid
waste.
The EPA finds DOE in compliance with Sec. 194.24(c)(1). The EPA
concurred with DOE that it was not necessary to provide estimates of
uncertainty for waste limits, so long as the PA demonstrated compliance
at the fixed limits. However, since DOE's waste limits do not address
uncertainty, the Department must account for uncertainty in the
quantification of waste components when tracking compliance with the
waste limits. That is, the fixed waste limits essentially constitute an
upper confidence level (in the case of limits on the maximum amount of
a waste component) or a lower confidence level (in the case of limits
on the minimum amount of a component) for measurements or estimates of
waste components that must be tracked. The DOE must demonstrate that
the characterized waste components, including associated uncertainty
(i.e., margin of error), meet the fixed waste component limits.
Section 194.24(c)(2) requires DOE to identify and describe the
methods used to quantify the limits of important waste components
identified in Sec. 194.24(b)(2). The DOE proposed to use non-
destructive assay (``NDA''), non-destructive examination (``NDE''), and
visual examination (``VE'') as the methods used to quantify various
waste components. (See Docket A-93-02, Item V-B-2, CARD 24, Section
24.F.1 for further information about the methods.) The DOE described
numerous NDA instrument systems and described the equipment and
instrumentation found in NDE and VE facilities. The DOE also provided
information about performance demonstration programs intended to show
that data obtained by each method could meet data quality objectives
established by DOE. The EPA found that these methods, when implemented
appropriately, would be adequate to characterize the important waste
components. Therefore, EPA finds DOE in compliance with
Sec. 194.24(c)(2).
Section 194.24(c)(3) requires DOE to demonstrate that the use of
process
[[Page 27390]]
knowledge 32 to quantify components in waste for disposal
conforms with the quality assurance (``QA'') requirements found in
Sec. 194.22. The DOE did not submit site-specific information on the
process knowledge to be used at waste generator sites as part of the
CCA. The EPA requires such information to conduct proper review of
whether use of the process knowledge is appropriate and reliable. The
DOE provided some information on its overall plans for using process
knowledge in the CCA. The DOE did not, however, provide specific
information on the use of process knowledge or Acceptable Knowledge
(``AK''--hereafter only ``AK'' is used; process knowledge is a subset
of acceptable knowledge) at any waste generator site in the CCA, nor
did it provide information demonstrating establishment of the required
QA programs.
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\32\ Process knowledge refers to knowledge of waste
characteristics derived from information on the materials or
processes used to generate the waste. This information may include
administrative, procurement, and quality control documentation
associated with the generating process, or past sampling and
analytic data. Usually, the major elements of process knowledge
include information about the process used to generate the waste,
material inputs to the process, and the time period during which the
waste was generated.
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After submission of the CCA, EPA subsequently received information
regarding AK to be used at the Los Alamos National Laboratory
(``LANL''). The EPA determined that DOE adequately described the use of
AK for legacy debris waste at LANL. The EPA has confirmed establishment
and execution of the required QA programs at that waste generator site
through inspections. Therefore, EPA finds that DOE has demonstrated
compliance with the Sec. 194.24(c)(3) QA requirement for LANL. The EPA
does not find, however, that DOE has adequately described the use of AK
for any waste at LANL other than the legacy debris waste which can be
characterized using the processes examined in EPA's inspection. (See
Docket A-93-02, Item V-B-15 for further information on the conclusions
of EPA's inspection. See Docket A-93-02, Item II-I-70 for a list of the
items and processes inspected by EPA.) Furthermore, DOE has not
demonstrated compliance with Sec. 194.24(c)(3) for any other waste
generator site. For any LANL waste streams using other characterization
processes or any other waste generator site, before waste can be
shipped to the WIPP, EPA must determine that the site has provided
information on how AK will be used for waste characterization of the
waste stream(s) proposed for disposal at the WIPP. Condition 3 of the
final rule embodies this limitation. The site-specific use of process
knowledge must conform with QA requirements, as addressed by Condition
2. (For further information on EPA's approval process, see Sec. 194.8,
``Approval Process for Waste Shipment from Waste Generator Sites for
Disposal at the WIPP.'')
Sections 194.24(c) (4) and (5) require DOE to demonstrate that a
system of controls has been and will continue to be implemented to
confirm that the waste components emplaced in the WIPP will not exceed
the upper limit or fall below the lower limit calculated in accordance
with Sec. 194.24(c)(1) and that the system of controls conforms to the
QA requirements specified in Sec. 194.22. The DOE described a system of
controls over waste characterization activities, such as the
requirements of the TRU QA Program Plan (``TRU QAPP'') and the Waste
Acceptance Criteria (``WAC''). The EPA found that the TRU QAPP
established appropriate technical quality control and performance
standards for sites to use in developing site-specific sampling plans.
Further, DOE outlined two phases in waste characterization controls:
(1) waste stream screening/verification (pre-shipment from waste
generator site); and (2) waste shipment screening/verification (pre-
receipt of waste at the WIPP). The tracking system for waste components
against their upper and/or lower limits is found in the WIPP Waste
Information System (``WWIS''). The EPA finds that the TRU QAPP, WAC,
and WWIS are adequate to control important components of waste emplaced
in the WIPP. The EPA audited DOE's QA programs at Carlsbad Area Office,
Sandia National Laboratory and Westinghouse Waste Isolation Division
and determined that DOE properly adhered to QA programs that implement
the applicable Nuclear Quality Assurance standards and requirements.
(See the preamble discussion of Sec. 194.22, Quality Assurance, for
further information.) However, in the CCA, DOE did not demonstrate that
the WWIS is fully functional and did not provide information regarding
the specific system of controls to be used at individual waste
generator sites.
After submission of the CCA, EPA subsequently received information
regarding the system of controls (including measurement techniques) to
be used at LANL. The Agency confirmed through inspections that the
system of controls--and in particular, the measurement techniques--is
adequate to characterize waste and ensure compliance with the limits on
waste components for some waste streams, and also confirmed that a QA
program had been established and executed at LANL in conformance with
Nuclear Quality Assurance requirements. Moreover, DOE demonstrated that
the WWIS is functional with respect to LANL--i.e., that procedures are
in place at LANL for adding information to the WWIS system, that
information can be transmitted from LANL and incorporated into the
central database, and that data in the WWIS database can be compiled to
produce the types of reports described in the CCA for tracking
compliance with the waste limits. At the same time, DOE demonstrated
that the WWIS is functional with respect to the WIPP facility--i.e.,
that information incorporated into the central database can be
retrieved at the WIPP and compiled to produce reports for tracking
compliance with the waste limits. Therefore, EPA finds DOE in
compliance with Secs. 194.24(c)(4) and (5) for legacy debris waste at
LANL. (Docket A-93-02, Items V-B-15 and V-B-2, CARD 24) The EPA's
decision is limited to the waste that can be characterized using the
systems and processes audited by DOE, inspected by EPA, and found to be
adequately implemented at LANL.33 The EPA does not find,
however, that DOE has demonstrated compliance with Sec. 194.24(c)(4)
for any other waste stream at LANL, or with Secs. 194.24(c)(4) and (5)
at any other waste generator site.
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\33\ See Docket A-93-02, Item II-I-70 for a list of the systems
and processes audited by DOE. See Docket A-93-02, Item II-I-51 for a
description of the waste identifier and a discussion of the items
and activities inspected by EPA. They include characterization
methodologies and relevant procedures, such as that used for
entering data into the WWIS database.
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For any LANL waste streams using other characterization processes
or any other waste generator site, before waste can be shipped to the
WIPP, EPA must determine that the site has implemented a system of
controls at the site, in accordance with Sec. 194.24(c)(4), to confirm
that the total amount of each waste component that will be emplaced in
the disposal system will not exceed the upper limiting value or fall
below the lower limiting value described in the introductory text of
paragraph (c) of Sec. 194.24. The implementation of such a system of
controls shall include a demonstration that the site has procedures in
place for adding data to the WWIS, and that such information can be
transmitted from that site to the WWIS database; and a demonstration
that measurement techniques and control methods can be implemented in
accordance with Sec. 194.24(c)(4) for the
[[Page 27391]]
waste stream(s) proposed for disposal at the WIPP. Condition 3
prohibits DOE from shipping waste for disposal at WIPP until EPA has
approved site-specific waste characterization programs and controls.
The system of controls must also be implemented in accordance with the
QA requirements of 40 CFR 194; see Condition 2. (For further
information on EPA's approval process, see Sec. 194.8, ``Approval
Process for Waste Shipment from Waste Generator Sites for Disposal at
the WIPP.'')
Section 194.24(d) requires DOE either to include a waste loading
scheme which conforms to the waste loading conditions used in the PA
and in compliance assessments, or to assume random placement of waste
in the disposal system. The DOE elected to assume that radioactive
waste would be emplaced in the WIPP in a random fashion. The DOE
examined the possible effects of waste loading configurations on
repository performance (specifically, releases from human intrusion
scenarios) and concluded that the waste loading scheme would not affect
releases. The DOE incorporated the assumption of random waste loading
in its performance and compliance assessments (pursuant to Secs. 194.32
and 194.54, respectively).
The EPA determined that, because the DOE had assumed random waste
loading, a final waste loading plan was unnecessary. The EPA determined
that, in the PA, DOE accurately modeled random placement of waste in
the disposal system. Since EPA concurred with DOE that a final waste
loading plan was unnecessary, DOE does not have to further comply with
Sec. 194.24(f), requiring DOE to conform with the waste loading
conditions, if any, used in the PA and compliance assessment.
Therefore, EPA finds that DOE complies with Secs. 194.24(d) and (f).
Section 194.24(e) prohibits DOE from emplacing waste in the WIPP if
its disposal would cause the waste component limits to be exceeded.
Section 194.24(g) requires DOE to demonstrate that the total inventory
emplaced in the WIPP will not exceed limitations on TRU waste described
in the WIPP LWA. Specifically, the WIPP LWA defines limits for: surface
dose rate for remote-handled (``RH'') TRU waste, total amount (in
curies) of RH-TRU waste, and total capacity (by volume) of TRU waste to
be disposed. (WIPP LWA, Section (7)(a)) In order to meet the
Secs. 194.24(e) and (g) limits, DOE intends to rely on the TRU QAPP,
WAC, and a two-phase system of controls for waste characterization--
pre-shipment (at waste generator sites) and pre-receipt (at the WIPP).
The DOE stated that the WWIS will be used to track specific data
related to each of the WIPP LWA limits; by generating routine WWIS
reports, DOE will be able to determine compliance with the imposed
limits. The WWIS will also be used to track information on each of the
important waste components for which limits were established. The EPA
finds that the WWIS is adequate to track adherence to the limits, and
that the WWIS has been demonstrated to be fully functional at the WIPP
facility; as discussed above, waste generator sites will demonstrate
WWIS procedures before they can ship waste for disposal at the WIPP.
Therefore, EPA finds DOE in compliance with Secs. 194.24(e) and (g).
Section 194.24(h) allows EPA to conduct inspections and record
reviews to verify compliance with the waste characterization
requirements. As discussed above, EPA intends to monitor execution of
waste characterization and QA programs at waste generator sites through
inspections and record reviews.
In summary, EPA finds that DOE is in compliance with Sec. 194.24,
and that LANL has demonstrated compliance with Secs. 194.24(c)(3)
through (5) for legacy debris waste and may therefore ship TRU waste
for disposal at the WIPP (as such shipments relate solely to compliance
with EPA's disposal regulations; other applicable requirements or
regulations still may need to be fulfilled before disposal may
commence). The EPA's final determination of compliance is limited to
the EPA's decision is limited to the legacy debris waste that can be
characterized using the systems and processes audited by DOE, inspected
by EPA, and found to be adequately implemented at LANL. It is important
to note that EPA's LANL approval does not imply that DOE's internal
certification processes can substitute for EPA's approval of waste
generator sites or processes used to characterize waste stream(s)--
including QA measures, use of process knowledge, and the system of
controls (other than LANL's legacy debris waste approved in today's
action). The EPA will inspect the individual certification process for
each waste generator site and for one or more waste stream(s). (For
further information on EPA's approval process, see Sec. 194.8,
``Approval Process for Waste Shipment from Waste Generator Sites for
Disposal at the WIPP.'')
The DOE may not ship other waste streams for emplacement at the
WIPP until EPA determines that (1) DOE has provided adequate
information on how process knowledge will be incorporated into waste
characterization activities for a particular waste stream (or group of
waste streams) at a generator site, and (2) DOE has demonstrated that
the system of controls described in Sec. 194.24(c)(4) and (5) has been
established for the site. In particular, DOE must demonstrate that the
WWIS system is functional for any waste generator site before waste may
be shipped, and that the system of controls (including measurement
techniques) can be implemented for each waste stream which DOE plans to
dispose in the WIPP. As discussed in the preamble for Sec. 194.22, DOE
must also demonstrate that sites have established and executed the
requisite QA programs described in Secs. 194.22(a)(2)(i) and
194.24(c)(3) and (5).
