[Federal Register Volume 62, Number 210 (Thursday, October 30, 1997)]
[Proposed Rules]
[Pages 58792-58838]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-28647]



[[Page 58791]]

_______________________________________________________________________

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 40 CFR Part 191 Disposal 
Regulations: Certification Decision; Proposed Rule

Federal Register / Vol. 62, No. 210 / Thursday, October 30, 1997 / 
Proposed Rules

[[Page 58792]]



ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 194

[FRL-5915-1]
RIN 2060-AG85


Criteria for the Certification and Re-Certification of the Waste 
Isolation Pilot Plant's Compliance With the 40 CFR Part 191 Disposal 
Regulations: Certification Decision

AGENCY: Environmental Protection Agency.

ACTION: Proposed rule; opening of public comment period.

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SUMMARY: The Environmental Protection Agency (``EPA'') is proposing to 
certify that the Department of Energy's (``DOE'') Waste Isolation Pilot 
Plant (``WIPP'') will comply with the radioactive waste disposal 
regulations set forth at 40 CFR Part 191 (Environmental Standards for 
the Management and Disposal of Spent Nuclear Fuel, High-Level and 
Transuranic Radioactive Waste). 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, if finalized, would allow the 
emplacement of radioactive waste in the WIPP to begin, provided that 
all other applicable health and safety standards have been met. The 
proposed certification would allow Los Alamos National Laboratory to 
ship TRU waste from specific waste streams for disposal at the WIPP. 
However, the proposed certification is subject to several conditions, 
notably that EPA must approve site-specific waste characterization 
measures and quality assurance plans before allowing other waste 
generator sites to ship waste for disposal at the WIPP. The Agency 
proposes to amend 40 CFR Part 194 by adding an appendix describing 
EPA's certification, and by adding a definition. Finally, EPA is 
proposing its decision, also pursuant to the LWA, that DOE does not 
need to acquire existing oil and gas leases near the WIPP in order to 
meet the disposal regulations. Today's notice marks the beginning of a 
120-day public comment period on EPA's proposed certification decision, 
and on the other proposed actions described above.

DATES: Comments on today's proposal must be received by February 27, 
1998. Public hearings on today's proposal will be held in New Mexico. A 
separate announcement will be published in the Federal Register to 
provide public hearing information.

ADDRESSES: Comments should be submitted, in duplicate, to: Docket No. 
A-93-02, Air Docket, Room M-1500 (LE-131), U.S. Environmental 
Protection Agency, 401 M Street, SW., Washington, DC 20460. See 
additional docket information in the SUPPLEMENTARY INFORMATION.

FOR FURTHER INFORMATION CONTACT: Betsy Forinash or Scott Monroe; 
telephone number (202) 233-9310; address: Radiation Protection 
Division, Center for the Waste Isolation Pilot Plant, Mail Code 6602-J, 
U.S. Environmental Protection Agency, 401 M Street SW., Washington, DC 
20460. For copies of the Compliance Application Review Documents 
supporting today's proposal, contact Scott Monroe at the above phone 
number and address.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Background
II. Statutory Authority
III. Purpose and Scope of Today's Action
IV. Limits of EPA's Regulatory Authority at the WIPP
V. Public Participation
    A. Advance Notice of Proposed Rulemaking (ANPR)
    B. Public Hearings on ANPR
    C. Additional Public Input
    D. Public Comments on ANPR
    E. Completeness Determination
    F. Public Comments on Completeness
    G. Proposed Certification Decision
    H. Final Certification Decision
    I. Dockets
VI. National Academy of Sciences Report on the WIPP
VII. Codification of EPA's Certification Decision
VIII. Determination of Whether the WIPP Complies with the Disposal 
Regulations
    A. Basis for EPA's Compliance Determination
    B. Compliance Application Review Documents (CARDs)
IX. Section 194.14, Content of Compliance Certification Application
    A. Site Characterization
    B. Disposal System Design
    C. Results of Assessments
    D. Input Parameters to Performance Assessments
    E. Assurance Requirements
    F. Waste Acceptance Criteria
    G. Background Radiation
    H. Topographic Maps
    I. Past and Current Meteorological Conditions
    J. Other Information Needed for Demonstration of Compliance
    K. Conclusion
X. General Requirements
    A. Section 194.22, Quality Assurance
    B. Section 194.23, Models and Computer Codes
    1. Conceptual models
    a. Description of conceptual models
    b. Alternative conceptual models
    c. Future states of the disposal system and peer review
    d. Public comments
    2. Progression from conceptual models to computer codes
    a. Mathematical models
    b. Public comments on mathematical models
    c. Numerical models
    d. Computer codes
    3. Quality assurance
    4. Documentation of models and codes
    a. Theoretical background
    b. Descriptions of models
    c. Parameters
    d. Public comments on parameter values
    e. Software licenses
    f. Parameter correlation
    5. EPA's independent testing
    C. Section 194.24, Waste Characterization
    D. Section 194.25, Future State Assumptions
    E. Section 194.26, Expert Judgment
    F. Section 194.27, Peer Review
XI. Containment Requirements
    A. Section 194.31, Application of Release Limits
    B. Section 194.32, Scope of Performance Assessments (PA)
    C. Section 194.33, Consideration of Drilling Events in PA
    D. Section 194.34, Results of PA
    1. Complementary cumulative distribution functions (CCDFs)
    2. Generation of the full range of CCDFs
    3. Probability distributions and random sampling of uncertain 
parameters
    4. Sufficient number of CCDFs generated
    5. Compliance of the mean CCDF
XII. Assurance Requirements
    A. Section 194.41, Active Institutional Controls
    B. Section 194.42, Monitoring
    C. Section 194.43, Passive Institutional Controls
    D. Section 194.44, Engineered Barriers
    E. Section 194.45, Consideration of the Presence of Resources
    F. Section 194.46, Removal of Waste
XIII. Individual and Ground-water Protection Requirements
    A. Section 194.51, Consideration of Protected Individual
    B. Section 194.52, Consideration of Exposure Pathways
    C. Section 194.53, Consideration of Underground Sources of 
Drinking Water
    D. Section 194.54, Scope of Compliance Assessments (CA)
    E. Section 194.55, Results of CA
    1. Uncertainty of CA
    2. Probability distributions for uncertain parameters
    3. Sampling of uncertain parameters
    4. Sufficient number of estimates generated
    5. Display full range of CA results
    6. Compliance with radiation dose and radionuclide concentration 
limits
XIV. Land Withdrawal Act Section 4(b)(5)(B) Leases
XV. Administrative Requirements
    A. Executive Order 12866
    B. Regulatory Flexibility
    C. Paperwork Reduction Act

[[Page 58793]]

    D. Unfunded Mandates Reform Act
    E. Executive Order 12898

I. Background

    Congress authorized development and construction of the Waste 
Isolation Pilot Plant (``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 U.S. Department 
of Energy (``DOE'' or ``the Department'') is developing the WIPP near 
Carlsbad in southeastern New Mexico as a potential deep geologic 
repository for the disposal of defense transuranic (``TRU'') 
radioactive waste. TRU waste consists of materials containing alpha-
emitting radio-isotopes, with half-lives greater than twenty years and 
atomic numbers greater than 92, in concentrations greater than 100 
nano-curies per gram of waste.\2\ 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, 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 on Federal 
lands 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 as weapons are disassembled and additional facilities are 
decontaminated and decommissioned.
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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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    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.<SUP>3</SUP> The purpose of today's action is to 
propose EPA's certification decision.
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    \3\ WIPP LWA, section 8(d).
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II. Statutory Authority

    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. The LWA delegates to EPA three main tasks, to be 
completed sequentially, for reaching a compliance certification 
decision. First, EPA must finalize general regulations which apply to 
all sites--except Yucca mountain--for the disposal of highly 
radioactive waste.<SUP>4</SUP> The regulations, located at Subparts B 
and C of 40 CFR Part 191 (``disposal 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. The disposal regulations were published in 
the Federal Register in 1985 and 1993.<SUP>5</SUP>
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    \4\ WIPP LWA, section 8(b).
    \5\ 50 FR 38066-38089 (September 19, 1985) and 58 FR 66398-66416 
(December 20, 1993).
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    Second, EPA must develop, by rulemaking, criteria to implement and 
interpret the generic radioactive waste disposal regulations 
specifically for the WIPP. EPA issued these ``WIPP Compliance 
Criteria,'' which are found at 40 CFR Part 194, in 1996.<SUP>6</SUP> 
The criteria describe in detail what information DOE must submit for 
EPA's review, and clarify the basis on which EPA's compliance 
determination will be made.
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    \6\ 61 FR 5224-5245 (February 9, 1996), ``Criteria for the 
Certification and Re-certification of the Waste Isolation Pilot 
Plant's Compliance with the 40 CFR Part 191 Disposal Regulations.'' 
(Certain aspects of the Compliance Criteria were challenged in the 
Court of Appeals for the D.C. Circuit. The Court upheld the 
Compliance Criteria in their entirety. State of New Mexico v. Envt'l 
Protection Agency, No. 96-1107 (D.C. Cir. June 6, 1997)).
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    Third, EPA must review information submitted by DOE and publish a 
certification decision.<SUP>7</SUP> Today's action constitutes EPA's 
proposed certification decision as required by section 8 of the LWA. On 
October 29, 1996, DOE submitted a compliance certification application 
(``CCA'') containing information intended to demonstrate that WIPP will 
comply with the disposal regulations. Since then, DOE has submitted 
additional information. On May 22, 1997, EPA announced that DOE's 
application was deemed to be complete. (62 FR 27996-27998) EPA's 
evaluation of whether the WIPP will comply with the disposal 
regulations is made by comparing the CCA and other relevant 
information--including supplementary information requested by EPA from 
DOE, and the results of EPA's confirmatory audits and inspections--to 
the WIPP Compliance Criteria. The Administrator's certification of 
compliance depends on DOE demonstrating that it has satisfied the 
specific requirements of the WIPP Compliance Criteria.
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    \7\ WIPP LWA, section 8(d).
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III. Purpose and Scope of Today's Action

    Today's action is limited primarily to the certification decision 
required under section 8(d) of the LWA. In addition, the proposal 
addresses the provision of section 4(b)(5)(B) of the LWA which requires 
EPA to determine whether existing oil and gas leases in the vicinity of 
the WIPP must be acquired by DOE. EPA has decided that it is 
appropriate to include this determination in this rulemaking because 
Congress explicitly conditioned emplacement of wastes in the repository 
on DOE's acquisition of the specified leaseholds, unless EPA determines 
that such acquisition is not required. (LWA, section 7(b)(2)) While 
Congress' mandate that EPA make this determination is separate and 
apart from the section 8(d) mandate to conduct the WIPP certification 
proceeding pursuant to notice-and-comment rulemaking procedures, EPA 
nonetheless believes it appropriate to address the leases in this 
rulemaking. The determination of whether potential drilling on the 
specified leases could possibly affect the integrity of the repository 
is closely related to the similar determinations that must be made 
under Secs. 194.32(c) and 194.54(b) of the Compliance Criteria. 
Moreover, EPA is committed to the intent of Congress, clearly expressed 
in the LWA, that the public be involved in these important regulatory 
determinations. Therefore, by including this decision in this proposal, 
EPA is providing the public with the opportunity for input on this 
matter.
    The Agency is proposing to add to the Compliance Criteria an 
appendix describing EPA's certification decision and to define the term 
``Administrator's authorized representative.'' Except for these 
additions, EPA's proposed decision regarding WIPP's compliance does not 
otherwise amend or affect the final disposal regulations (at Subparts B 
and C of 40 CFR Part 191), or the final WIPP Compliance Criteria (at 
Subparts A through D of 40 CFR Part 194).
    Today's proposal does not address all the actions required of EPA 
by the LWA. For example, the proposal does not address compliance with 
EPA's radioactive waste management regulations--found in Subpart A of 
40 CFR Part 191--which are referenced in section 9(a)(1)(A) of the LWA. 
Instead, the Agency has issued, in a separate action, guidance 
describing how EPA intends to implement Subpart A at the 
WIPP.<SUP>8</SUP> For copies of the WIPP Subpart

[[Page 58794]]

A Guidance (Document Number EPA 402-R-97-001), call the EPA WIPP 
Information Line at 1-800-331-WIPP, or write to Betsy Forinash, Center 
for the Waste Isolation Pilot Plant, Mail Code 6602-J, U.S. 
Environmental Protection Agency, 401 M Street, SW., Washington, DC 
20460.
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    \8\ 62 FR 9188 (February 28, 1997), Notice of Availability for 
``Guidance for the Implementation of EPA's Radiation Protection 
Standards for Management and Storage of Transuranic Waste at the 
Waste Isolation Pilot Plant ('WIPP Subpart A Guidance').''
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    Finally, today's proposal does not address requirements of the LWA 
which must be fulfilled by other regulatory agencies. Enforcement of 
some parts of the hazardous waste regulations, for example, 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 constrained by EPA's proposed certification decision.

IV. Limits of EPA's Regulatory Authority at the WIPP

    As discussed above, the 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 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 Advanced Notice of Proposed 
Rulemaking for today's proposal, a desire for the Agency to oversee 
other aspects of WIPP's operation. In response to such concerns, EPA 
must clarify that its authority to regulate DOE and the WIPP is limited 
by the 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 current rulemaking.
    Several 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. EPA must conduct its WIPP activities in accordance with 
the intent of Congress as expressed in the 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 the EPA as established in 
the LWA and, thus, necessarily outside the scope of this rulemaking.
    Some commenters requested that EPA consider certain factors in 
making its certification decision. These factors include: reviews by 
organizations other than EPA, safety at other DOE facilities, and the 
political or economic motivations of interested parties. Pursuant to 
the LWA, EPA's certification decision must be made based on the WIPP 
Compliance Criteria at 40 CFR Part 194, and in accordance with 
requirements governing informal rulemaking proceedings. EPA is tasked 
only with examining the scope and quality of relevant information, and 
comparing such information to the objective criteria of 40 CFR Part 
194. Where relevant, the Agency has considered public comments and 
outside reviews which support or refute technical positions taken by 
DOE. Emotional pleas, comments on the motives of interested parties, 
and the safety of sites or disposal methods other than the WIPP are 
factors that are not relevant to a determination of whether DOE has 
demonstrated compliance with the WIPP Compliance Criteria, and are 
therefore outside the scope of this rulemaking.
    In addition, the hazards of transporting radioactive waste from 
storage sites to the WIPP have been of great concern to the public. EPA 
has received numerous public comments, oral and written, concerning the 
possible transport of TRU waste to the WIPP. Transportation is entirely 
outside EPA's general authority for regulating radioactive waste. 
Moreover, in the LWA, Congress did not authorize any role for EPA with 
respect to transportation. Congress addressed transportation issues by 
requiring DOE to (1) use only shipping containers approved by the 
Nuclear Regulatory Commission; (2) notify in advance States and Indian 
Tribes of the transport of TRU waste through their jurisdictions; (3) 
provide technical assistance and funding to ensure that jurisdictions 
along WIPP transportation routes receive appropriate training for 
accident prevention and emergency preparedness; (4) provide 
transportation safety assistance to States or Indian tribes through 
whose jurisdictions TRU waste will be transported; and (5) study 
transportation alternatives. (LWA, section 16) Transportation of 
radioactive waste is regulated by the Nuclear Regulatory Commission and 
the U.S. Department of Transportation. Because all transportation 
requirements for the WIPP are established and enforced by other 
regulators, EPA does not address the issue further in this proposal.

V. Public Participation

    Section 8(d)(2) of the LWA requires that the Administrator's 
certification decision be conducted by informal (or ``notice-and-
comment'') rulemaking pursuant to Section 553 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 
adopted.<SUP>9</SUP>
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    \9\ 5 U.S.C. 553.
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    The WIPP is a first-of-a-kind project, and New Mexico citizens have 
expressed a great deal of interest in the safety of the site. 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. EPA 
either has or will comply with each of these requirements.
    In addition, EPA has taken other measures to assure that the public 
is involved in the present rulemaking. EPA allowed the New Mexico 
Environment Department, the New Mexico Environmental Evaluation Group, 
and more recently, the New Mexico Attorney General's Office as well, to 
observe meetings between EPA and DOE staff to discuss technical issues 
during the pre-proposal period. EPA also committed to summarize all 
meetings between EPA and DOE (including management level meetings

[[Page 58795]]

and meetings between EPA and DOE legal staff) and to place such 
summaries in the public docket. While these commitments are not 
required by the APA, EPA believes that they are useful given the 
importance of this rulemaking to the nation as a whole, and New Mexico 
in particular.

A. Advance Notice of Proposed Rulemaking (ANPR)

    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. Upon receipt of the CCA, EPA 
immediately began its review of the application in accordance with 40 
CFR 194.11, ``Completeness and accuracy of compliance applications.'' 
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.

B. Public Hearings on ANPR

    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. All individuals who requested an opportunity 
to address the EPA panel during the hearings were afforded five minutes 
if they were representing themselves, or ten minutes if they were 
representing a group. In Albuquerque and Santa Fe, EPA extended the 
hours of the hearings in order to accommodate all individuals who 
requested that they be allowed to address the panel.

C. Additional Public Input

    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, including the New Mexico Attorney General's 
Office, the New Mexico Environmental Evaluation Group, 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, Category II-
E.

D. Public Comments on ANPR

    The Agency received over 220 sets of written and oral public 
comments in response to the ANPR. All comments received on the ANPR 
were made available to members of the public through the public docket. 
(Docket A-93-02, Category II-H) In accordance with 40 CFR 194.61(f), 
DOE submitted to the Agency additional information specifically 
addressing many of the comments received; these submittals were treated 
by EPA as public comments.
    The Agency reviewed all public comments submitted during the ANPR 
120-day comment period or presented at the preliminary meetings with 
stakeholders. Public comments received in response to the ANPR 
generally focused on the completeness of the CCA, specific technical 
issues relating to compliance with the disposal regulations, and EPA's 
approach to public participation in accordance with the provisions of 
the WIPP Compliance Criteria, and pursuant to the LWA and the APA.
    The EPA is providing responses to these comments in this preamble 
as well as in the compliance application review documents (``CARDs'') 
which are part of today's proposed certification decision. The CARDs 
also address late comments--and comments on completeness (see below)--
received after the close of the public comment period (on March 17, 
1997) but before August 8, 1997. 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. Comments received after August 8 were considered by EPA, to 
the extent possible, in its development of the proposed rule, but were 
not addressed in CARDs because of time constraints. Such comments will 
be addressed in the Response to Comments document for EPA's final 
certification decision.

E. Completeness Determination

    Section 8(d)(1)(B) of the LWA establishes a one-year time frame for 
the Administrator to reach a certification decision regarding WIPP's 
compliance with the disposal regulations. Section 8(d)(4) of the LWA 
requires that EPA make its certification determination only after DOE 
has submitted the ``full application'' to EPA. The Compliance Criteria, 
at Sec. 194.11, interpret these requirements to mean one year from 
receipt of a ``complete'' certification application from DOE. This 
assures that the one-year review period is devoted exclusively to 
substantive, meaningful review of the CCA.
    Upon receipt of the CCA in October 1996, EPA began reviewing the 
CCA for both completeness and, to the extent possible, technical 
adequacy. Pursuant to section 8(d)(1) of the LWA, EPA provided requests 
to DOE for specific information needed for completeness on December 19, 
1996. (Docket A-93-02, Item II-I-1, Attachment 1) DOE submitted the 
requested information with letters dated January 17, January 24, 
February 7, February 14, and February 26, 1997. (This correspondence is 
available in Docket A-93-02, Category II-I.) On May 16, 1997, the 
Administrator informed the Secretary, in writing, that the CCA was 
complete. The completeness determination was announced in the Federal 
Register on May 22, 1997. (62 FR 27996-27998)
    The determination of completeness meant only that all sections of 
the disposal regulations and Compliance Criteria had been addressed in 
the CCA. The completeness determination did not state or imply that 
compliance with the disposal regulations or WIPP Compliance Criteria 
had been achieved. In short, the completeness determination was an 
interim administrative step to announce that the CCA contained the 
information necessary for the Agency to proceed with its technical 
evaluation of compliance.
    Moreover, section 8(d)(1) of the LWA specifically allows EPA to 
request additional information ``as needed to certify'' at any time. 
EPA made such additional requests in letters to DOE 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-32, and II-I-37, respectively)

F. Public Comments on Completeness

    The Agency received numerous public comments regarding the timing 
of the Administrator's completeness determination. While some comments 
stated that the CCA was administratively complete upon submission, 
others argued that the CCA was incomplete and simply should be returned 
to DOE. The latter set of commenters expressed that it was not 
appropriate for the Agency to close the public comment period on the 
ANPR prior to the Administrator's determination of completeness, and 
that the public hearings should be delayed until after the completeness 
determination. Other commenters

[[Page 58796]]

requested an additional 120-day comment period after the completeness 
determination was issued, as well as an additional set of public 
hearings during such a comment period.
    In making its completeness determination, EPA considered public 
comments which explicitly addressed the issue of completeness and were 
submitted to the docket or to EPA's Office of Radiation and Indoor Air. 
In response to concerns expressed by commenters, the Agency notified 
the public in the Federal Register announcement regarding the 
completeness determination that EPA would continue to accept public 
comments on the CCA subsequent to the completeness determination. (62 
FR 27997) (Comments on completeness received before August 8, 1997, are 
addressed in more detail in the CARDs supporting this proposal. 
Comments received after August 8 will be addressed in the Response to 
Comments document for EPA's final certification rule.) In accordance 
with Sec. 194.62, the public is being afforded a 120-day period in 
which to comment on today's proposal. This comment period will provide 
the public with another opportunity to comment on DOE's CCA, as well as 
an opportunity to address EPA's proposed certification decision.
    Public comments received during and after the ANPR comment period 
also requested that EPA clarify what specific material constitutes the 
``complete'' CCA. This concern was raised because, at EPA's request, 
DOE supplemented the docket with substantial additional materials 
beyond what was initially submitted on October 29, 1996. Many of the 
issues raised by public comments were addressed in a December 19, 1996 
letter to DOE in which EPA identified additional information necessary 
for the CCA to constitute a complete application. (Docket A-93-02, Item 
II-I-1, Attachment 1) To address completeness concerns, EPA requested 
additional information on (among other topics) site conditions, 
documentation of computer codes, and the effects of explosions--issues 
all identified in public comments. DOE submitted the requested 
information with letters dated January 17, January 24, February 7, 
February 14, and February 26, 1997. The complete CCA consists of the 
application that was submitted to EPA on October 29, 1996, and 
supplementary materials provided by DOE that were identified by EPA, in 
the December 19 letter, as necessary for completeness. A list of the 
specific items that comprise the complete application is located in 
Docket A-93-02, Item II-G-29. All correspondence between DOE and EPA 
regarding completeness of the CCA is available in the Agency's public 
dockets. (Docket A-93-02, Category II-I)
    Other issues raised by commenters, such as fluid injection 
scenarios, were not considered relevant to the completeness 
determination and instead were addressed by EPA in its technical 
comments to DOE.

G. Proposed Certification Decision

    Today's Notice of Proposed Rulemaking for certification fulfills 
the requirements of the WIPP Compliance Criteria at Sec. 194.62. 
Today's notice announces the Administrator's proposed decision, 
pursuant to section 8(d)(1) of the LWA, as amended, to issue a 
certification that the WIPP facility will comply with the disposal 
regulations, and solicits comment on the proposal. Today's notice also 
marks the beginning of a 120-day public comment period on EPA's 
proposed certification decision. Finally, today's notice announces that 
public hearings will be held in New Mexico during the public comment 
period. Further information on the hearings will be provided in a 
subsequent Federal Register notice. Any comments received on today's 
notice will be made available for inspection in Docket A-93-02, 
Category IV-D.

H. Final Certification Decision

    The Agency will publish a final rule in the Federal Register 
announcing the Administrator's final decision, pursuant to section 
8(d)(1) of the LWA and in accordance with the Compliance Criteria at 40 
CFR 194.63, whether to issue a certification that the WIPP facility 
will comply with the disposal regulations. EPA will review comments 
submitted on EPA's proposed decision. (Comments regarding the ANPR and 
completeness that are addressed in the CARDs for the proposed rule have 
already been considered and will not be addressed again in the Response 
to Comments document for the final rule.) A document summarizing 
significant comments and issues arising from comments received on 
today's Notice of Proposed Rulemaking, as well as the Administrator's 
response to such significant comments and issues, will be prepared and 
will be made available for inspection in Docket A-93-02.

I. Dockets

    In accordance with 40 CFR 194.67, EPA maintains a public docket 
(Docket A-93-02) that will contain 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 proposed certification decision 
regarding whether the WIPP facility will comply with the disposal 
regulations. Copies of the CCA were placed in Category II-G of the 
docket. Supplementary information received from DOE in response to EPA 
requests was placed in Categories II-I and II-G.
    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.

