[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 (K<INF>d</INF>)
    (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.'' <SUP>1</SUP> 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.<SUP>2</SUP>
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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).<SUP>3</SUP> 
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.<SUP>4</SUP> 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.<SUP>5</SUP> 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'').<SUP>6</SUP> 
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.<SUP>7</SUP> 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.
---------------------------------------------------------------------------

    \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).
---------------------------------------------------------------------------

    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\
---------------------------------------------------------------------------

    \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)
---------------------------------------------------------------------------

    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:
    <bullet> 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).
    <bullet> 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))
    <bullet> 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,<SUP>11</SUP> cavings,<SUP>12</SUP> 
spallings,<SUP>13</SUP> 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 <SUP>14</SUP> 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 <SUP>15</SUP> and gas erosion <SUP>16</SUP> 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, <SUP>17</SUP> 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 <SUP>18</SUP> 
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<SUP>-16</SUP> 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 <SUP>19</SUP> 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.
---------------------------------------------------------------------------

    <bullet> Air drilling technology is currently successfully used in 
the Delaware Basin.
    <bullet> Air drilling is thought to be a viable drilling technology 
under the hydrological and geological conditions at the WIPP site.
    <bullet> 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 
<SUP>20</SUP> 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 <SUP>21</SUP> 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:
    <bullet> Commenters' modeling of fluid injection that predicted 
potential releases exceeding EPA standards was based upon unrealistic 
assumptions that would maximize releases.
    <bullet> 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.
    <bullet> Modeling by DOE predicts that fluid injection will cause 
low flows that will not significantly impact the results of PA.
    <bullet> 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.
    <bullet> 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 (CO<INF>2</INF>) 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 
CO<INF>2</INF> into an oil reservoir to improve recovery. 
CO<INF>2</INF> injection is typically used in tertiary recovery 
processes after the economic limits for waterflooding have been 
reached. When CO<INF>2</INF> is injected and mixing occurs, the 
viscosity of the crude oil in the reservoir is reduced. The 
CO<INF>2</INF> 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 CO<INF>2</INF> begins to 
appear at the producing well, it is typically recovered, cleaned of 
impurities, pressurized and re-injected.
    The use of CO<INF>2</INF> flooding for enhanced oil recovery in 
west Texas and southern New Mexico began in 1972. In this area, most 
CO<INF>2</INF> injection activity is located on the Central Basin 
Platform and on the Northwest Shelf. A limited number of CO<INF>2</INF> 
flooding projects have occurred in the Texas portion of the Delaware 
Basin. Economy of scale, oil prices, proximity to CO<INF>2</INF> 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 CO<INF>2</INF> 
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 CO<INF>2</INF> injection was not a 
current practice. However, as a result of the public comments, EPA 
reviewed the issue and determined that CO<INF>2</INF> injection does 
occur in the Texas portion of the Delaware Basin. In responding to 
comments, EPA found no evidence of CO<INF>2</INF> injection practices 
in the New Mexico portion of the Delaware Basin. (Docket A-93-02, Item 
V-C-1, Section 8) All CO<INF>2</INF> injection projects found in New 
Mexico occurred outside the Delaware Basin. The EPA found that 
CO<INF>2</INF> 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 CO<INF>2</INF> injection is practiced in the Delaware 
Basin, EPA conducted an analysis of the consequences that 
CO<INF>2</INF> injection could have on the PA calculations.
    In order to investigate the potential effect of CO<INF>2</INF> 
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 CO<INF>2</INF> 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 CO<INF>2</INF> 
migration. Other conservative assumptions included a long time frame 
for injection, constant CO<INF>2</INF> 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 CO<INF>2</INF> would be injected into the Delaware 
Mountain Group below WIPP and readily migrate to Marker Bed 139, 
through which CO<INF>2</INF> 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 
CO<INF>2</INF> flood indicate that, even if it were to occur, 
CO<INF>2</INF> 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 CO<INF>2</INF> to ever reach the repository. In summary, 
DOE determined that CO<INF>2</INF> 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 CO<INF>2</INF> injection activities in the Delaware 
Basin. The EPA conducted an analysis of the effects of CO<INF>2</INF> 
injection on the repository and found that CO<INF>2</INF> injection can 
be omitted from the PA because of the minimal consequences that would 
occur as a result of CO<INF>2</INF> 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 
(<INF>2</INF>) and methane (CH<INF>4</INF>). 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:
    <bullet> Gas is generated primarily by metal corrosion and 
microbial processes;
    <bullet> Gas generation is closely linked to other processes;
    <bullet> Gas generation from microbial processes will not always 
occur;
    <bullet> High gas pressures in the repository can cause the Salado 
anhydrite interbeds to fracture; and
    <bullet> 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 CO<INF>2</INF> 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 H<INF>2</INF> 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 CO<INF>2</INF> 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 CO<INF>2</INF> 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 CO<INF>2</INF> 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 <SUP>22</SUP>) 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]]