The EPA received many public comments on Sec. 194.24. The majority
of the comments focused primarily on whether or not DOE could
adequately characterize waste to be sent to the WIPP. In response to
such concerns, EPA believes it is useful to explain and clarify the
general process of waste characterization as required by Sec. 194.24,
and to describe the activities EPA expects to monitor for future waste
characterization. First, Sec. 194.24(a) requires DOE to describe the
chemical, radiological, and physical composition of the wastes to be
emplaced in the WIPP. Second, DOE must conduct an analysis that
substantiates that: (1) all characteristics of the wastes which may
influence containment in the repository have been identified and
assessed (Sec. 194.24(b)(1)); (2) all components of the wastes which
influence such waste characteristics have been identified and assessed
(Sec. 194.24(b)(2)); and (3) any decision not to consider a waste
characteristic or component on the basis that it will not significantly
influence containment of the waste. (Sec. 194.24(b)(3)) Third, for each
waste component identified as being significant, DOE is to specify a
``limiting value'' of the total inventory of such waste components to
be emplaced in the repository. (Sec. 194.24(c)) Fourth, DOE must
demonstrate that, for the total inventory of waste proposed to be
emplaced in the disposal system, the WIPP will comply with the numeric
requirements of Secs. 194.34 and 194.55 for the upper and lower
limiting values of the identified waste components. (Sec. 194.24(c)(1))
Fifth, DOE must identify and describe the methods used to quantify the
limits of waste components. (Sec. 194.24(c)(2))
At this point, Sec. 194.24 imposes requirements that shift the
focus from information on, and assessment of, the total waste inventory
to procedures for
[[Page 27392]]
characterization of the waste at individual waste generator sites and
accurate assessment of the waste inventory. First, DOE must show that
the AK used to quantify the waste components at the waste generator
sites will conform with QA requirements of Sec. 194.22. Then, to ensure
that the generator sites ship only waste that conforms with the waste
component limits, a system of controls must be implemented that tracks
and measures the waste components destined for the WIPP. This system of
controls must also comply with the QA requirements of Sec. 194.22.
The approval process for site-specific waste characterization
controls and QA programs includes a Federal Register notice, public
comment period, and on-site EPA audits or inspections to evaluate
implementation. (See Condition 2, Condition 3, and Sec. 194.8.) Prior
to an EPA audit or inspection, EPA expects to receive certain documents
from DOE. To determine that the procedures used to characterize waste
(e.g., measuring and testing, sample control, equipment assessments)
are based on good technical practices, and the personnel are qualified
to perform the task, EPA expects to receive the following general
documents which conform with the requirements of Sec. 194.22: Site-
Specific Quality Assurance Program Plan (``QAPP'') and a report or
reports from CAO's QA organization that verifies the establishment and
implementation of the Nuclear Quality Assurance requirements identified
in Sec. 194.22.
Likewise, DOE will provide technical documents prior to an audit or
inspection to verify the methods for characterizing, quantifying, and
tracking waste. Such technical documents will include information on
the use of both process knowledge and measurement methods for waste
characterization. First, for measurement equipment such as NDA, NDE,
and VE, DOE may provide information on measuring and testing, equipment
assessments, sample control, data documentation, and software control.
For AK, DOE may provide the AK package which provides information on
the areas and buildings from which the waste stream was generated, the
waste stream volume and time period of generation, the waste generating
process described for each building, the process flow diagrams, and the
material inputs or other information that identifies the chemical and
radionuclide content of the waste stream and the physical waste form.
In addition, the following supplemental information may be provided for
AK records: process design documents, standard operating procedures,
preliminary and final safety analysis reports and technical safety
requirements, waste packaging logs, site databases, information from
site personnel, standard industry information, previous analytical data
relevant to the waste stream, material safety data sheets or other
packaging information, sampling and analysis data from comparable or
surrogate waste streams, and laboratory notebooks that detail the
research processes and raw materials used in experiments.
The fundamental objective of EPA's review of DOE's waste
characterization at waste generator sites is to ensure that the
proposed system of controls can quantify and track both the
radionuclides and the four waste component limits identified as
important for the repository performance. Because DOE's defense
missions varied at the sites, the waste generated and the methods to
characterize waste vary accordingly. These variations in practices and
methods result in the need to review two general areas: (1) AK packages
and (2) the system of controls, including measurement methods and
tracking procedures. Therefore, EPA finds that it is important to
clarify what is entailed by both general areas.
Thirty-five percent of WIPP waste is currently classified as
``retrievably stored waste,'' which is TRU waste generated after the
1970's but before the implementation of the TRU Waste Characterization
Quality Assurance Program Plan (``QAPP''). Retrievably stored waste
containers will be classified into waste streams using acceptable
knowledge.34 All retrievably stored waste containers will be
examined using radiography or visual examination to confirm the
physical waste form (or ``Summary Category Group''), to verify the
absence of prohibited items, and to determine the waste
characterization techniques to be used. To confirm the results of
radiography, a statistically selected number of the Contact-Handled
Transuranic waste container population will be visually examined by
opening the containers to inspect waste contents to verify the
radiography results. If visual examination results for a drum conflict
with the results of radiography, the drum and possibly the entire waste
stream is reclassified, and a higher percentage of future drums will be
required to undergo visual examination. Representativeness of
containers selected for visual examination will be validated by
reviewing documents that show that true random samples were collected.
Repackaged retrievably stored waste may be handled as newly generated
waste, with the Summary Category Group confirmed by using visual
examination instead of radiography. Retrievably stored waste will be
assayed using Non Destructive Assay (``NDA'') 35, and will
undergo headspace-gas sampling and analysis for volatile organic
compound concentrations.36
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\34\ AK is used by DOE to (1) delineate waste streams to
facilitate further characterization; (2) identify radionuclide
content as a basis for further radioassay (``NDA'') determinations,
and identify the combustible and metal content to determine the
radionuclide content as a basis for radiography and/or visual
examination (``NDE/VE''); and (3) make hazardous waste
determinations for wastes regulated under the Resource Conservation
and Recovery Act.
\35\ All waste containers will undergo NDA techniques to allow
an item to be tested without altering its physical or chemical form.
NDA techniques approved for use on WIPP containers can be classified
as active or passive. Passive NDA methods measure spontaneously
emitted radiations produced through radioactive decay of isotopes
inside the waste containers. Active NDA methods measure radiations
produced by artificially generated reactions in waste material.
\36\ Results of head-space gas sampling and chemical analyses
are compared with acceptable knowledge determinations to assess the
accuracy of acceptable knowledge. Additional analysis of head-space
gas for volatile organic compounds, and additional use of NDA,
radiography, and other characterization methods may be employed to
further characterize waste to meet regulations that apply to the
hazardous (but not necessarily radioactive) portions of the WIPP
waste. The requirements for hazardous waste are enforced by the
State of New Mexico.
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Sixty-five percent of all WIPP waste is to-be-generated TRU waste.
To-be-generated waste characterization will begin with verification
that processes generating the waste have operated within established
written procedures. Waste containers will be classified into waste
streams using acceptable knowledge. Hazardous and radioactive
constituents in to-be-generated wastes will be documented and verified
at the time of generation to provide acceptable knowledge for the waste
stream.
Verifying that the physical form of the waste (Summary Category
Group) corresponds to the physical form of the assigned waste stream is
accomplished by visual examination during packaging of the waste into
the drums. This process consists of operator confirmation that the
waste is assigned to a waste stream that has the correct Summary
Category Group for the waste being packaged into the drums. If
confirmation cannot be made, corrective actions will be taken. A second
operator, who is equally trained to the requirements of the WAC and TRU
Waste Characterization QAPP, will provide additional verification by
reviewing the contents of the waste
[[Page 27393]]
container to ensure correct reporting. If the second operator cannot
provide concurrence, corrective actions will be taken. To-be-generated
waste will not undergo radiography, as the waste will be identified by
visual examination during packaging. All to-be-generated waste
containers will undergo headspace-gas analysis for volatile organic
compound and their concentrations, and NDA for radioisotopes and their
activities.
Acceptable knowledge, visual examination during packing, NDA and
headspace-gas sampling and analysis are used to further characterize
homogeneous solids, soils/gravel, and debris waste. In addition, newly
generated streams of such wastes will be randomly sampled a minimum of
once per year and analyzed for total volatile and semi-volatile organic
compounds and metals.
A system of controls is used to confirm that the total amount of
each waste component that will be emplaced in the disposal system does
not exceed the upper limiting value or fall below the lower limiting
value for the component. The system of controls for WIPP waste has two
phases for DOE's internal process. Phase I entails Waste Stream
Screening and Verification, which will occur before waste is shipped to
the WIPP, and is a three-step process. First, an initial audit of the
site will be conducted by DOE's Carlsbad Area Office as part its audit
program before the WIPP could begin the process of accepting waste from
a site. The audit provides on-site verification of characterization
procedures, data package preparation and recordkeeping. Second, the
generator site personnel perform the waste characterization data
package completeness/accuracy review and either accept or reject the
data. Third, if the data are accepted, the site waste characterization
data are transferred manually or electronically via the WWIS to the
WIPP. At the WIPP, screening includes verification that all of the
required elements of a waste characterization data package are present
and that the data meet acceptance criteria required for compliance.
Waste stream approval or rejection to ship to the WIPP is the outcome
of Phase I.
Phase II includes examination of a waste shipment after it has
arrived at the WIPP, and is a three-step process. First, upon receipt
of a waste shipment, the WIPP personnel determine manifest completeness
and sign the manifest before the driver may depart. Second, WIPP
personnel determine waste shipment completeness by checking the bar-
coded identification number found on each TRU waste container. The bar-
coded identification number is noted and checked against the WWIS. The
WWIS maintains waste container receipt and emplacement information.
Third, waste shipment irregularities or discrepancies are identified
and resolved. If there are discrepancies, the generator site is
contacted for resolution. Finally, WIPP personnel compare the container
identification number with a list of those approved for disposal at the
WIPP. Waste shipment approval or rejection for disposal at the WIPP is
the outcome of Phase II. (For further information on the system of
controls, see Docket A-93-02, Item V-B-2, CARD 24, Section 24.H.2.)
In summary, all waste sent to WIPP will be appropriately and
thoroughly characterized. First, the acceptable knowledge provides
essential waste content information that later determines the waste
categories. The AK process undergoes quality assurance checks to
confirm good technical practices and qualified personnel. Then, the
measurement techniques (NDA, NDE, VE) confirm the AK data, and further
define the content and limits of the waste. Further confirmation of the
accuracy of the waste characterization is provided by the extensive
tracking system. Again, quality assurance checks are applied to the
tracking and measurement controls. The waste characterization process,
if implemented accordingly, provides complete and thorough
characterization of the waste. The DOE has committed to implement this
process. No waste generator site will be allowed to ship proposed waste
streams to the WIPP until the waste characterization process detailed
above is met at that generator site for the given waste stream(s).
3. Future State Assumptions (Sec. 194.25)
Section 194.25 stipulates that performance assessments (``PA'') and
compliance assessments ``shall assume that characteristics of the
future remain what they are at the time the compliance application is
prepared, provided that such characteristics are not related to
hydrogeologic, geologic or climatic conditions.'' Section 194.25 also
requires DOE to provide documentation of the effects of potential
changes of hydrogeologic, geological, and climatic conditions on the
disposal system over the regulatory time frame. The purpose of the
future state assumptions is to avoid unverifiable and unbounded
speculation about possible future states of society, science,
languages, or other characteristics of mankind. The Agency has found no
acceptable methodology that could make predictions of the future state
of society, science, languages, or other characteristics of mankind.
However, the Agency does believe that established scientific methods
can make plausible predictions regarding the future state of geologic,
hydrogeologic, and climatic conditions. Therefore, Sec. 194.25 focuses
the PA and compliance assessments on the more predictable significant
features of disposal system performance, instead of allowing unbounded
speculation on all developments over the 10,000-year regulatory time
frame.
The EPA proposed to find DOE in compliance with the requirements of
Sec. 194.25 because the future state assumptions that DOE made and
documented in the CCA were inclusive of all relevant elements of the PA
and compliance assessments and were consistent with the requirements of
Sec. 194.25. (62 FR 58816-7) The Agency reviewed the future state
assumptions DOE made about hydrogeologic and geologic characteristics
and found that DOE accurately characterized, screened, and modeled the
potential changes from current conditions. For climatic changes, EPA
found DOE's approach to be conservative and consistent with the
compliance criteria, since DOE examined the worst-case scenario of
increased precipitation at the WIPP rather than the potential effects
of global warming, which could be beneficial to the WIPP.