VI. National Academy of Sciences Report on the WIPP

    The National Academy of Sciences (``NAS'') has long considered the 
issue of proper disposal of radioactive wastes. The NAS first discussed 
the likely suitability of salt formations as a medium for geologic 
disposal of high-level radioactive wastes in 1957.<SUP>10</SUP> A later 
study recommended the use of

[[Page 58797]]

bedded salt formations for geologic disposal. <SUP>11</SUP>
---------------------------------------------------------------------------

    \10\  National Research Council (NRC), ``The Disposal of 
Radioactive Wastes on Land'' (National Academy Press 1957).
    \11\  NRC, ``Disposal of Solid Radioactive Wastes in Bedded Salt 
Deposits'' (National Academy Press 1970).
---------------------------------------------------------------------------

    The NAS has provided specific scientific and technical guidance to 
DOE regarding the WIPP since the inception of the NAS WIPP Committee in 
1978. In October 1996, the NAS released a report assessing the long-
term safety and performance of the WIPP disposal system. The report is 
available in Docket A-93-02, Item II-A-38. The WIPP committee's 
schedule did not allow for review of the CCA submitted to EPA in 
October 1996; instead, the committee examined a preliminary performance 
assessment (``PA'') conducted in 1992, and draft versions of DOE's CCA. 
For this reason and others, the NAS noted that the report was ``a 
review of ongoing activities and should be viewed as a progress report 
rather than a final evaluation.'' <SUP>12</SUP>
---------------------------------------------------------------------------

    \12\  NRC, ``The Waste Isolation Pilot Plant: A Potential 
Solution for the Disposal of Radioactive Waste'' (National Academy 
Press 1996), p. 12.
---------------------------------------------------------------------------

    The report reiterates NAS belief that salt is an attractive medium 
for geologic isolation of radioactive waste. Based on its review of the 
1992 PA, the committee found no credible or probable scenario for 
release of radionuclides from the WIPP if it is undisturbed by human 
intrusion. The report concluded that disturbed scenarios--i.e., those 
involving deliberate or unintentional human intrusion--could compromise 
the integrity of the disposal system. Finally, the committee 
recommended several changes intended to produce a more technically 
defensible and more easily understood PA.
    EPA considered the NAS report in developing its proposed 
certification decision. Specific recommendations on alternative 
modeling approaches or other improvements to the 1992 PA were 
considered by EPA in evaluating whether the CCA is adequate. The Agency 
treated such recommendations as public comments on the ANPR, and 
responds in detail to particular issues in the CARDs supporting today's 
proposal. EPA did not give substantial consideration to the committee's 
general conclusions on the PA because, subsequent to the NAS review, 
EPA required numerous changes to the preliminary PA considered by the 
committee. The committee recommended that human intrusion scenarios 
could be made less speculative by refining probability estimates for 
the occurrence of future human activities, but suggested neither a 
methodology for doing so, nor an alternative approach to human 
intrusion which could be implemented within the framework of the 
Compliance Criteria.<SUP>13</SUP>
---------------------------------------------------------------------------

    \13\  NAS never submitted official comments on proposed 40 CFR 
Part 194. In contexts other than the WIPP report, however, NAS has 
acknowledged the impossibility of making decisions regarding nuclear 
waste disposal based solely on scientific information: ``[I]t became 
clear in the course of our work that designing the standards 
requires making decisions based as much or more on policy 
considerations than on science. It is equally clear that there is no 
sharp dividing line between science and policy.'' [NRC, Technical 
Bases for Yucca Mountain Standards (National Academy Press, 1995), 
p. viii] The rulemaking process used to develop the WIPP compliance 
criteria provided a forum for EPA to gather and weigh scientific 
evidence, public concerns, and other policy issues regarding the 
treatment of human intrusion in PA.
---------------------------------------------------------------------------

VII. Codification of EPA's Certification Decision

    The requirements which apply to the rulemaking process used to 
develop EPA's certification decision (including measures for soliciting 
and considering public input) do not prescribe what form the final 
decision must take. In analogous situations where EPA issues or denies 
hazardous waste no-migration petitions for landfills or other sites, 
public notice of the decision is provided by publication in the Federal 
Register, and such notice serves as the record of EPA's action. 
<SUP>14</SUP> Because of the one-of-a-kind nature of the WIPP facility, 
EPA has determined that it is appropriate to provide a more permanent 
record of the Agency's decision. To that end, EPA's decision is being 
published in the Federal Register and also will be codified as an 
appendix to the WIPP Compliance Criteria at 40 CFR Part 194. A lasting 
record of EPA's certification decision will be established since the 
appendix will be included each time in the future that the Code of 
Federal Regulations is compiled and published.
---------------------------------------------------------------------------

    \14\  See, e.g., the RCRA Conditional No-Migration Petition, 55 
FR 47709.
---------------------------------------------------------------------------

VIII. Determination of Whether the WIPP Complies With the Disposal 
Regulations

    The proposed rule states the Agency's determination that the WIPP 
will comply with the disposal standards and Compliance Criteria, taken 
as a whole. In addition, the proposal specifies all conditions which 
apply to the certification. As noted previously, EPA's certification of 
compliance depends on DOE satisfying the specific requirements of the 
WIPP Compliance Criteria. The ensuing sections of the SUPPLEMENTARY 
INFORMATION address each of the technical WIPP Compliance Criteria in 
turn; the Agency describes the basis for evaluating compliance with 
each criterion, and discusses briefly how the CCA submitted by DOE, and 
other relevant information, demonstrated compliance with EPA's 
requirements. CARDs provide more detailed support for EPA's proposed 
decisions regarding compliance with individual criteria. The CARDs are 
available for public review in Docket A-93-02, Category III-B. See 
``additional docket information'' in the SUPPLEMENTARY INFORMATION.
    Not all sections of the WIPP Compliance Criteria are discussed 
below because not all the provisions of 40 CFR Part 194 are directly 
relevant to an evaluation of compliance with the disposal regulations. 
Some sections of 40 CFR Part 194--such as Sec. 194.1, ``Purpose, scope 
and applicability''--are entirely administrative in nature. Other 
sections, including those related to public participation, address 
procedural aspects of the certification rulemaking. Still others refer 
to future actions which may occur, such as inspections or the need to 
suspend an existing certification. Such criteria are not relevant to 
EPA's analysis of whether information in the CCA and elsewhere 
demonstrates that the WIPP site will comply with EPA's disposal 
regulations. Some of these criteria are addressed elsewhere in the 
SUPPLEMENTARY INFORMATION. For example, EPA's adherence to the public 
participation requirements of the LWA and 40 CFR Part 194 is documented 
under ``public participation.''

A. Basis for EPA's Compliance Determination

    EPA's proposed certification decision is based on the entire record 
available to the agency, which is contained in Docket A-93-02. The 
record consists of the complete DOE CCA, supplementary information 
submitted by DOE in response to EPA requests for additional information 
for technical sufficiency, technical reports generated by EPA and EPA 
contractors, EPA audit reports, and public comments submitted on EPA's 
ANPR for the certification decision.
    Thus, as contemplated by Congress, EPA's compliance determination 
is based on more than the ``complete'' application. (LWA, section 
8(d)(1)) 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. 
Examples of such documents include EPA technical and audit reports and 
letters submitted by DOE (i.e., those contained in Docket A-93-02, 
Category II-I).
    In response to public comments regarding the precise materials EPA 
considered in reaching today's proposed decision, the CARDs reference 
the

[[Page 58798]]

relevant portion(s) of the October 29, 1996, CCA and any supplementary 
information that was relied on in reaching a particular proposed 
compliance decision. All materials which informed EPA's proposed 
decision have been placed in the WIPP dockets or are otherwise publicly 
available. EPA has specified in the docket the location of all 
reference materials to aid the public in its evaluation of such 
information. A full description of the supporting documentation for 
EPA's proposed decision and a full list of the DOE compliance 
documentation considered by the Agency are located at Docket A-93-02, 
Item III-B-1. Through these means, the Agency believes the public will 
have a clear indication of what materials constitute the complete CCA, 
and what materials constitute the record basis for EPA's proposed 
certification decision.

B. Compliance Application Review Documents (CARDs)

    The preamble for today's proposed rule describes the basis for the 
Agency's compliance determination for each of the relevant WIPP 
Compliance Criteria. The detailed technical rationale for EPA's 
proposed decision is contained in the Compliance Application Review 
Documents (CARDs) supporting today's action. Taken as a whole, the 
CARDs are analogous to the Background Information Document usually 
provided for EPA rulemakings. These documents are found at Docket A-93-
02, Item III-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.'' In the section of each CARD called ``Compliance 
Review Criteria,'' EPA restates the specific requirement and identifies 
the relevant information expected in the CCA, as described in the 
``Compliance Application Guidance for the WIPP: A Companion Guide to 40 
CFR Part 194'' (``CAG,'' EPA 402-B-95-014, March 1996). EPA also 
clarifies the Agency's rationale for evaluating the CCA's completeness 
and technical adequacy.
    After explaining the Agency's compliance review criteria, each CARD 
summarizes DOE's approach to compliance and describes EPA's compliance 
review. CARDs also list additional EPA technical support documents and 
any other references used by EPA in rendering a proposed decision on 
compliance. All technical support documents and references are found 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. DOE has committed to make such 
documents readily available to the public. Instructions for obtaining 
access to DOE documents can be found at Docket A-93-02, Item III-B-1.
    Finally, CARDs contain EPA's response to comments received on the 
Agency's ANPR of November 15, 1996 (61 FR 58499) and on other comments 
received prior to August 8, 1997. For more discussion of EPA's response 
to these comments, see ``Public Participation'' in the SUPPLEMENTARY 
INFORMATION.
    For technical information or more detailed discussion on EPA's 
evaluation of compliance with any individual provision of 40 CFR Part 
194, readers should refer to the corresponding CARD in Docket A-93-02, 
Item III-B-2.

IX. Section 194.14, Content of Compliance Certification Application

    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.
    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.
    Much of the information referenced by DOE as demonstrating 
compliance with Sec. 194.14, and EPA's review of the information, was 
principally used to demonstrate compliance with other sections of the 
Compliance Criteria. Thus, this section of the preamble discusses many 
of the requirements of Sec. 194.14 only briefly because they are fully 
discussed in other sections of the preamble. EPA thoroughly reviewed 
DOE's compliance certification application (``CCA'') submitted on 
October 29, 1996, and additional information submitted by DOE.

A. Site Characterization

    40 CFR 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. The characteristics of 
the site and identification of potential pathways are crucial to the 
conceptual models and computer modeling that is done to determine 
compliance with the containment requirements at 40 CFR 191.13 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. EPA also 
required DOE to project how geophysical, hydrogeologic and geochemical 
conditions of the disposal system would change due to the presence of 
waste.
    EPA examined the CCA and determined that it and the supplemental 
information provided by DOE 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. The CCA discussed that very few potential pathways 
exist for radionuclide transport. DOE projected future geophysical, 
hydrogeologic and geochemical conditions due to the presence of waste. 
A brief overview of the site is provided below.
    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 precipitation increases were 
accounted for in the performance assessment (``PA''). The Delaware 
Basin contains thick sedimentary deposits (over 15,000 feet (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 (<difference>200-250 million years old) Salado Formation, 
which is composed primarily of salt (halite).
    DOE considered the primary geologic units of concern to be (from 
below the repository to the surface): (1) Castile Formation 
(``Castile''), consisting of

[[Page 58799]]

anhydrite and halite with pressurized brine pockets found locally 
throughout the vicinity of the WIPP site; (2) Salado Formation 
(``Salado''), consisting primarily of halite with some anhydrite 
interbeds and accessory minerals and approximately 2,000 feet (600 
meters) thick; (3) Rustler Formation (``Rustler''), containing salt, 
anhydrite, clastics, and carbonates (primarily dolomite), with the 
Culebra dolomite member of the Rustler as the unit of most interest; 
and, (4) 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 PA calculations because they did 
not affect the performance of the disposal system. See Sec. 194.32 for 
a detailed discussion of screening of features, events, and processes.
    DOE indicated that the major geologic process in the vicinity of 
the WIPP is dissolution. To the west, the slight (one degree) dip in 
the Salado has exposed the formation to dissolution processes, and 
commenters argued that lateral dissolution processes will affect the 
WIPP's ability to contain radionuclides. However, DOE estimated that 
the dissolution front will not reach the WIPP site for at least 
hundreds of thousands of years--well past the regulatory time frame. 
EPA agrees with DOE's conclusion that while deep dissolution has 
occurred elsewhere in the Delaware Basin, the process of deep 
dissolution, if it occurs under the WIPP site, would occur at such a 
slow rate that it would not affect the containment capabilities of the 
WIPP during the regulatory time period.
    Many commenters suggested that WIPP can not contain radionuclides 
because WIPP is in a region of karst (topography created by the 
dissolution of rock). EPA reviewed information submitted by DOE and 
stakeholders regarding the occurrence and development of karst at the 
WIPP (e.g., Docket A-93-02, Items II-H-46 and II-D-102). EPA concluded 
that while the WIPP site is in a karst region and karst features are 
found to the west of the site in Nash Draw, only limited evidence 
exists that dissolution-related features occur near the WIPP boundary 
(e.g., well WIPP-33). These features are neither pervasive nor 
associated with any identified preferential groundwater flow paths or 
anomalies. WIPP field mapping and site-specific hydrologic information 
(e.g., well tracer tests) do not indicate that any cavernous or other 
karst-related flow is present at the WIPP site. As stated in a 
technical document submitted by one commenter, ``the karst phenomena do 
not appear to warrant a rejection of the WIPP site.'' (Docket A-93-02, 
Item II-D-102) EPA agrees and concludes that karst is not a problem at 
WIPP and that geologic evidence of the last approximately 500,000 years 
and results from DOE's groundwater modeling indicate that future 
development of karst at the WIPP is not likely.
    DOE conducted geologic studies and field measurements as part of 
its evaluation of the hydrology of the WIPP site and identified two 
potential pathways for radionuclides in the disposal system: the 
Culebra dolomite and Salado anhydrite markerbeds 138 and 139. However, 
only the Culebra dolomite has the capability to transmit significant 
amounts of radionuclides. The Salado markerbeds have very low 
permeability and are the primary pathways in the undisturbed case. The 
results of the CCA PA indicated that radionuclide transport through the 
anhydrites does not contribute significantly to total releases. The 
Culebra dolomite is a potential pathway only in intrusion scenarios. 
Commenters stated that the Dewey Lake should be considered a potential 
pathway and thus needed better characterization; however, the CCA PA 
results indicated that no contaminated brine traveled up an intrusion 
borehole past the Culebra to the Dewey Lake or other units. While DOE 
did identify the Dewey Lake as a potential underground source of 
drinking water, the CCA PA results indicated that the Dewey Lake did 
not play an active role in radionuclide release scenarios. EPA 
concludes that the Culebra dolomite and the Salado anhydrite markerbeds 
138 and 139 are the only ground-water radionuclide transport pathways 
in the disposal system.
    As the primary radionuclide pathway during an intrusion, the 
Culebra was the subject of many public comments, especially related to 
karst (discussed above), K<INF>d</INF> values (distribution 
coefficients used in calculating the retardation factor) and 
geochemistry and flow directions. 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.
    The CCA indicated that there were no contributions to total 
releases from the ground-water pathway. This was due, in large part, to 
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 was based on laboratory tests 
using crushed rocks and small columns of rock. EPA 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. However, EPA believes that a lognormal 
distribution is a more appropriate representation of the data 
distribution, and required the use of a lognormal distribution in the 
Performance Assessment Verification Test (PAVT). For further discussion 
of the PAVT, refer to the preamble for Sec. 194.34.
    DOE indicated in the CCA that there is considerable variation in 
the groundwater chemistry of the Culebra member of the Rustler 
Formation. In addition, DOE provided supplemental information 
pertaining to Culebra groundwater flow and geochemistry which contended 
that the observed geochemistry and flow directions can be explained 
with the ground-water basin modeling. (Docket A-93-02, Item II-I-17) 
The ground-water basin model addressed near surface hydrologic 
conditions (including the water table and potential recharge areas) and 
reconciled inconsistencies between the geochemistry data and the 
current ground-water flow direction.
    The probability of intercepting a Castile brine reservoir (i.e., 
brine pocket) and the characteristics of a brine reservoir once it has 
been hit were the subject of many public comments as well as a source 
of EPA concern. Because of the low permeability of the Salado 
Formation, there is no natural connection between a Castile brine 
pocket and the waste panel area. However, in the case of a deep 
drilling intrusion that goes through a waste panel and into the 
Castile, it is possible that the drilling will intercept brine in the 
Castile and create a pathway for Castile brine to flow into the 
repository and interact with the waste.
    In the 1992 PA, Sandia National Laboratory (``SNL'') considered the 
probability of hitting a brine pocket under the waste area an uncertain 
parameter that required sampling over a

[[Page 58800]]

range of 0.25 to 0.62. This range of probabilities was based on 
geophysical work that suggested brine may be present. For the CCA PA, 
SNL conducted a new analysis based on a geostatistical analysis of oil 
and gas wells in the vicinity of WIPP. From this study, SNL identified 
the probability of hitting brine as 0.08, partly because the brine is 
expected to be in fractures that are oriented vertically or slightly 
less than vertical. EPA reviewed the CCA and public comments and 
concluded that, while the probability of hitting a brine pocket may be 
low, there was no justification for assuming a fixed value for such an 
uncertain parameter. EPA therefore directed DOE, for the PAVT, to 
change the probability of hitting a brine pocket to a range that 
incorporated low to moderate probabilities (0.01 to 0.6).
    The potential volume of brine reservoirs was also the subject of 
numerous comments claiming that, in the PA, DOE underestimated the 
brine volume. DOE assumed that passive institutional controls 
(``PICs'') will limit the available brine pocket volume to that within 
the area covered by the surface berm used to mark the subsurface 
location of the waste panels. EPA reviewed information in the CCA, 
public comments, and the SNL Records Center. EPA concluded that the 
approach of excluding Castile brine pocket volumes based on the waste 
panel ``foot print'' is inappropriate because the efficacy of drilling 
in the area outside the berm cannot be reasonably defined. EPA directed 
DOE, for the PAVT, to change the brine pocket volume to a volume that 
is more representative of data from site characterization activities 
(i.e., the WIPP-12 exploratory well). The PAVT also omits the credit 
for PICs.
    The results of the PAVT indicated that changing the probability of 
hitting a brine pocket has a negligible effect on releases, but 
changing the brine volume from 160,000 cubic meters to 17 million cubic 
meters does have a noticeable effect on releases for the scenarios in 
which a brine pocket is hit. Nevertheless, the PAVT results indicated 
that, even with these changes combined with other parameter changes, 
the PAVT results are similar to those in the CCA and still meet the 
containment requirements by more than one order of magnitude. EPA 
believes that the PAVT verifies that the original CCA Castile brine 
reservoir parameters were adequate for use in PA and comparison against 
the radioactive waste containment requirements. See the preamble for 
Sec. 194.34(f) for additional information on the results of the PAVT.
    EPA agrees with DOE's conclusion in the CCA that the most important 
extractable resources near the WIPP are hydrocarbons, potassium salts 
(potash), and water. DOE indicated that some of the geologic formations 
below the repository area contain oil and gas resources that are 
currently being exploited in the Delaware Basin. According to DOE's 
analysis, most of the water in the vicinity of the WIPP is highly 
saline, with the closest dependable potable aquifer associated with the 
Capitan Reef at the edge of the Basin. With respect to potash, the CCA 
indicated that only the 4th and 10th potash zones qualify as economic 
reserves. Commenters noted that the extent of potash identified by DOE 
is different than that identified by the Bureau of Land Management in 
its map of resources. EPA concludes that DOE's presentation is 
reasonable, given the 40 CFR Part 194 requirements that DOE assess 
resources relative to those currently being mined.
    The projected effect of waste on the disposal system are primarily 
limited to gas generation that increases repository pressure and 
actinide solubility. Gas will be generated: (1) By corrosion of metals 
and (2) as a byproduct of microbial degradation of cellulosics, 
plastics and rubbers. Gas generation primarily affects spallings (due 
to high pressures) and direct brine releases (due to high pressures and 
increasing solubility). DOE indicated that magnesium oxide (``MgO'') 
backfill emplaced with transuranic waste would mitigate the solubility-
enhancing effects of carbon dioxide from waste degradation. EPA concurs 
with DOE's assessment. Refer to Sec. 194.44 for further discussion of 
the effects of MgO.
    Although commenters questioned DOE's characterization of the WIPP 
site, especially the hydrology, EPA concluded after extensive review 
that DOE identified, characterized, and used in the calculations the 
major components of the geologic and hydrologic system around the WIPP. 
DOE provided a detailed discussion of the geology and identified the 
few geologic units that are important to PA. DOE also identified that 
very few geologic units could transmit fluids and transport 
radionuclides; after an intrusion, only the Culebra dolomite is a 
significant pathway above the Salado with other overlying units not 
receiving any contaminated brine. EPA reviewed DOE's discussion on 
dissolution and karst and concludes that these processes are not 
currently significant and will not affect WIPP over the regulatory time 
period. EPA disagreed with DOE's characterizations of the Castile brine 
pocket and required changes for the PAVT; however, PAVT results 
verified that the original parameters were acceptable for use in the 
PA.

B. Disposal System Design

    Section 194.14(b) requires DOE to describe the design of the 
disposal system, including natural and man-made materials, and 
architectural and structural aspects of the disposal system. DOE also 
must describe the computer codes and standards that have been applied 
to the design and construction of WIPP.
    The CCA contained a general description of the WIPP facility and a 
detailed description of the underground disposal system (including the 
engineered barriers in the repository and shaft system as well as the 
geologic units). The WIPP repository is an underground mine that will 
eventually have eight panels (each of which will include seven 
football-field long rooms) connected by drifts. Waste will be emplaced 
in the WIPP through the waste shaft. An exhaust shaft, salt handling 
shaft, and air intake shaft also penetrate the WIPP repository. The 
underground mine is attended by surface equipment and buildings that 
will handle waste prior to its emplacement in the WIPP. DOE intends to 
pack bags of magnesium oxide (``MgO'') around the waste containers, and 
will seal each panel after it is filled with waste. The Salado salt 
will eventually ``creep'' and close WIPP rooms and panels. The WIPP was 
designed to take advantage of this encapsulation so that transuranic 
waste emplaced in the WIPP will be completely enveloped by salt, thus 
minimizing the potential for waste migration.
    The major disposal system engineered features related to long-term 
performance are the general design, shaft seals, panel closures, 
borehole plugs, and the additional engineered barrier of backfill 
around the waste. 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 disposal system 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, clay, compacted salt, cementitious 
grout, and earthen fill. DOE identified the compacted salt column as 
the most critical element in the long-term performance of the shaft 
seal. The compacted salt column component of the system within the 
Salado is intended to serve as the

[[Page 58801]]

primary long-term barrier by limiting fluid transport along the shaft 
during the 10,000-year regulatory period. The other components of the 
shaft seal within the Salado are intended to prevent migration of 
radionuclides in the short term and protect the compacted salt column 
until it is sufficiently consolidated to act as an effective long-term 
barrier. Components of the seal system within the Rustler are intended 
to limit the commingling of groundwater between the water bearing 
members. The seal system overlying the Rustler will consist of 
compacted earthen fill. The shaft seal design in the CCA received 
extensive technical review by DOE, and was also subjected to an 
independent design review. EPA concludes that the shaft seal design is 
adequate because the system can be built and is expected to function as 
intended.
    The purpose of borehole plugs is to mitigate the potential for 
migration of contaminants toward the accessible environment. DOE 
indicated that it will abide by the applicable State oil and gas well 
plugging requirements. While there are four deep research wells drilled 
in the disposal system, DOE stated that ``the ERDA-9 exploratory hole 
was the only hole within the underground development area which was 
permitted to penetrate the Salado formation to the underground facility 
horizon.'' ERDA-9 did not penetrate an area that will become a waste 
panel and DOE has indicated that abandoned boreholes more than a meter 
away from the waste can be screened out of PA due to low consequence. 
EPA agrees with DOE's assessment that these boreholes are not 
significant to performance of the disposal system and can be screened 
out of PA.
    The primary long-term effect of the panel closure will be to block 
the flow of brine between panels. DOE provided four design options for 
panel closures but did not specify in the CCA which panel closure 
option would be used at WIPP, an omission that was pointed out in 
public comments. (Docket A-93-02, Item II-H-10) In reviewing the four 
panel closure design options, EPA identified Option D in the CCA as the 
most robust design, and reviewed that design as the basis for an 
evaluation of compliance. EPA found that the design for Option D would 
be expected to perform as described, but that the use of a Salado mass 
concrete (consistent with the type specified for the shaft seal system) 
rather than fresh water concrete would be more consistent with the 
permeability assumptions used in PA. EPA determined that such a design 
is adequate to achieve the long-term performance modeled in PA, and 
therefore proposes to find that DOE complies with Sec. 194.14(b). 
However, because EPA is basing its proposed compliance determination on 
the Option D panel seal design, the EPA is also proposing to establish 
a certification condition requiring DOE to implement the Option D 
design, with Salado mass concrete replacing fresh water concrete. (See 
Condition 1 in the proposed Appendix A to 40 CFR Part 194.) Although 
EPA's sensitivity analysis indicates that the panel closure 
permeability is not a sensitive parameter, especially with the 
disturbed rock zone at the same or higher permeability, the Agency 
believes it is important to ensure that the proposed design on which 
compliance was based is actually implemented at the site. Because of 
the presence of the disturbed rock zone, EPA expects that gas flow 
between panels for long-term performance purposes would be relatively 
unaffected by the design choice.

C. Results of Assessments

    Section 194.14(c) requires the CCA to present the results of 
assessments of the WIPP's performance, given human intrusion into the 
disposal system (performance assessment) and undisturbed conditions 
(compliance assessment). EPA determined that DOE's results showed 
compliance with the containment (Sec. 191.13), individual 
(Sec. 191.15), and ground water (40 CFR Part 191, Subpart C) 
requirements of the disposal regulations. Refer to discussions of 
Sec. 194.34 and Sec. 194.55 for EPA's full evaluation of results of 
assessments. Based on EPA's finding that information submitted by DOE 
was sufficient for compliance with Secs. 194.34 and 194.55, the Agency 
proposes to find that DOE also complies with Sec. 194.14(c).

D. Input Parameters to Performance Assessments

    40 CFR 194.14(d) requires DOE to describe the input parameters to 
the PA and discuss the basis for their selection. DOE provided 
descriptions of input parameters to the PA. EPA's evaluation of this 
information is addressed in the discussion of Sec. 194.23 of this 
preamble. Based on EPA's finding that information was sufficient for 
compliance with Sec. 194.23, the Agency proposes to find that DOE also 
complies with Sec. 194.14(d).

E. Assurance Requirements

    Section 194.14(e) requires documentation of measures taken to meet 
the assurance requirements. EPA considers DOE to have complied with 
Sec. 194.14(e) if it provided the information required for Secs. 194.41 
through 194.46. Based on EPA's determination of compliance for all six 
assurance requirements (active institutional controls, monitoring, 
passive institutional control, engineered barriers, consideration of 
the presence of resources, and removal of waste), EPA proposes to find 
that DOE also complies with Sec. 194.14(e).

F. Waste Acceptance Criteria

    Section 194.14(f) requires DOE to describe waste acceptance 
criteria and the measures taken to assure adherence to such criteria. 
EPA reviewed documentation provided by DOE and observed DOE audits and 
other activities, and concluded that DOE provided satisfactory 
descriptions of actions that will be followed to ensure adherence to 
the waste acceptance criteria. EPA therefore proposes to find DOE in 
compliance with Sec. 194.14(f). Refer the preamble discussion of 
Sec. 194.24 for a complete discussion of EPA's review of waste 
acceptance criteria and other waste characterization information.

G. Background Radiation

    40 CFR 194.14(g) requires DOE 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. DOE provided 
information regarding the levels of background radiation in air, soil, 
surface water, sediments, groundwater, and biota. DOE also provided a 
description of the procedures used to determine the background 
radiation. DOE indicated that background radiation in the vicinity of 
the WIPP site is influenced by natural sources of radiation, fallout 
from nuclear tests, and one local research project (Project Gnome, 
which involved the underground detonation of a nuclear device on 
December 10, 1961, at a site approximately 8 miles (13 kilometers) 
southwest of the WIPP site).
    EPA found that DOE provided sufficient discussion of background 
radiation levels and associated procedures to monitor these media for 
radiation. EPA, therefore, proposes to find that DOE complies with 
Sec. 194.14(g).

H. Topographic Maps

    40 CFR 194.14(h) requires DOE to provide one or more topographic 
maps of the vicinity of the disposal system. At least one map must show 
boundaries of the controlled area and the location of active, inactive 
and abandoned injection and withdrawal wells in the controlled area and 
in the vicinity of the disposal

[[Page 58802]]

system. The CCA must include topographic maps with a contour interval 
sufficient to show clearly the pattern of surface water flow in the 
vicinity of the disposal system.
    DOE provided four topographic maps that show the pattern of surface 
water flow in the vicinity of the WIPP. The CCA included three figures 
showing the locations of the controlled area within the U.S. Public 
Land Survey coordinate system, as well as a map showing the location of 
active, inactive, and abandoned injection and withdrawal wells in the 
controlled area and in the vicinity of the disposal system. EPA 
reviewed the topographic maps provided in the CCA to determine their 
sufficiency. EPA determined that DOE met the requirements of 
Sec. 194.14(h) because it provided multiple, appropriately scaled, 
topographic maps of the vicinity of the disposal system.

I. Past and Current Meteorological Conditions

    40 CFR 194.14(i) requires DOE to describe past and current 
climatologic and meteorological conditions in the vicinity of the 
disposal system. DOE is also required to project how these conditions 
are expected to change over the regulatory time frame.
    DOE described past glaciation events, climatic changes, and 
precipitation and temperature averages. DOE also discussed how 
historical climatic conditions were used to anticipate climatic 
conditions 10,000 years in the future. DOE described current climatic 
conditions in the WIPP area, including summaries of recent rainfall, 
temperature, and wind data. DOE discussed how climate changes were 
incorporated in conceptual models.
    Based on public comments and EPA's review of the CCA, EPA requested 
additional information on dissolution. Supplemental information 
submitted by DOE addressed EPA's concerns. EPA concluded that the 
description of past and present climatic changes and associated impacts 
on the WIPP disposal system were adequately addressed, and therefore 
proposes to find DOE in compliance with Sec. 194.14(i).