    <bullet> Parameters that were likely to contribute significantly to 
releases or seemed to be poorly justified;
    <bullet> 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
    <bullet> 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 (K<INF>d</INF>), 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 (K<INF>d</INF>). As the primary 
radionuclide pathway during an intrusion, the Culebra was the subject 
of many public comments, especially related to distribution 
coefficients <SUP>23</SUP> (K<INF>d</INF> 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 K<INF>d</INF> 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<SUP>+4</SUP> or 
U<SUP>+6</SUP>. 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 K<INF>d</INF>'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 K<INF>d</INF> 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 K<INF>d</INF> 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 K<INF>d</INF> 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 
K<INF>d</INF> 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 
K<INF>d</INF> values that are representative of conditions in the 
Culebra. The DOE data on actinide K<INF>d</INF> 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 K<INF>d</INF> 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 K<INF>d</INF> values obtained from the DOE 
experiments are inclusive of any scale-effects that might produce a 
different average K<INF>d</INF> 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 K<INF>d</INF> 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 K<INF>d</INF> values and concluded 
that the population of K<INF>d</INF> 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 
K<INF>d</INF> 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 
K<INF>d</INF> values necessary to achieve compliance with EPA limits. 
The bounding estimates were obtained for plutonium (<SUP>239</SUP>Pu) 
and americium (<SUP>241</SUP>Am), 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 K<INF>d</INF> of 3 milliliter per gram 
(ml/g) is sufficient for compliance for <SUP>239</SUP>Pu and

[[Page 27378]]

<SUP>241</SUP>Am. Estimates based on typical CCA sample sets indicate 
that K<INF>d</INF> values greater than 1 ml/g are sufficient for 
compliance. (A higher K<INF>d</INF> value indicates greater 
retardation--or less movement--of radionuclides.) The K<INF>d</INF> 
ranges determined from DOE column experiments, conducted since 
submission of the CCA, for <SUP>239</SUP>Pu and <INF>241</INF>Am are 
typically greater than 100 ml/g, thus inferring that K<INF>d</INF> 
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 K<INF>d</INF> 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 
K<INF>d</INF> values and finds the K<INF>d</INF> values used in the PA 
are sufficient. Refer to EPA Technical Support Document for Section 
194.14: Assessment of K<INF>d</INF> 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 CO<INF>2</INF> 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 <SUP>24</SUP>, 
BRAGFLO--DBR <SUP>25</SUP>, CUTTINGS--S <SUP>26</SUP>, SOURCE TERM 
<SUP>27</SUP>, and CCDFGF <SUP>28</SUP>. 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 <SUP>29</SUP> 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 (K<INF>d</INF>), 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, CO<INF>2</INF> 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 
CO<INF>2</INF> 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, CO<INF>2</INF> 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, 
CO<INF>2</INF> 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 ``CO<INF>2</INF> 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.<SUP>30</SUP> 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.
---------------------------------------------------------------------------

    \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.<SUP>31</SUP> 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 <SUP>32</SUP> 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.<SUP>33</SUP> 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.
---------------------------------------------------------------------------

    \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.
---------------------------------------------------------------------------

    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.<SUP>34</SUP> 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'') <SUP>35</SUP>, and will 
undergo headspace-gas sampling and analysis for volatile organic 
compound concentrations.<SUP>36</SUP>
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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.
---------------------------------------------------------------------------

    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 
CO<INF>2</INF> 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.<SUP>37</SUP> (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.
---------------------------------------------------------------------------

    \37\ Pub. L. 102-579, sections 4(b)(5) and 7(b)(2).
---------------------------------------------------------------------------

    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.<SUP>38</SUP> 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.<SUP>39</SUP>
---------------------------------------------------------------------------

    \38\ WIPP LWA, section 8(b).
    \39\ 50 FR 38066-38089 (September 19, 1985) and 58 FR 66398-
66416 (December 20, 1993).
---------------------------------------------------------------------------

    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.<SUP>40</SUP>
---------------------------------------------------------------------------

    \40\ 61 FR 5224-5245 (February 9, 1996).
---------------------------------------------------------------------------

    Third, EPA must review the information submitted by DOE and publish 
a certification decision.<SUP>41</SUP> Today's action constitutes EPA's 
certification decision as required by section 8 of the WIPP LWA.
---------------------------------------------------------------------------

    \41\ WIPP LWA, section 8(d).
---------------------------------------------------------------------------

    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.<SUP>42</SUP> 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?''
---------------------------------------------------------------------------

    \42\ WIPP LWA, section 8(f).
---------------------------------------------------------------------------

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.<SUP>43</SUP> 
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.
---------------------------------------------------------------------------

    \43\ WIPP LWA, sections 7(b)(3) and 9.
---------------------------------------------------------------------------

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.<SUP>44</SUP>
---------------------------------------------------------------------------

    \44\ 5 U.S.C. 553.
---------------------------------------------------------------------------

    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