(Sec. 194.25(b)(3)) The EPA found that DOE's incorporation of these
changes into the PA was adequate. Finally, EPA found that the CCA's
approach to dealing with uncertainty, including use of conservative
assumptions to compensate for uncertainty, are consistent with the
features, events, and processes list, screening arguments, and model
descriptions.
The EPA received no public comments on this topic beyond those
addressed in the proposal, and so finds DOE in compliance with the
requirements of Sec. 194.25. For further information concerning EPA's
evaluation of compliance with Sec. 194.25, see CARD 25. (Docket A-93-
02, Item V-B-2) For additional information on the features, events, and
processes included in the PA and compliance assessments, see CARD 32
(Docket A-93-02, Item V-B-2) and the preamble discussion of performance
assessment issues (Section VIII.B). For additional information on both
geologic and hydrogeologic conditions of the WIPP, see the preamble
discussion of Sec. 194.14.
4. Expert Judgment (Sec. 194.26)
The requirements of 40 CFR 194.26 apply to expert judgment
elicitation.
[[Page 27394]]
Expert judgment is typically used to elicit two types of information:
numerical values for parameters (variables) that are measurable only by
experiments that cannot be conducted due to limitations of time, money,
and physical situation; and essentially unknowable information, such as
which features should be incorporated into passive institutional
controls to deter human intrusion into the repository. (61 FR 5228)
Quality assurance requirements (specifically Sec. 194.22(a)(2)(v)) must
be applied to any expert judgment to verify that the procedures for
conducting and documenting the expert elicitation have been followed.
The requirements of 40 CFR Part 194 prohibit expert judgment from
being used in place of experimental data, unless DOE can justify that
the necessary experiments cannot be conducted. Expert judgment may
substitute for experimental data only in those instances in which
limitations of time, resources, or physical setting preclude the
successful or timely collection of data.
The CCA did not identify any formal expert elicitation activities.
During the Agency's review of performance assessment (``PA'')
parameters, EPA found inadequate explanation and information for 149
parameters that DOE claimed had been derived using professional
judgment. The compliance criteria do not provide for utilization of
``professional judgement.'' Input parameters are to be derived from
data collection, experimentation, or expert elicitation. The EPA
requested that DOE provide additional information on the derivation of
the 149 parameters. (Docket A-93-02, Items II-I-17, II-I-25, and II-I-
27)
The DOE responded to EPA's requests by adding information to and
improving the quality of the records stored in the Sandia National
Laboratory (``SNL'') Records Center in order to enhance the
traceability of parameter values. The EPA deemed the documentation
provided by DOE adequate to demonstrate proper derivation of all but
one of the ``professional judgment'' parameters--the waste particle
size distribution parameter. For a comprehensive discussion of the
technical review of PA parameters, see the preamble discussion of
performance assessment, CARD 23 (Section 12.0), and EPA's ``Parameter
Report'' and ``Parameter Justification Report.'' (Docket A-93-02, Items
V-B-2, V-B-12, V-B-14) The EPA required DOE to use the process of
expert elicitation to develop the value for the waste particle size
distribution parameter. (Docket A-93-02, Item II-I-27)
The waste particle size parameter is important in performance
assessments because the distribution of waste particle diameters
affects the quantity of radioactive materials released in spallings
from inadvertent human intrusion. Because particle diameters are
uncertain and cannot be estimated either directly from available data
or from data collection or experimentation, the waste particle size
parameter had to be based on an elicitation of expert judgment.
The DOE conducted the expert judgment elicitation on May 5-9, 1997.
The results of the expert elicitation consisted of a model for
predicting waste particle size distribution as a function of the
processes occurring within the repository, as predicted by the PA. The
DOE completed a final report entitled, ``Expert Elicitation on WIPP
Waste Particle Size Distributions(s) During the 10,000-Year Regulatory
Post-closure Period.'' (Docket A-93-02, Item II-I-34) The particle size
distribution derived from the expert elicitation was incorporated in
the PA verification test (``PAVT'') calculations.
The EPA's review of DOE's compliance with the requirements of
Sec. 194.26 principally focused on the conduct of the elicitation
process, since Sec. 194.26 sets specific criteria for the performance
of an expert judgement elicitation. The EPA observed DOE's elicitation
process and conducted an audit of the documentation prepared in support
of DOE's compliance with Sec. 194.26. The scope of the audit covered
all aspects of the expert judgment elicitation process, including:
panel meetings, management and team procedures, curricula vitae of
panel members, background documents, and presentation materials. The
EPA also assessed compliance with the quality assurance requirements of
Sec. 194.22(a)(2)(v). The EPA found that the documentation was
appropriate, that the panel members were appropriately qualified, and
that the results of the elicitation were used consistent with the
stated purpose; EPA, therefore, proposed to find DOE in compliance with
Sec. 194.26. (62 FR 58817-18)
Comments on EPA's proposed decision for Sec. 194.26 related to two
main issues: (1) Commenters questioned DOE's statement that it did not
conduct any expert judgement activities in developing the CCA; and (2)
commenters questioned the use or role of ``professional judgement'' in
the development of input parameters used in the CCA. The DOE's
understanding of expert judgment was consistent with EPA's use of the
term ``expert judgment'' in the compliance criteria, namely a formal,
highly structured elicitation of expert opinion. (Response to Comments
for 40 CFR Part 194, Docket A-92-56, Item V-C-1, p. 8-4) However, EPA
agrees that the CCA initially did not contain adequate information to
ascertain whether a large number of the input parameters had been
properly derived. The DOE subsequently provided additional information,
and substantially improved the quality of the records at the SNL
Records Center, which enabled EPA to confirm that all but one of the
parameters were adequately supported.
In regard to the use of professional judgement in the development
of input parameters, the compliance criteria in Sec. 194.26 do not
provide for derivation of input parameters through ``professional
judgement.'' Input parameters used in the PA are to be derived from
data collection, experimentation, or expert elicitation. The Agency,
however, recognizes that raw data resulting from data collection or
experimentation may require ``professional judgment'' in the
development of input parameters. Professional scientific judgment may
be used to interpolate, extrapolate, interpret, and apply data to
develop parameter values but cannot substitute for data. (Expert
judgment may substitute for data, but only when information cannot
reasonably be obtained through data collection or experimentation.) The
applicability of Sec. 194.26 does not extend to professional scientific
judgment used in such circumstances. (Docket A-92-56, Item V-C-1, p. 8-
5)
Based on its review of documentation developed by DOE and its
contractors, the results of EPA's audit, and consideration of public
comments, EPA concludes that DOE complied with the requirements of
Sec. 194.26 in conducting the required expert elicitation. For further
information on EPA's evaluation of compliance with Sec. 194.26, see
CARD 26. (Docket A-93-02, Item V-B-2)
5. Peer Review (Sec. 194.27)
Section 194.27 requires DOE to conduct peer review evaluations
related to conceptual models, waste characterization analyses, and a
comparative study of engineered barriers. A peer review involves an
independent group of experts who are convened to determine whether
technical work was performed appropriately and in keeping with the
intended purpose. The required peer reviews must be performed in
accordance with the Nuclear Regulatory
[[Page 27395]]
Commission's NUREG-1297, ``Peer Review for High-Level Nuclear Waste
Repositories,'' which establishes guidelines for the conduct of a peer
review exercise. Section 194.27 also requires DOE to document in the
compliance application any additional peer reviews beyond those
explicitly required.
The EPA proposed to find DOE in compliance with the requirements of
Sec. 194.27 because EPA's independent audit established that DOE had
conducted and documented the required peer reviews in a manner
compatible with NUREG-1297. The Agency also proposed that DOE
adequately documented additional peer reviews in the CCA. The EPA
received no public comments on this topic beyond those addressed in the
proposal (62 FR 58818), and so finds DOE in compliance with the
requirements of Sec. 194.27. For further information concerning EPA's
evaluation of compliance with Sec. 194.27, see CARD 27. (Docket A-93-
02, Item V-B-2)
D. Assurance Requirements
1. Active Institutional Controls (Sec. 194.41)
Section 194.41 implements the active institutional controls
(``AICs'') assurance requirement. The disposal regulations define AICs
as ``controlling access to a disposal site by any means other than
passive institutional controls, performing maintenance operations or
remedial actions at a site, controlling or cleaning up releases from a
site, or monitoring parameters related to disposal system
performance.'' (40 CFR 191.12) Section 194.41 requires AICs to be
maintained for as long a period of time as is practicable after
disposal; however, contributions from AICs for reducing the rate of
human intrusion in the PA may not be considered for more than 100 years
after disposal.
The DOE proposed to: construct a fence and roadway around the
surface footprint of the repository; post warning signs; conduct
routine patrols and surveillance; and repair and/or replace physical
barriers as needed. The DOE also identified other measures that
function as AICs, such as DOE's prevention of resource exploration at
the WIPP and DOE's construction of long-term site markers. The DOE will
maintain the proposed AICs for at least 100 years after closure of the
WIPP, and the WIPP PA assumed that AICs would prevent human intrusion
for that period.
The EPA reviewed the proposed AICs in connection with the types of
activities that may be expected to occur in the vicinity of the WIPP
site during the first 100 years after disposal (i.e., ranching,
farming, hunting, scientific activities, utilities and transportation,
ground water pumping, surface excavation, potash exploration,
hydrocarbon exploration, construction, and hostile or illegal
activities) and examined the assumptions made by DOE to justify the
assertion that AICs will be completely effective for 100 years. The DOE
stated in the CCA that the proposed AICs will be maintained for 100
years, and that regular surveillance could be expected to detect a
drilling operation in a prohibited area that is set up in defiance or
ignorance of posted warnings.
The EPA received public comments on its proposed certification
decision stating that it was unreasonable to assume that AICs could be
completely effective for 100 years. While EPA recognizes that 100
percent effectiveness of AICs over 100 years cannot be established with
certainty, the proposed AICs are fully within DOE's present capability
to implement and may be expected to be enforceable for a period of 100
years. Therefore, EPA found it reasonable for DOE to assume credit in
the PA for 100 years. The EPA found the assumptions regarding longevity
and efficacy of the proposed AICs to be acceptable based on the fact
that the types of inadvertent intrusion which AICs are designed to
obviate are not casual activities, but require extensive resources,
lengthy procedures for obtaining legal permission, and substantial time
to set up at the site before beginning.
Contributions from AICs in the PA are considered as a reduction in
the rate of human intrusion. The EPA reviewed the CCA and the parameter
inputs to the PA and determined that DOE did not assume credit for the
effectiveness of active institutional controls for more than 100 years
after disposal. The EPA found DOE's assumptions to be sufficient to
justify DOE's assertion that AICs will completely prevent human
intrusion for 100 years after closure. Because DOE adequately described
the proposed AICs and the basis for their assumed effectiveness and did
not assume in the PA that AICs would be effective for more than 100
years, EPA finds DOE in compliance with Sec. 194.41. For further
information on EPA's evaluation of compliance for Sec. 194.41, refer to
CARD 41. (Docket A-93-02, Item V-B-2)
2. Monitoring (Sec. 194.42)
Section 194.42 requires DOE to monitor the disposal system to
detect deviations from expected performance. The monitoring requirement
distinguishes between pre-and post-closure monitoring because the
monitoring techniques that may be used to access the repository during
operations (pre-closure) and after the repository has been backfilled
and sealed (post-closure) are different. Monitoring is intended to
provide information about the repository that may affect the
predictions made about the PA or containment of waste. The EPA proposed
that DOE was in compliance with this requirement. (62 FR 58827)
Public comments on EPA's proposed decision stated that the
monitoring plan presented by DOE does not comply with certain hazardous
waste (Resource Conservation and Recovery Act) and Nuclear Regulatory
Commission (``NRC'') requirements. However, the monitoring techniques
and parameters suggested by commenters are not required by Sec. 194.42,
which requires only that the post-closure monitoring plan be
complementary to certain applicable hazardous waste monitoring
requirements. The purpose of this language is to eliminate potential
overlap with hazardous waste monitoring requirements while ensuring
that monitoring will be conducted even if not required by the
applicable hazardous waste regulations. (Response to Comments for 40
CFR Part 194, Docket A-92-56, Item V-C-1, p. 14-7)
One commenter stated that DOE should monitor additional parameters
and perform remote monitoring to prolong the length of time that data
is gathered. The EPA determined that monitoring the additional
parameters would provide no significant benefit because these
parameters were not identified as significant to the containment of
waste or to verifying predictions made about the repository. The EPA
also determined that additional remote monitoring of the panel rooms
would neither provide significant information on the performance of the
repository nor verify predictions about its performance.