J. Other Information Needed for Demonstration of Compliance

    40 CFR 194.14(j) requires DOE 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.
    The preamble for other sections of the Compliance Criteria discuss 
in greater detail DOE's responses to EPA's formal requests for 
additional information and any other supplementary information reviewed 
by EPA after October 29, 1996. All documents sent to EPA are available 
in the EPA docket. Additional documentation that was not sent to EPA 
but was reviewed by the Agency (e.g., 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 III-B-1 for further information on the 
location of all documentation reviewed by EPA.
    EPA determined that DOE responded adequately to EPA's formal 
requests for additional information, analyses, and records; and 
therefore proposes to find that DOE complies with Sec. 194.14(j).

K. Conclusion

    Based on the information provided in the CCA and additional 
information submitted by DOE, EPA proposes that DOE demonstrates 
compliance with all subsections of Sec. 194.14. For additional 
information on EPA's evaluation of compliance for Sec. 194.14, see CARD 
14.

X. General Requirements

    The general requirements of 40 CFR Part 194, Subpart C, are 
intended to ensure that any compliance certification application 
(``CCA'') is based on dependable and verifiable information and that 
EPA has the right to confirm the accuracy of such information. Although 
they have no direct corollary in the disposal regulations, EPA issued 
these requirements in implementing the disposal regulations because the 
Agency believes that a reasonable expectation of compliance with the 
containment requirements (discussed in subsequent portions of this 
preamble) can be achieved only if the information and methods used to 
conduct performance assessments are valid and reliable. To that end, 
the general requirements at Secs. 194.22 through 194.27 establish 
requirements for quality assurance programs, models and computer codes, 
waste characterization, future state assumptions, expert judgment, and 
peer review.

A. Section 194.22, Quality Assurance

    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 (including waste characterization activities, environmental 
monitoring, field measurements, computer codes, procedures for expert 
elicitation, disposal system designs, and data), (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 in 
the CCA, and (e) allow verification of the above measures through EPA 
inspections. The DOE's QA program must adhere to specific Nuclear 
Quality Assurance (``NQA'') standards and requirements issued by the 
American Society of Mechanical Engineers (``ASME'').
    The EPA assessed compliance with the QA requirements in two ways. 
First, EPA reviewed QA information in the CCA and associated reference 
documents. EPA's second level of review consisted of visits to the WIPP 
site, as well as WIPP-related facilities, to perform audits and 
inspections to verify DOE's compliance with the QA requirements. For 
example, 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. In this way, EPA was able to review 
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-

[[Page 58803]]

 1989 edition (excluding Section 2.1 (b) and (c), and Section 17.1). 
DOE incorporated these requirements in the Quality Assurance Program 
Document (``QAPD'') contained in the CCA. The QAPD is the documented 
plan for the WIPP project, as a whole, to comply with the NQA 
requirements; it applies to all activities and items important to 
containment of waste in the WIPP. The QAPD addresses the 18 basic 
requirements of NQA-1, including supplemental requirements as 
established by NQA-1; the computer software requirements as established 
by NQA-2a, part 2.7; and the collection of scientific and technical 
information requirements for site characterization of high level 
nuclear waste repositories as established by NQA-3. The QAPD is 
implemented by DOE's CAO, which provides overall coordination of WIPP 
activities and has 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 conform to 
the QAPD. EPA audited DOE's QA program at CAO and determined that DOE 
properly adhered to a QA program that implements the NQA standards and 
requirements. Therefore, EPA proposes to find DOE in compliance with 
Sec. 194.22(a)(1). (For information on the incorporation of NQA 
requirements into lower tier program plans, refer to the subsequent 
discussion of Sec. 194.22(a)(2), which addresses specific activities 
under the direct control of organizations other than DOE's CAO.)
    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 and referenced criteria for the review and approval 
of a site-specific Quality Assurance Project Plan (``QAPjP'') to 
address technical criteria and implementation procedures. The CCA 
listed five waste generator site QAPjPs that have been approved by DOE. 
DOE proposed that sites also will prepare site certification Quality 
Assurance Plans (``QAPs'') that, together with the QAPjPs, are intended 
to establish all the NQA requirements applicable to waste 
characterization.<SUP>15</SUP> EPA finds that the QAPD, as it applies 
to waste characterization, is in conformance with the NQA requirements. 
As discussed below, the Agency intends to verify the adequacy of site-
specific QA programs in the future.
---------------------------------------------------------------------------

    \15\ 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 or 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.''
---------------------------------------------------------------------------

    Another important activity related to waste characterization is the 
ability to track waste shipped to and emplaced in the WIPP. The WIPP 
Waste Information System (``WWIS'') is a computer database and 
reporting program that will track and tally the waste that comes to the 
WIPP. The WWIS is covered by QA programs both at the WID and at waste 
generator sites. At Westinghouse, the WID QAPD, which addresses the 
specific requirements of the NQA standards, governs operation of the 
system. In September 1997, EPA performed an inspection of the WID QA 
program applicable to the WWIS. At that time, the WWIS was demonstrated 
to be operational, and EPA determined that a QA program had been 
properly executed for the WWIS in accordance with the applicable NQA 
requirements.
    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 waste characterization 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 (QAPs and, where applicable, QAPjPs) and 
programs.
    To date, one WIPP waste generator site, Los Alamos National 
Laboratory (``LANL''), has been approved by EPA to have established 
adequate QA programs (encompassed in a QAP and QAPjP) and to have 
properly executed QA procedures in accordance with the applicable NQA 
requirements. 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. 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. Therefore, EPA 
proposes to find that the requirements of Sec. 194.22(a)(2)(i) have 
been met for the WID QAPD, the WWIS, and waste characterization 
activities at LANL.
    With respect to other waste generator sites, EPA proposes to 
certify 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 subsequent to LANL establish QA 
programs, EPA will assess their compliance with NQA requirements. In 
making any determination to approve a site-specific QA program for a 
waste generator, EPA will conduct an audit or an inspection of a DOE 
audit of a waste generator site. EPA will publish a notice in the 
Federal Register announcing its scheduled audit or inspection of a DOE 
audit and will provide at least a 30-day comment period during which 
interested parties may submit written comments. EPA will place in the 
docket copies of the site-specific QA program documents and other 
documentation relevant to the audit or audit inspection. Thus, the 
Agency's decision whether to approve the establishment and execution of 
a QA program at a specific waste generator site will be informed by 
both public comments and the results of the Agency's own independent 
evaluation of the site's compliance with the applicable NQA 
requirements.
    EPA believes that approval of site specific QA programs is required 
by, and that this proposed procedure is consistent with the provisions 
of Sec. 194.22(a)(2)(i) because it requires DOE to demonstrate 
``establishment and execution'' of quality assurance programs for waste 
characterization assumptions and activities at the individual waste 
generator sites prior to shipment of wastes from such sites. EPA 
requests comment on whether the Agency should place a condition on its 
certification of compliance at WIPP consisting of future demonstrations 
by DOE that QA programs have been established and executed at 
individual waste generator sites, prior to shipment of TRU waste to 
WIPP from such sites. In particular, EPA requests comment on

[[Page 58804]]

its preliminary conclusion that the proposed procedures for determining 
whether adequate quality assurance programs have been established and 
executed by DOE are consistent with Part 194. However, if, based upon 
public comment on today's proposed action, EPA concludes that it would 
be appropriate to make clarifying changes to Part 194 that specifically 
set forth these procedures, EPA may do so as part of its final action 
on today's proposal.
    EPA will indicate its approval of site-specific QA programs by a 
letter from the Administrator's authorized representative to the 
Department; a copy of the letter will be placed in EPA's public docket. 
(As part of the certification rulemaking, EPA is proposing to define 
the Administrator's authorized representative as the ``director in 
charge of radiation programs at the Agency,'' in order to clarify the 
delegation of responsibilities for 40 CFR Part 194, including 
activities such as requesting additional information from DOE, and 
inspecting and approving quality assurance programs.) After approval of 
site-specific QA programs, EPA will exercise its authority under 
Secs. 194.21 and 194.22(e) to conduct unfettered inspections of 
approved waste generator sites to confirm that the approved plans are 
being properly maintained for waste characterization activities. For 
specific language on the quality assurance conditions of compliance, 
see Condition 2 of the proposed Appendix A to 40 CFR Part 194. For 
further discussion of waste characterization programs and certification 
of individual waste streams from generator sites, see the discussion of 
Sec. 194.24 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 implementing this requirement under the WID QAPD 
described in the CCA. The WID developed a WIPP Environmental Monitoring 
Plan (``EMP''), which applies to current site characterization and also 
to proposed pre-closure monitoring in accordance with Sec. 194.42. The 
EMP included QA procedures for radiological and non-radiological 
environmental monitoring. Also included in the EMP were sample 
handling, laboratory procedures, required records and reports, and data 
analyses guidelines. DOE stated that the EMP is consistent with 
applicable elements of ASME NQA-1.
    The EPA determined during its audit of WID that the requisite QA 
program had been established and executed for environmental monitoring, 
sampling and analysis activities. Therefore, EPA proposes to certify 
compliance with Sec. 194.22(a)(2)(ii). Continued adherence to the 
executed QA program as it applies to disposal system monitoring will be 
confirmed by EPA in future inspections under its authority at 
Secs. 194.21 and 194.22(e).
    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, groundwater, meteorologic, and 
topographic characteristics. EPA conducted an audit of the WID QA 
program and found the QAPD to be adequate and to be implemented in 
accordance with the applicable NQA requirements. Therefore, EPA 
proposes to find DOE in compliance with Sec. 194.22(a)(2)(iii).
    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. In the CCA, DOE provided the 
CAO QAPD, which incorporates the application NQA requirements for 
computation and computer code information. Software development and 
management are controlled in accordance with criteria established by 
SNL software QA procedures and the WID QAPD. EPA reviewed information 
in the CCA and conducted audits of both SNL and WID QA programs. The 
Agency found that DOE's computer codes were documented in a manner that 
complies with the applicable NQA requirements, and that DOE's software 
QA procedures were implemented in accordance with ASME NQA-2a, part 
2.7. EPA therefore proposes to determine 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. EPA found 
that the requirements of this regulation were met with the 
implementation of CAO Team Procedure (``TP'') 10.6 (Revision 0), CAO 
Team Plan for Expert Panel Elicitation (Revision 2), and CAO Technical 
Assistance Contractor (``CTAC'') Experimental Programs Desktop 
Instruction No.1 (Revision 1). EPA proposes to find DOE in compliance 
with Sec. 194.22(a)(2)(v). The process of expert judgment elicitation 
is discussed in further detail in the preamble for 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. Design work for the repository sealing 
system was conducted under the SNL QA program. The repository seal 
system design was extensively reviewed by DOE, SNL, WID, and CAO 
Technical Assistance Contractor personnel, as well as independent 
design reviewers. 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. EPA audits of SNL and WID showed that the QA programs are 
adequate and properly executed. Therefore, EPA proposes to find 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 adequately addressed these requirements by 
implementing numerous QA procedures to ensure the quality of data and 
information collected in support of the WIPP. EPA's audit of SNL 
concluded that the QA program was adequate and appropriately 
implemented. Therefore, EPA proposes to find 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. 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. EPA has also not identified to date any other items or activities 
which require controls. However, EPA has reviewed the CAO QAPD and 
conducted audits of the CAO, SNL, and WID QA programs. 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 proposes to find DOE in compliance with 
Sec. 194.22(a)(2)(viii).

[[Page 58805]]

    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 CCA 
listed existing data that were reviewed by an Independent Review Team 
and that DOE determined to have been collected under a QA program 
equivalent to the NQA standards. DOE also provided information on 
NUREG-1297 peer reviews that were conducted to qualify existing data 
for engineered systems, natural barriers, waste form, and disposal room 
data. Finally, DOE identified data from literature sources.
    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. EPA also concluded that the use of existing data from peer-
reviewed technical journals was appropriate, since the level of such 
reviews was likely to provide QA equivalent to NUREG-1297 peer reviews 
conducted by DOE. Therefore, EPA proposes to find DOE in compliance 
with Sec. 194.22(b). Furthermore, the Agency is proposing to approve 
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 parameters, but 
asserted that the intent of DQCs was fulfilled by other QA programs and 
quality control measures. In response to EPA's request for additional 
information, DOE clarified but did not substantially alter its 
approach. (Docket A-93-02, Items II-I-17 and II-I-24)
    The Agency agrees that it is not appropriate to apply DQCs to 
parameters in the PA (e.g., anhydrite permeability parameter), but 
believes that they can be applied to measured data (i.e., field 
monitoring and laboratory experiments) on which parameter values are 
based. Because DOE misinterpreted EPA's requirements as applying to 
parameters, EPA found that the CCA and supplementary information did 
not systematically or adequately address DOE's consideration of DQCs 
for measured data. Therefore, 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 
PA. Data record packages document measured data considered by DOE in 
developing parameter values. 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 
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 
compliance application; EPA concluded that the peer review panels 
considered the use of DQCs in determining that such data were adequate. 
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).
    Based on its review of data record packages, the Agency finds that 
DOE has assessed DQCs, to the extent practicable, for data used in the 
compliance application. EPA thus proposes to find that DOE complies 
with Sec. 194.22(c). The Agency expects that DOE will assess DQCs for 
future waste characterization and monitoring activities; EPA will 
confirm assessment of DQCs for such measured data through inspections 
and evaluation of any compliance re-certification applications.
    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. 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 proposes to find 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 plans to conduct additional 
inspections, including audits, of CAO, SNL, and WID prior to publishing 
a final certification decision. The purpose of these inspections will 
be to verify that the QA programs for these organizations--which have 
already been found to be properly executed in accordance with the 
applicable NQA requirements--are being appropriately maintained. EPA 
will docket the results of these inspections, but will not consider 
them for the purpose of the proposed or final rule unless the 
inspections result in new information that indicates that the programs 
are no longer in conformance with the applicable NQA requirements.
    In summary, EPA proposes to find 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.) 
For further information on EPA's evaluation of compliance for 
Sec. 194.22, refer to CARD 22.

B. Section 194.23, Models and Computer Codes

    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

[[Page 58806]]

the PA. Design of computer codes begins with the development of 
conceptual models. Conceptual models consider the design of the 
repository and the features, events, processes, and scenarios that may 
occur at the WIPP which could affect the containment or release of 
radionuclides. In order for the final computer codes to obtain 
realistic solutions, the underlying conceptual models must be sound. 
DOE must next develop mathematical models from the conceptual models. 
Mathematical models set up a mathematical expression to describe the 
conditions in the repository and its surroundings. Numerical models are 
then created to describe how to solve the equations in the mathematical 
models. Since most of the mathematical models are sufficiently complex 
that analytical solutions are not possible, numerical models are used 
to provide iterative, approximate solutions to the mathematical models. 
Finally, DOE must program the numerical solutions from the numerical 
models into computer codes that perform calculations to estimate the 
cumulative releases of radionuclides caused by all significant 
processes and events.
    In examining models and computer codes, EPA evaluated the 
development of the underlying conceptual models, evaluated the 
derivation of mathematical models and implementation of numerical 
models and computer codes, verified the quality assurance of computer 
codes, and performed its own independent computer calculations. In 
order to allow EPA to evaluate the underlying conceptual models, 
Sec. 194.23 of the compliance criteria requires descriptions of 
conceptual models and scenario construction (Sec. 194.23(a)(1)), 
consideration of alternative conceptual models (Sec. 194.23(a)(2)), and 
documentation of peer review of the conceptual models 
(Sec. 194.23(a)(3)(v)). To ensure proper implementation of these 
conceptual models, Sec. 194.23 also requires documentation that: future 
states of the disposal system are reasonably represented by conceptual 
models (Sec. 194.23(a)(3)(i)); mathematical models (or algorithms) 
reasonably represent the conceptual models (Sec. 194.23(a)(3)(ii)); 
numerical models (or solution methods) provide stable solutions to the 
mathematical models (Sec. 194.23(a)(3)(iii)); and computer codes 
accurately implement the numerical models and are free from coding 
errors and produce stable solutions (Sec. 194.23(a)(3)(iv)). In 
addition, DOE must describe the theoretical background of models and 
their method of analysis; how the computer codes operate and were 
developed; methods of data collection, data reduction and analysis; 
parameters developed from source data; the structure of the computer 
codes and a complete listing of source codes; and the effects of 
parameter correlation (Secs. 194.23(c)(1) through (6)). Section 
194.23(b) requires DOE to document that models and computer codes were 
developed in accordance with the specified QA requirements contained in 
the ASME NQA standards. Finally, Sec. 194.23(d) requires DOE to provide 
all necessary data, information, software, and any other material to 
enable EPA to conduct its own independent computer simulations.
1. Conceptual Models
    a. Description of Conceptual Models. Section 194.23(a)(1) requires 
the CCA to describe the conceptual models and the scenarios used in the 
CCA PA calculations. DOE developed 24 conceptual models to describe the 
WIPP disposal system. DOE also undertook an extensive screening process 
to determine which features, events, and processes (FEPs) were 
applicable to the disposal system. From the list of applicable FEPs, 
DOE developed scenarios to describe both undisturbed performance 
(natural processes and events) and disturbed performance (human 
intrusion, including mining and deep drilling) of the repository. The 
CCA included scenarios that satisfy the specific requirements of 
Secs. 194.32 and 194.33 concerning the scope of PA and consideration of 
drilling events in PA. (See preamble discussions of Secs. 194.32 and 
194.33 for further details.)
    EPA reviewed the descriptions of the 24 conceptual models and the 
scenario construction methods in the CCA and supplementary information 
and found them to be presented with sufficient clarity to permit full 
understanding of the descriptions and methods. However, both EPA and 
public commenters 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, EPA required DOE 
to perform additional analyses of fluid injection. Based on 
supplementary information provided by DOE, EPA concluded that fluid 
injection can be screened out from the PA based upon low consequences 
to disposal system performance. EPA and commenters also had concerns 
about DOE's conceptual model for spallings.\16\ The results of the 
spallings model were eventually determined to be reasonable and 
adequate for use in PA. For further discussion of the spallings model, 
refer to the discussion of models and computer codes later in this 
section.
---------------------------------------------------------------------------

    \16\ ``Spallings'' refers to releases of solids forced up and 
out of an intrusion borehole by gas pressure in the repository.
---------------------------------------------------------------------------

    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 conceptual models include those 
characteristics and attributes of the WIPP disposal system and its 
surroundings that adequately describe the possible future performance 
of the disposal system. The conceptual models contain appropriate 
simplifications of the characteristics, attributes, and processes of 
the disposal system. 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 its review of DOE's descriptions of the 
conceptual models and the scenario construction procedures presented in 
the CCA and supporting documents, the Agency proposes to determine that 
the DOE has demonstrated compliance with the requirements of 
Sec. 194.23(a)(1).
    b. Alternative Conceptual Models. Section 194.23(a)(2) requires the 
CCA to describe plausible, alternative conceptual models that DOE 
seriously considered but did not use to support compliance, and to 
explain why DOE decided the alternative conceptual model does not 
accurately portray performance of the disposal system. This requirement 
allows EPA to evaluate whether the conceptual models underlying the PA 
and compliance assessment are appropriate and adequate.
    DOE provided information on alternative conceptual models in the 
CCA, both in its discussion of FEPs and in its documentation of the 
conceptual models peer review panel. The peer review panel identified 
no major issues concerning alternative models.
    EPA reviewed information on alternative conceptual models in the 
CCA and in documentation from the peer review panel. EPA requested, and 
DOE provided, supplementary information containing a focused, detailed 
description of plausible alternative conceptual models considered but 
not used in the PA. DOE also explained the reasons why these 
alternative models were not used to

[[Page 58807]]

describe the performance of the repository. EPA determined that DOE 
sufficiently documented the rationale and approach used to select the 
conceptual models employed in the CCA PA and to reject other models.
    As discussed elsewhere in this section, the conceptual models peer 
review panel and EPA had concerns specifically with the spallings 
conceptual model. Because the conceptual models peer review panel 
initially judged the spallings model used in the CCA to be inadequate, 
DOE developed an alternative mechanistically-based computational 
approach to estimate the volume of spallings released to the accessible 
environment. The volumes of radioactive waste to be released that were 
calculated by the alternative mechanistically-based model were less 
than one tenth those predicted in the model used in the CCA. Because 
the original spallings model results used in the CCA were conservative, 
the conceptual models peer review panel and EPA found the predicted 
results from the original model to be acceptable for use in the PA.
    Based on information provided in the CCA together with 
supplementary information provided by DOE in response to specific EPA 
requests, EPA concluded that DOE provided an adequate and complete 
description of alternative conceptual models seriously considered but 
not used in the CCA. DOE provided adequate discussion of why these 
alternative models were not deemed to adequately portray the 
performance of the disposal system. Therefore, EPA proposes to find DOE 
in compliance with Sec. 194.23(a)(2).
    c. Future States of the Disposal System and Peer Review. Section 
194.23(a)(3)(i) requires the CCA conceptual models and scenarios to 
reasonably represent future states of the disposal system. Section 
194.23(a)(3)(v) requires the CCA to document that conceptual models 
have undergone peer review in accordance with Sec. 194.27, which 
requires that the peer review meets the guidance of NUREG-1297. Under 
this guidance, the peer review must include the following: A listing of 
the reviewers; requirements for the acceptability of each reviewer; 
individual statements by peer reviewers reflecting dissenting views, if 
any; a discussion of the conceptual models peer reviewed; an evaluation 
of data and information used to develop conceptual models; an 
evaluation of the validity of conceptual model assumptions; an 
evaluation of alternative conceptual models; an evaluation of the 
uncertainty in the conceptual models and a discussion of consequences 
if the conceptual model chosen is inappropriate for the site; a 
statement indicating the adequacy of the conceptual models used for the 
disposal system; a statement of the accuracy of the results based on 
the conceptual models employed; and a discussion of the validity of the 
conclusions drawn based on the conceptual models. As part of the review 
of adequacy of the conceptual models, peer reviewers considered whether 
conceptual models reasonably represented future states of the disposal 
system. The NUREG-1297 requirements and the process of peer review are 
discussed in greater detail in the preamble for Sec. 194.27.
    DOE convened a conceptual models peer review panel to review the 24 
conceptual models used in the CCA PA. During the initial review, the 
panel found that 11 models were not adequate and 13 models were 
adequate for use in PA. The panel initially found the 11 conceptual 
models to be inadequate for a variety of reasons, mostly related to the 
adequacy of assumptions incorporated in the conceptual models and the 
amount of supporting data or analyses for certain features of the 
conceptual models. Based on additional information provided by DOE and 
three subsequent review sessions, the panel found all the models to be 
adequate for use in PA except the spallings model. They found that the 
original CCA PA spallings model did not reasonably represent possible 
future states of the disposal system because it did not fully model all 
potential mechanisms that may cause pressure-driven solid releases. The 
panel ultimately concluded, based on substantial analytical and 
experimental work provided by DOE, that the spallings values used in 
the CCA are reasonable for use in PA. The panel found that, while the 
spallings model does not accurately represent the future state of the 
disposal system, its inaccuracies are of an overly conservative nature, 
and in fact, may overestimate the actual waste volumes that would be 
expected to be released by the spallings process.
    EPA concurs with the conceptual model peer review panel's findings, 
based upon the results of DOE's analysis and development of an 
alternative model for spallings, which showed that the CCA PA spallings 
model overestimates spallings releases by up to ten times or more. The 
peer review panel's findings considered whether conceptual models 
reasonably represented future states of the disposal system. EPA does 
not propose to determine that the spallings model ``reasonably 
represents possible future states of the repository.'' The additional 
modeling conducted by DOE, and the additional data developed by DOE, 
however, 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. Because the spallings 
model produces reasonable and conservative results, EPA proposes to 
accept it for purposes of demonstrating compliance with 
Sec. 194.23(a)(3)(i).
    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. Therefore, the 
Agency proposes to find that DOE has demonstrated compliance with the 
requirements of Sec. 194.23(a)(3)(v).
    d. Public Comments. During the public comment period on the Advance 
Notice of Proposed Rulemaking (``ANPR''), EPA received numerous 
comments challenging various aspects of the spallings model. EPA and 
the conceptual models peer review panel, among others, shared concerns 
about the adequacy of the spallings model and on numerous occasions 
informed DOE of their concerns. In response to these concerns, DOE did 
substantial additional work, developed a mechanistically-based model 
and supported this model with 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. On this 
basis, and as discussed above, EPA proposes that it is appropriate to 
accept the results from the spallings model for purposes of 
demonstrating compliance with Sec. 194.23(a)(3)(i).
    EPA also received public comments on the ANPR concerning modeling 
of fluid injection. Commenters expressed concern that the CCA PA 
calculations did not model possible effects of pressurized brine 
injection that may fracture the anhydrite beds near WIPP, enter the 
repository, become contaminated and flow to various release points. EPA 
required DOE to perform extensive supplementary analyses to evaluate 
the effects that brine injection could have on the repository. EPA also 
performed independent analyses to address concerns related to brine 
injection. EPA has determined that brine injection does not pose an 
unacceptable risk and that associated scenarios can be reliably 
screened from further consideration.