The plans in the CCA addressed both pre-closure and post-closure
monitoring and included the information required by the compliance
criteria. Therefore, EPA finds that DOE is in compliance with the
requirements of Sec. 194.42. Under its authority at Sec. 194.21, EPA
intends to conduct inspections of DOE's implementation of the
monitoring plans that DOE has set forth. For further information on
EPA's evaluation of compliance for Sec. 194.42, see CARD 42. (Docket A-
93-02, Item V-B-2)
[[Page 27396]]
3. Passive Institutional Controls (Sec. 194.43)
The compliance criteria at Sec. 194.43 require a description of
passive institutional controls (``PICs'') that will be implemented at
the WIPP. The EPA defined PICs in the disposal regulations as markers,
public records and archives, government ownership of and restrictions
on land use at a site, and any other means of preserving knowledge of a
site. (40 CFR 191.12) PICs are intended to deter unintentional
intrusions into a disposal system by people who otherwise might not be
aware of the presence of radioactive waste at the site.
Section 194.43 requires DOE to: (1) identify the controlled area
with markers designed, fabricated, and emplaced to be as permanent as
practicable; (2) place records in local State, Federal, and
international archives and land record systems likely to be consulted
by individuals in search of resources; and (3) employ other PICs
intended to indicate the location and dangers of the waste. In
accordance with Sec. 194.43(b), DOE also must indicate the period of
time that PICs are expected to endure and be understood by potential
intruders. Finally, DOE is permitted to propose a credit for PICs in
the PA, as explained in Sec. 194.43(c). This credit must be based on
the proposed effectiveness of PICs over time, and would take the form
of reduced likelihood in the PA of human intrusion over several hundred
years. The compliance criteria prohibit DOE from assuming that PICs
could entirely eliminate the likelihood of future human intrusion into
the WIPP.
The EPA proposed that DOE complied with Sec. 194.43(a) and (b)
because the measures proposed in the CCA are comprehensive,
practicable, and likely to endure and be understood for long periods of
time. The EPA also proposed a condition that DOE submit additional
information concerning the schedule for completing PICs, the
fabrication of granite markers, and commitments by various recipients
to accept WIPP records. (62 FR 58827-29) The EPA did not receive any
comments disputing this decision, and so finds DOE in compliance with
Sec. 194.43(a) and (b). However, DOE must fulfill Condition 4 of
Appendix A to 40 CFR Part 194 no later than the final recertification
application. For further information on EPA's evaluation of compliance
with Sec. 194.43, see CARD 43. (Docket A-93-02, Item V-B-2)
Some commenters expressed the concern that PICs in general, and
DOE's plan in particular, would not be sufficient to prevent drilling
or other intrusions into the WIPP over 10,000 years. The EPA has never
asserted that PICs, as an assurance measure, could or must be
sufficient to prevent human intrusion into a site entirely or for a
specified period (such as 10,000 years). In fact, the WIPP compliance
criteria prohibit DOE from assuming that PICs can completely eliminate
the likelihood of human intrusion. (Sec. 194.43(c)) DOE's design
incorporates features that will serve to promote the endurance and
comprehensibility of PICs over time, such as: redundant markers, highly
durable materials with low intrinsic value, messages in multiple
languages, and record storage in multiple locations. Also, the CCA
clearly discusses the manner in which DOE accounted in the design for
possible, realistic failures. The Agency believes that the existence of
site-specific markers and records, designed to be durable over long
periods of time, will greatly improve the chances that future
generations will retain knowledge of the hazard posed by waste stored
at the WIPP.
The EPA proposed to deny DOE's request under Sec. 194.43(c) that
the likelihood of human intrusion into the WIPP during the first 700
years after closure be reduced by 99 percent based on the anticipated
effectiveness of PICs. The EPA denied the credit because DOE did not
use an expert judgment elicitation to derive the credit, as explicitly
envisioned by the Agency. The EPA expected that an expert judgment
elicitation that makes use of the best available information and
expertise would be used to account for the considerable uncertainties
associated with a prediction of the ability of PICs to prevent human
intrusion hundreds of years into the future. Since the WIPP is located
in an area of resource exploitation, the uncertainty was not
sufficiently reflected in the near 100 percent credit proposed in the
CCA.
The Agency received comments both supporting and refuting this
decision. Comments supporting EPA's proposed decision tended to reflect
the position that any PICs credit would be too uncertain for use in the
PA. In opposition to EPA's decision, comments stated that EPA drew
improper conclusions about DOE's use of expert judgment and treatment
of uncertainty. These comments requested that EPA reverse its denial of
PICs credit, or at least consider future credit proposals, but did not
identify why EPA's conclusions were incorrect other than to reiterate
positions taken in the CCA that were explicitly assessed by EPA in the
proposal. (62 FR 58828) Therefore, EPA sees no cause to reverse its
decision to deny DOE's request for PICs credit under Sec. 194.43(c).
However, EPA's final decision today applies only to the credit proposal
in the CCA and should not be interpreted as a judgment on the use of
PICs credit in performance assessments generally. In the future, DOE
may present to EPA additional information derived from an expert
elicitation of PICs credit. Any future PICs credit proposals will be
considered in the context of a modification rulemaking, and will be
subject to public examination and comment.
4. Engineered Barriers (Sec. 194.44)
Section 194.44 requires DOE to conduct a study of available options
for engineered barriers at the WIPP and submit this study and evidence
of its use with the compliance application. Consistent with the
assurance requirement found at 40 CFR 191.14, DOE must analyze the
performance of the complete disposal system, and any engineered
barrier(s) that DOE ultimately implements at the WIPP must be
considered in the PA and EPA's subsequent evaluation. Based on the
comparative study that constitutes Appendix EBS of the CCA, DOE
proposed magnesium oxide (MgO) backfill as an engineered barrier and
proposed to emplace bags of MgO between and around waste containers in
the repository. The EPA proposed to find DOE in compliance with
Sec. 194.44 because DOE conducted and documented the required study in
a manner consistent with the WIPP compliance criteria and proposed to
implement an engineered barrier to delay the movement of water or
radionuclides. (62 FR 58829)
Public comments on the proposal stated that the waste should be
treated before being placed in the repository. Commenters stated that
treatment of waste could serve to provide additional confidence in the
safety of the disposal system beyond that demonstrated by the
performance assessment, based on the assumption that waste treatment
would reduce the potential effects of a repository breach. Commenters
therefore urged EPA to encourage DOE to treat the waste in order to add
additional assurance in the predicted performance of the WIPP.
Section 194.44 of the compliance criteria requires DOE to perform a
comparison of the benefits and detriments of waste treatment options
(referred to as ``engineered barriers'' by EPA and as ``engineered
alternatives'' by DOE). DOE's evaluation incorporated such treatment
methods as vitrification and shredding. Based on this
[[Page 27397]]
evaluation, DOE selected the use of MgO as an engineered barrier. The
EPA determined that MgO will be an effective barrier, based on DOE's
scientific evaluation of the proposed barrier's ability to prevent or
substantially delay the movement of radionuclides toward the accessible
environment.
Section 194.44 does not require specific engineered barriers or the
implementation of more than one engineered barrier. Since DOE will
employ the use of a barrier as required by this section, and since the
performance assessment results showed compliance with the containment
requirements with the use of this barrier, EPA does not consider it
necessary to require DOE to treat waste prior to emplacement. However,
EPA agrees that waste treatment or additional barriers may further
enhance the containment ability of the WIPP. In the future, if DOE were
to select a new treatment option (such as vitrification) that differs
significantly from the option in the most recent compliance
application, DOE must inform EPA prior to making such a change.
(Sec. 194.4(b)(3)(i) and (vi)) The EPA will evaluate the information
provided by DOE and determine if the certification warrants
modification.
Other commenters expressed concern that DOE failed to consider
alternatives to the proposed 55-gallon steel waste drums that could
reduce releases or the formation of gas in the repository due to the
degradation of carbon. Commenters further stated that DOE failed to
consider adequately how engineered barriers could reduce releases from
four human intrusion scenarios: fluid injection, air drilling, stuck
pipe, and direct brine release.
The EPA recognized that gas production from waste drum degradation
was a relevant issue and so included consideration of ``improved waste
containers'' in the list of factors for DOE to consider when evaluating
engineered barriers. (40 CFR 194.44(b)) The DOE did, in fact, consider
various aspects of waste packages in the engineered barrier study.
Appendix A of Appendix EBS (p. A-10) states that the ``improved waste
container'' options scored low in a qualitative assessment because of
their minimal ability to improve conditions with respect to waste
solubility and shear strength. As explained in CARD 44 (Docket A-93-02,
Item V-B-2), DOE also examined the effects of engineered barriers on
the long-term performance of the WIPP using the Design Analysis Model
(``DAM''), which provided a relative comparison of the potential
benefits of the different barriers on the performance of the
repository. There was no attempt to determine the absolute effect of
the barriers on the performance of the repository since the objective
of the study (in accordance with the WIPP compliance criteria) was only
to provide DOE with information for use in the selection or rejection
of additional engineered barriers. (Docket A-93-02, Item V-B-2, CARD
44, Section 44.C.4) It was not necessary for DOE to show the absolute
effect of each barrier on the WIPP's performance in the face of a
specific human intrusion scenario such as air drilling. Rather, it was
sufficient for DOE to consider the relative ability of barriers to
prevent or delay radionuclide migration in the event of human
intrusion.
Other comments expressed concern that the ``containment'' and
``assurance'' requirements were not kept separate, as was intended by
EPA's disposal standards. The separation of the requirements is valid
only to the extent that engineered barriers may be used to meet the
containment requirements, but must be used to meet the assurance
requirements. The effects of all engineered barriers employed at the
WIPP must be considered in performance assessments. Excluding such
barriers from consideration would result in inaccurate modeling of the
disposal system, which is defined in Sec. 191.12(a) to include
engineered barriers. (Response to Comments for 40 CFR Part 194, Docket
A-92-56, Item V-C-1, pp. 16-10, 16-13) Although not required to comply
with Sec. 194.44, DOE and others performed calculations showing that
the WIPP can comply with the containment requirements with or without
the use of MgO as an engineered barrier. (Docket A-93-02, Items IV-D-12
and IV-G-7)
The EPA finds that DOE complies with Sec. 194.44. The EPA found
that DOE conducted the requisite analysis of engineered barriers and
selected an engineered barrier designed to prevent or substantially
delay the movement of water or radionuclides toward the accessible
environment. The DOE provided sufficient documentation to show that MgO
can effectively reduce actinide solubility in the disposal system. The
DOE proposed to emplace a large amount of MgO around waste drums in
order to provide an additional factor of safety and thus account for
uncertainties in the geochemical conditions that would affect
CO2 generation and MgO reactions. For further information on
EPA's evaluation of compliance for Sec. 194.44, see CARD 44. (Docket A-
93-02, Item V-B-2) For further information regarding the PA modeling of
solubility and chemical conditions in the repository, see CARD 23--
Models and Computer Codes. (Docket A-93-02, Item V-B-2)
5. Consideration of the Presence of Resources (Sec. 194.45)
Section 194.45 implements the assurance requirement that the
disposal system be sited so that the benefits of the natural barriers
of the disposal system will compensate for any increased probability of
disruptions to the disposal system resulting from exploration and
development of existing resources. (61 FR 5232) In issuing the WIPP
compliance criteria, EPA determined that the performance assessment
(``PA'') is the appropriate tool to weigh the advantages and
disadvantages of the WIPP site because the PA demonstrates whether
potential human intrusion will cause unacceptably high releases of
radioactive material from the disposal system. Comments on Sec. 194.45
for the proposed certification decision did not address the question of
compliance with this requirement but instead focused on the criterion
itself, stating that it was inconsistent with the original basis for
the assurance requirements to be qualitative in nature. The EPA
believes that the presence of resources requirement is reasonable
because the performance assessment must account for the increased
potential for human intrusion into the disposal system due to the
presence of known resources, based on historical rates of drilling and
mining in the vicinity of the WIPP. (Docket A-92-56, Item V-C-1, p. 17-
1) In any case, it is beyond the scope of the certification rulemaking
to fundamentally re-examine or change the disposal regulations or
compliance criteria as they relate to the presence of resources.