[[Page 58808]]

2. Progression From Conceptual Models to Computer Codes
    Most of the requirements of Sec. 194.23(a)(3) concern the Agency's 
evaluation of the progression from conceptual models to computer codes 
used in the CCA PA and compliance assessment. Each requirement in 
Secs. 194.23(a)(3)(i) through (iv) is intended to ensure that DOE has 
correctly implemented the steps between development of the underlying 
conceptual models and encoding the computer software that implements 
the PA and compliance assessment calculations. The initial step of 
evaluating the fundamental conceptual models is discussed above.
    a. Mathematical Models. Section 194.23(a)(3)(ii) requires the CCA 
to document that mathematical models incorporate equations and boundary 
conditions which reasonably represent the mathematical formulation of 
the conceptual models. This requirement is intended to ensure that PA 
calculations are based upon mathematical equations that truly implement 
the conditions in the fundamental conceptual models. Many of the 
mathematical equations are partial differential equations, which 
consider rates of change; thus, codes incorporating these mathematical 
models need initial and boundary conditions between which the rates of 
change in the equations will operate.
    DOE documented the development of each computer code used in PA and 
compliance assessment, including the associated mathematical models and 
numerical models. This information was contained primarily in Users 
Manuals, Validation Documents, Implementation Documents, and 
Requirements Document & Verification and Validation Plans for each CCA 
PA computer code. EPA reviewed information supplemental to the CCA for 
each CCA PA computer code and evaluated whether the mathematical models 
incorporate equations and boundary conditions which reasonably 
represent the mathematical formulation of the conceptual models.
    EPA reviewed the mathematical model equations and boundary 
conditions for the following codes: PANEL, BRAGFLO, NUTS, FMT, SANTOS, 
BRAGFLO__DBR, GRASP-INV, SECOFL2D, SECOTP2D, CCDFGF, and CUTTINGS__S. 
These are the codes DOE used to model the behavior of the repository 
and its surroundings and to compute results of the PA calculations. The 
codes PANEL, BRAGFLO, NUTS, FMT, and SANTOS incorporate mathematical 
model equations that implement the conceptual models for predicting 
future characteristics of the waste repository. These five codes 
simulate the following effects, respectively: concentrations of 
radioactive waste in brine within the waste-containing panels in the 
repository; flow of brine and gas in the repository; solubility and 
transport of radionuclides released from the repository; solubility of 
radionuclides in the repository; and collapse of the repository through 
salt creep closure of the Salado. The computer code BRAGFLO__DBR 
describes waste dissolution in brine and transport of the contaminated 
brine through direct brine releases. The three computer codes GRASP-
INV, SECOFL2D, and SECOTP2D mathematically describe flow and transport 
of waste-laden brine in the Culebra dolomite. The computer code 
CUTTINGS__S incorporates mathematical model equations modeling releases 
of radioactive waste upon intrusion of a drill bit into the repository. 
The computer code CCDFGF computes complementary cumulative distribution 
functions (``CCDFs'') for the results of PA.
    In general, EPA found that the descriptions of mathematical 
formulations were adequately explained and were reasonable. The Agency 
found that DOE adequately documented and described simplifications of 
conceptual models in the CCA. EPA also concluded that DOE provided an 
adequate technical basis to support the mathematical formulations. EPA 
tested each of the codes with functional tests to verify that each 
computer code would perform according to its functional 
requirements.<SUP>17</SUP> This analysis and testing indicated that 
equations and boundary conditions were properly incorporated into the 
mathematical models and that boundary conditions were reasonable 
representations of how the conceptual models should be implemented.
---------------------------------------------------------------------------

    \17\ A functional requirement specifies how the code is intended 
to operate, including inputs and outputs.
---------------------------------------------------------------------------

    EPA encountered problems with the governing equations of the 
mathematical models and the representation of the boundary conditions 
in the codes CUTTINGS__S, SECOFL2D, SECOTP2D, NUTS and BRAGFLO. EPA 
specified that the equations in the codes be corrected and that the 
changes to the codes be documented. 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 necessary corrections to input parameters, conceptual 
models, and computer codes used in PA was not significant enough to 
necessitate a new PA. For the PAVT, DOE used corrected versions of the 
BRAGFLO, NUTS and SECOTP2D computer codes. The results of the PAVT 
demonstrate that the cumulative impact of all these necessary 
corrections did not require new PA runs. DOE resolved all of EPA's 
questions related to the equations that make up the mathematical models 
and the incorporation of the boundary conditions of the various codes 
by correcting the codes and performing the PAVT.
    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. DOE resolved all issues raised by 
the Agency. DOE has provided an adequate technical basis to support the 
mathematical formulations used in the PA. Therefore, the Agency 
proposes to find DOE in compliance with Sec. 194.23(a)(3)(ii).
    b. Public Comments on Mathematical Models. During the public 
comment period on the ANPR, EPA received comments on aspects of the 
mathematical models. Several commenters felt that the mathematical 
models in the CCA PA, particularly those related to ground-water flow 
in the Culebra dolomite, did not account sufficiently for three-
dimensional processes and boundary conditions. A DOE report provided a 
detailed sensitivity analysis of ground-water flow characteristics in 
the Culebra. This report concluded that the majority of ground-water 
flow through the Culebra is horizontal. (Docket A-93-02, Item II-G-1, 
Reference #147) From the perspective of calculating the potential 
consequences to repository performance, neglecting vertical leakage 
into and out of the Culebra is conservative. EPA believes that the two-
dimensional modeling approach used in the PA for ground-water flow in 
the Culebra dolomite is conservative and adequate. EPA also reviewed 
the FEP screening analysis related to flow of brine and gas in the 
repository and concluded that there are only minor differences between 
the two-dimensional and three-dimensional computations. Therefore, EPA 
believes that the two-dimensional geometry used in the BRAGFLO computer 
code is reasonable and appropriate for the CCA PA.
    EPA also received public comments on the ANPR concerning the 
modeling

[[Page 58809]]

of ground-water flow and radionuclide transport processes in the 
Culebra. Commenters stressed that scientific understanding of ground-
water flow in fractured rock systems is still developing and that DOE 
requires greater documentation of processes and parameters embodied in 
the CCA PA. EPA notes in response to public comments that DOE conducted 
an extensive investigative program to improve its theories of ground-
water flow and radionuclide transport through the Culebra. Although 
these activities have greatly improved the understanding of the 
geohydrologic system, EPA recognizes that a degree of uncertainty will 
always exist when attempting to make predictions about the performance 
of WIPP 10,000 years into the future. EPA required DOE to address this 
uncertainty in its PA by assigning ranges and distributions to 
uncertain variables, such as fracture spacings, distribution 
coefficients, porosities and transmissivity. EPA also required DOE to 
perform further analysis using different parameter values and 
distributions in the PAVT. EPA believes that this approach to handling 
uncertainty is appropriate because the uncertainty will be captured by 
the ranges and distributions assigned to parameters.
    c. Numerical Models. Section 194.23(a)(3)(iii) requires 
documentation that numerical models provide numerical schemes which 
enable the mathematical models to obtain stable solutions. Although 
some mathematical models can be solved directly, many of the 
mathematical equations used in PA for the WIPP are so complex that they 
require the use of numerical solution methods to provide an approximate 
solution. It is important that solutions to the mathematical models be 
stable because unstable solutions may make it impossible to proceed to 
the next step in obtaining PA results or may call into question the 
results of the model.
    The relevant information was contained in supplemental information 
from DOE, including Analysis Packages for each code and the documents 
described in the previous section. This documentation includes testing 
results for problems that are very similar to those solved by the 
code(s) in the CCA PA, in order to evaluate the stability of solutions 
from the numerical schemes used to solve the mathematical model 
equations. DOE also maintained a computational record of whether any of 
the codes experienced stability problems during the CCA PA 
calculations. The codes that use numerical solvers include: SANTOS, 
CUTTINGS__S, SECOFL2D, SECOTP2D, PANEL, BRAGFLO, BRAGFLO__DBR, NUTS, 
and GRASP-INV.
    EPA reviewed all the relevant documentation on numerical solution 
schemes contained in the CCA and supplementary information about each 
code. EPA also executed DOE code verification tests to search for 
possible stability problems. EPA's review identified stability concerns 
related to the following codes: CUTTINGS__S, SECOFL2D, SECOTP2D, and 
NUTS. In the case of the NUTS and SECOTP2D codes, DOE was able to make 
minor changes to the codes to correct their stability problems. EPA's 
concerns regarding potential stability problems with CUTTINGS__S and 
SECOFL2D were alleviated after DOE provided results from further 
stability and code verification testing that showed these problems had 
been corrected. DOE satisfactorily resolved all EPA concerns regarding 
code stability issues.
    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 determined that the numerical models produced stable 
solutions. DOE resolved stability problems with the BRAGFLO, NUTS, 
SECOFL2D and SECOTP2D computer codes by completing code revisions and 
supplementary testing requested by the Agency. Therefore, EPA proposes 
to find DOE in compliance with Sec. 194.23(a)(3)(iii).
    d. Computer Codes. Section 194.23(a)(3)(iv) requires documentation 
that computer models accurately implement the numerical models, such 
that computer codes are free of coding errors and produce stable 
solutions. This is the final step to ensure that the underlying 
conceptual models are implemented correctly in the PA calculations and 
to ensure that the PA calculations will yield valid results.
    To ensure that PA computer codes accurately implement the numerical 
models and are free of coding errors, DOE adopted a number of Quality 
Assurance Procedures for each step in the software development process. 
(See also the preamble discussions of Secs. 194.22 and 194.23(b).) DOE 
documented information on the software development process in Users 
Manuals, Validation Documents, Implementation Documents and 
Requirements Document & Verification and Validation Plans for each 
computer code.
    EPA performed an independent review of the CCA PA computer codes 
used to support the PA. As part of this review, EPA executed functional 
tests established by DOE for each of the codes to verify that each 
computer code performed according to its functional requirements, and 
to verify that the computer codes accurately implemented the numerical 
models, were free of coding errors, and produced stable solutions. The 
codes that EPA reviewed and tested include: SANTOS, CUTTINGS__S, 
SECOFL2D, SECOTP2D, CCDFGF, LHS, PANEL, BRAGFLO, BRAGFLO__DBR, FMT, 
NUTS, GRASP-INV and ALGEBRA. EPA also reviewed all of the relevant 
documentation pertaining to each of the major codes described above.
    EPA identified issues related to coding errors for the following 
codes: SECOFL2D, SECOTP2D, and NUTS. To address these concerns, EPA 
requested that DOE perform a number of additional analyses. In the 
process of responding to EPA's concerns, DOE discovered, rectified and 
documented several minor coding errors. Results from an impact analysis 
by DOE indicated that the coding errors would have very little impact 
on the WIPP's compliance with the disposal regulations. These issues 
were resolved to EPA's satisfaction.
    Based on the CCA and supplementary information, the Agency 
determined that DOE provided sufficient technical information to 
document the numerical models used in the CCA. Based on verification 
testing, EPA determined that the computer codes accurately implement 
the numerical models and that the computer codes are free of coding 
errors and produce stable solutions. DOE resolved coding error problems 
that EPA initially encountered by performing code revisions and 
supplementary testing requested by the Agency. Therefore, the Agency 
proposes to conclude that DOE has demonstrated compliance with 
Sec. 194.23(a)(3)(iv).
3. Quality Assurance
    Section 194.23(b) requires that computer codes used in the CCA must 
be documented in a manner that complies with the quality assurance 
requirements of ASME NQA-2a-1990 addenda, part 2.7, to ASME NQA-2-1989 
edition. This requirement is intended to ensure proper development and 
documentation of software and to identify any potential problems. Based 
on EPA audits and CCA review, EPA found that code documentation meets 
the NQA requirements, and thus proposes to find that DOE complies with 
Sec. 194.23(b). See the preamble discussion of Sec. 194.22(a)(2)(iv), 
Quality assurance, for further discussion of EPA's evaluation of 
compliance.

[[Page 58810]]

4. Documentation of Models and Codes
    Sections 194.23(c)(1) through (6) contains a number of requirements 
related to documentation of models and computer codes. These 
requirements allow EPA to evaluate the design of the models, to 
evaluate the numerical values selected to describe the repository and 
its surroundings, and to operate the software used to perform the PA 
calculations.
    DOE documented the development of computer software in a series of 
documents that supplement the CCA. The information that EPA reviewed 
was contained primarily in Analysis Packages, User's Manuals, 
Validation Documents, Implementation Documents and Requirements 
Document & Verification and Validation Plans for each code. DOE used 
these documents to track development of software codes beginning from 
the conceptual model stage, and continuing through derivation of the 
mathematical equations and their solutions, setting computational 
requirements for computer codes, designing the computer software, 
programming the software, and testing the codes after they are 
programmed. Among the types of information found in these documents are 
general descriptions of the models, descriptions of the theoretical 
background of models, discussions of the limits of the models, 
instructions for executing computer codes, information on the required 
input and output formats with examples, reports on testing of the 
computer codes, structure of the computer codes, source 
codes,<SUP>18</SUP> and sources of data used to support parameter 
values used in the models and codes.
---------------------------------------------------------------------------

    \18\ ``Source code'' means the written description of each step 
the computer code will follow when it is executed.
---------------------------------------------------------------------------

    a. Theoretical Background. Section 194.23(c)(1) requires the CCA to 
describe the theoretical backgrounds of each model and the method of 
analysis or assessment used by each model. EPA evaluated whether DOE's 
descriptions of the computer codes provided sufficient detail to 
determine if the codes are formulated on a sound theoretical 
foundation, and whether DOE provided clear documentation describing 
exactly how each of the codes was used to support the PA. The codes 
that EPA reviewed include: CUTTINGS__S, SECOFL2D, SECOTP2D, CCDFGF, 
LHS,<SUP>19</SUP> PANEL, BRAGFLO, BRAGFLO__DBR, NUTS, FMT, GRASP-INV, 
SANTOS and ALGEBRA.<SUP>20</SUP> These codes describe the repository, 
the movement of radionuclides in contaminated brine through the 
overlying Culebra dolomite, releases of radionuclides when a drill 
penetrates the repository, and calculations of releases for final 
results of the PA. EPA located the majority of the information in the 
Users Manuals and Analysis Packages for each code, found in the Sandia 
National Laboratories WIPP Record Center.
---------------------------------------------------------------------------

    \19\ LHS, or Latin Hypercube Sampling, is a code that selects or 
``samples'' a numerical value from a distribution of probable values 
for a parameter. For more information on LHS, see the preamble 
discussion of the requirements of Sec. 194.34.
    \20\ The ALGEBRA computer code manipulates input data and 
initial conditions that allow other codes to perform their 
calculations.
---------------------------------------------------------------------------

    In a few cases, EPA initially found the theoretical description of 
the computer codes to be inadequate. Most notably, the mathematical 
description of the solution precipitation model contained in the NUTS 
code, which predicts radionuclide transport in the repository and in 
units underlying the Culebra, was absent from the documentation. DOE 
addressed EPA's concerns by providing supplementary reports that 
describe in detail those theoretical discussions that were originally 
deficient. With respect to the documentation pertaining to the method 
of analysis, EPA found the descriptions in the Analysis Packages for 
each code to be sufficiently complete. In several instances, EPA 
requested that DOE clarify the written documentation, which DOE did.
    Based on information contained in the Users Manual and Analysis 
Packages for each code and supplementary information requested by EPA 
to address specific problems uncovered in the course of the compliance 
review, EPA found that DOE has provided sufficient 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. EPA also found that the level of documentation is consistent 
with the ASME requirements for quality assurance as well as consistent 
with recent standards on ground-water modeling published by the 
American Society for Testing and Materials (ASTM). Therefore, EPA 
proposes to determine that DOE has complied with the requirements of 
Sec. 194.23(c)(1).
    b. Descriptions of Models. Section 194.23(c)(2) requires the CCA to 
document the following kinds of information: general descriptions of 
the models; discussions of the limits of applicability of each model; 
detailed instructions for executing the computer codes, including 
hardware and software requirements; input and output formats with 
explanations of each input and output variable and parameter; listings 
of input and output files from a sample computer run; and reports on 
code verification, bench marking, validation,<SUP>21</SUP> and quality 
assurance (``QA'') procedures. Section 194.23(c)(3) requires 
documentation of the structure of the computer codes in detail and 
complete listings of the source codes.
---------------------------------------------------------------------------

    \21\ Verification, bench marking and validation are steps in 
testing computer codes to ensure they operate as intended. 
Verification means that the aspect of the code being tested matches 
known solutions. Bench marking means that solutions from the code 
are compared to results from an outside reference or ``bench mark'' 
calculation, for more complicated situations where the solutions to 
a problem may not be known exactly. Validation means all aspects of 
the code work together properly.
---------------------------------------------------------------------------

    The codes that EPA reviewed include: CUTTINGS__S, SECOFL2D, 
SECOTP2D, CCDFGF, LHS, PANEL, BRAGFLO, BRAGFLO__DBR, NUTS, FMT, GRASP-
INV, SANTOS and ALGEBRA. The supplemental information from DOE that 
documented code development was described above in this section. DOE 
also set forth a number of objectives regarding issues that must be 
covered in code documentation to meet the QA criteria outlined in 
Sections 4 and 6 of the ASME NQA-2a-1990 addenda, part 2.7, to ASME 
NQA-2-1989.
    EPA reviewed the supplemental documents, executed the computer 
codes, and evaluated the code verification, bench marking, and 
validation documentation. During its review, EPA identified a number of 
areas where the Agency initially judged the documentation to be 
inadequate. EPA required the Department to perform an analysis on the 
NUTS computer code, to develop a code requirement and test the 
statistical validity of certain aspects of the GRASP-INV code, to 
provide evidence that the GRASP-INV code was tested in a manner 
consistent with its implementation in the PA, and to document a sample 
computer run that corresponds to calculation of the CCA PA results. DOE 
provided this additional supporting analysis and documentation and 
satisfied EPA's concerns.
    DOE submitted all of the source code listings and a detailed 
description of the structure of computer codes in the Implementation 
Documents for each code. With this information, a user can compile the 
source code and install it on a computer system identical to that used 
in the CCA PA calculation. EPA found that DOE submitted all of the 
source code listings. EPA identified no

[[Page 58811]]

problems with the detailed descriptions of the structure of the 
computer codes.
    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 that 
are adequate for use in the CCA PA. 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. Therefore, EPA proposes to 
determine that DOE has demonstrated compliance with Secs. 194.23(c) (2) 
and (3).
    c. Parameters. Section 194.23(c)(4) requires detailed descriptions 
of data collection procedures, data reduction and analysis, and code 
input parameter development. Parameters are numerical values or ranges 
of numerical values used 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. 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.
    DOE discussed information supporting parameter development in the 
CCA and in parameter records located in the SNL WIPP Record Center. The 
records at SNL Record Center include WIPP parameter entry forms, 
Parameter Records Packages, Principal Investigator Records Packages, 
Data Records Packages, and Analysis Packages. DOE uses all of these 
documents to explain the full development of parameter values used as 
inputs to the CCA PA calculations.
    The Agency reviewed the CCA, parameter documentation and record 
packages for approximately 1,600 parameters used as input values to the 
CCA PA calculations. 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: parameters that were likely to 
contribute significantly to releases or seemed to be poorly justified; 
parameters that control various functions of the CCA PA computer codes 
that were likely to be important to calculations of releases and 
important to compliance with the containment requirements of 
Sec. 191.13; and other parameters the Agency used to evaluate the 
overall quality of SNL's documentation traceability. The Agency 
examined DOE's parameter documentation to see if the following elements 
were present: detailed listings of code input parameters and the 
parameters that were sampled; codes in which the parameters were used 
and the computer code names of the sampled parameters; descriptions of 
the sources of data; descriptions of the parameters, data collection 
procedures, data reduction and analysis, and code input parameter 
development; discussions of the linkage between input parameter 
information and data used to develop the input information; discussions 
of the importance of the sampled parameters relative to final 
calculations of releases, correlations among sampled parameters, and 
how these are addressed in PA; a listing of the sources of data used to 
establish parameters; and data reduction methodologies used for CCA PA 
parameters, including an explanation of QA activities.
    After its initial review, the Agency 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, 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 did not find adequate documentation to 
support one of DOE's professional judgement parameters, the waste 
particle size value (expressed as a particle diameter). Other 
parameters such as professional judgment parameters and some parameters 
that were used in DOE's 1992 PA calculations were found to have 
adequate documentation to support the value used in the CCA PA 
calculations.
    During its review, EPA found that the following types of 
documentation were necessary to improve DOE's records: a comprehensive 
database of all parameters used in the CCA PA, a database of all 
parameters based on experimental data, ``roadmaps'' that document and 
link CCA PA parameters to their sources, complete record packages in 
the SNL Record Center, background documentation on the development of 
those parameters that were originally used in DOE's 1992 PA 
calculations and again were used in the CCA PA calculation, and 
adequate explanations of why the 149 professional judgment parameters 
in the comprehensive parameter database did not need expert 
elicitation. DOE provided all of these pieces of documentation, 
primarily by improving the quality of the records stored in the SNL 
WIPP Records Center. The Agency did not accept the use of professional 
judgement to derive the waste particle size parameter, and thus 
required DOE to use the process of expert elicitation to develop the 
value for this parameter. (See also the preamble discussion for 
Sec. 194.26 regarding expert elicitation for the waste particle size.) 
After subsequent review and evaluation of the SNL WIPP Record Center 
records and after completion of expert elicitation, EPA was satisfied 
with the additional documentation provided by DOE for these areas of 
concern.
    The Agency requested further documentation from DOE, expressing 
concern about information supporting 58 parameters. EPA divided these 
parameters into those parameters lacking supporting evidence, those 
parameters that have records supporting values other than those 
selected by DOE, and those parameters that are not explicitly supported 
by the relevant data or information. DOE provided additional 
information supporting some of the parameters of concern to EPA. The 
Agency also performed its own sensitivity analyses for the parameters 
to determine if changes to some parameters have a significant impact on 
the final computer calculations. The Agency's concerns were resolved 
for thirty-four of these parameters, either by DOE's submission of 
additional documentation or by the results of sensitivity analyses 
conducted by EPA that indicated that changes to certain parameter 
values would not

[[Page 58812]]

significantly impact results of computer calculations.
    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 PA 
was not significant enough to necessitate a new PA. EPA directed DOE to 
incorporate modified values or distributions for twenty-four parameters 
in the PAVT. 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. For further information about results of the PAVT, see 
the preamble for Sec. 194.34, ``Results of PA.'' DOE satisfied EPA's 
concerns about the parameters by incorporating EPA's changes to the 
parameter values and parameter distributions in the PAVT.
    Upon subsequent review and evaluation, 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. Therefore, the 
Agency proposes to determine that the CCA complies with 
Sec. 194.23(c)(4).
    d. Public Comments on Parameter Values. During the public comment 
period for the ANPR, EPA received comments on specific parameter 
values. After the end of the ANPR public comment period, EPA also 
received comments on parameter distribution values that the Agency 
mandated DOE include in the PAVT.
    The Agency performed a thorough review of the parameters and the 
parameter development process, as discussed in the previous section. In 
its initial review, the Agency found that DOE had a great deal of 
documentation supporting most of the parameters used in the CCA PA 
available in the SNL Records Center. EPA specifically requested DOE to 
perform the PAVT in order to determine the effects of different 
parameter distributions for those parameters that concerned EPA and 
that appeared to have a significant impact on the results of PA.
    e. Software Licenses. Section 194.23(c)(5) requires the CCA to 
document any licenses necessary for software used in the PA. DOE stated 
that it did not use any software requiring licenses, since software was 
developed by DOE or its contractors. EPA concurs with DOE's statement, 
and thus proposes to find that the CCA complies with Sec. 194.23(c)(5).
    f. Parameter Correlation. Section 194.23(c)(6) requires the CCA to 
provide an explanation of the manner in which models and computer codes 
incorporate the effects of parameter correlation. Parameters are 
correlated if they are not completely independent of each other. For 
example, if two parameters are programmed into computer codes so that 
both increase or decrease under the same conditions, the two parameters 
are correlated. Such a correlation can be directly programmed as an 
explicit correlation specified by the computer user. A parameter 
correlation also can be programmed into computer codes indirectly 
through an induced correlation when one parameter is used to derive a 
second parameter in the code. EPA evaluated parameter correlation in 
the CCA because an improper parameter correlation may call into 
question some parameter values and may even call into question the 
validity of the results from PA, depending on how significant the 
correlated parameters are.
    User-specified (explicit) parameter correlations are introduced 
into the CCA PA calculations using a correlation matrix or table in the 
Latin Hypercube Sampling (LHS) computer program. Of all the parameters, 
only rock compressibility and permeability are explicitly correlated in 
the LHS computer code input file. When values that are sampled using 
the LHS computer code are used to calculate other values in the CCA PA 
calculations, an induced correlation parameter relationship is created 
through mathematical formulas used in subsequent computer codes. This 
is the prevalent method of correlation used in DOE's PA.
    EPA reviewed the documentation in the LHS Users Manual that 
explains how parameter correlation is included in the parameter sample 
process. EPA also reviewed information in the CCA which discussed the 
mathematical methods used to incorporate parameter correlation into the 
CCA PA calculations. EPA also reviewed DOE's sensitivity analysis of 
the parameters sampled in the CCA PA, which includes a discussion of 
the impacts of parameter correlations.
    Based on its review of CCA documentation and supplementary 
information, EPA determined that DOE has adequately demonstrated the 
manner in which the models and computer codes incorporate the effects 
of parameter correlation. Specifically, the CCA contains adequate: (1) 
Discussions that explain how the effects of parameter correlation are 
incorporated; (2) explanations of the mathematical functions that 
describe these relationships; and (3) descriptions of 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. Thus, the 
Agency proposes to find that DOE has demonstrated compliance with the 
requirements of Sec. 194.23(c)(6).
5. EPA's Independent Testing
    Section 194.23(d) allows EPA to verify the results of computer 
simulations used in the CCA by performing independent simulations. This 
requirement also requires DOE to provide EPA with data files, source 
codes, executable versions of computer software for each model, other 
material or information needed to permit EPA to perform independent 
simulations, and to access necessary hardware to perform such 
simulations within 30 days of a request from EPA. This requirement 
ensures that EPA can verify calculations in the CCA and analyze the 
potential impact of changes to the PA calculations if changes are made 
to computer codes or parameters.
    DOE provided EPA with unrestricted access to computer hardware 
required to perform simulations related to the CCA. DOE also provided 
EPA with access to data files, source codes, and executable computer 
codes for each model used in the CCA. DOE provided staff to assist EPA 
in executing various verification tests and sensitivity analyses with 
DOE hardware and software. EPA performed code verification tests on all 
CCA PA computer codes using CCA hardware and software. In some cases, 
EPA required DOE to perform additional verification tests. EPA 
conducted extensive parameter sensitivity tests using the same system 
of CCA PA computer codes. The PAVT was an independent computer 
simulation of the WIPP's performance conducted under EPA's authority to 
require independent verification computer simulations under 
Sec. 194.23(d). DOE provided assistance in all of this work on a timely 
basis. 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,

[[Page 58813]]

EPA proposes to find DOE in compliance with Sec. 194.23(d). For further 
information on EPA's evaluation of compliance for Sec. 194.23, see CARD 
23.

C. Section 194.24, Waste Characterization

    Section 194.24, waste characterization, generally requires DOE to 
identify and describe quantitative information on the chemical, 
radiological and physical characteristics of the waste proposed for 
disposal at the WIPP that can influence disposal system performance. 
The DOE has not demonstrated compliance with all the requirements of 
Sec. 194.24 as they pertain to waste characterization activities at 
generator sites. Therefore, EPA is proposing certification of 
compliance with these requirements, with the condition that DOE must 
submit additional information to demonstrate full compliance for waste 
generator sites. The proposed conditions of certification are addressed 
under EPA's discussion of the requirements at Secs. 194.24(c)(3) 
through (5).
    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. DOE described the existing waste 
by combining like waste streams into eleven final waste forms and waste 
stream profiles. A waste stream is defined by DOE as waste material 
generated from a single process or activity that is similar in 
material, physical form, isotopic make-up, and hazardous constituents. 
The waste stream profiles contained information on the waste material 
parameters, or components, that could affect repository performance. 
DOE extrapolated information from the existing waste streams to 
determine the amount of to-be-generated waste. DOE's waste profiles 
contained appropriate specific information on the components and their 
approximate quantities in the waste. Therefore, EPA proposes to find 
DOE in compliance with Sec. 194.24(a).
    Sections 194.24(b)(1) through (3) require 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. For example, the waste 
characteristic gas generation is controlled, in part, by the type and 
amount of waste components such as metal waste containers and plastic 
material. DOE identified waste-related elements pertinent to the WIPP 
as part of its screening for features, events, and processes 
(``FEPs''). The FEPs used in the performance assessment (``PA'') served 
as the basis from which characteristics and associated components were 
identified and further analyzed. (Refer to the preamble discussion of 
Sec. 194.32, ``Scope of PA,'' for additional information pertaining to 
FEPs.)
    DOE concluded that six characteristics were expected to have a 
significant effect on disposal system performance and were used in PA 
(i.e., parameters were identified for each): solubility, formation of 
colloidal suspensions containing radionuclides, gas generation, shear 
strength of waste, radioactivity of specific isotopes, and TRU activity 
at disposal. 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 PA. 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 proposes to find DOE in compliance with 
requirements in Secs. 194.24(b)(1) through (3).
    Section 194.24(c)(1) requires DOE to specify numeric limits on 
significant waste components and demonstrate that, for those 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. DOE explicitly included numeric limits, 
identified as fixed values with no associated uncertainty, for four 
waste components. Lower limits were established for ferrous and non-
ferrous metals; upper limits were established for cellulosics and free 
water. The three components related to radioactivity and radionuclides 
were effectively limited by the inventory estimates used in the PA. The 
fixed-value limits and radionuclide inventory estimates were included 
in the PA calculations through parameters closely related to these 
components, and the results demonstrated compliance with EPA's 
standards. 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.
    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. Therefore, EPA proposes to find DOE in compliance with 
Sec. 194.24(c)(1).
    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). DOE proposed to use non-destructive 
assay (``NDA'') (e.g., passive active neutron assay), non-destructive 
examination (``NDE'') (e.g., radiography), and visual examination 
(``VE'') as the methods used to quantify various waste components. The 
CCA described numerous NDA instrument systems and described the 
equipment and instrumentation found in NDE and VE facilities. 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. EPA found that these methods, when 
implemented appropriately, would be adequate to characterize the 
important waste components. Therefore, EPA proposes to find that DOE 
has demonstrated compliance with Sec. 194.24(c)(2). (Implementation of 
measurement programs at waste generator sites is addressed below for 
the requirements at Secs. 194.24(c)(4) and (5).)
    Section 194.24(c)(3) requires DOE to demonstrate that the use of 
process knowledge to quantify components in waste for disposal conforms 
with the quality assurance (``QA'') requirements found in Sec. 194.22. 
EPA expected DOE to submit specific information on the process 
knowledge to be used at waste generator sites as part of DOE's 
certification application. EPA requires such information to conduct 
proper regulatory review of whether use of the process knowledge is 
appropriate and reliable. DOE provided some information on its overall 
plans for using process knowledge in the CCA. DOE did not, however, 
provide specific information on the use of process knowledge at any 
waste generator site in the CCA, nor did it provide information

[[Page 58814]]

demonstrating establishment of the required QA programs.
    After submission of the CCA, EPA subsequently received information 
regarding process knowledge to be used at the Los Alamos National 
Laboratory (``LANL''). EPA determines DOE to have adequately described 
the use of process knowledge for retrievably stored (legacy) debris 
waste streams at LANL. EPA has confirmed establishment and execution of 
the required QA programs at that waste generator site through 
inspections. (See the preamble discussion of Sec. 194.22, ``Quality 
Assurance,'' for further information on inspections.) Therefore, the 
Agency determines that DOE has demonstrated compliance with the 
Sec. 194.24(c)(3) QA requirement for LANL. EPA does not find, however, 
that DOE has adequately described the use of process knowledge for any 
other waste streams at LANL (other than the retrievably-stored (legacy) 
debris waste streams discussed above). Furthermore, DOE has not 
demonstrated compliance with Sec. 194.24(c)(3) for any other waste 
generator site.
    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). The system of controls must conform to the QA 
requirements specified in Sec. 194.22 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''). 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: waste stream 
screening/verification (pre-shipment) and 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''). If implemented as 
proposed, EPA believes that the TRU QAPP, WAC, and WWIS are adequate to 
control important components of waste emplaced in the WIPP. EPA audited 
DOE's QA programs at CAO, SNL and WID and determined that DOE properly 
adhered to QA programs that implement the applicable NQA standards and 
requirements. (See the preamble discussion of Sec. 194.22 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 to be used at LANL. The Agency 
confirmed through inspections that the system of controls is adequate 
to characterize waste and ensure compliance with the limits on waste 
components, and also confirmed that a QA program had been established 
and executed at LANL in conformance with NQA 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. Therefore, EPA 
determines DOE to have demonstrated compliance with Secs. 194.24(c)(4) 
and (5) for several waste streams in the category of retrievably stored 
(legacy) debris waste at LANL. EPA's proposed determination of 
compliance is limited to those retrievably stored (legacy) debris waste 
streams that can be characterized using the systems and processes 
audited by DOE, inspected by EPA, and found to be adequately 
implemented at LANL. <SUP>22</SUP> 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.
---------------------------------------------------------------------------

    \22\ See Docket A-93-02, Item II-I-70 for a list of these 
systems and processes. They include characterization methodologies 
and relevant procedures, such as that used for entering data into 
the WWIS database.
---------------------------------------------------------------------------

    In order to ship transuranic waste from other waste generator sites 
for emplacement at the WIPP, DOE will have to demonstrate compliance 
with the Sec. 194.24(c)(3) through (5) requirements. Compliance with 
the requirements as they relate to QA programs will be evaluated and 
approved for each generator site in accordance with the language in 
Condition 2 (``Quality Assurance'') of the proposed Appendix A to 40 
CFR Part 194. To fully comply with these requirements, DOE must also 
submit--and EPA must approve--for each waste stream or group of waste 
streams, information on how process knowledge will be incorporated into 
waste characterization activities, and on the system of controls 
proposed for (a) given waste stream(s). A waste stream is defined by 
DOE as waste material generated from a single process or activity that 
is similar in material, physical form, isotopic make-up, and hazardous 
constituents. EPA expects that this information will be contained in 
site-specific documents including, for example, site certification 
quality assurance plans (``QAPs'') and quality assurance project plans 
(``QAPjPs''). All such documentation submitted by DOE regarding plans 
for waste characterization of specific waste streams will be placed in 
EPA's dockets for public inspection.
    As waste generator sites establish waste characterization programs 
for new waste streams (or groups of waste streams), EPA will assess 
their compliance with the Secs. 194.24(c)(3) and (4) requirements. EPA 
will conduct an audit or inspection of a DOE audit at each site to 
evaluate the use of process knowledge and the establishment of a system 
of controls for each waste stream or group of waste streams. In order 
for a site to demonstrate the implementation of a system of controls, 
the WWIS must be demonstrated to be functional at any waste generator 
site before any waste stream(s) may be shipped from that site for 
disposal at the WIPP. By this, EPA means that a waste generator site 
must demonstrate that it has procedures in place for entering data into 
the WWIS tracking system, and that such data can be transmitted to the 
WWIS database so that it is available for compilation and reporting. In 
order for EPA to confirm that a system of controls has been adequately 
executed in accordance with Sec. 194.24(c)(4), DOE must demonstrate 
that measurement techniques and control methods can be implemented for 
each waste stream or streams which DOE plans to emplace in the WIPP.
    As described in the proposed certification condition, EPA's 
decision to approve site-specific plans for the use of process 
knowledge and the system of controls--and thus to approve a site to 
transport a waste stream for disposal at the WIPP--would be made only 
after public comment has been solicited and after EPA has conducted an 
audit or an inspection of a DOE audit of the waste generator site. 
Therefore, before making any determination to approve the use of 
process knowledge or the system of controls, EPA would publish a notice 
in the Federal Register announcing its intent to evaluate waste 
characterization programs for a given waste stream (or waste streams) 
at one or more sites. There would be allowed at least a 30-day comment 
period on DOE's proposed programs for process knowledge and a

[[Page 58815]]

system of controls for one or more specific waste streams.
    EPA believes that approval of site specific QA programs is required 
by, and that this proposed procedure is consistent with the provisions 
of Section 194.24(c)(3)-(5) because it requires DOE to (1) demonstrate 
application of established and executed quality assurance programs to 
use of process knowledge; (2) demonstrate implementation of the 
required system of controls; and (3) demonstrate application of 
established and executed quality assurance programs to the system of 
controls, at the individual waste generator sites prior to shipment of 
wastes from such sites. EPA requests comment on whether the Agency 
should place a condition on its certification of compliance at WIPP 
consisting of future demonstrations by DOE that the Secs. 194.24(c)(3)-
(5) requirements have been met, prior to shipment of TRU waste to WIPP 
from such sites. In particular, EPA requests comment on its preliminary 
conclusion that the proposed procedures for determining whether 
adequate quality assurance programs have been established and executed 
by DOE are consistent with 40 CFR Part 194. However, if, based upon 
public comment on today's proposed action, EPA concludes that it would 
be appropriate to make clarifying changes to 40 CFR Part 194 that 
specifically set forth these procedures, EPA may do so as part of its 
final action on today's proposal.
    EPA's written determination that DOE has demonstrated compliance 
with these requirements, as well as the results of any audits or 
inspections, would be placed in the public dockets. EPA will confirm 
ongoing compliance with these requirements through unfettered access to 
waste generator sites for the purpose of conducting inspections under 
its authority at Secs. 194.21 and 194.24(h).
    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. DOE elected to assume that radioactive waste 
would be emplaced in the WIPP in a random fashion. 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. 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 DOE had assumed random waste 
loading and also had found that potential non-random loading of waste 
would not affect releases, a final waste loading plan was unnecessary. 
EPA determined that DOE cross-referenced the resultant waste 
distribution assumptions from the waste loading plan with the waste 
distribution assumptions used in PA, and 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. EPA proposes to find 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 LWA. Specifically, the 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. 
(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 two-phase waste 
characterization (pre-shipment at generator sites, and pre-receipt at 
the WIPP). The CCA stated that the WWIS will be used to track specific 
data related to each of the 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. 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 proposes to find 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 proposes to find that DOE is in compliance with 
Sec. 194.24, and that LANL has demonstrated compliance with 
Secs. 194.24(c)(3) through (5) for certain retrievably stored (legacy) 
debris waste streams 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). EPA's 
proposed determination of compliance is limited to those retrievably 
stored (legacy) debris waste streams that can be characterized using 
the systems and processes audited by DOE, inspected by EPA, and found 
to be adequately implemented at LANL.
    The Agency also proposes to certify compliance subject to the 
condition that 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 at a 
generator site, and (2) DOE has demonstrated that the system of 
controls described in Sec. 194.24(c)(4) 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 can be implemented for each waste 
stream which DOE plans to dispose in the WIPP. As discussed in the 
preamble for Sec. 194.22 (and in Condition 2 of the proposed Appendix A 
to 40 CFR Part 194), 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 Agency proposes that the decision to allow a waste generator 
site to dispose of a waste stream at the WIPP will be made only after 
public comments have been solicited on DOE's proposed site-specific 
programs and after EPA has conducted an audit or an inspection of a DOE 
audit of the waste generator site. EPA will make available, in its 
public docket, the site-specific program documents being considered by 
the Agency, and will publish a notice in the Federal Register 
announcing its intent to evaluate such plans. There will be allowed at 
least a 30-day public comment period for interested parties to comment 
on DOE's proposed programs for process knowledge and a system of 
controls for one or more specific waste streams. EPA also plans to 
conduct an

[[Page 58816]]

audit or an inspection of a DOE audit at each site to evaluate the 
execution of such plans for pertinent waste streams.
    EPA's approval of the plans relevant to compliance with 
Secs. 194.24(c)(3) and (4) will be indicated in a letter from the 
Administrator's authorized representative to the Department. EPA is 
proposing to define the Administrator's authorized representative as 
``the director in charge of radiation programs at the Agency'' to 
clarify the delegation of responsibilities described in the Compliance 
Criteria and in the proposed conditions of certification. A copy of the 
approval letter, as well as the results of any inspections, will be 
placed in the public dockets. After approval of the site-specific plans 
for characterization of (a) waste stream(s), EPA will confirm the 
execution of the programs at each waste generator site and continued 
compliance with the requirements of Secs. 194.24(c)(3) through (5) 
through inspections and audits under its authority at Secs. 194.21, 
194.22(e) and 194.24(h). Results of such inspections will be made 
available to the public through the Agency's public dockets, as 
described in Sec. 194.67.
    For specific language on the waste characterization conditions of 
certification, see Condition 3 of the proposed Appendix A to 40 CFR 
Part 194; for specific language on the quality assurance requirements 
that relate to waste characterization, see Condition 2 of the proposed 
appendix. For further information on EPA's evaluation of compliance for 
Sec. 194.24, refer to CARD 24.

D. Section 194.25, Future State Assumptions

    Section 194.25 stipulates that performance assessments (``PA'') and 
compliance assessments (``CA'') ``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.'' 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 
PA and CA 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.
    EPA required DOE to identify and document all future state 
characteristics and conditions that are used in the PA and CA. For all 
elements of the PA and CA that do not relate to hydrogeologic, geologic 
or climatic conditions, DOE was required to assume that characteristics 
of the future remain what they are at the time the compliance 
application was prepared. DOE was required to document the effects of 
potential changes to hydrogeologic, geologic and climatic conditions on 
the disposal system. For geologic conditions, EPA required DOE to 
address dissolution, near surface geomorphic features and processes, 
and subsidence in the geologic units of the disposal system. For 
climatic conditions, EPA required DOE use current climatic conditions 
for comparison and to consider cycles of increased precipitation.
    In accordance with Sec. 194.25(a), DOE provided a description of 
the future state assumptions for the features, events and processes 
(``FEPs'') used in the PA and CA. Except where specified otherwise 
(i.e., Secs. 194.32 and 194.33), DOE assumed that current 
characteristics for the FEPS not related to hydrogeology, geology and 
climatic conditions will remain constant throughout the 10,000-year 
regulatory time frame. EPA reviewed the information in the CCA and 
agrees with the future state assumptions that DOE has made. EPA found 
this information to be inclusive of all relevant elements of the PA and 
CA.
    To fulfill the requirements of Sec. 194.25(b)(1), DOE predicted the 
potential future hydrogeologic conditions at the WIPP. DOE developed 
several future state assumptions about the hydrogeological conditions 
of the WIPP, such as increased precipitation impacts on recharge 
location and capacity, hydraulic gradient, and transmissivity in the 
Culebra member of the Rustler and Dewey Lake formations. In a few 
cases, DOE found that hydrogeologic conditions can change with time and 
can possibly affect the PA. DOE addressed these potential changes in 
the PA. EPA reviewed the adequacy of the uncertainty of key parameter 
assumptions, such as the impacts of mining subsidence on Culebra 
transmissivity. EPA found that DOE adequately addressed the effects of 
mining-induced subsidence on Culebra hydrogeologic conditions. EPA 
reviewed the future state assumptions DOE made about hydrogeologic 
conditions and concludes that DOE has accurately characterized and 
modeled the potential changes from current conditions. EPA found that 
DOE's incorporation of these changes into the PA was adequate. Other 
potential changes to hydrogeologic conditions, notably those associated 
with climate change, are addressed in the discussion of 
Sec. 194.25(b)(3).
    Section 194.25(b)(2) requires DOE to consider the effects of 
potential changes to geologic conditions on the disposal system. DOE 
predicted potential future geologic conditions at the WIPP. DOE 
analyzed the stratigraphy and physiography of undistributed geologic 
conditions, salt creep and excavation-induced stress changes, 
geochemistry, seismic activity, disturbed rock zone, dissolution, and 
mining in the McNutt potash zone above the repository. DOE also 
analyzed the geologic effects of existing boreholes, brine reservoirs, 
and drilling intrusions. EPA found DOE's assumptions of the future 
geologic conditions to cover the significant geologic units and 
conditions that affect PA and determined that the screening arguments 
adequately justify the exclusion of the majority of the geological FEPs 
from the PA and CA. For additional information on the FEPs included in 
the PA and CA, see Sec. 194.32. EPA evaluated the CCA and additional 
information provided by DOE at EPA's request regarding the uncertainty 
associated with deep dissolution and considers DOE's analysis adequate. 
For additional information on both geologic and hydrogeologic 
conditions of the WIPP, see Sec. 194.14(a).
    Section 194.25(b)(3) requires DOE to consider the effects of 
potential changes to climatic conditions on the disposal system. At the 
WIPP, availability of water for recharge is the primary concern related 
to global climate change. Future global warming would be expected to 
continue the trend to less precipitation in the vicinity of the WIPP 
(which would be beneficial to disposal system performance). DOE 
concluded that global cooling--and increased precipitation--is the 
worst case scenario for the WIPP. In accordance with Sec. 194.25(b)(3), 
DOE identified and described the effects of increased precipitation in 
future cooler climate cycles on the repository. DOE considered 
potential increased participation over the next 10,000 years and 
incorporated the uncertainty of the effects of this climate change in 
the PA through modeling of dissolution, groundwater flow, and potential 
radionuclide transport in groundwater. DOE described climate change due 
to

[[Page 58817]]

potential natural causes and the resulting changes in recharge rates, 
groundwater flow velocity, and flow direction. DOE included models of 
the impact of potential climate changes on groundwater flow in the 
Culebra over the regulatory time period.
    EPA found that the CCA included adequate discussions of the current 
and previous climate at the WIPP site and found that DOE addressed the 
impacts of potential climate change over the regulatory time frame. EPA 
concludes that DOE appropriately considered climate-related factors 
such as precipitation, temperature, and evapotranspiration that might 
affect groundwater flow in the regional three-dimensional groundwater 
basin model. EPA also examined DOE's descriptions of recharge 
associated with potential climate change effects and found that DOE 
adequately described the uncertainties associated with potential change 
to the future climate cycles. For additional information on climate 
change ground water flow, see Secs. 194.14(a) and (i).
    In addition, EPA evaluated potential hydrogeologic changes related 
to climate change, including: groundwater recharge, Culebra flow rate 
variations, and water table elevation. EPA evaluated the additional 
information DOE provided at EPA's request regarding vertical inflow to 
the Dewey Lake Formation and three-dimensional groundwater flow 
modeling, and concluded that DOE provided adequate documentation to 
sufficiently address the issues. EPA verified that the CCA acknowledges 
and quantifies uncertainties in hydrogeologic conditions found in the 
site characterization data descriptions and modeling assumptions. EPA 
also found that DOE modeled the effects of climate changes during the 
next 10,000 years on the groundwater flow in the Culebra. After 
reviewing the CCA and the additional information provided by DOE at 
EPA's request, EPA concluded that DOE's explanation of uncertainty 
associated with the potential wetter climate impacts on Culebra 
transmissivities resulting from potential dissolution of fracture 
infillings is acceptable.
    EPA determined that the overall CCA approach to dealing with 
uncertainty, and the examples of conservative assumptions used to 
compensate for uncertainty, is consistent with the FEPs list, screening 
arguments, and model descriptions. EPA proposes to find DOE in 
compliance with Sec. 194.25. For further information on EPA's 
evaluation of compliance with Sec. 194.35, refer to CARD 25.

E. Section 194.26, Expert Judgment

    The requirements of Sec. 194.26 apply to expert judgment 
elicitation. 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 (``QA'') requirements in 
accordance with 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 Sec. 194.26(a) 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 and timely collection of data.
    The CCA submitted on October 29, 1996, did not identify any expert 
elicitation activities. During the Agency's review of PA parameters, 
EPA found that inadequate explanation and information was provided on 
the derivation of 149 parameters identified in the CCA as resulting 
from professional judgment (e.g., code control parameters, physical 
constants). The Compliance Criteria do not provide for utilization of 
``professional judgment.'' Input parameters are to be derived from data 
collection, experimentation, or expert elicitation. EPA requested in 
letters to DOE dated March 19, April 17, and April 25, 1997, 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) In the absence of 
data collection or experimentation, EPA expected DOE to derive these 
input parameters through expert elicitation.
    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 to enhance the traceability of 
parameter values. EPA deemed the documentation provided by DOE adequate 
to demonstrate proper derivation of all but one of the so-called 
professional judgment parameters--the waste particle size distribution 
parameter. The remaining parameters questioned by EPA were found to 
have adequate documentation to support the values used in the CCA PA 
calculations. For further discussion of the technical review of PA 
parameters, see the preamble for Sec. 194.23. EPA required DOE to use 
the process of expert elicitation to develop the value distribution for 
the waste particle size parameter. (Docket A-93-02, Item II-I-27)
    The waste particle size parameter is important in the PA because it 
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.
    DOE conducted the expert judgment elicitation on May 5 through May 
9, 1997. The process included: definition of technical issues; public 
notification; selection of experts; general orientation and elicitation 
training; presentation and review of issues; preparation of expert 
analysis by elicitor; discussion of analysis by panel members; 
elicitation; recomposition; review and approval of dissenting opinions 
provided by experts; and documentation of the process and results. 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. This particle 
size distribution was incorporated in the PAVT calculations; for a 
detailed discussion on the sampling of uncertain parameter 
distributions, refer to the preamble discussion of Sec. 194.34, 
``Results of PA.'' 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) EPA proposes to find that DOE complies with Sec. 194.26(a) 
because the Agency found adequate support for the derivation of all 
parameter values with the exception of the waste particle size 
parameter, for which DOE undertook an expert elicitation.
    EPA's review of DOE's compliance with the requirements of 
Sec. 194.26 principally focused on the conduct of the elicitation 
process. Sections 194.26 (b) and (c) set specific criteria for the 
performance of an expert judgment elicitation. DOE must: identify the 
expert judgments used to support the compliance application; identify 
the experts involved in the process; describe the process of eliciting 
expert

[[Page 58818]]

judgment; document the results; document that the experts have the 
necessary independence and qualifications for addressing the questions 
and issues presented; explain the connection between the questions 
posed to the expert panel and the manner in which the final report of 
the panel is used in the compliance application; adhere to requirements 
on the composition of the expert panel, including the fraction of the 
panel members who are employed by DOE; assure the public be given the 
opportunity to present their views in the expert judgment process; and 
document the elicitation process so as to demonstrate a logical 
progression from the first statement of issue given to the panel to the 
combination and presentation in the final report.
    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, curriculum vitae of panel members, background 
documents, and presentation materials. EPA also assessed compliance 
with the QA requirements of Sec. 194.22. EPA found that the 
documentation provided by DOE addressed the requirements of 
Sec. 194.26(b)(2).
    In accordance with Sec. 194.26(b)(1), DOE identified the individual 
experts on the panel. EPA found that the expert panel was composed of 
six experts, including four from consulting firms and two associated 
with universities. Two of the six panel members were DOE contractors at 
the time of the elicitation.
    Therefore, in accordance with Sec. 194.26(b)(7), the panel included 
at least five individuals, two-thirds of whom were not employed by DOE 
or DOE contractors. In accordance with Sec. 194.26(b)(3), the panel did 
not include individuals who will use the judgments or who maintain, at 
any organizational level, a supervisory role or who are supervised by 
those who will utilize the judgment. EPA found DOE's documentation to 
demonstrate compliance with these requirements.
    Based on its review of curriculum vitaes and completed 
organizational conflict of interest forms, EPA determined that the 
experts on the panel demonstrated the required independence and level 
of knowledge required by the questions or issues presented. 
(Sec. 194.26(b)(4)) EPA found the background and orientation materials 
addressed the relationship among information and issues as well as the 
purpose and intent of the judgment, in accordance with 
Sec. 194.26(b)(5). The Agency determined that the expert elicitation 
met the requirement at Sec. 194.26(b)(6) since the result of the 
process was a parameter distribution that could be implemented directly 
in the PA. EPA also found that DOE afforded the public an opportunity 
to present scientific and technical views to the expert panel. 
(Sec. 194.26(c))
    Based on the review of expert elicitation supporting documentation 
developed by DOE and its contractors, as well as the results of the EPA 
audit to verify compliance, EPA proposes to determine that DOE complies 
with the requirements of Sec. 194.26 in conducting the required expert 
elicitation.
    Numerous public comments were received on DOE's statement that it 
did not conduct any expert judgement activities in developing the CCA. 
As many commenters correctly pointed out, the CCA did not contain 
adequate information to allow a reviewer to ascertain whether a large 
number of the input parameters were properly derived in accordance with 
the explicit requirements of the Compliance Criteria. DOE subsequently 
provided additional information, and substantially improved the quality 
of the records at the SNL Records Center to make it possible to confirm 
that all but one of the suspect input parameters were adequately 
supported. For further discussion of EPA's evaluation of compliance 
with Sec. 194.26 and related public comments, see CARD 26.

F. Section 194.27, Peer Review

    Section 194.27(a) requires DOE to conduct peer review evaluations 
related to conceptual models, waste characterization analyses, and the 
evaluation of engineered barriers. This section, at Secs. 194.27(b) and 
(c)(1), also requires DOE to submit documentation showing that the 
required peer reviews were conducted in a manner compatible with NUREG-
1297, ``Peer Review for High-Level Nuclear Waste Repositories.'' 
(Docket A-92-56, Item III-B-1h) NUREG-1297 is incorporated by reference 
in the Compliance Criteria. As stated in NUREG-1297, the purpose of 
peer review is to provide confidence in the validity of technical and 
programmatic judgments involving scientific uncertainty or ambiguity by 
subjecting those judgments to the evaluation of qualified, independent 
specialists. (NUREG-1297, p. 2)
    DOE completed the required peer reviews and included a description 
of the peer review process in the CCA. EPA's CAG indicates the types of 
documentation necessary for Sec. 194.27(b) to demonstrate that peer 
reviews were conducted in accordance with the NUREG-1297 guidance. For 
example, the CCA should show the process by which peer review panels 
deliberated, should present the conclusions they reached, and should 
show that panel members were qualified and free of conflicts of 
interest. EPA reviewed the CCA to determine whether DOE's procedures 
and plans for the required peer reviews were consistent with the CAG 
and whether the required peer reviews had actually been conducted in 
accordance with those procedures and plans.
    Many of the documents detailing DOE's implementation of NUREG-1297 
are kept by DOE as quality assurance (``QA'') records and were not 
included in the CCA but were made available to EPA. EPA first reviewed 
the CCA and supplementary reports and confirmed that the required peer 
reviews had been conducted. To evaluate the peer review process 
further, EPA conducted an audit of DOE's QA records for peer review in 
February 1997. The audit consisted of an extensive review of DOE's 
records and interviews with DOE staff and contractors who managed the 
required peer reviews. The audit raised several isolated findings, but 
none of these was sufficient to lead EPA to conclude that any of the 
peer reviews had been conducted in a manner incompatible with NUREG-
1297.
    EPA proposes to find DOE in compliance with Secs. 194.27(a) and 
(b). DOE submitted documentation in the CCA showing that the required 
peer reviews had been conducted. DOE's procedures for the conduct of 
peer review satisfactorily incorporated the essential elements of 
NUREG-1297, as identified in the CAG. The audit conducted by EPA 
verified that DOE properly followed its procedures for peer review.
    Section 194.27(c)(1) requires DOE to show that the three required 
peer reviews, if conducted prior to promulgation of 40 CFR Part 194, 
were conducted in accordance with an alternative process substantially 
equivalent to NUREG-1297. Because DOE conducted the required peer 
reviews after the promulgation of 40 CFR Part 194, this requirement is 
not applicable.
    Section 194.27(c)(2) requires DOE to document any peer reviews 
conducted by DOE other than those required by Sec. 194.27(a). The 
additional peer reviews were not required to be compatible with the 
guidance in NUREG-1297, but EPA recommended in the CAG that they be 
documented in a manner similar to the required peer reviews. EPA 
expected

[[Page 58819]]

that documentation would be sufficient to identify the purpose, scope, 
membership, and findings of a given peer review.
    DOE developed a list of criteria, based principally on guidance in 
NUREG-1297, to determine whether a review activity conducted prior to 
promulgation of the Compliance Criteria constituted a peer review. DOE 
then identified past activities that met the criteria and incorporated 
relevant documentation in the CCA. EPA reviewed the materials provided 
and found that sixteen peer reviews were properly included in the CCA. 
EPA also found that the CCA contained sufficient documentation to allow 
EPA to identify the purpose, scope, membership, and findings of those 
sixteen peer review activities. Therefore, EPA proposes to find DOE in 
compliance with Sec. 194.27(c)(2).
    Comments received in regard to peer review expressed mainly two 
concerns. First, commenters considered the CCA incomplete because some 
peer reviews were reopened after the CCA was sent to EPA in October 
1996. EPA requested, received, and docketed pertinent documentation 
resulting from the reopened peer reviews prior to determining that the 
CCA was complete.
    Second, commenters questioned the findings of some peer reviews. 
EPA's compliance review for Sec. 194.27(b) focused on the extent to 
which the required peer reviews were conducted in a manner compatible 
with NUREG-1297. The Agency believes that the critical evaluation of 
peer review findings is necessary but not directly relevant to DOE's 
compliance with Sec. 194.27. EPA carefully examined the findings of all 
peer reviews conducted after the promulgation of 40 CFR Part 194 and 
discusses them under the relevant technical sections: quality assurance 
(Sec. 194.22), conceptual models (Sec. 194.23), waste characterization 
(Sec. 194.24), passive institutional controls (Sec. 194.43), and 
engineered barriers (Sec. 194.44). For further information of EPA's 
evaluation of compliance for Sec. 194.27, see CARD 27.