Because the PA incorporated human intrusion scenarios and met EPA's
release limits in accordance with the WIPP compliance criteria, EPA
determines that DOE has demonstrated compliance with Sec. 194.45. For
discussion of comments on human intrusion scenarios, results, and other
aspects of the PA, refer to Section B (``Performance Assessment:
Modeling and Containment Requirements'') of this preamble. For further
information on EPA's evaluation of compliance for Sec. 194.45, refer to
CARD 45. (Docket A-93-02, Item V-B-2)
6. Removal of Waste (Sec. 194.46)
Section 194.46 requires DOE to provide documentation that the
removal of waste from the disposal system is feasible for a reasonable
period of time
[[Page 27398]]
after disposal. In the proposed certification decision on WIPP, EPA
proposed that DOE was in compliance with this requirement.
Public comments on EPA's proposed decision expressed concern that
there would be no way to remove the waste once the WIPP repository is
sealed. The technology used to dispose of the waste is substantially
the same as the technology that would be used to remove it. This
technology may reasonably be expected to remain available for at least
100 years after the repository is sealed. Public comments also stated
that EPA and DOE should identify the limitations of DOE's removal of
waste plan. In Appendix WRAC of the CCA, DOE acknowledges the expense
and hazard of removing the waste from the repository. The purpose of
the requirement at Sec. 194.46 is to demonstrate that the removal of
waste remains possible, not necessarily simply or inexpensive, for a
reasonable period of time after disposal. (50 FR 38082)
The DOE demonstrated that it is possible to remove waste from the
repository for a reasonable period of time after disposal. Therefore,
EPA determines that DOE is in compliance with Sec. 194.46. For further
information on EPA's evaluation of compliance with Sec. 194.46, see
CARD 46. (Docket A-93-02, Item V-B-2)
E. Individual and Ground-water Protection Requirements (Secs. 194.51-
55)
Sections 194.51 through 194.55 of the compliance criteria implement
the individual protection requirements of 40 CFR 191.15 and the ground-
water protection requirements of Subpart C of 40 CFR Part 191.
Assessment of the likelihood that the WIPP will meet the individual
dose limits and radionuclide concentration limits for ground water is
conducted through a process known as compliance assessment. Compliance
assessment uses methods similar to those of the PA (for the containment
requirements) but is required to address only undisturbed performance
of the disposal system. That is, compliance assessment does not include
human intrusion scenarios (i.e., drilling or mining for resources).
Compliance assessment can be considered a ``subset'' of performance
assessment, since it considers only natural (undisturbed) conditions
and past or near-future human activities (such as existing boreholes),
but does not include the long-term future human activities that are
addressed in the PA.
Section 194.51 requires DOE to assume in compliance assessments
that an individual resides at the point on the surface where the dose
from radionuclide releases from the WIPP would be greatest. The EPA
required that the CCA identify the maximum annual committed effective
dose and the location where it occurs, and explain how DOE arrived at
those results.
In DOE's analysis, an individual receives the highest dose if one
assumes that the individual takes drinking water directly from the
Salado Formation at the subsurface boundary of the WIPP area. The DOE
assumed that an individual would receive the maximum estimated dose
regardless of location on the surface and calculated the resultant
doses accordingly. EPA found this approach to be conservative and
proposed that DOE complied with Sec. 194.51. The Agency received no
public comments on this topic beyond those addressed in the proposal
(62 FR 58831), and so finds DOE in compliance with the requirements of
Sec. 194.51.
Section 194.52 requires DOE to consider in compliance assessments
all potential exposure pathways for radioactive contaminants from the
WIPP. The DOE must assume that an individual consumes two liters per
day of drinking water from any underground source of drinking water
outside the WIPP area.
The DOE considered the following pathways: an individual draws
drinking water directly from the Salado Formation; an individual
ingests plants irrigated with contaminated water or milk and beef from
cattle whose stock pond contained contaminated water from the Salado;
and an individual inhales dust from soil irrigated with contaminated
water from the Salado. Intended to result in the maximum dose, DOE's
assumption that water is ingested directly from the Salado actually is
so conservative as to be unrealistic, since Salado water is highly
saline and would have to be greatly diluted in order to function as
drinking or irrigation water.
The EPA proposed that DOE complied with Sec. 194.52 because DOE
considered all potential exposure pathways and assumed that an
individual consumes two liters of Salado water a day, following
dilution. The Agency received no public comments on this topic beyond
those addressed in the proposal (62 FR 58831), and so finds DOE in
compliance with the requirements of Sec. 194.52. For further
information concerning EPA's evaluation of compliance for Secs. 194.51
and 194.52, see CARD 51/52. (Docket A-93-02, Item V-B-2)
Section 194.53 requires DOE to consider in compliance assessments
underground sources of drinking water (``USDWs'') near the WIPP and
their interconnections. A USDW is defined at 40 CFR 191.22 as ``an
aquifer or its portion that supplies a public water system, or contains
a sufficient quantity of ground water to do so and (i) currently
supplies drinking water for human consumption or (ii) contains fewer
than 10,000 mg per liter of total dissolved solids.''
The DOE identified three potential USDWs near the WIPP--the Culebra
Member of the Rustler Formation, the Dewey Lake Red Beds, and the Santa
Rosa Sandstone of the Dockum Group--despite incomplete data showing
that they meet the regulatory definition of a USDW. The DOE did not
analyze underground interconnections among these water bodies, instead
assuming conservatively that people would draw water directly from the
Salado Formation, bypassing other USDWs closer to the surface and thus
resulting in greater exposure.
The EPA proposed that DOE complied with Sec. 194.53 because DOE
adequately considered potential USDWs near the WIPP. The Agency
received a few public comments that raised questions about DOE's
approach to evaluating USDWs. For example, some commenters questioned
DOE's assertion that USDWs such as Laguna Grande de la Sal would not be
contaminated if the WIPP is left undisturbed. In fact, the compliance
assessments assumed that water in the Salado Formation constituted a
hypothetical USDW that would provide drinking water after being
diluted. Radionuclide concentrations would be expected to be greatest
in the Salado at the subsurface boundary of the WIPP, since the
disposal system is located in that geologic formation. Thus, by
demonstrating that EPA's drinking water standards would be met where
radioactive contamination would be greatest, DOE also showed that
other, more distant potential aquifers also would comply. This
conservative approach compensates for substantial uncertainties that
would otherwise be involved in the calculation of radionuclide
transport to potential USDWs.
Even using an analysis that was designed to maximize radionuclide
releases, DOE showed that the WIPP will comply with EPA's limits for
radionuclides in ground water by a wide margin. The EPA therefore finds
DOE in compliance with Sec. 194.53. For further information concerning
EPA's evaluation of compliance with Sec. 194.53, see CARD 53. (Docket
A-93-02, Item V-B-2)
Sections 194.54 and 194.55 relate to the scope and results of
compliance assessments conducted to determine
[[Page 27399]]
compliance with the individual dose and ground-water protection
requirements. The EPA found that DOE appropriately evaluated and
screened out natural features, processes, and events related to
undisturbed performance, and proposed to find DOE in compliance with
Sec. 194.54. (62 FR 58832) The Agency received no specific comments on
this decision. Comments on issues that could affect predictions of
undisturbed performance, such as site characterization or ground-water
modeling, are discussed separately in this preamble and did not
necessitate changes to compliance assessments. (See ``Geologic
Scenarios and Disposal System Characteristics'' under the Performance
Assessment sections of this preamble.) The EPA therefore finds that DOE
complies with Sec. 194.54. For further information on EPA's evaluation
of compliance with Sec. 194.54, see CARD 54. (Docket A-93-02, Item V-B-
2)
The EPA found that compliance assessments conducted by DOE
appropriately documented uncertainty, documented probability
distributions for uncertain parameters, randomly sampled across the
distributions, and generated and displayed a sufficient number of
estimates of radiation doses and ground-water concentrations. Further,
the resulting estimates of radiation doses and radionuclide
concentrations in ground water (and independent calculations by EPA)
were well below the limits in Sec. 191.15 and Subpart C of 40 CFR Part
191. In its proposal, the Agency found that DOE is in compliance with
the requirements of Sec. 194.55, and received no comments disputing
this decision, which is therefore finalized. For further information on
EPA's evaluation of compliance for Sec. 194.55, see CARD 55. (Docket A-
93-02, Item V-B-2)
IX. Does DOE Need to Buy Existing Oil and Gas Leases Near the WIPP?
The EPA finds that DOE does not need to acquire existing oil and
gas leases in the vicinity of the WIPP in order to comply with EPA's
disposal regulations. These existing leases, and EPA's need to evaluate
their effects on the WIPP, are addressed by the 1992 WIPP Land
Withdrawal Act (``LWA'') which provides for EPA's regulatory authority
at the WIPP.37 (See Section X of this preamble, entitled
``Why and How Does EPA Regulate the WIPP,'' for more information on the
WIPP LWA.) The 1992 WIPP LWA withdrew the geographic area containing
the WIPP facility from all forms of entry, appropriation, and disposal
under public land laws. The WIPP LWA transferred jurisdiction of the
land to the Secretary of Energy explicitly for the use of constructing,
operating, and conducting other authorized activities related to the
WIPP. The WIPP LWA prohibits all surface or subsurface mining or oil or
gas production is prohibited at all times on or under the land
withdrawal area. (WIPP LWA, section 4(b)(5)(A)) However, section
4(b)(5)(B) states that existing rights under two oil and gas leases
(Numbers NMNM 02953 and 02953C) (referred to as ``the section
4(b)(5)(B) leases'') shall not be affected unless the Administrator
determines, after consultation with DOE and the Department of the
Interior, that the acquisition of such leases by DOE is required to
comply with EPA's final disposal regulations.
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\37\ Pub. L. 102-579, sections 4(b)(5) and 7(b)(2).
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Before DOE can emplace waste in the WIPP, DOE must acquire the
leases, unless EPA determines that such acquisition is not required.
(WIPP LWA, section 7(b)(2)) This determination is separate and apart
from the WIPP LWA requirement for EPA to conduct the certification
decision by notice-and-comment rulemaking. (WIPP LWA, section 8(d)).
Nonetheless, the Agency chose to address this matter as part of the
certification process because the determination of whether potential
drilling on the leases could possibly affect the integrity of the WIPP
is closely related to similar determinations that must be made to
determine compliance with the disposal regulations and WIPP compliance
criteria. (See Secs. 194.32(c), 194.54(b))
As discussed in the proposed certification decision, EPA examined
DOE's analysis of a number of potential activities in the life cycle of
a well-drilling, fluid injection (for both waterflooding and brine
disposal), and abandonment--that could affect the WIPP disposal system.
The Agency agreed with DOE that the effects of drilling a borehole
would be highly localized, due to well casing procedures and borehole
plugging practices. The EPA found that the effects of fluid injection
can also be expected to be localized, due to underground injection
control requirements. Finally, even abandoned boreholes would have
little consequence on waste panels more than a meter away. Because the
closest possible approach of a borehole drilled from the section
4(b)(5)(B) leases is over 2400 meters (8000 feet) from the WIPP waste
disposal rooms, EPA determined that such a borehole would have an
insignificant effect on releases from the disposal system (and in turn,
on compliance with the disposal regulations). (62 FR 58835-58836)
For the reasons discussed above, EPA concluded in its proposed rule
that the Secretary of Energy does not need to acquire Federal Oil and
Gas Leases No. NMNM 02953 and No. NMNM 02953C. (62 FR 58836) A number
of comments on the proposed rule suggested that DOE conducted
inadequate performance assessment analyses on drilling activities
occurring prior to or soon after disposal in the vicinity of the WIPP,
but only one commenter took issue directly with EPA's decision to not
require the Secretary of Energy to acquire the Section 4(b)(5)(B)
leases. This commenter questioned the impact of drilling activities by
lease holders.
The DOE's analysis of drilling for the performance assessment
indicated that wells drilled into the controlled area, but away from
the waste disposal room and panels, will not adversely affect the
disposal system's capability to contain radionuclides. A slant-drilled
borehole from outside the Land Withdrawal Area, into the section
4(b)(5)(B) lease area at least 6000 feet below the surface, would be at
least 2400 meters (8000) feet away from the WIPP disposal rooms and
would thus have an insignificant effect on releases from the disposal
system or compliance with the disposal regulations. The EPA finds that
potential activities at the section 4(b)(5)(B) leases will not cause
the WIPP to violate the disposal regulations. (For more information on
drilling scenarios, see the preamble discussions related to performance
assessment.) Therefore, EPA determines that it is not necessary for the
Secretary of Energy to acquire the Federal Oil and Gas Leases No. NMNM
02953 and No. NMNM 02953C.
X. Why and How Does EPA Regulate the WIPP?
The WIPP Land Withdrawal Act is the statute that provides EPA the
authority to regulate the WIPP. The EPA's obligations and the
limitations on EPA's regulatory authority under that law are discussed
below.
A. The WIPP Land Withdrawal Act
The EPA's oversight of the WIPP facility is governed by the WIPP
Land Withdrawal Act (``LWA''), passed initially by Congress in 1992 and
amended in 1996. (Prior to the passage of the WIPP LWA in 1992, DOE was
self-regulating with respect to the WIPP; that is, DOE was responsible
for determining whether its own facility complies with applicable
regulations for radioactive waste disposal.) The WIPP LWA delegates to
EPA three main tasks, to be completed sequentially, for reaching a
compliance certification decision. First, EPA must finalize
[[Page 27400]]
general regulations which apply to all sites--except Yucca Mountain--
for the disposal of highly radioactive waste.38 These
regulations, located at Subparts B and C of 40 CFR Part 191 (``disposal
regulations''), were published in the Federal Register in 1985 and
1993.39
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\38\ WIPP LWA, section 8(b).
\39\ 50 FR 38066-38089 (September 19, 1985) and 58 FR 66398-
66416 (December 20, 1993).
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Second, EPA must develop, by rulemaking, criteria to implement and
interpret the general radioactive waste disposal regulations
specifically for the WIPP. The EPA issued the WIPP compliance criteria,
which are found at 40 CFR Part 194, in 1996.40
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\40\ 61 FR 5224-5245 (February 9, 1996).
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Third, EPA must review the information submitted by DOE and publish
a certification decision.41 Today's action constitutes EPA's
certification decision as required by section 8 of the WIPP LWA.
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\41\ WIPP LWA, section 8(d).
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Today's action also addresses the requirement at section 7(b)(2)
that, before DOE can emplace waste in the WIPP, DOE must acquire
existing oil and gas leases near the WIPP unless EPA determines that
such acquisition is not required in order for DOE to comply with the
disposal regulations. The EPA determines that acquisition of the leases
is not necessary. For further discussion of this requirement, refer to
the preamble section entitled, ``Does DOE need to buy existing oil and
gas leases near the WIPP?''
Besides requiring EPA to issue a certification decision, the WIPP
LWA also requires the Agency to conduct periodic recertifications, if
the facility is initially certified. Every five years, EPA must
determine whether documentation submitted by DOE demonstrates that the
WIPP continues to be in compliance with the disposal
regulations.42 Recertifications are not conducted through
rulemaking, and are not addressed by today's action. However, the WIPP
compliance criteria address the process by which EPA intends to conduct
recertifications, including publishing public notices in the Federal
Register and providing a public comment period. (Sec. 194.64) For
further information on recertification, refer to the preamble sections
entitled, ``EPA's Future Role at the WIPP'' and ``How will the public
be involved in EPA's future WIPP activities?''
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\42\ WIPP LWA, section 8(f).
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B. Limits of EPA's Regulatory Authority at the WIPP
As discussed above, the WIPP LWA conveys specific responsibilities
on EPA to ensure the safety of the WIPP as a permanent disposal
facility. The Agency's primary responsibility, described in section 8
of the WIPP LWA, is to determine whether the WIPP facility will comply
with EPA's disposal regulations. Members of the public have expressed,
in written comments and in oral testimony on the proposed rule, a
desire for the Agency to oversee other aspects of the WIPP's operation.
In response to such concerns, EPA must clarify that its authority to
regulate DOE and the WIPP is limited by the WIPP LWA and other statutes
which delineate EPA's authority to regulate radioactive materials in
general. The limitations on EPA's authority necessarily limit the scope
of the present rulemaking.
A number of commenters suggested that EPA should explore
alternative methods of waste disposal, such as neutralizing radioactive
elements, before proceeding with a certification decision. Others
stated that the WIPP should be opened immediately because underground
burial of radioactive waste is less hazardous than the current strategy
of above-ground storage. In the WIPP LWA, Congress did not delegate to
EPA the authority to abandon or delay the WIPP because future
technologies might evolve and eliminate the need for the WIPP. Also,
Congress did not delegate to EPA the authority to weigh the competing
risks of leaving radioactive waste stored above ground compared to
disposal of waste in an underground repository. These considerations
are outside the authority of EPA as established in the WIPP LWA, and
thus outside the scope of this rulemaking. However, as technologies
evolve over the operating period of the WIPP, DOE may incorporate them
into the facility design through a modification or during the required
recertification process. The EPA will evaluate how any such changes in
design or activities at the WIPP may affect compliance with the
radioactive waste disposal regulations.
Some commenters requested that EPA consider certain factors in
making its certification decision. These factors include reviews by
organizations other than EPA, and the political or economic motivations
of interested parties. The EPA's certification decision must be made by
comparing the scope and quality of relevant information to the
objective criteria of 40 CFR Part 194. Where relevant, the Agency has
considered public comments which support or refute technical positions
taken by DOE. Emotional pleas and comments on the motives of interested
parties are factors that are not relevant to a determination of whether
DOE has demonstrated compliance with the disposal regulations and WIPP
compliance criteria, and are therefore outside the scope of this
rulemaking.
Finally, the hazards of transporting radioactive waste from storage
sites to the WIPP is of great concern to the public. Transportation is
entirely outside EPA's general authority for regulating radioactive
waste. Moreover, in the WIPP LWA, Congress did not authorize any role
for EPA to regulate transportation. Instead, the WIPP LWA reiterated
that DOE must adhere to transportation requirements enforced by the
U.S. Nuclear Regulatory Commission and the U.S. Department of
Transportation. (WIPP LWA, section 16) Because all transportation
requirements for the WIPP are established and enforced by other
regulators, EPA does not address the issue further in today's action.
The preamble section entitled, ``What is EPA's response to general
comments received on the certification decision?'' provides further
discussion of general issues, including several related to the scope of
EPA's certification rulemaking.
C. Compliance With Other Environmental Laws and Regulations
The WIPP must comply with a number of other environmental and
safety regulations in addition to EPA's disposal regulations--
including, for example, the Solid Waste Disposal Act and EPA's
environmental standards for the management and storage of radioactive
waste. Various regulatory agencies are responsible for overseeing the
enforcement of these Federal laws. For example, the WIPP's compliance
with EPA's radioactive waste management regulations, found at Subpart A
of 40 CFR Part 191, is addressed by an EPA guidance document which
describes how EPA intends to implement Subpart A at the WIPP. (Copies
of the WIPP Subpart A Guidance are available by calling the WIPP
Information Line at 1-800-331-WIPP or from EPA's WIPP home page at
www.epa/gov/radiation/wipp.) Enforcement of some parts of the hazardous
waste management regulations has been delegated to the State of New
Mexico. The State's authority for such actions as issuing a hazardous
waste operating permit for the WIPP is in no way affected by EPA's
certification decision. It is the responsibility of the Secretary of
Energy to report the WIPP's compliance with all applicable Federal laws
pertaining to public health and the environment.43
Compliance with environmental or
[[Page 27401]]
public health regulations other than EPA's disposal regulations and
WIPP compliance criteria is not addressed by today's action.
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\43\ WIPP LWA, sections 7(b)(3) and 9.
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XI. How Has the Public Been Involved in EPA's WIPP Activities?
Section 8(d)(2) of the WIPP LWA requires that the Administrator's
certification decision be conducted by informal (or ``notice-and-
comment'') rulemaking pursuant to Section 4 of the Administrative
Procedure Act (``APA''). Notice-and-comment rulemaking under the APA
requires that an agency provide notice of a proposed rulemaking, an
opportunity for the public to comment on the proposed rule, and a
general statement of the basis and purpose of the final
rule.44
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\44\ 5 U.S.C. 553.
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The WIPP compliance criteria, at Subpart D of 40 CFR Part 194,
established a process of public participation that exceeds the APA's
basic requirements, and provides the public with the opportunity to
participate in the regulatory process at the earliest opportunity. The
WIPP compliance criteria contain provisions that require EPA to:
publish an advance notice of proposed rulemaking (``ANPR'') in the
Federal Register; allow public comment on DOE's compliance
certification application (``CCA'') for at least 120 days, prior to
proposing a certification decision; hold public hearings in New Mexico,
if requested, on the CCA; provide a minimum of 120 days for public
comment on EPA's proposed certification decision; hold public hearings
in New Mexico on EPA's proposal; produce a document summarizing the
Agency's consideration of public comments on the proposal, and maintain
informational dockets in the State of New Mexico to facilitate public
access to the voluminous technical record, including the CCA. The EPA
has complied with each of these requirements.
A. Public Involvement Prior to Proposed Rule
The EPA received DOE's CCA on October 29, 1996. Copies of the CCA
and all the accompanying references submitted to EPA were placed in
EPA's dockets in New Mexico and Washington, DC. On November 15, 1996,
the Agency published in the Federal Register (61 FR 58499) an ANPR
announcing that the CCA had been received, and announcing the Agency's
intent to conduct a rulemaking to certify whether the WIPP facility
will comply with the disposal regulations. The notice also announced a
120-day public comment period, requested public comment ``on all
aspects of the CCA,'' and stated EPA's intent to hold public hearings
in New Mexico.
The EPA published a separate notice in the Federal Register
announcing hearings to allow the public to address all aspects of DOE's
certification application. (62 FR 2988) Public hearings were held on
February 19, 20 and 21, 1997, in Carlsbad, Albuquerque and Santa Fe,
New Mexico, respectively. In addition to the public hearings, EPA held
three days of meetings in New Mexico, on January 21, 22 and 23, 1997,
with the principal New Mexico Stakeholders. Detailed summaries of these
meeting were placed in Docket A-93-02, Category II-E.
The Agency received over 220 sets of written and oral public
comments in response to the ANPR. The Agency reviewed all public
comments submitted during the ANPR 120-day comment period or presented
at the preliminary meetings with stakeholders. The EPA provided
responses to these comments in the preamble to the proposed
certification as well as in the compliance application review documents
(``CARDs'') for the proposed certification decision. The CARDs also
addressed late comments--and comments on the completeness of DOE's
CCA--received after the close of the public comment period (on March
17, 1997) but before August 8, 1997. (62 FR 27996-27998) All relevant
public comments, whether received in writing, or orally during the
public hearings, were considered by the Agency as the proposed
certification decision was developed. For further discussion of EPA's
completeness determination and other pre-proposal activities, see the
preamble to the proposed certification decision, 62 FR 58794-58796.
B. Proposed Certification Decision
On October 30, 1997, EPA published a Notice of Proposed Rulemaking
in the Federal Register, fulfilling the requirements of the WIPP
compliance criteria at Sec. 194.62. (62 FR 58792-58838) The notice
announced the Administrator's proposed decision, pursuant to section
8(d)(1) of the WIPP LWA, as amended, to issue a certification that the
WIPP facility will comply with the disposal regulations, and solicited
comment on the proposal. The notice also marked the beginning of a 120-
day public comment period on EPA's proposed certification decision.
Finally, the notice announced that public hearings would be held in New
Mexico during the public comment period.
C. Public Hearings on Proposed Rule
Further information on the hearings was provided in a Federal
Register notice published on December 5, 1997. (62 FR 64334-64335) The
Agency conducted hearings in three cities in New Mexico--Carlsbad,
Albuquerque, and Santa Fe--on January 5 through 9, 1998. The EPA took a
number of steps to ensure that citizens were aware of the hearings and
to accommodate requests to testify before the EPA panel. For example,
EPA placed forty-six notices in newspapers across the State to
advertise the hearings and provided a manned, toll-free telephone line
for pre-registration. The Agency also allowed on-site registration, and
extended the hours of the hearings in both Albuquerque and Santa Fe in
order to allow everyone present who wished to testify the opportunity
to do so.
D. Additional Public Input on the Proposed Rule
In addition to the public hearings, EPA held two days of meetings
in New Mexico, on December 10-11, 1997, with the principal New Mexico
stakeholders, including the New Mexico Attorney General's Office, the
New Mexico Environmental Evaluation Group (``EEG''), Concerned Citizens
for Nuclear Safety, Citizens for Alternatives to Radioactive Dumping,
and Southwest Research and Information Center. Detailed summaries of
these meetings were placed in Docket A-93-02, Item IV-E-8. Additional
meetings were also held in January 1998 in New Mexico and Washington,
DC with the New Mexico EEG (IV-E-10 and IV-E-11) and other stakeholders
(IV-E-11).
In response to concerns expressed in meetings with stakeholders and
in public hearings, EPA performed additional analyses of air drilling
(a specialized drilling method which stakeholders raised as an issue
which could potentially affect the WIPP if it occurred near the site).
In light of the significant public interest in this issue, EPA
conducted its analysis and released its report during the comment
period on the proposed rule, in order to allow an opportunity for the
public to comment on EPA's technical analysis. The Agency published a
Federal Register notice of availability for the report and provided a
30-day public comment period. (63 FR 3863; January 27, 1998) The report
was placed in the public docket and also sent electronically to a
number of interested stakeholders, including the New Mexico Attorney
General, the New Mexico Environmental Evaluation Group, Citizens for
Alternatives to Radioactive
[[Page 27402]]
Dumping, Concerned Citizens for Nuclear Safety, and Southwest Research
and Information Center.