XI. Containment Requirements

    The disposal regulations include requirements for containment of 
radionuclides. The containment requirements at 40 CFR 191.13 specify 
that release of radionuclides to the accessible environment shall not 
exceed specific limits, which are based on the amount of waste in the 
WIPP at the time of disposal. (Sec. 194.31) Assessment of the 
likelihood that the WIPP will meet these release limits is conducted 
through use of a process known as performance assessment (``PA''). The 
WIPP PA essentially consists of a series of computer simulations that 
attempt to describe the physical attributes of the disposal system 
(site, geology, 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 then translated into computer code. The results of the 
simulations show the potential releases of radioactive materials from 
the disposal system to the accessible environment over the 10,000-year 
regulatory time frame. (Models and computer codes are addressed in more 
detail in the preamble for Sec. 194.23 of the general requirements.)
    The PA must include both natural and man-made processes and events 
which have an effect on the disposal system. It must consider all 
reasonable potential 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 both human-initiated releases (e.g., via drilling 
intrusions) and releases by natural processes that would occur 
independently of human activities. The requirements at Secs. 194.32 and 
194.33 address the scope of PA and the types of human intrusion which 
must be considered in PA.
    The results of 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'' (discussed in more 
depth in subsequent sections of this preamble). The results of PA are 
assembled into complementary cumulative distribution functions 
(``CCDFs'') which indicate the probability of exceeding various levels 
of normalized releases. Section 194.34 of the WIPP Compliance Criteria 
imposes specific statistical requirements on the results of PA and on 
the single curve used to judge compliance with the containment 
requirements.

A. Section 194.31, Application of Release Limits

    Section 194.31 indicates that DOE is to quantify releases of 
radionuclides from the WIPP in terms of ``cumulative releases,'' which 
are calculated from ``release limits.'' Release limits for 
radionuclides at a radioactive waste disposal facility must be 
calculated in accordance with 40 CFR Part 191, Appendix A. There, a 
``release limit'' for a radionuclide is introduced as a measure of the 
cumulative amount of radioactivity, measured in curies, that is allowed 
to reach the accessible environment (that is, land surface, the 
atmosphere, surface waters, oceans, and all the land beyond the 
boundary of the WIPP land withdrawal area) over the 10,000 years after 
the disposal <SUP>23</SUP> of radioactive waste. Release limits are to 
be calculated using the activity from radioactive waste, in curies, 
that will exist in the WIPP at the time of disposal.
---------------------------------------------------------------------------

    \23\ ``Disposal'' is defined as ``[P]ermanent isolation of . . . 
radioactive waste from the accessible environment with no intent of 
recovery whether or not such isolation permits the recovery of such 
fuel or waste. For example, disposal of waste in a mined geologic 
repository occurs when all of the shafts to the repository are 
backfilled and sealed.'' 40 CFR 191.02(l)
---------------------------------------------------------------------------

    To calculate normalized releases and release limits, DOE must first 
identify all the radionuclides that are present in the waste that it 
plans to put in the WIPP (e.g., plutonium-238). Next, the Department 
projects which radionuclides will be present in the waste at the time 
of disposal, including those isotopes created by radioactive decay 
between the time of the waste inventory (approximately 1995) and the 
time of disposal (estimated to be the year 2033). DOE then determines 
which of these radionuclides emit alpha-particles, have an atomic 
number greater than that of uranium (transuranic), and have half-lives 
greater than twenty years. These radionuclides comprise the ``TRU 
component'' of the waste. The total activity of the TRU component of 
the waste, in curies, divided by one million curies, is called the 
``waste unit factor.'' For the WIPP, Table 1 of Appendix A of 40 CFR 
Part 191 presents values of release limits (in curies) per unit of this 
``waste unit factor.''
    To obtain the release limit for a radionuclide, DOE must multiply 
each release limit value in Table 1 by the numerical value of the waste 
unit factor. Finally, to obtain the normalized release for a scenario, 
DOE must divide the projected estimated release (obtained from PA 
modeling), in curies, for every radionuclide (whether TRU or non-TRU) 
by its respective release limit, and sum these quotients.
    In the CCA, the Department provided an inventory of the various 
radionuclides in the waste expected at the time of disposal, including 
those radionuclides in the waste inventory that are currently stored at 
different DOE sites, those radionuclides that are projected to be 
generated at different DOE sites between 1995 and the time of

[[Page 58820]]

disposal, and those radionuclides that would be created by radioactive 
decay between the time of the waste inventory in 1995 and the time of 
disposal, approximately in the year 2033. The waste inventory showed 
that plutonium and americium produce almost all of the radioactivity 
from waste that would be in the WIPP at the time of disposal. Based on 
the fifteen radionuclides in the inventory that were transuranic, 
alpha-emitting, and had half-lives greater than twenty years, DOE 
calculated that the relevant total activity at the time of disposal 
would be 3.44 million curies and that the waste unit factor would be 
3.44.
    DOE used the waste unit factor to obtain the release limit for each 
radionuclide found in Table 1 in Appendix A of 40 CFR Part 191. These 
release limits were then used in the calculation of cumulative 
releases. The Department designated six transuranic radionuclides that 
contributed more than 99.9 percent of the activity as ``major 
radionuclides.'' The Department calculated the release limits and 
relative contributions to releases for the six major radionuclides 
using a computer program called EPAUNI. The Department verified the 
computer calculations with sample hand calculations.
    EPA reviewed DOE's description of the procedure used to estimate 
the activity of waste proposed for disposal, examined DOE's hand 
calculations, and verified the computer code and output to determine 
whether DOE correctly calculated the waste unit factor, including 
radioactive decay up to the year 2033. EPA also evaluated whether DOE 
appropriately calculated release limits for each major radionuclide and 
identified the relative contribution of each major radionuclide.
    EPA found DOE's simplification of using the six transuranic 
radionuclides that contribute the greatest activity in computer 
calculations to be appropriate. Because these six radionuclides would 
make up more than 99.9 percent of the activity from the transuranic 
waste, DOE's simplification could contribute at most an error of 0.1 
percent to its calculations of the contribution to releases from 
individual radionuclides, which would not have a significant impact 
upon the calculation of release limits or the contribution to releases 
from individual radionuclides.
    EPA found that the TRU waste component used to calculate the waste 
unit factor of 3.44 omitted some waste stored at an off-site facility 
at Savannah River. DOE corrected this error by recalculating the waste 
unit factor based on a TRU inventory that included the Savannah River 
waste; the revised waste unit factor was 3.59. EPA did not require DOE 
to recalculate the release limits based on the new value for the waste 
unit factor, because using the larger revised factor would have 
resulted in higher release limits (and thus, lower normalized 
releases). That is, the use of the incorrect value in the CCA is more 
conservative than using the correct value of 3.59. The correction of 
the error would only show that the WIPP will comply with the disposal 
regulations by a wider margin than had been previously demonstrated.
    The Agency confirmed that the Department calculated the waste unit 
factor of 3.44 and the release limits at the time of disposal in 
accordance with the requirements of Appendix A of 40 CFR Part 191. In 
addition, the Agency found that the Department correctly identified the 
relative contribution of each major radionuclide to releases. Finally, 
the Agency confirmed that the computer codes, model results, and hand 
calculations were consistent and thus supported the use of the computer 
codes. Because the Agency's review concluded that the Department 
calculated release limits for the WIPP using an appropriate methodology 
and conservative waste inventory estimates, the Agency proposes that 
the requirements of Sec. 194.31 have been met. For further information 
on EPA's evaluation of compliance for Sec. 194.31, see CARD 31.

B. Section 194.32, Scope of Performance Assessments (PA)

    Section 194.32 requires DOE to consider, in the performance 
assessment (``PA''), both natural and man-made processes and events 
which can have an effect on the disposal system. EPA expected DOE to 
consider all features, events and processes (``FEPs'') that may have an 
effect on the disposal system. In particular, EPA expected DOE to 
consider mining effects on hydraulic conductivity, fluid injection, 
future development of leases and existing boreholes in the scope of the 
PA. The CCA was also expected to document which FEPs (or sequences or 
combinations of FEPs) are included in the PA. DOE is required to 
document the decision not to include any feature, event, or process in 
the PA. Deep and shallow drilling, over the regulatory time frame, are 
addressed in more detail in the preamble discussion of Sec. 194.33.
    To fulfill the requirements of Secs. 194.32(a), (d) and (e), DOE 
developed and followed a process for considering FEPs in the PA. DOE 
initially identified 1,200 FEPs from a list of FEPs developed by the 
Swedish Nuclear Power Inspectorate (``SKI''). This list was compiled 
and categorized based on location of occurrence and cause by nine 
organizations world wide. DOE modified this list to make it relevant to 
WIPP. DOE's final list of FEPs was then classified and screened for 
consideration in the PA. DOE screened FEPs from consideration in the PA 
based on regulatory exemption, low probability and low consequence. 
FEPs were then combined to form scenarios. Scenarios were also screened 
based on regulations, probability or consequence. The remaining 
scenarios were retained for implementation in the PA. The CCA documents 
DOE's decision not to include specific FEPs in the PA.
    Approximately 237 FEPs were retained for screening. DOE concluded 
that 17 of 72 initial natural FEPs should be retained for the PA, 
including stratigraphy, shallow dissolution, saturated groundwater, 
infiltration, precipitation, and climate change. Of 108 waste and 
repository-induced FEPs, DOE concluded that 51 of these should be 
retained for the PA, including disposal geometry, waste inventory, salt 
creep, backfill chemical composition, actinide solubility, spallings, 
and cavings. DOE concluded that 15 of the 57 human-initiated events and 
processes should be retained for the PA, including oil and gas 
exploration. Examples of FEPs screened from use in the PA include: 
lateral dissolution, regional tectonics, salt deformation, mechanical 
effects of backfill, liquid waste disposal and groundwater extraction.
    EPA concluded that the initial FEP list assembled by DOE was 
sufficiently comprehensive, in accordance with Secs. 194.32(a) and 
(e)(1). In compiling this list, DOE appropriately screened out events 
and processes on the basis of probability, consequence or regulatory 
requirements. DOE considered and incorporated into the PA numerous 
natural processes and events, mining, and deep drilling. DOE considered 
shallow drilling and appropriately screened it out on the basis of low 
consequence. (See preamble for Sec. 194.33.)
    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, in accordance with Sec. 194.32(d).
    Review of the CCA and the submitted supporting documents confirms 
that DOE used a thorough process to identify all the appropriate FEPs 
as well as the related combinations and sequences that can potentially 
occur within the

[[Page 58821]]

regulatory time frame and affect disposal system performance. EPA 
determined that the process is sufficiently documented and that DOE 
justified the retention and elimination of FEPs. 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). DOE provided 
documentation and justification for eliminating those FEPs that were 
not included in the PA. In some cases (e.g., fluid injection and 
dissolution), the CCA did not provide adequate justification or 
convincing arguments to eliminate FEPs from consideration in PA. (Fluid 
injection is discussed in more detail below, relative to compliance 
with Sec. 194.32(c).) However, DOE provided supplemental information 
and analyses to demonstrate compliance with Sec. 194.32(e)(3). EPA 
found this supplementary information to be adequate in fulfilling the 
requirements to justify FEP exclusion from the PA.
    For disturbed scenarios (i.e., human activities), DOE discussed how 
mining was incorporated into the PA. DOE identified potash as the only 
natural resource currently being mined near the WIPP. DOE, in 
accordance with Sec. 194.32(b), used the EPA-specified mining 
probability and considered changes in hydraulic conductivity up to 1000 
times the base hydraulic conductivity of the Culebra. In its 
calculation of the potash area to be mined, DOE considered minable 
reserves inside and outside of the controlled area. The Compliance 
Criteria require DOE to examine only currently extractable resources, 
not to speculate on what other resources may become economically 
viable.
    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. These values for 
hydraulic conductivity considered the impact of institutional controls 
on mining, mining practices and mineral resources. 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. EPA proposes to find that DOE complies with Sec. 194.32(b).
    EPA's review of the CCA raised questions regarding DOE's analysis, 
in accordance with Sec. 194.32(c), of human-initiated activities, 
including fluid injection. 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. An oil well operator, Mr. Hartman, drilling in the 
Salado Formation in the Rhodes-Yates Field, encountered a salt water 
blowout in an oil development well. In subsequent litigation, the court 
found that the source of the water flow was injection water from a 
long-term waterflood borehole located more than a mile away.
    DOE addressed the fluid injection scenario in the CCA with an 
analysis of waterflooding (for enhanced oil recovery) and brine 
disposal activities. (Docket A-93-02, Item II-G-1, Reference #611) In 
accordance with Sec. 194.32(c), DOE determined that these two 
activities were the only fluid injection scenarios that were currently 
occurring or could be initiated in the near future in the vicinity of 
the WIPP. DOE identified the Bell Canyon Formation under the Salado and 
Castile Formations as the primary target for fluid injection for brine 
disposal. DOE stated that this scenario had the potential to produce 
more brine inflow to the WIPP. DOE modeled the fluid injection scenario 
using WIPP geology, and again using the geology identified in the 
Rhodes-Yates Field. The two sites differ significantly because the 
Castile Formation, which underlies the Salado at the WIPP, is absent in 
the Rhodes-Yates Field. DOE assumed that fluid injection activities 
would occur continuously for 50 years, and evaluated the subsequent 
effects of such injection activities over the entire 10,000-year 
regulatory time frame. The modeling results indicated that some brine 
could potentially get into the WIPP from fluid injection activities. 
However, the amount of brine from the worst case scenario (the 
``Rhodes-Yates'' scenario) was low compared to the amount of brine 
expected to enter the waste area naturally. DOE thus screened out the 
fluid injection scenario on the basis of low consequence.
    EPA's review of the CCA raised additional questions regarding DOE's 
screening analysis of fluid injection. EPA believes that 50 years is an 
accurate estimate for the life of a single oil field, but that it does 
not account for the possibility of multiple fields. Because drilling 
restrictions currently applicable to potash areas in the Delaware Basin 
could be lifted, it is possible that multiple oil fields could be 
developed in the foreseeable future near the WIPP. Based on the current 
resources and leases in the vicinity of the WIPP, EPA estimated that 
oil could still be drilled up to 150 years from now. EPA thus required 
DOE to extend the 50-year time frame in its models to 150 years. EPA 
also required DOE to use modified values for some input parameters, and 
to model the behavior of the disturbed rock zone consistent with 
assumptions used in the PA. (Docket A-93-02, Item II-I-17) Finally, EPA 
required DOE to provide additional information on the frequency of 
fluid injection well failures.
    In supplemental work on fluid injection, DOE addressed all the 
issues identified by EPA. DOE modified the computer model grid 
configuration and added a new model to address concerns raised by both 
EPA and stakeholders. DOE researched injection well operating practices 
and construction in the Delaware and identified significant differences 
between those in the vicinity of the WIPP and the Rhodes-Yates Field. 
For example, wells near the WIPP are typically less than ten years old 
and are constructed to much higher mechanical standards than the older, 
less robust wells found in the Rhodes-Yates Field. DOE identified a 
range of well failure scenarios, from undetectable brine flow to 
catastrophic well failure. DOE's data indicated that the probability of 
a catastrophic well failure in the vicinity of the WIPP is extremely 
low. DOE confirmed that the presence of the Castile at the WIPP also 
substantially inhibits injected brine movement into the Salado 
anhydrite markerbeds.
    Public comments on this issue included a detailed report that 
contradicted the DOE fluid injection modeling and indicated that fluid 
injection activities could overwhelm the WIPP with brine. (Docket A-93-
02, Item II-H-28) EPA has reviewed the report and considers it to model 
conditions that are highly unrealistic for the WIPP. For example, all 
modeled scenarios assumed that the entire volume of brine was injected 
directly into the anhydrite marker beds in the Salado Formation. In 
addition, the report modeled the occurrence of fluid injection well 
beyond the time frame contemplated by Sec. 194.32(c). The report also 
ignored current well construction and fluid injection operating 
practices, which are more robust than that used in the 45-year-old 
Rhodes-Yates Field.
    EPA agreed with commenters that the original fluid injection 
screening was not adequate. Thus EPA required DOE to provide additional 
information and to do additional modeling. The additional modeling 
showed rates of brine inflow (and thus effects on the disposal system) 
even smaller than those estimated by the original CCA screening 
analysis. DOE provided documented evidence that the well construction 
and operating practices near the WIPP are much more robust than that in 
the Rhodes-Yates

[[Page 58822]]

well. Both DOE's research and EPA's own review of fluid injection, 
indicated that the probability of a long-term fluid injection well 
failure is below the regulatory cutoff of 1 in 10,000 over 10,000 
years. Based on DOE's modeling and examination of fluid injection 
practices, EPA believes that a salt water blowout situation in the 
Rhodes-Yates Field is extremely unlikely to occur and affect WIPP's 
ability to contain radionuclides. Thus, EPA concurs with DOE that fluid 
injection is a low-probability scenario that can be screened out of the 
PA based on low consequence.
    DOE, in accordance with Sec. 194.32(c), also 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. DOE included and assessed the potential effects of existing 
boreholes as part of its FEPs screening analysis. DOE concluded that 
natural borehole fluid flow through abandoned boreholes would be of 
little consequence during current and operational phase activities. In 
addition, DOE screened out the occurrence of flow through undetected 
boreholes based on low probability.
    To further address Sec. 194.32(c), DOE assessed scenarios ranging 
from the effects of deep and shallow drilling and mining to undisturbed 
disposal system performance. DOE retained the FEPs describing both 
undisturbed and disturbed system performance. DOE identified the 
specific locations in the CCA that related to modeling of the 
individual FEPs. These discussions focused on conceptual model 
development, but often linked the conceptualizations with associated 
computational (computer) models.
    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. However, DOE inadequately analyzed 
in the application some future activities in the vicinity of the 
disposal system, including injection of drilling fluids for brine 
disposal and enhanced oil recovery, solution mining, and full 
extraction potential of the leaseholds (in the vicinity of WIPP). In 
response to the concerns expressed by EPA and stakeholders, DOE 
conducted additional analyses and submitted follow-up information. This 
information was adequate and EPA concurred with the conclusions, 
concluding that DOE's analysis met the requirements of Sec. 194.32(c).
    In summary, EPA proposes to find DOE in compliance with 
Sec. 194.32. For further information on EPA's evaluation of compliance 
for Sec. 194.32, refer to CARD 32.

C. Section 194.33, Consideration of Drilling Events in PA

    Section 194.33 requires DOE to make specific assumptions about 
future deep and shallow drilling in the Delaware Basin. Section 194.33 
requires that the following assumptions be incorporated into the PA: 
drilling will occur randomly in space and time; the drilling rate may 
vary with the resources; drilling practices will remain constant for a 
single resource but may be different for others; and plugging practices 
will remain constant, but the permeability of a borehole may change 
with time. Deep and shallow drilling practices and related activities 
can directly impact the cumulative potential for contaminant release to 
ground, surface or geologic units.
    For this requirement, EPA required DOE to discuss the resources for 
which deep and shallow drilling occur in the Delaware Basin. DOE was 
also required to describe the techniques and rates for deep and shallow 
drilling for each resource. In these analyses, DOE was required to 
document assumptions and sources of information. EPA also required DOE 
to document assumptions that DOE made in analyzing the consequences of 
drilling events in PA. Finally, DOE was required to evaluate the 
effects of boreholes on the properties of the disposal system.
    To fulfill the requirements of Sec. 194.33(a), DOE identified 
several deep and shallow drilling activities as being present in the 
Delaware Basin. DOE identified oil and gas exploration and 
exploitation, and water and potash exploration, as the principal 
drilling activities to be considered in the PA. The shallow drilling 
components of these activities were screened from inclusion in the PA 
because DOE considered these activities to be of low consequence to PA 
calculations. DOE considered three scenarios in PA for deep drilling: 
(1) One or more boreholes penetrate(s) the Castile brine reservoir and 
also intersect(s) a repository panel, (2) one or more boreholes 
intersect(s) a repository panel, and (3) multiple penetrations of waste 
panels, by boreholes of the first or second type, at many possible 
combinations of intrusion times, locations and combinations of borehole 
types. EPA found that the PA incorporated deep and shallow drilling 
events, in accordance with Sec. 194.33(a).
    To comply with the requirements of Sec. 194.33(b), DOE incorporated 
assumptions into the PA about the severity, frequency and randomness of 
human intrusion. DOE considered intermittent and inadvertent drilling, 
including exploratory and developmental drilling, as the most severe 
human intrusion scenarios and used them to calculate cumulative 
radionuclide releases. The drilling rate is one of the most important 
parameters affecting compliance with the containment requirements. 
Using a publicly available petroleum database, DOE established the rate 
of future deep drilling to be 46.8 boreholes per square kilometer per 
10,000 years. EPA found that DOE identified the number of deep drilling 
events for each resource, and that sources of information used to do so 
were thorough and appropriate. (The rate of shallow drilling in the 
Delaware Basin was not needed because, as noted above, shallow drilling 
was screened from inclusion in the PA based on low consequence.) DOE 
applied the deep drilling rate in the PA by randomly sampling with 
respect to: (1) The location of a borehole in the repository footprint, 
and (2) the time of occurrence during the regulatory time frame. EPA 
therefore proposes to find DOE in compliance with Sec. 194.33(b).
    DOE evaluated, in accordance with Sec. 194.33(c), 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. DOE evaluated borehole drilling 
and borehole seal degradation for their effects on properties of the 
disposal system and their impact on radionuclide migration and 
transport. DOE determined that boreholes can impact radionuclide 
migration and transport through cuttings, cavings, spallings and direct 
brine releases. In addition, DOE considered the effects of borehole 
degradation and its impact on the permeability of borehole plugs.
    EPA and public commenters disagreed with the constant value DOE 
used in the PA for the short-term (up to 200 years after disposal) 
borehole plug permeability. EPA therefore directed DOE to use a range 
of borehole plug permeabilities when conducting the EPA-mandated 
Performance Assessment Verification Test (``PAVT''). While EPA's 
sensitivity analysis indicated that the short-term plug permeability 
affected some performance measures, the results of the PAVT 
demonstrated that the range of short-term plug permeability values, 
compared to the long-term borehole permeability, had little impact on 
the results of modeling.

[[Page 58823]]

    EPA and public commenters also disagreed with DOE's use of a small 
range of values for the long-term borehole plug permeability. (Docket 
A-93-02, Item II-I-17) For example, one commenter asserted that DOE 
should evaluate both ``perfect plugs'' (i.e., low permeability) and 
plugs that ``fail'' (i.e, very high permeability). (Docket A-93-02, 
Item II-E-34, comment #113) In the PAVT, the long-term borehole plug 
permeability was changed so that the sampled parameter range included 
both low and high permeability values to simulate perfect plugs and 
borehole plug failure, respectively. Low permeability plugs did 
increase releases by increasing repository pressure and allowing more 
spallings and direct brine releases. However, the PAVT results 
indicated that changing the long-term borehole permeability, in 
combination with several other changes requested in public comments 
(notably those related to pressurized brine pockets), still would not 
cause predicted releases to violate the containment requirements; this 
indicates that the original CCA parameter values were acceptable for 
comparison to the containment requirements. (See preamble discussion of 
Sec. 194.34 for further information on the PAVT.)
    EPA reviewed the information contained in the CCA and concluded 
that DOE demonstrated that the effects of drilling events have been 
adequately considered. EPA found that the documentation in the CCA 
demonstrated that DOE thoroughly considered deep and shallow drilling 
activities and rates within the Delaware Basin. EPA found that DOE 
appropriately screened out shallow drilling from consideration in the 
PA. 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). EPA determined that the PA models did not 
incorporate the effects of techniques used for resource recovery, in 
accordance with Sec. 194.33(d). EPA further concludes that the 
information in the CCA is consistent with available data. EPA proposes 
to find DOE in compliance with the requirements of Sec. 194.33. For 
further information on EPA's evaluation of compliance for Sec. 194.33, 
see CARD 33.