E. Final Certification Decision, Response to Comments Document
Today's notice of EPA's final certification decision pursuant to
section 8(d)(1) of the WIPP LWA fulfills the requirement of the WIPP
compliance criteria at Sec. 194.63(a). Also in accordance with
Sec. 194.63(b), EPA is publishing a document, accompanying today's
action and entitled ``Response to Comments,'' which contains the
Agency's response to all significant comments received during the
comment period on the proposed certification decision. (Docket A-93-02,
Item V-C-1) (For further discussion of EPA's treatment of ANPR and
other pre-proposal comments, refer to the preamble to the proposed
rule, 62 FR 58794-58796.) All comments received by EPA, whether written
or oral, were given equal consideration in developing the final rule.
All comments received by the Agency were made available for public
inspection through the public docket. (Docket A-93-02, Categories IV-D,
IV-F, and IV-G)
F. Dockets
In accordance with 40 CFR 194.67, EPA maintains a public docket
(Docket A-93-02) that contains all information used to support the
Administrator's proposed and final decisions on certification. The
Agency established and maintains the formal rulemaking docket in
Washington, D.C., as well as informational dockets in three locations
in the State of New Mexico (Carlsbad, Albuquerque, and Santa Fe). The
docket consists of all relevant, significant information received to
date from outside parties and all significant information considered by
the Administrator in reaching a certification decision regarding
whether the WIPP facility will comply with the disposal regulations.
The EPA placed copies of the CCA in Category II-G of the docket. The
Agency placed supplementary information received from DOE in response
to EPA requests in Categories II-G and II-I.
The final certification decision and supporting documentation can
be found primarily in the following categories of Docket A-93-02:
Category V-A (final rule and preamble), Category V-B (Compliance
Application Review Documents and Technical Support Documents), and
Category V-C (Response to Comments document).
The hours and locations of EPA's public information dockets are as
follows: Docket No. A-93-02, located in room 1500 (first floor in
Waterside Mall near the Washington Information Center), U.S.
Environmental Protection Agency, 401 M Street, S.W., Washington, D.C.,
20460 (open from 8:00 a.m. to 4:00 p.m. on weekdays); 2) EPA's docket
in the Government Publications Department of the Zimmerman Library of
the University of New Mexico located in Albuquerque, New Mexico, (open
from 8:00 a.m. to 9:00 p.m. on Monday through Thursday, 8:00 a.m. to
5:00 p.m. on Friday, 9:00 a.m. to 5:00 p.m. on Saturday, and 1:00 p.m.
to 9:00 p.m. on Sunday); 3) EPA's docket in the Fogelson Library of the
College of Santa Fe in Santa Fe, New Mexico, located at 1600 St.
Michaels Drive (open from 8:00 a.m. to 12:00 midnight on Monday through
Thursday, 8:00 a.m. to 5:00 p.m. on Friday, 9:00 a.m. to 5:00 p.m. on
Saturday, 1:00 p.m. to 9:00 p.m. on Sunday); and 4) EPA's docket in the
Municipal Library of Carlsbad, New Mexico, located at 101 S. Halegueno
(open from 10:00 a.m. to 9:00 p.m. on Monday through Thursday, 10:00
a.m. to 6:00 p.m. on Friday and Saturday, and 1:00 p.m. to 5:00 p.m. on
Sunday). As provided in 40 CFR Part 2, a reasonable fee may be charged
for photocopying docket materials.
XII. How Will the Public be Involved in EPA's Future WIPP
Activities?
The EPA's regulatory role at the WIPP does not end with its initial
certification decision. The Agency's future WIPP activities will
include periodic recertifications, review of DOE reports on activities
at the WIPP, assessment of waste characterization and QA programs at
waste generator sites, announced and unannounced inspections of the
WIPP and other facilities, and possibly modification, revocation, or
suspension of the certification for cause. These activities are
described above in the preamble section entitled ``EPA's Future Role at
the WIPP.'' The EPA has provided for public involvement in these
activities through rulemaking procedures, Federal Register notices and
public comment periods, and by making information available in its
public dockets. (See the preamble sections entitled ``Dockets'' and
``Where can I get more information about EPA's WIPP activities?'' for
more information regarding EPA's rulemaking docket.)
While a suspension may be initiated at the discretion of the
Administrator in order to promptly reverse or mitigate a potential
threat to public health, any modification or revocation of the
certification will be conducted through rulemaking. (Secs. 194.65-66)
To modify or revoke the certification, EPA will first publish a Notice
of Proposed Rulemaking in the Federal Register. This notice will
announce EPA's proposed action, describe the basis for the decision,
and provide the opportunity for public comment on the proposal.
Documentation related to the decision will be made available to the
public through EPA's docket. Any final rule on modification or
revocation will also be published in the Federal Register. In addition,
EPA will release a document which summarizes and responds to
significant public comments received on its proposal.
The recertification process--EPA's periodic review of the WIPP's
continued compliance with the disposal regulations and WIPP compliance
criteria--will include many of the same elements as notice-and-comment
rulemaking. For example, EPA will publish a Federal Register notice
announcing its intent to conduct such an evaluation. The certification
application for recertification will be placed in the docket, and at
least a 30-day period will be provided for submission of public
comments. The Agency's decision on whether to recertify the WIPP
facility will again be announced in a Federal Register notice.
(Sec. 194.64)
Although not required by the APA, the WIPP LWA, or the WIPP
compliance criteria, EPA intends to place in the docket all inspection
or audit reports and annual reports by DOE on conditions and activities
at the WIPP. The Agency also plans to docket information pertaining to
the enforcement of certification conditions. For the enforcement of
Conditions 2 and 3 (regarding quality assurance (``QA'') and waste
characterization programs at waste generator sites), a number of
additional steps will be taken. As described in Sec. 194.8 of the WIPP
compliance criteria, before approving QA and waste characterization
controls at generator sites, EPA will publish a Federal Register notice
announcing EPA inspections or audits. The requisite plans and other
appropriate inspection or audit documentation will be placed in the
docket, and the public will be allowed the opportunity to submit
written comments. A comment period of at least 30 days will be
provided. Thus, EPA's decisions on whether to approve waste generator
QA program plans and waste characterization controls'--and thus, to
allow shipment of specific waste streams for disposal at the WIPP'--
will be made only after EPA has conducted an inspection or audit of the
waste generator site and after public comment has been solicited on the
matter. The Agency's decisions will be conveyed by a letter from EPA to
DOE.
[[Page 27403]]
A copy of the letter, as well as the results of any inspections or
audits, will be placed in EPA's docket.
XIII. Where Can I Get More Information About EPA's WIPP Activities?
The EPA's docket functions as the official file for Agency
rulemakings. The EPA places all information used to support its
proposed and final decisions in the docket, which is available for
review by the public. For the WIPP certification rulemaking,
information is placed in Air Docket Number A-93-02. The official docket
is located in Washington, DC, and informational dockets are provided in
three cities in New Mexico. (See the ``Dockets'' section of this
preamble for more information on the location and hours of EPA's WIPP
dockets.) The contents of the docket include technical information
received from outside parties and other information considered by EPA
in reaching a certification decision, as well as the Agency's rationale
for its decision. The technical support documents which describe the
basis for EPA's certification decision are discussed below; sources of
more general information on EPA's WIPP activities are also addressed.
A. Technical Support Documents
For more specific information about the basis for EPA's
certification decision, there are a number of technical support
documents available. The Compliance Application Review Documents, or
CARDs, contain the detailed technical rationale for EPA's certification
decision. This document is found at Docket A-93-02, Item V-B-2.
The CARDs discuss DOE's compliance with the individual requirements
of the WIPP compliance criteria. Each CARD is a section in the document
which is numbered according to the section of 40 CFR Part 194 to which
it pertains. For example, CARD 23 addresses Sec. 194.23, ``Models and
Computer Codes.'' Each CARD: restates the specific requirement,
identifies relevant information expected in the CCA, explains EPA's
compliance review criteria, summarizes DOE's approach to compliance,
and describes EPA's compliance review and decision. The CARDs also list
additional EPA technical support documents and any other references
used by EPA in rendering its decision on compliance. All technical
support documents and references are available in Docket A-93-02 with
the exception of generally available references and those documents
already maintained by DOE or its contractors in locations accessible to
the public. (Instructions for obtaining access to DOE documents can be
found at Docket A-93-02, Item V-B-1.)
B. WIPP Information Line, Mailing List, and Internet Homepage
For more general information and updates on EPA's WIPP activities,
interested citizens may contact EPA's toll-free WIPP Information Line
at 1-800-331-WIPP. The hotline offers a recorded message, in both
English and Spanish, about current EPA WIPP activities, upcoming
meetings, and publications. Callers are also offered the option of
joining EPA's WIPP mailing list. Periodic mailings, including a WIPP
Bulletin and fact sheets related to specific EPA activities, are sent
to members of the mailing list (currently numbering over 800). The WIPP
internet homepage, at www.epa.gov/radiation/wipp, provides general
information on EPA's regulatory oversight of the WIPP. Federal Register
notices are also announced on the homepage, and a number of documents
(ranging from outreach materials and hearings transcripts to technical
support documents) are available to review or download.
XIV. With What Regulatory and Administrative Requirements Must This
Rulemaking Comply?
A. Executive Order 12866
Under Executive Order 12866, (58 FR 51735; October 4, 1993), the
Agency must determine whether the regulatory action is ``significant''
and therefore subject to OMB review and the requirements of the
Executive Order. The Order defines ``significant regulatory action'' as
one that is likely to result in a rule that may: (1) have an annual
effect on the economy of $100 million or more or adversely affect in a
material way the economy, a sector of the economy, productivity,
competition, jobs, the environment, public health or safety, or State,
local, or tribal governments or communities; (2) create a serious
inconsistency or otherwise interfere with an action taken or planned by
another agency; (3) materially alter the budgetary impact of
entitlements, grants, user fees, or loan programs or the rights and
obligations of recipients thereof; or (4) raise novel legal or policy
issues arising out of legal mandates, the President's priorities, or
the principles set forth in the Executive Order. Pursuant to the terms
of Executive Order 12866, it has been determined that this final rule
is a ``significant regulatory action'' because it raises novel policy
issues which arise from legal mandates. As such, this action was
submitted to OMB for review. Changes made in response to OMB
suggestions or recommendations are documented in the public record.
B. Regulatory Flexibility
The Regulatory Flexibility Act (``RFA'') generally requires an
agency to conduct a regulatory flexibility analysis of any rule subject
to notice and comment rulemaking requirements unless the agency
certifies that the rule will not have a significant economic impact on
a substantial number of small entities. Small entities include small
businesses, small not-for-profit enterprises, and small governmental
jurisdictions. This final rule will not have a significant impact on a
substantial number of small entities because it sets forth requirements
which apply only to Federal agencies. Therefore, I certify that this
action will not have a significant economic impact on a substantial
number of small entities.
C. Paperwork Reduction Act
The EPA has determined that this proposed rule contains no
information collection requirements as defined by the Paperwork
Reduction Act (44 U.S.C. 3501 et seq).
D. Unfunded Mandates Reform Act
Title II of the Unfunded Mandates Reform Act of 1995 (``UMRA''),
Pub. L. 104-4, establishes requirements for Federal agencies to assess
the effects of their regulatory actions on State, local and tribal
governments and the private sector. Pursuant to Title II of the UMRA,
EPA has determined that this regulatory action is not subject to the
requirements of sections 202 and 205, because this action does not
contain any ``federal mandates'' for State, local, or tribal
governments or for the private sector. The rule implements requirements
that are specifically set forth by the Congress in the Waste Isolation
Pilot Plant Land Withdrawal Act (Pub. L. 102-579) and that apply only
to Federal agencies.
E. Executive Order 12898
Pursuant to Executive Order 12898 (59 FR 7629, February 16, 1994),
entitled ``Federal Actions to Address Environmental Justice in Minority
Populations and Low-Income Populations,'' the Agency has considered
environmental justice related issues with regard to the potential
impacts of this action on the environmental and health conditions in
low-income, minority, and native American communities. The EPA has
complied with this mandate. The requirements specifically set forth by
[[Page 27404]]
the Congress in the Waste Isolation Pilot Plant Land Withdrawal Act
(Pub. L. 102-579), which prescribes EPA's role at the WIPP, did not
provide authority for EPA to examine impacts in the communities in
which wastes are produced, stored, and transported, and Congress did
not delegate to EPA the authority to consider alternative locations for
the WIPP.