D. Section 194.34, Results of PA

    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 194.34 of the Compliance Criteria provides specific 
requirements for presenting the results of the PA for the WIPP.
    The restriction on releases of radioactive material is expressed in 
terms of ``normalized releases'' or ``cumulative releases.'' Normalized 
releases refer to amounts of radioactivity projected (by means of the 
mathematical models of the PA) to be released from the repository over 
10,000 years under various physical conditions and intrusion scenarios. 
To calculate the normalized release for a given intrusion scenario, one 
first obtains the normalized release separately for each individual 
radionuclide; this involves dividing the amount projected to be 
released, in curies, by its radionuclide-specific release limit, as 
calculated in accordance with Appendix A of 40 CFR Part 191. (See the 
discussion of release limits for Sec. 194.31 in today's preamble.) One 
then adds together the normalized releases for all radionuclides to 
determine the overall normalized release for the scenario. Section 
191.13 requires that a disposal system be designed so that there is 
reasonable assurance 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.
    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 PA. The PA must include a statistically sufficient 
number of CCDFs; in particular, the number of CCDFs must be large 
enough to ensure that the maximum CCDF curve exceeds the 99th 
percentile of the population of CCDFs, with at least a 95 percent 
probability, at the specific values of 1 and 10 for normalized 
releases. 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.
    EPA found that the CCA PA demonstrated that the WIPP meets the 
containment requirements of Sec. 191.13 by more than an order of 
magnitude in probability. The largest release at any point on the mean 
CCDF curve was a normalized release of only 0.3. The PA calculations 
indicated no cases where cumulative releases would be ten times greater 
than the release limits.
    In the process of reviewing the CCA, the Agency and public 
commenters raised concerns about certain assumptions and specific 
parameter values incorporated into the PA. Also, DOE found some coding 
problems in the PA computer software. The Agency therefore directed the 
Department to conduct additional modeling that included corrections to 
computer coding problems and modifications to parameter values and 
distributions. The PAVT also excluded the assumption of credit for 
passive institutional controls. EPA required this additional modeling 
in the PAVT in order to determine whether the cumulative impact of the 
changes in the PA codes and parameters would be small enough that the 
WIPP would still meet the containment requirements of Sec. 191.13. (For 
further discussion of parameter values, see the discussion of 
parameters in the preamble for Sec. 194.23.) The results of the PAVT 
showed somewhat higher cumulative release values than the original CCA 
PA. However, even these higher cumulative release values were more than 
an order of magnitude lower than the containment requirements, at the 
probability levels prescribed by Sec. 191.13. Based upon the results of 
the CCA PA and the PAVT, EPA proposes to find that the WIPP meets the 
containment requirements of Sec. 191.13.
    Further discussion of the specific compliance criteria of 
Sec. 194.34 follows.
1. Complementary Cumulative Distribution Functions (CCDFs)
    Section 194.34(a) requires DOE to report the results of the PA in 
the form of ``complementary, cumulative distribution functions'' 
(``CCDFs''), which may be presented graphically as a set of curves. A 
CCDF curve presents the probability that releases from the repository, 
caused by all significant processes and events, might exceed any 
particular level of cumulative (normalized) release. That is, a point 
on a CCDF curve displays, on the vertical axis, the relative number of 
release scenarios or ``futures'' that could result in calculated 
releases larger than the corresponding normalized release value found 
on the horizontal axis. Each CCDF curve starts with a maximum 
probability of one on the left side of the graph (i.e., there is a 100% 
probability that cumulative releases from the disposal system will be 
either zero or greater, and will not take on negative values); and then 
decreases toward the right as the normalized release becomes

[[Page 58824]]

larger, and as relatively fewer simulations yield releases that exceed 
the corresponding normalized release value.
    Each CCDF curve in the CCA is calculated using 10,000 simulations 
or ``futures,'' each of which models a ten-thousand year period in 
which a series of human intrusion events may occur. (For further 
information about how the possible effects of human intrusion are 
included in the PA, see the preamble discussions of Secs. 194.32 and 
194.33.) A single CCDF curve uses a fixed set of uncertain physical, 
chemical and geologic characteristics at the WIPP and its surroundings, 
but uses 10,000 different, randomly-determined sequences of intrusion 
events. Different CCDF curves are developed by using different 
information about the uncertain physical, chemical and geologic 
characteristics of the WIPP and its surroundings. The CCA PA included 
300 different CCDF curves so that, in all, it calculated normalized 
releases for three million different possible futures.
    EPA reviewed features, events and processes, scenarios, conceptual 
models and computer codes that support CCDF generation. EPA found that 
all significant features, events and processes and scenarios were 
included in the generation of CCDFs. (See preamble discussions of 
Secs. 194.32 and 194.33 for more detailed information on EPA's 
evaluation of PA scenarios.) DOE used the same approach in calculating 
and presenting results of the Performance Assessment Verification Test 
(``PAVT'').
    The Agency found that DOE assembled the results of the CCA PA and 
the PAVT into CCDFs incorporating all significant processes and events. 
Therefore, the Agency proposes to find DOE in compliance with the 
requirements of Sec. 194.34(a).
2. Generation of the Full Range of CCDFs
    Section 194.34(e) requires the CCA to display the full range of 
CCDFs generated. The CCA included all three hundred CCDFs. These were 
presented in three graphs, one for each replicate of one hundred CCDF 
curves. In addition, DOE provided summary CCDF curves for descriptive 
statistics. DOE generated a mean CCDF curve, 95th-percentile confidence 
bound curves for the mean, a 10th percentile curve, a median curve, and 
a 90th percentile curve for each replicate, and generated a mean curve 
and 95th-percentile confidence bound curves for the mean of all three 
replicates. The Department also provided the same information for the 
PAVT.
    EPA determined that the CCA displayed the full range of CCDF curves 
over the full range of CCDF values and displays normalized releases 
relevant to the determination of DOE's compliance with Sec. 194.34(e). 
EPA also concluded that DOE applied the same methodology to the PAVT 
for displaying the full range CCDF curves over the full range of 
probabilities and normalized releases. Therefore, EPA proposes to find 
that DOE has demonstrated compliance with Sec. 194.34(e).
3. Probability Distributions and Random Sampling of Uncertain 
Parameters
    Section 194.34(b) requires DOE to develop and document probability 
distributions for uncertain disposal system parameter values used in 
PA. Section 194.34(c) requires DOE to use and to document computational 
techniques which draw random samples from across the entire range of 
these probability distributions to generate CCDFs.
    Parameters are numerical values or ranges of numerical values used 
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 parameters are well-established 
chemical and physical constants, such as Avogadro's Number or the 
Universal Gas Constant. Other parameters describe characteristics 
unique to the WIPP, such as the solubility and mobility of specific 
actinides in brines in the WIPP. It is not possible to determine a 
single, constant value to describe particular characteristics of the 
WIPP, in which case one must consider a range of values. The relative 
probabilities of occurrence of different uncertain parameter values 
within that range can be presented as a mathematical expression known 
as a probability distribution. A probability distribution may be 
described in terms of statistical parameters such as the average 
(mean), median, maximum and minimum values of the parameter, or 
standard deviation. Section 194.34(b) requires development and 
documentation of these probability distributions.
    DOE selected 57 uncertain parameters whose values were to be 
obtained through random sampling in the PA. DOE also performed a 
sensitivity analysis to show if changes to some parameter values would 
affect the results of PA.
    The uncertainty in the value of a parameter is built into PA 
computer codes by programs that ``sample,'' or select, numeric values 
from within the probability distribution for that parameter. Section 
194.34(c) requires these sampling techniques to draw random samples 
from across the entire range of each probability distribution. This 
requirement ensures that PA calculations fully consider the possible 
extremes of calculated releases of radioactivity without systematically 
underestimating or overestimating releases.
    The Department used the Latin Hypercube Sampling (``LHS'') code to 
sample the parameter distributions related to physical, chemical and 
geologic conditions of the repository and its surroundings. DOE used 
Monte Carlo-type random sampling to determine the effects of human 
intrusion through drilling or mining. Both codes select values from 
across the entire range of the probability distributions. The LHS code 
requires fewer samples to cover the entire range of the distribution 
because it samples randomly within divisions spread across the entire 
probability distribution.
    EPA reviewed the parameters used in the modeling, the probability 
distributions for the sampled parameters and DOE's sensitivity 
analysis. As a result of its review, the Agency found that 58 parameter 
values and distributions were not well supported by the data available. 
(See the preamble discussion of Sec. 194.23 for further details on 
EPA's review of parameters.) EPA performed its own sensitivity analysis 
on some parameters to determine if uncertainties in the parameter 
values of concern would have a significant impact on the PA. The Agency 
concluded that many of the parameters of concern had little impact, but 
twenty-four parameters could significantly affect the PA results, 
either individually or in combination with other parameters.
    As a result of the parameter review, EPA requested that DOE perform 
additional modeling. This additional modeling, the PAVT, included, 
among other things, parameter value and distribution modifications to 
twenty-four parameters that the Agency believed might have a 
significant impact on the results of PA. DOE conducted the PAVT using 
the same computer codes and the same sampling methodologies as for the 
CCA PA, but changed the 24 parameters in accordance with EPA's 
direction and modified some of the computer codes in response to EPA's 
questions about the codes. DOE conducted 300 simulations for the PAVT, 
resulting in 300 CCDF curves, just as for the CCA PA. The results of 
the PAVT showed higher normalized releases than those in the CCA PA, 
but were still more than an order of

[[Page 58825]]

magnitude below the containment requirements at Sec. 191.13. Thus, the 
PAVT incorporated changes that addressed EPA's concerns about PA, and 
showed that the resulting releases were still within the containment 
requirements. Because the PAVT used identical technical methods to the 
CCA PA, EPA concludes that the PAVT results are numerically equivalent 
to those that would be obtained by performing a new PA incorporating 
the changes required in the PAVT. EPA believes that the PAVT verifies 
that the original CCA PA was adequate for comparison against the 
radioactive waste containment requirements.
    Because DOE has developed and documented the probability 
distributions for uncertain disposal system parameter values used in 
the PA, EPA proposes to find the DOE to be in compliance with 
Sec. 194.34(b). After reviewing the results of sensitivity analyses and 
of the PAVT, the Agency concludes that the probability distributions 
are adequate. The Agency found that the LHS and Monte Carlo sampling 
techniques draw random samples from across the entire ranges of the 
probability distributions used for the uncertain disposal system 
parameters in the PA. The use of these computational techniques are 
documented in the CCA. Therefore, EPA proposes to find that DOE has 
demonstrated compliance with Sec. 194.34(c).
4. Sufficient Number of CCDFs Generated
    Section 194.34(d) requires DOE to generate a sufficiently large 
number of CCDF curves to ensure that, at cumulative releases of 1 and 
10, the maximum CCDF exceeds the 99th percentile of the population of 
CCDFs with at least a 95-percent probability. Section 194.34(d) also 
requires DOE to calculate cumulative release values according to Note 6 
of Table 1 in Appendix A of 40 CFR Part 191.
    The PA process uses techniques based upon probability theory to 
calculate the potential for releases. Because of the many sources of 
uncertainty, a computer model could calculate results of billions of 
situations without exhausting every possibility. However, running 
billions of simulations is not feasible given the cost and time 
involved. Furthermore, this is not necessary in order to provide a 
reasonable expectation that a disposal system will contain waste and 
protect human health and the environment. So long as the PA includes a 
large enough number of randomly-produced simulations covering the full 
range of possible calculated release values, the results of PA will 
yield a valid result that shows whether or not a disposal system meets 
the containment requirements of Sec. 191.13. (61 FR 5230) Section 
194.34(d) provides a statistical test to determine if the CCA contains 
enough CCDF curves: there must be at least a 95 percent probability 
that the CCDF curve generated in PA with the highest cumulative release 
exceeds the 99th percentile of the entire population of CCDFs (that is, 
the full range of possible calculated release values).
    As was mentioned above in this section, each CCDF is generated 
using a specific set of sampled values from distributions of uncertain 
parameters related to the physical, chemical and geologic conditions of 
the repository and its surroundings. In the case of the WIPP, the CCA 
PA included three sets or replicates of one hundred CCDF curves, for a 
total of 300 CCDF curves. Each of the CCDF curves is based upon a 
sample of 57 uncertain parameters.
    DOE used the LHS code to take samples of the parameter values. The 
Department also presented a probabilistic analysis, based on the 
definition of the 99th percentile, and determined that there would be a 
0.95 probability that at least one CCDF curve will exceed the 99th 
percentile so long as the PA includes at least 298 CCDF curves. Since 
the CCA PA included 300 CCDF curves, DOE concluded that this was enough 
CCDF curves to meet the requirements of Sec. 194.34(d).
    EPA agreed with DOE's argument based upon probability and the 
definition of the 99th percentile, and concluded that the CCA PA 
generated a sufficient number of CCDFs. As another approach to 
evaluating compliance with Sec. 194.34(d), EPA also examined the 
statistical characteristics of the 300 CCDF curves in the CCA PA. EPA 
compared the CCDF curves in the CCA PA to a statistical distribution 
that the Agency believes is a plausible description of what the entire 
population of all possible CCDFs would produce. EPA found that the 
maximum CCDF curve in the CCA PA had a higher cumulative release than 
the 99th percentile predicted using the probability distribution which 
represents the entire population of CCDFs. Based upon this statistical 
analysis, the Agency concluded that there was at least a 95 percent 
probability that the maximum CCDF curve would exceed the 99th 
percentile of the population of CCDFs.
    Section 194.34(d) also requires PA to calculate cumulative release 
values according to Note 6 of Table 1 in Appendix A of 40 CFR Part 191. 
DOE's approach to calculating cumulative release (or ``normalized 
release'') values is described in the introduction to this section of 
the preamble. EPA found DOE's approach to be consistent with Note 6 of 
Table 1 in Appendix A of 40 CFR Part 191.
    EPA found that DOE generated 300 CCDF curves in the PA, using the 
appropriate method to calculate cumulative releases, as specified in 
Note 6 of Table 1 in Appendix A of 40 CFR Part 191. Because of the 
statistical arguments described above, EPA is satisfied that the number 
of CCDFs is large enough such that, at cumulative releases of 1 and 10, 
the maximum CCDF generated exceeds the 99th percentile of the 
population of CCDFs with at least a 0.95 probability. Therefore, EPA 
proposes to find that DOE has demonstrated compliance with 
Sec. 194.34(d).
5. Compliance of the Mean CCDF
    Section 194.34(f) requires the CCA to 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. 
This statistical demonstration allows DOE to demonstrate compliance 
using a finite number of CCDFs, rather than having to generate the 
entire (infinitely large) population of CCDFs.
    In order to meet the requirements of Sec. 194.34(f), DOE must 
calculate the mean CCDF curve from all 300 CCDF curves generated in the 
CCA PA, must compute the 95 percent confidence limits for that overall 
mean curve, and must compare the 95 percent upper confidence limit CCDF 
curve to the containment requirements of Sec. 191.13. The DOE must show 
that the mean of its 300 CCDF curves, and the 95th percentile upper 
confidence limit on the mean, both lie below a probability of 0.1 at a 
cumulative release value of 1, and lie below a probability of 0.001 at 
a cumulative release value of 10.
    In the CCA, DOE presented the steps used in its PA to generate the 
300 CCDF curves. DOE also showed how it then calculated the mean of all 
CCDFs, by first computing the mean CCDF for each of the three 
replicates of 100 curves, and then averaging those three mean CCDF 
curves. Using the three mean CCDF curves, DOE calculated the 95 percent 
confidence limits for the overall mean CCDF curve. DOE identified the 
mean of all CCDFs generated and the 95 percent confidence limits and 
showed that both the mean CCDF and the CCDF for the upper confidence 
limit satisfy the containment requirements by more than an order of 
magnitude.

[[Page 58826]]

    EPA examined DOE's calculations of the mean CCDF curve and the CCDF 
curve for the 95 percent confidence limit on the mean, and found that 
they were appropriate and were correctly executed. EPA concurred with 
DOE's conclusion that both the mean CCDF and the CCDF for the upper 
confidence limit satisfy the containment requirements by more than an 
order of magnitude.
    As discussed above, EPA was dissatisfied with many of the parameter 
ranges and values used in PA and had concerns about some codes and the 
assumption of credit for passive institutional controls. EPA required 
DOE to perform the PAVT to determine whether the cumulative impact of 
the changes in PA codes and parameters would require additional PA 
runs. DOE applied the same methodology in the CCA PA and in the PAVT 
for calculating the mean CCDF curve and the 95 percent upper confidence 
limit. The PAVT results demonstrate that the level of statistical 
confidence is significantly greater than 95% that the mean of the CCDFs 
meets the Sec. 191.13 containment requirements. Therefore, EPA 
concludes that the final results of the PAVT are also in compliance 
with the containment requirements of Sec. 191.13 and that the results 
are presented in accordance with Sec. 194.34(f).
    A public comment received on EPA's Advance Notice of Proposed 
Rulemaking (ANPR) expressed concern about the fact that at least some 
of the CCDF curves in the CCA PA indicated that there would be releases 
into the accessible environment. EPA's containment requirements limit 
the likelihood of releases at specific levels, but do not require DOE 
to demonstrate that no releases of any magnitude will occur. EPA 
recognized that some parameters used in CCA PA were questionable, and 
required DOE to perform a PAVT that included revised parameters in 
order to alleviate concerns such as those raised by the commenter. Less 
than one percent of CCDF curves in the CCA PA exceeded normalized 
releases of one. EPA concludes that the probabilities of such releases 
are still well below the EPA release limits.
    The CCA demonstrates that there is at least a 95 percent level of 
statistical confidence that the mean of the population of CCDFs meets 
the containment requirements of Sec. 191.13. (The PAVT results indicate 
that PA would still demonstrate that the WIPP is in compliance with the 
containment requirements of Sec. 191.13, even including substantial 
modifications to some of the significant uncertain parameters used in 
PA.) Therefore, EPA proposes that the WIPP complies with the 
containment requirements of Sec. 191.13 and with Sec. 194.34(f). EPA 
believes that the WIPP will safely contain radioactive waste for up to 
10,000 years after disposal and will protect public health and the 
environment. For further information on the EPA's evaluation of 
compliance for Sec. 194.34, or on the results of the PA or the PAVT, 
see CARD 34.

XII. Assurance Requirements

    In 40 CFR 191.14, EPA included six qualitative assurance 
requirements to assure that the desired level of protection is achieved 
at disposal facilities. (60 FR 5777) The assurance requirements address 
active institutional controls, monitoring, passive institutional 
controls, engineered barriers, consideration of the presence of 
resources, and removal of waste. These measures are designed to 
compensate for the inherent uncertainty in projecting the behavior of 
natural and engineered components of the repository for many thousands 
of years. (50 FR 38072) The assurance requirements are implemented at 
the WIPP by Secs. 194.41 through 194.46 of the WIPP Compliance 
Criteria.

A. Section 194.41, Active Institutional Controls

    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 may not be considered in the 
PA for more than 100 years after disposal.
    In evaluating DOE's compliance with Sec. 194.41, EPA sought a 
detailed description of DOE's proposed AICs and how those controls 
would be implemented. EPA reviewed this description for thoroughness, 
feasibility, and likely effectiveness. 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. 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. DOE stated that it would maintain the proposed AICs for at 
least 100 years after closure of the WIPP, and that the WIPP PA assumed 
that AICs would prevent human intrusion for that period.
    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, 
groundwater pumping, surface excavation, potash exploration, 
hydrocarbon exploration, construction, and hostile or illegal 
activities). EPA also examined the assumptions made by DOE to justify 
the assertion that AICs will be completely effective for 100 years. The 
assumptions were that: (1) The fence and signs will convey the message 
that the WIPP site is hazardous and protected; (2) legal prohibitions 
on resource recovery activities will be enforced; and (3) the time 
required to initiate a resource extraction operation will allow routine 
site patrols to discover and halt such activities.
    EPA found the assumptions regarding longevity and efficacy of the 
proposed AICs to be acceptable. This finding was 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.
    Section 194.41 prohibits the consideration of contributions from 
AICs in the PA for more than 100 years after disposal. Contributions 
from AICs in the PA are considered as a reduction in the rate of human 
intrusion. 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.
    EPA found the description of each active control measure (fence, 
signs, roadways, site maintenance, and security patrols) and its 
location to be adequate to support its intended function. Also, 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 proposes to find 
DOE in compliance with Sec. 194.41. For further information on EPA's

[[Page 58827]]

evaluation of compliance for Sec. 194.41, refer to CARD 41.

B. Section 194.42, Monitoring

    Section 194.42 implements the assurance requirement that DOE 
monitor the disposal system to detect deviations from expected 
performance. The monitoring requirement distinguishes between pre- and 
post-closure monitoring because of the differences in the monitoring 
techniques that may be used during operations (pre-closure) and once 
the repository has been backfilled and sealed (post-closure). 
Monitoring is intended to provide information about the repository that 
may affect the results of the PA or containment of waste.
    To meet the criteria of Sec. 194.42, EPA required DOE to conduct an 
analysis of the effects of disposal system parameters on the 
containment of waste. At a minimum, this analysis must include the 
seven specific parameters listed in Sec. 194.42(a). DOE was required to 
present the analysis methodology, assumptions and results. DOE also was 
required to justify the decision not to monitor any of the parameters 
analyzed. (Sec. 194.42(b))
    Section 194.42 requires that the screening of parameters be 
conducted to develop plans for pre- and post-closure monitoring 
described in Secs. 194.42(c) and (d). In accordance with 
Sec. 194.42(e), these monitoring plans must: (1) identify the 
parameters to be monitored and how the baseline data will be 
determined, (2) indicate how the parameters will be used to evaluate 
deviations from the expected performance of the disposal system, and 
(3) discuss the length of time over which each parameter will be 
monitored.
    DOE conducted an analysis of disposal system parameters that 
included the parameters specified in Sec. 194.42(a), along with other 
parameters. The analysis assigned high, medium or low significance to 
each parameter for its importance to the containment of waste and to 
the verification of predictions about disposal system performance. DOE 
then screened parameters out of consideration for monitoring based on 
the ability of the parameter to produce meaningful data during the 
monitoring period and on whether parameters can be monitored without 
violating disposal system integrity.
    EPA evaluated the analysis and screening of parameters, including 
the methodology, assumptions, and results. EPA found that the analysis 
included the required parameters and adequately justified both the 
selection and rejection of parameters for inclusion in monitoring 
plans. Therefore, EPA proposes to find DOE in compliance with 
Secs. 194.42(a) and (b).
    Based on the results of its analysis, DOE submitted plans that 
identified ten parameters that will be monitored for pre-closure 
monitoring, five of which will also be monitored for post-closure 
monitoring. The pre-closure monitoring parameters are: (1) Culebra 
groundwater composition, (2) change in Culebra groundwater flow, (3) 
probability of encountering a Castile brine reservoir, (4) drilling 
rate, (5) subsidence measurements, (6) waste activity, (7) creep 
closure and stresses, (8) extent of deformation, (9) initiation of 
brittle deformation and (10) displacement of deformation features. 
Parameters one through five are also post-closure monitoring 
parameters. The parameters selected for monitoring included several of 
those listed in Sec. 194.42(a), such as creep closure and stresses, 
extent of deformation, initiation of brittle deformation, displacement 
of deformation features, Culebra ground water composition and flow and 
Castile brine reservoir location.
    The CCA described how DOE intends to implement monitoring programs 
for both pre-and post-closure parameters. The monitoring plans included 
information on establishing baseline data, how monitoring data will be 
used to evaluate deviations from expected performance and on the length 
of time each parameter will be monitored. EPA finds that DOE submitted 
monitoring plans in accordance with Secs. 194.42(c), (d), and (e). The 
monitoring plans in the CCA addressed both pre-closure monitoring 
(planned to begin before emplacement of waste) and post-closure 
monitoring (using methods that would not jeopardize containment of 
waste in the disposal system), and included information required by the 
Compliance Criteria.
    EPA proposes to find DOE in compliance with the requirements of 
Sec. 194.42. In accordance with its authority under Sec. 194.21, EPA 
intends to conduct an inspection of the pre-closure monitoring 
activities prior to emplacement of waste to confirm implementation of 
the plans detailed in the CCA. The results of this inspection will be 
placed in the public dockets described under Sec. 194.67. For further 
information on EPA's evaluation of compliance for Sec. 194.42, see CARD 
42.

C. Section 194.43, Passive Institutional Controls

    The Compliance Criteria at Sec. 194.43 require a description of 
passive institutional controls (PICs) that will be implemented at the 
WIPP. PICs are measures that do not require human intervention in order 
to warn away potential intruders from disposal sites. EPA defined PICs 
in the disposal regulations as markers, public records and archives, 
government ownership of a site and restrictions on land use at the 
site, and any other means of preserving knowledge of a site. (50 FR 
38085) PICs are intended to deter unintentional intrusions by people 
who otherwise might not be aware of the presence of radioactive waste 
at the site.
    Sections 194.43(a)(1) through (3) of the Compliance Criteria 
implement the disposal regulations by requiring DOE to: (1) identify 
the controlled area by 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). Such 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.
    The PICs design proposed by DOE in the CCA calls for the 
construction at the WIPP site of a large earthen berm, dozens of 
granite monuments, and three granite information rooms, two of which 
will be buried for their protection. DOE also proposed to bury 
thousands of small markers at shallow depths around the site. All 
markers except the berm will be engraved with warning messages in 
several languages and of varying complexity.
    DOE plans to distribute WIPP records and other information to over 
one hundred archives, record centers, professional organizations, and 
commercial enterprises in the United States and abroad. Finally, DOE 
points to its ownership of the WIPP site as a measure that will 
identify the site as Federal property and off limits to resource 
exploration.
    EPA evaluated whether the proposed markers are ``as permanent as 
practicable'' by considering the manner in which DOE accounted for 
potential marker failures and by confirming that

[[Page 58828]]

the proposed markers could be fabricated. EPA's analysis of the 
proposed markers suggests that they are practicable, although DOE may 
decide to revise the design as implementation proceeds. Any such 
revisions would constitute a modification of the design and would 
therefore require EPA approval in accordance with Secs. 194.65 and 
194.66. Also, the CCA showed that the proposed design incorporates 
features intended to promote the endurance of markers. Examples of 
these features are: redundant markers, highly durable materials with 
low intrinsic value, large dimensions, and location both above and 
below the surface. EPA proposes to find that the proposed markers are 
designed to be as permanent as practicable, in accordance with 
Sec. 194.43(a)(1).
    With regard to placement of records, DOE has prioritized archives 
and record centers in order to target those closest to the WIPP and 
most likely to be consulted by resource exploration industries 
nationally and abroad. The additional PICs proposed by DOE, which 
involve placement of WIPP information on maps and in various reference 
materials, also appear to be practicable. Therefore, EPA proposes to 
find that DOE complies with Secs. 194.43(a)(2) and (3).
    DOE estimated the amount of time that most of the proposed PICs are 
expected to endure by comparing them to analogues with similar 
properties that have survived to the present. The estimates of 
endurance, the lowest of which is at least 2,400 years and the greatest 
of which is at least 5,000 years, vary according to the age of 
analogues. DOE estimated the length of time that messages and records 
are expected to be understood (at least 1,000 years) by making 
assumptions about the future and then stating why those assumptions are 
reasonable. Because DOE based its design on sound principles, took into 
account likely failures of PICs, based estimates of endurance on 
relevant analogues, and based estimates of comprehensibility on a 
reasonable framework of assumptions, EPA believes that the proposed 
design for markers meets the criterion of ``as permanent as 
practicable'' and that DOE's estimates for that purpose are acceptable 
for compliance with Sec. 194.43(b).
    DOE proposed to take most of the steps necessary for implementing 
the proposed PICs, such as making arrangements with archives and record 
centers and refining marker messages, during the WIPP's operational 
period. However, DOE also plans to extend some activities, particularly 
testing of markers, over nearly 100 years after closure (i.e., during 
the proposed active institutional control period) before finalizing 
important aspects of the design, in the belief that future technology 
may improve the design. EPA cannot base a regulatory determination that 
DOE has demonstrated compliance with the requirements at Sec. 194.43 on 
a speculative plan to finalize the required design during the active 
institutional control period. It would be inconsistent with Congress' 
intent in the LWA for EPA to allow DOE to alter the approved PICs 
design after EPA's regulatory function comes to an end.
    Rather, EPA's determination must be based on the design proposed in 
the CCA. EPA acknowledges that future technological developments might 
improve the design of certain PICs components. Should DOE develop 
evidence that aspects of the proposed design can be improved during the 
operational period, DOE could then request modification of the approved 
plan in a recertification application. DOE also will not be precluded 
in the future from implementing other measures in addition to those 
comprising the final design. During the period that EPA exercises 
regulatory oversight over the WIPP, DOE may not alter or delete aspects 
of the approved plan in the CCA without notifying EPA and subjecting 
the certification to modification, if EPA deems it necessary.
    Given that EPA considered the design proposed in the CCA to be 
final for the purposes of its compliance review, EPA finds that DOE has 
not justified sufficiently the need for additional testing of markers 
after closure of the repository or the need to delay implementation for 
many years after closure. EPA believes that PICs should be implemented 
as soon as possible after the WIPP facility is sealed, and that 
measures necessary to prepare for such implementation should be 
accomplished during the operational period for the WIPP, unless doing 
so would compromise the effectiveness of the CCA design. For example, 
EPA believes that it is appropriate and practicable during the 
operational period for DOE to establish agreements with national 
archives to accept and maintain records related to the WIPP. EPA 
therefore proposes to find DOE in compliance with the PICs requirements 
at Secs. 194.43(a) and (b), on the condition that DOE submit additional 
information to EPA for approval. No later than the final re-
certification application submitted prior to closure of the disposal 
system, DOE must provide a schedule for implementing PICs 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 disposal system. DOE also must 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 may be expected to result from 
such testing. (See Condition 4 of the proposed Appendix A to 40 CFR 
Part 194.)
    DOE proposed to take a credit of 99 percent over 700 years in the 
PA. In other words, DOE requested that the likelihood of human 
intrusion into the WIPP during the first 700 years after closure be 
reduced to one percent of the drilling rates calculated in accordance 
with the requirements of Secs. 194.33(b)(3) and (4). The proposed 
credit was based largely on DOE's approach to compliance with 
Sec. 194.43(b), which led DOE to conclude that all PICs are ``virtually 
certain'' to endure and be understood for at least 700 years. DOE 
identified drilling in the wrong location on a properly issued lease as 
the only plausible scenario whereby the proposed PICs could fail to 
deter an inadvertent intrusion. DOE then surveyed the Delaware Basin 
and other areas for such failures and determined that wells were 
drilled in the wrong location in 5 out of 429,000 instances, a rate of 
0.001 percent. Finally, DOE bounded the failure rate (of 0.001) at 1.0 
percent for the sake of conservatism.
    EPA agrees with DOE that the proposed PICs appear likely to endure 
and be understood for hundreds of years. However, EPA proposes to deny 
DOE's request for PICs credit. The reasons for EPA's denial of PICs 
credit are discussed briefly below.
    First, in promulgating its PICs credit criterion, EPA explicitly 
stated that ``the degree to which PICs might reduce the future drilling 
rate can be reliably determined only through informed judgment.'' (61 
FR 5232) EPA clearly expected the proposed PICs credit to be derived 
through an expert elicitation conducted in accordance with the 
requirements at 40 CFR 194.26. DOE instead prepared a justification and 
submitted it to peer review. EPA regards peer review as qualitatively 
different from expert judgment, in which the independent panel itself 
prepares the justification.
    Second, Sec. 194.43(c) states, ``In no case . . . shall passive 
institutional controls be assumed to eliminate the likelihood of human 
intrusion entirely.'' DOE's rationale for the proposed credit 
repeatedly states that PICs are ``virtually certain'' to eliminate the 
likelihood of human intrusion. EPA believes that the

[[Page 58829]]

assertion that PICs are virtually certain (i.e, 99.9 percent) to endure 
and be understood is equivalent in effect to assuming that they 
eliminate the likelihood of human intrusion entirely. Furthermore, 
DOE's estimate of the effectiveness of PICs does not adequately account 
for the considerable uncertainty associated with quantifying the 
effectiveness of PICs for use in the PA. Specifically, there are 
potential failure scenarios that DOE did not account for in developing 
the proposed credit. For example, within the next 700 years, someone 
could drill based on an incorrect permit, permits may be mistakenly 
granted, records of the WIPP could be lost, or a system of permits to 
control drilling may be abandoned. While DOE's proposal does not 
account conservatively for uncertainty, EPA recognizes that any level 
of credit EPA would propose in place of DOE's estimate would be 
arbitrary. Finally, EPA found that the issue of quantitative credit for 
PICs is of little consequence for the purpose of evaluating the WIPP's 
performance, since the removal of PICs credit from computer models (in 
the Performance Assessment Verification Test) produced no signification 
effect on the WIPP's compliance with EPA's numerical standards.
    EPA proposes to determine that DOE complies with Sec. 194.43, on 
the condition that additional information on the final PICs design be 
submitted for EPA's review no later than the final re-certification 
application. For additional information on EPA's evaluation of 
compliance for Sec. 194.43, see CARD 43.