The EPA involved minority and low-income populations early in the
rulemaking process. In 1993 EPA representatives met with New Mexico
residents and government officials to identify the key issues that
concern them, the types of information they wanted from EPA, and the
best ways to communicate with different sectors of the New Mexico
public. The feedback provided by this group of citizens formed the
basis for EPA's WIPP communications and consultation plan. To help
citizens, including a significant Hispanic population in Carlsbad and
the nearby Mescalero Indian Reservation, stay abreast of EPA's WIPP-
related activities, the Agency developed many informational products
and services. The EPA translated into Spanish many documents regarding
WIPP, including educational materials and fact sheets describing EPA's
WIPP oversight role and the radioactive waste disposal standards. The
EPA also established a toll-free WIPP Information Line, recorded in
both English and Spanish, providing the latest information on upcoming
public meetings, publications, and other WIPP-related activities. The
EPA also developed a vast mailing list, which includes many low-income,
minority, and native American groups, to systematically provide
interested parties with copies of EPA's public information documents
and other materials. Even after the final rule, EPA will continue its
efforts toward open communication and outreach.
F. Small Business Regulatory Enforcement Fairness Act of 1996
The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the
Small Business Regulatory Enforcement Fairness Act of 1996, generally
provides that before a rule may take effect, the agency promulgating
the rule must submit a rule report, which includes a copy of the rule,
to each House of the Congress and to the Comptroller General of the
United States. Section 804, however, exempts from section 801 the
following types of rules: rules of particular applicability; rules
relating to agency management or personnel; and rules of agency
organization, procedure, or practice that do not substantially affect
the right or obligations of non-agency parties. (5 U.S.C. 804(3)) The
EPA is not required to submit a rule report regarding today's action
under section 801 because this is a rule of particular applicability.
G. National Technology Transfer & Advancement Act of 1995
Section 12 of the National Technology Transfer & Advancement Act of
1995 is intended to avoid ``re-inventing the wheel.'' It aims to reduce
the costs to the private and public sectors by requiring federal
agencies to draw upon any existing, suitable technical standards used
in commerce or industry. To comply with the Act, EPA must consider and
use ``voluntary consensus standards,'' if available and applicable,
when implementing policies and programs, unless doing so would be
``inconsistent with applicable law or otherwise impractical.'' The EPA
has determined that this regulatory action is not subject to the
requirements of National Technology Transfer & Advancement Act of 1995
as this rulemaking is not setting any technical standards.
H. Executive Order 13045--Children's Health Protection
This final rule is not subject to E.O. 13045, entitled ``Protection
of Children from Environmental Health Risks and Safety Risks'' (62 FR
19885, April 23, 1997), because it does not involve decisions on
environmental health risks or safety risks that may disproportionately
affect children.
List of Subjects in 40 CFR Part 194
Environmental protection, Administrative practice and procedure,
Nuclear materials, Radionuclides, Plutonium, Radiation protection,
Uranium, Transuranics, Waste treatment and disposal.
Dated: May 13, 1998.
Carol M. Browner,
Administrator.
For the reasons set out in the preamble, 40 CFR Part 194 is amended
as follows.
PART 194--CRITERIA FOR THE CERTIFICATION AND RE-CERTIFICATION OF THE
WASTE ISOLATION PILOT PLANT'S COMPLIANCE WITH THE 40 CFR PART 191
DISPOSAL REGULATIONS
1. The authority citation for part 194 is revised to read as
follows:
Authority: Pub. L. 102-579, 106 Stat. 4777, as amended by Pub.
L. 104-201,110 Stat. 2422; Reorganization Plan No. 3 of 1970, 35 FR
15623, Oct. 6, 1970, 5 U.S.C. app. 1; Atomic Energy Act of 1954, as
amended, 42 U.S.C. 2011-2296 and 10101-10270.
2. In Sec. 194.2, a definition is added in alphabetical order to
read as follows:
Sec. 194.2 Definitions.
* * * * *
Administrator's authorized representative means the director in
charge of radiation programs at the Agency.
3. Section 194.8 is added to subpart A to read as follows:
Sec. 194.8 Approval Process for Waste Shipment from Waste Generator
Sites for Disposal at the WIPP
(a) Quality Assurance Programs at Waste Generator Sites. The Agency
will determine compliance with requirements for site-specific quality
assurance programs as set forth below:
(1) Upon submission by the Department of a site-specific quality
assurance program plan the Agency will evaluate the plan to determine
whether it establishes the applicable Nuclear Quality Assurance (NQA)
requirements of Sec. 194.22(a)(1) for the items and activities of
Secs. 194.22(a)(2)(i), 194.24(c)(3) and 194.24(c)(5). The program plan
and other documentation submitted by the Department will be placed in
the dockets described in Sec. 194.67.
(2) The Agency will conduct a quality assurance audit or an
inspection of a Department quality assurance audit at the relevant site
for the purpose of verifying proper execution of the site-specific
quality assurance program plan. The Agency will publish a notice in the
Federal Register announcing a scheduled inspection or audit. In that or
another notice, the Agency will also solicit public comment on the
quality assurance program plan and appropriate Department documentation
described in paragraph (a)(1) of this section. A public comment period
of at least 30 days will be allowed.
(3) The Agency's written decision regarding compliance with the
requisite quality assurance requirements at a waste generator site will
be conveyed in a letter from the Administrator's authorized
representative to the Department. No such compliance determination
shall be granted until after the end of the public comment period
described in paragraph (a)(2) of this section. A copy of the Agency's
compliance determination letter will be placed in the public dockets in
accordance with Sec. 194.67. The results of any inspections or audits
conducted by the Agency to evaluate the quality assurance programs
described in paragraph (a)(1) of this section will also
[[Page 27405]]
be placed in the dockets described in Sec. 194.67.
(4) Subsequent to any positive determination of compliance as
described in paragraph (a)(3) of this section, the Agency intends to
conduct inspections, in accordance with Secs. 194.21 and 194.22(e), to
confirm the continued compliance of the programs approved under
paragraphs (a)(2) and (a)(3) of this section. The results of such
inspections will be made available to the public through the Agency's
public dockets, as described in Sec. 194.67.
(b) Waste Characterization Programs at Waste Generator Sites. The
Agency will determine compliance with the requirements for use of
process knowledge and a system of controls at waste generator sites as
set forth below:
(1) For each waste stream or group of waste streams at a site, the
Department must:
(i) Provide information on how process knowledge will be used for
waste characterization of the waste stream(s) proposed for disposal at
the WIPP; and
(ii) Implement a system of controls at the site, in accordance with
Sec. 194.24(c)(4), to confirm that the total amount of each waste
component that will be emplaced in the disposal system will not exceed
the upper limiting value or fall below the lower limiting value
described in the introductory text of paragraph (c) of Sec. 194.24. The
implementation of such a system of controls shall include a
demonstration that the site has procedures in place for adding data to
the WIPP Waste Information System (``WWIS''), and that such information
can be transmitted from that site to the WWIS database; and a
demonstration that measurement techniques and control methods can be
implemented in accordance with Sec. 194.24(c)(4) for the waste
stream(s) proposed for disposal at the WIPP.
(2) The Agency will conduct an audit or an inspection of a
Department audit for the purpose of evaluating the use of process
knowledge and the implementation of a system of controls for each waste
stream or group of waste streams at a waste generator site. The Agency
will announce a scheduled inspection or audit by the Agency with a
notice in the Federal Register. In that or another notice, the Agency
will also solicit public comment on the relevant waste characterization
program plans and Department documentation, which will be placed in the
dockets described in Sec. 194.67. A public comment period of at least
30 days will be allowed.
(3) The Agency's written decision regarding compliance with the
requirements for waste characterization programs described in paragraph
(b)(1) of this section for one or more waste streams from a waste
generator site will be conveyed in a letter from the Administrator's
authorized representative to the Department. No such compliance
determination shall be granted until after the end of the public
comment period described in paragraph (b)(2) of this section. A copy of
the Agency's compliance determination letter will be placed in the
public dockets in accordance with Sec. 194.67. The results of any
inspections or audits conducted by the Agency to evaluate the plans
described in paragraph (b)(1) of this section will also be placed in
the dockets described in Sec. 194.67.
(4) Subsequent to any positive determination of compliance as
described in paragraph (b)(3) of this section, the Agency intends to
conduct inspections, in accordance with Secs. 194.21 and 194.24(h), to
confirm the continued compliance of the programs approved under
paragraphs (b)(2) and (b)(3) of this section. The results of such
inspections will be made available to the public through the Agency's
public dockets, as described in Sec. 194.67.
4. Appendix A to Part 194 is added to read as follows:
Appendix A to Part 194--Certification of the Waste Isolation Pilot
Plant's Compliance With the 40 CFR Part 191 Disposal Regulations
and the 40 CFR Part 194 Compliance Criteria
In accordance with the provisions of the WIPP Compliance
Criteria of this part, the Agency finds that the Waste Isolation
Pilot Plant (``WIPP'') will comply with the radioactive waste
disposal regulations at part 191, subparts B and C, of this chapter.
Therefore, pursuant to Section 8(d)(2) of the WIPP Land Withdrawal
Act (``WIPP LWA''), as amended, the Administrator certifies that the
WIPP facility will comply with the disposal regulations. In
accordance with the Agency's authority under Sec. 194.4(a), the
certification of compliance is subject to the following conditions:
Condition 1: Sec. 194.14(b), Disposal system design, panel
closure system. The Department shall implement the panel seal design
designated as Option D in Docket A-93-02, Item II-G-1 (October 29,
1996, Compliance Certification Application submitted to the Agency).
The Option D design shall be implemented as described in Appendix
PCS of Docket A-93-02, Item II-G-1, with the exception that the
Department shall use Salado mass concrete (consistent with that
proposed for the shaft seal system, and as described in Appendix
SEAL of Docket A-93-02, Item II-G-1) instead of fresh water
concrete.
Condition 2: Sec. 194.22: Quality Assurance. The Secretary shall
not allow any waste generator site other than the Los Alamos
National Laboratory to ship waste for disposal at the WIPP until the
Agency determines that the site has established and executed a
quality assurance program, in accordance with Secs. 194.22(a)(2)(i),
194.24(c)(3) and 194.24(c)(5) for waste characterization activities
and assumptions. The Agency will determine compliance of site-
specific quality assurance programs at waste generator sites using
the process set forth in Sec. 194.8.
Condition 3: Sec. 194.24: Waste Characterization. The Secretary
may allow shipment for disposal at the WIPP of legacy debris waste
at the Los Alamos National Laboratory (``LANL'') that can be
characterized using the systems and processes inspected by the
Agency and documented in Docket A-93-02, Item II-I-70. The Secretary
shall not allow shipment of any waste from any additional LANL waste
stream(s) or from any waste generator site other than LANL for
disposal at the WIPP until the Agency has approved the processes for
characterizing those waste streams for shipment using the process
set forth in Sec. 194.8.
Condition 4: Sec. 194.43, Passive institutional controls.
(a) Not later than the final recertification application
submitted prior to closure of the disposal system, the Department
shall provide, to the Administrator or the Administrator's
authorized representative:
(1) a schedule for implementing passive institutional controls
that has been revised to show that markers will be fabricated and
emplaced, and other measures will be implemented, as soon as
possible following closure of the WIPP. Such schedule should
describe how testing of any aspect of the conceptual design will be
completed prior to or soon after closure, and what changes to the
design of passive institutional controls may be expected to result
from such testing.
(2) documentation showing that the granite pieces for the
proposed monuments and information rooms described in Docket A-93-
02, Item II-G-1, and supplementary information may be: quarried (cut
and removed from the ground) without cracking due to tensile
stresses from handling or isostatic rebound; engraved on the scale
required by the design; transported to the site, given the weight
and dimensions of the granite pieces and the capacity of existing
rail cars and rail lines; loaded, unloaded, and erected without
cracking based on the capacity of available equipment; and
successfully joined.
(3) documentation showing that archives and record centers will
accept the documents identified and will maintain them in the manner
identified in Docket A-93-02, Item II-G-1.
(4) documentation showing that proposed recipients of WIPP
information other than archives and record centers will accept the
information and make use of it in the manner indicated by the
Department in Docket A-93-02, Item II-G-1 and supplementary
information.
(b) Upon receipt of the information required under paragraph (a)
of this condition, the Agency will place such documentation in the
public dockets identified in Sec. 194.67. The Agency will determine
if a modification to the
[[Page 27406]]
compliance certification in effect is necessary. Any such
modification will be conducted in accordance with the requirements
at Secs. 194.65 and 194.66.
[FR Doc. 98-13100 Filed 5-15-98; 8:45 am]
BILLING CODE 6560-50-P