D. Section 194.44, Engineered Barriers

    Section 194.44 requires that DOE 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, which requires the 
use of one or more engineered barriers, 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.
    To comply with this requirement, EPA expected DOE to describe the 
engineered barrier(s) selected for implementation at the WIPP. EPA also 
expected the CCA to document how the engineered barrier(s) prevents or 
substantially delays the movement of water or radionuclides to the 
accessible environment, and how it reduces uncertainties in modeling 
performance of the disposal system. EPA expected DOE to conduct a 
comprehensive evaluation of engineered barrier alternatives in order to 
compare the benefits and detriments of various barriers and then use 
the results of such a comparison to justify selecting or rejecting a 
barrier(s).
    In accordance with Sec. 194.44(b), EPA observed DOE's scoping study 
and screening process during March and April 1995. The scoping effort 
produced a list of 111 potential barriers and combinations of barriers 
(including the barriers described in Sec. 194.44(b)), of which 18 were 
evaluated against the factors described in Sec. 194.44(c). Although DOE 
did not specifically address the waste categories in Sec. 194.44(d), 
the study effectively accounted for the categories by analyzing three 
waste types (sludges, solid organics, and solid inorganics) and 
considering multiple waste processing schemes. DOE's evaluation of 
engineered barriers was peer reviewed in accordance with 
Sec. 194.27(a)(3). See Sec. 194.27, ``Peer Review,'' for details of 
EPA's evaluation of the general peer review process. On the basis of 
its evaluation of the benefits and detriments of eighteen engineered 
barrier types, DOE concluded that a chemically-buffering backfill was a 
high-benefit, low-cost, and practicable engineered alternative. DOE 
selected magnesium oxide (MgO) backfill as an engineered barrier, and 
proposed to emplace bags of MgO between and around waste containers in 
the repository. DOE stated that the backfill will serve to: (1) 
substantially delay movement of radionuclides by controlling chemical 
conditions in the underground waste panels so that the solubility of 
radionuclides in water is reduced, (2) delay movement of water by 
reacting with brine to reduce free water in the disposal system, and 
(3) fix pH levels within a narrow range, thereby bounding an important 
modeling parameter whose value might otherwise be highly uncertain.
    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. DOE provided substantial documentation in the 
CCA and supplementary information that MgO can effectively reduce 
actinide solubility in the disposal system. EPA agrees that the 
chemical reactions that DOE associated with MgO can occur under 
predicted repository conditions. 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. (For details regarding chemical reactions of MgO, see CARD 
24, ``Waste Characterization.'' For further information regarding the 
PA modeling of solubility and chemical conditions in the repository, 
see CARD 23, ``Models and Computer Codes.'')
    Public comments received on EPA's Advance Notice of Proposed 
Rulemaking (``ANPR'') questioned two aspects of DOE's treatment of 
engineered barriers in the CCA. First, commenters disagreed that 
borehole plugs, shaft seals, and panel seals should be treated by DOE 
as engineered barriers for the purpose of complying with Sec. 194.44. 
EPA found that DOE had treated plugs and seals as part of the baseline 
design of the disposal system, not as additional barriers for the 
purpose of assurance. The effectiveness of plugs and seals is discussed 
as part of EPA's evaluation of the disposal system design under 
Sec. 194.14, ``Content of Compliance Certification Applications.'' 
Second, commenters expressed concern that the CCA did not support 
conclusions about the effectiveness of MgO with experimental data or 
other documentation. EPA shared this concern and so requested that DOE 
provide additional documentation showing that backfill could be 
emplaced in the required manner and would function in the disposal 
system as proposed. EPA believes that supplementary information sent by 
DOE adequately addressed insufficiencies in the CCA.
    EPA proposes to find DOE in compliance with Sec. 194.44. For 
further information on EPA's evaluation of compliance for Sec. 194.44, 
see CARD 44.

E. Section 194.45, Consideration of the Presence of Resources

    Section 194.45 implements the assurance requirement that the 
disposal system be sited such that the benefits of the natural barriers 
of the disposal system compensate for the increased probability of 
disruptions to the disposal system resulting from exploration and 
development of existing resources. (61 FR 5232) In promulgating this 
requirement, EPA determined that the performance assessment (``PA'') is 
the appropriate tool to weigh the advantages and disadvantages of the 
WIPP site because PA demonstrates whether potential human intrusion 
will cause unacceptably high releases of radioactive material from the 
disposal facility.

[[Page 58830]]

    In accordance with the Compliance Criteria, DOE must demonstrate 
that PA has incorporated the potential effects of human activities near 
the WIPP prior to disposal, and of drilling and excavation mining over 
the regulatory time frame. DOE also must document that the results of 
the PA demonstrate compliance with the containment requirements at 40 
CFR 191.13. No further demonstration of compliance is needed for 
Sec. 194.45.
    The Agency confirmed that PA incorporated human intrusion scenarios 
and met EPA's release limits in accordance with the WIPP Compliance 
Criteria. Based on EPA's findings that DOE complied with requirements 
related to scope of PA, conduct of PA, mining and drilling activities 
over the regulatory time frame, results of PA, and pertinent assurance 
requirements, EPA proposes to determine that DOE has demonstrated 
compliance with Sec. 194.45. For further explanation of EPA's proposed 
compliance decisions for these related compliance criteria, see 
preceding preamble discussions for Sec. 194.14, Sec. 194.23, 
Sec. 194.32, Sec. 194.33, Sec. 194.34, Sec. 194.41, and Sec. 194.43. 
For further information on EPA's evaluation of compliance for 
Sec. 194.45, refer to CARD 45.

F. Section 194.46, Removal of Waste

    Section 194.46 requires documentation that the removal of waste 
from the disposal system is feasible for a reasonable period of time 
after disposal. (61 FR 5244) The intent of this provision is to 
implement the assurance requirement at 40 CFR 191.14(f) that ``disposal 
systems be selected so that removal of most of the waste is not 
precluded for a reasonable period of time after disposal.'' To meet the 
criteria of Sec. 194.46, EPA expected the CCA to provide a 
comprehensive strategy that showed the manner in which waste could be 
removed from the repository for a reasonable period of time after 
closure and an estimate of how long after disposal removal of waste 
would remain technologically feasible. Although the eventual 
disposition of the waste is an important environmental concern, 40 CFR 
Part 194 does not require DOE to speculate on the possible location or 
hazards of the waste once it is removed from the repository.
    In the CCA, DOE presented a five-phase approach to removing waste 
from the WIPP repository, including: planning and permitting; initial 
above-ground set-up and shaft sinking; underground excavation and 
facility set-up; waste location and removal operations; and 
decontamination and decommission of the facility. The CCA included a 
discussion of techniques that could be used to remove the waste given 
the repository conditions at the time of removal, and also discussed 
several existing mining techniques that could be used to remove waste 
from the WIPP repository.
    EPA reviewed the CCA to assess the completeness of the strategy for 
removing the waste and the justification of the proposed technology for 
removing the waste. EPA believes that the five phases described for 
waste removal provide an orderly sequence of planning and 
implementation procedures that could be implemented. EPA agrees that 
the proposed activities, techniques, and equipment that would be 
necessary to remove the waste are all presently feasible.
    EPA reviewed the CCA for an estimate of how long after disposal it 
would remain technologically feasible to remove the waste. DOE stated 
that, using the system and equipment proposed in the CCA, it would be 
feasible to remove the waste any time after emplacement. Thus, DOE 
appeared to conclude that no features of the disposal system (such as 
salt creep) will prevent the removal of waste from the repository as 
long as the technology described in the CCA remains available. The CCA 
did not address how long the technology might remain available.
    EPA agrees that waste removal would be feasible as long as current 
technology remains available, but does not believe it is reasonable to 
assume that the technology will remain available over the entire 
regulatory time frame. To estimate the length of time for which waste 
removal would be feasible, EPA considered how long the technology 
described in the CCA might remain available. The Agency concluded that, 
as long as our present society remains stable, it is reasonable to 
conclude that there will likely be a continuity or advancement of 
technology which would allow waste removal to occur. In the disposal 
regulations, EPA identified 100 years after disposal as a realistic but 
conservative limit on how long active controls could be assumed to be 
effective--i.e., how long present institutions would remain in place 
continuously to enforce such controls. (50 FR 38080) Based on this same 
rationale, EPA believes it is reasonable to assume that current 
technology will remain available for the 100-year period after 
disposal, and therefore that waste removal will remain feasible for 
that time. EPA believes that 100 years constitutes a reasonable period 
of time after disposal, in accordance with Sec. 194.46. Therefore, EPA 
concludes that DOE has met the regulatory requirements for the removal 
of waste, and proposes to find DOE in compliance with Sec. 194.46. For 
further information on EPA's evaluation of compliance for Sec. 194.46, 
see CARD 46.

XIII. Individual and Ground-water Protection Requirements

    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 
radiation dose limits and radionuclide concentration limits for ground 
water is conducted through use of a process known as compliance 
assessment (``CA''). Compliance assessments use methods similar to 
those of PA (for the containment requirements) but are required to 
address only undisturbed performance of the disposal system. Sections 
194.51 and 194.52 specify the requirements which must be incorporated 
into CA in the analyses of individual radiation doses to protected 
individuals. Section 194.53 addresses underground sources of drinking 
water. Finally, the criteria specify the scope of CA and establish 
statistical requirements on the results of CA in demonstrating 
compliance with the individual and ground-water protection requirements 
(Secs. 194.54 and 194.55).

A. Section 194.51, Consideration of Protected Individual

    Section 194.51 requires DOE to assume in compliance assessments 
(``CA'') that an individual resides at the point on the surface where 
the dose from radionuclide releases from the WIPP would be greatest. 
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.
    DOE's analysis of the WIPP's compliance with Sec. 194.51 and 
related sections of the Compliance Criteria was contained in the CCA 
and in supplementary information. DOE described its analysis as a 
``bounding analysis'' because it assumed that the maximum concentration 
of radionuclides was available in underground sources of drinking water 
(``USDWs'') and that humans using that water would therefore receive 
the maximum dose possible from that pathway.
    The bounding analysis was derived from the performance assessment 
for the undisturbed scenario. DOE analyzed all potential routes of 
release of radioactive

[[Page 58831]]

waste from the repository that could lead to exposure of an individual 
and determined that the only release to the accessible environment 
would be passage of contaminated water through the interbeds in the 
Salado Formation, where the WIPP is situated. In the analysis, DOE 
demonstrated that radionuclides migrated horizontally to the accessible 
environment in only nine out of 300 realizations.
    DOE then assumed that the highest concentration of radionuclides 
from the nine realizations was present at the subsurface boundary of 
the accessible environment, and that individuals would take water for 
consumption or agricultural use directly from this location in the 
Salado. DOE stated that it was not necessary to identify a single point 
of maximum dose because the analysis assumed that the maximum 
radionuclide concentration was available to individuals in brine taken 
from the Salado Formation; therefore, the dose from various pathways 
would be maximized regardless of an individual's location on the 
surface of the accessible environment. For more discussion of DOE's 
consideration of pathways in the bounding analysis, see Sec. 194.52, 
``Consideration of Exposure Pathways.''
    EPA agrees that it was conservative for DOE to base its 
calculations of individual dose on the maximum predicted radionuclide 
concentrations. EPA also accepts as technically sound DOE's rationale 
for not identifying a single geographic point at which individual 
committed effective dose is greatest, since under DOE's assumptions, 
all points on the surface would result in the same maximum dose. 
Therefore, EPA proposes to find DOE in compliance with Sec. 194.51. EPA 
discusses whether the results of DOE's dose calculations comply with 
the individual protection requirements at 40 CFR 191.15 under the 
evaluation for Sec. 194.55, ``Results of CA.'' Due to the relatedness 
of the requirements, EPA combined the discussion of DOE's compliance 
for Secs. 194.51 and 194.52 (``Consideration of Exposure Pathways'') in 
a single Compliance Application Review Document (CARD 51/52).

B. Section 194.52, Consideration of Exposure Pathways

    The individual protection requirements focus on the annual 
radiation dose of a hypothetical maximally-exposed person living on the 
surface just outside the boundary to the accessible environment. 
Section 194.52 requires DOE's compliance assessments for the individual 
protection requirements to consider all potential exposure pathways for 
radioactive contaminants from the WIPP. DOE must assume that an 
individual consumes 2 liters per day of drinking water from any 
underground source of drinking water in the accessible environment. EPA 
expected that DOE would postulate several release pathways and 
calculate the dose resulting from each pathway. In the CAG, EPA stated 
that DOE could employ simplified exposure models provided that DOE 
showed them to be more conservative than more detailed models. (CAG, 
pp. 67-68)
    DOE's modeling identified only one possible release of 
radionuclides to the accessible environment for the undisturbed 
performance scenario, resulting from contaminated brine flowing through 
the Salado Formation interbeds. DOE's modeling indicated that this 
release could occur if there were a significant buildup of gas and 
fluid pressure within the WIPP's waste panels.
    To assess this potential exposure pathway, DOE conservatively 
assumed that Salado brine would be available for human use once it 
reached the subsurface boundary of the accessible environment. Water in 
the Salado interbeds is actually a highly concentrated brine unsuitable 
for drinking; DOE has measured the average concentration of total 
dissolved (non-radioactive) solids (``TDS'') in Salado brine as 324,000 
milligrams per liter (mg/L). DOE therefore assumed that brine would 
have to be diluted with pure water in order to bring the concentration 
of TDS down to the highest allowable amount under the standard for 
potable water (10,000 mg/L TDS). DOE assumed that this diluted Salado 
brine would be consumed at the rate of two liters per day and then 
calculated the dose resulting from this single pathway of water 
ingestion.
    EPA required DOE to expand its analysis to include additional 
pathways. This expanded analysis is described in supplementary 
information sent by DOE. (Docket A-93-02, Item II-I-10) DOE examined 
pathways whereby humans either inhale dust from soil irrigated with 
contaminated water or consume agricultural products irrigated with 
contaminated water. In the latter case, pathways included plants eaten 
directly by humans and milk or beef from cattle whose stock pond 
contained contaminated water.
    Based on the CCA and the supplementary information described above, 
EPA found that DOE assumed in its analysis of pathways that individuals 
consume 2 liters per day of water from underground sources. EPA also 
conducted independent calculations and concluded that DOE had reliably 
reported the doses expected to result from all pathways considered. EPA 
discusses whether the results of DOE's dose calculations comply with 
the specific requirements of 40 CFR 191.15 under 194.55, ``Results of 
Compliance Assessments.''
    EPA found that the simplified ``bounding analysis'' employed by DOE 
(described under Sec. 194.51 above) was sufficiently conservative not 
to require the use of more detailed models. The bounding analysis was 
conservative because it assumed unrealistically that brine in the 
Salado Formation would be used as a source of water for drinking and 
irrigation. In fact, brine in the Salado is not likely to be used as an 
underground source of drinking water because it has an extremely high 
concentration of TDS. Salado brine would require considerable dilution 
in order to meet the criteria for potable water, and dilution would 
serve to reduce radionuclide concentrations. There are other, more 
likely sources of water than the Salado in the vicinity of the WIPP 
(see Sec. 194.53 below), but DOE's modeling demonstrated that 
radionuclides from the WIPP would not reach these sources in the 
undisturbed scenario.
    EPA therefore proposes to find the WIPP in compliance with 
Sec. 194.52. Due to the relatedness of the requirements, EPA combined 
the discussion of DOE's compliance with Secs. 194.51 (``Consideration 
of the Protected Individual'') and 194.52 in a single Compliance 
Application Review Document (CARD 51/52).

C. Section 194.53, Consideration of Underground Sources of Drinking 
Water

    Section 194.53 requires that compliance assessments of the 
undisturbed performance scenario consider underground sources of 
drinking water (``USDWs'') near the WIPP and their interconnections. 
The undisturbed scenario assumes that the disposal system will not be 
disturbed by human activities such as drilling or mining. 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) supplies drinking water for human consumption or (ii) 
contains fewer than 10,000 mg per liter of total dissolved solids.''
    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

[[Page 58832]]

they in fact meet the regulatory definition of a USDW. However, DOE did 
not identify a plausible release scenario in undisturbed conditions in 
which radionuclides from the WIPP reached these potential USDWs. DOE 
found instead that the only plausible release scenario in undisturbed 
conditions involved transport of radionuclides by brine laterally 
through the Salado Formation (where the WIPP is situated) to the 
subsurface boundary of the accessible environment. The concentration of 
radionuclides at the subsurface boundary in this scenario represents 
the maximum level possible in the accessible environment.
    DOE assumed that brine at the subsurface boundary would be directly 
available to a hypothetical individual on the surface for use as 
drinking water. In other words, DOE assumed that people would draw 
water directly from the Salado, thereby bypassing other potential 
USDWs, and would thus be exposed to the maximum concentration of 
radionuclides. Because DOE assumed the worst-case scenario and did not 
attempt to demonstrate in the analysis that transport of radionuclides 
through geological formations in the accessible environment would lower 
their concentrations, DOE concluded that it was not necessary to 
analyze underground interconnections among water bodies.
    EPA agrees that the Culebra, Santa Rosa, and Dewey Lake Formations 
are the most likely potential USDWs. Also, EPA agrees that it was not 
necessary to identify USDW interconnections because of DOE's 
conservative assumption that individuals, regardless of their location 
on the surface of the accessible environment, would be exposed to the 
maximum available concentration of radionuclides in drinking water.
    Based on information provided in the CCA, EPA concluded that DOE 
adequately considered USDWs in compliance assessments. EPA therefore 
proposes to find that DOE complies with Sec. 194.53. EPA discusses 
whether the results of DOE's calculations comply with the requirements 
of Sec. 191.15 and Subpart C of 40 CFR Part 191 in Sec. 194.55, 
``Results of CA.'' For further discussion of EPA's evaluation of 
compliance for Sec. 194.53, see CARD 53.

D. Section 194.54, Scope of Compliance Assessments (CA)

    Section 194.54 addresses the scope of compliance assessments 
(``CA'') conducted to determine compliance with the individual dose and 
ground-water protection requirements of the disposal regulations. The 
CA must account for the undisturbed performance of the disposal system; 
that is, the predicted behavior of the disposal system if it is not 
disrupted by human intrusion or the occurrence of unlikely natural 
events (Sec. 191.12). As with performance assessment, the CA must 
consider features, events, and processes (``FEPs'') and associated 
uncertainties. The CA can be considered a ``subset'' of performance 
assessment, as CA considers only natural/undisturbed conditions and 
past/near-future human induced activities, but does not include long-
term future human-induced activities that are included in performance 
assessment.
    EPA required DOE to consider FEPs that relate to undisturbed 
performance of the disposal system. EPA required DOE to identify how 
these FEPs were screened, combined, and used in the CA. DOE was 
required to document why any undisturbed scenario FEPs were not 
included in the CA. EPA also required the CA to consider activities 
that occur in the vicinity of the WIPP and their effect on radionuclide 
migration from the site. Specifically, DOE was required to consider 
existing boreholes and near future lease development.
    To fulfill the requirements of Sec. 194.54(a), DOE developed and 
followed a process for considering FEPs in the CA. Out of the initial 
list of approximately 72 natural FEPs, DOE eventually included 17 in 
the CA. This is the same process that was used in identifying FEPs for 
PA; EPA's evaluation of the process is addressed in the preamble 
discussion of Sec. 194.32. EPA concluded that the initial FEP list 
assembled by DOE was sufficiently comprehensive, in accordance with the 
requirements of Sec. 194.54(a). This list appropriately screened out 
events and processes on the basis of probability, consequence or 
regulatory requirements. DOE considered and incorporated into CA 
numerous natural processes and events. DOE adequately documented the 
decision not to include FEPs in the CA. (See preamble discussion for 
Sec. 194.32.)
    DOE, in accordance with the requirements of Sec. 194.54(b), 
conducted an analysis of the activities that are expected to occur in 
the vicinity of the WIPP in the near future. DOE's assessment of 
existing boreholes indicated that natural fluid flow through abandoned 
boreholes would be of very little consequence in the near future and 
was therefore not included in the CA. In addition to existing 
boreholes, DOE addressed a number of activities that could occur in the 
vicinity of the WIPP in the near future. These activities were: oil and 
gas exploration, exploitation and extraction; potash exploration and 
exploitation; fluid injection related to oil and gas production; sulfur 
coreholes; hydrocarbon/gas storage; brine wells for solution mining; 
and water supply wells. DOE determined that none of these activities 
will have an impact on the disposal system in the near future and 
therefore did not include them in the CA. DOE examined fluid injection 
for inclusion in the CA, but screened it out based on low consequences 
to the disposal system if it happened. DOE also provided information on 
leases in the WIPP area.
    EPA reviewed the CCA analysis of existing boreholes in the vicinity 
of the WIPP and their potential impact on radionuclide migration and 
agrees with DOE's conclusion that existing boreholes will not affect 
the disposal system. EPA and public commenters disagreed with DOE's 
initial analysis of the effects of fluid injection and salt water 
mining. Upon reviewing supplemental modeling of these scenarios, 
conducted by DOE and also independently by EPA, EPA agrees that these 
activities were correctly omitted from the CA. (See the preamble for 
Sec. 194.32 for further discussion of this additional modeling.) DOE 
satisfactorily identified leases near the WIPP and appropriately 
estimated the life of the leases for consideration in the CA.
    EPA proposes to find DOE in compliance with the requirements of 
Sec. 194.54. For further information on EPA's evaluation of compliance 
for Sec. 194.54, see CARD 54.

E. Section 194.55, Results of CA

    Section 194.55 establishes requirements for analyzing the WIPP's 
compliance with the individual and the ground-water protection 
requirements of the disposal regulations. These requirements: (1) limit 
the possible radiation dose from the WIPP to individuals in the 
accessible environment, and (2) limit the degree of radioactive 
contamination of groundwater for which the WIPP might be responsible. 
Both limitations are required to be analyzed for undisturbed 
performance of the disposal system for 10,000 years. (See the 
discussion for Sec. 194.54 in today's preamble.)
    40 CFR 191.15, the individual protection requirements, requires 
that there must be a reasonable expectation that undisturbed 
performance of the WIPP disposal system will not cause the annual 
committed effective dose equivalent to exceed 15 millirems (150 
microsieverts) to any member of the public in the accessible 
environment. Subpart C of 40 CFR Part 191, the ground-water protection 
requirements, sets requirements on the radiation levels

[[Page 58833]]

in underground sources of drinking water (``USDWs'') by referencing the 
standards of the Safe Drinking Water Act at 40 CFR Part 141. In order 
to determine compliance with these requirements, DOE must calculate the 
maximum individual radiation dose from all pathways, the maximum 
concentrations of specific radionuclides in any USDW, and the maximum 
annual dose equivalents from radioactivity in any USDW.
    Section 194.55 establishes six requirements for computing, 
presenting, and evaluating the results of compliance assessments 
(``CA''). The requirements of Secs. 194.55(b) through (f) are analogous 
to the requirements of Secs. 194.34(b) through (f) for the results of 
performance assessment (``PA''). As a result, DOE has been able to use 
the same computational techniques and the same computer codes to 
perform both PA and CA. The major differences between the analyses for 
PA and CA are that: (1) CA considers only undisturbed performance of 
the WIPP, and thus does not consider scenarios of human intrusion; (2) 
CA requires calculations of doses and radioactivity concentrations in 
USDWs, as well as cumulative releases; and (3) CA results are expressed 
as a set of dose and concentration values, while PA results are 
expressed as a series of complementary cumulative distribution function 
(``CCDF'') curves.
1. Uncertainty of CA
    Section 194.55(a) requires the CA to consider and to document 
uncertainty in the performance of the disposal system. There are two 
general sources of such uncertainty. The first is the uncertainty 
associated with physical, chemical and geologic conditions within and 
around the repository. The CA deals with this by running 300 different 
undisturbed-site scenarios, with 300 independent sets of sampled values 
for the most important uncertain parameters (i.e., parameters either 
that vary from place to place or that simply are not known with 
precision, but which have been determined to have a significant effect 
on the WIPP's ability to contain radionuclides). The second source of 
uncertainty is the lack of detailed knowledge of the ways in which 
contaminated ground water might be pumped out and utilized by persons 
living near the site in the future. DOE handles this uncertainty 
through a conservative bounding calculation on individual doses, which 
is intended to demonstrate compliance regardless of any uncertainties. 
The bounding calculation is discussed in further detail in the 
discussions of Secs. 194.51 and 194.52 in this preamble.
    DOE evaluated uncertainty in the amount of contaminants transported 
underground using the same method as in the PA, except that uncertainty 
from human intrusion scenarios was not considered. For further 
information on the treatment of uncertainty in PA, see the discussion 
of Sec. 194.34 in today's preamble. EPA found that the conservative 
bounding calculation is appropriate, in lieu of further uncertainty 
analysis, and that DOE's treatment of uncertainty in CA is sufficient. 
Therefore, the Agency proposes to find that WIPP complies with 
Sec. 194.55(a).
2. Probability Distributions for Uncertain Parameters
    Section 194.55(b) requires DOE to develop and document probability 
distributions for uncertain disposal system parameter values used in 
CA. This is similar to the requirement for parameter values used in the 
PA. DOE uses the same probability distributions for uncertain disposal 
system parameter values in both PA and CA calculations. This involves 
performing calculations with 300 independent sets of sampled parameter 
values for each of the 57 important parameters associated with 
uncertain physical, chemical and geological conditions in the 
repository and its surroundings. EPA conducted the same evaluation of 
probability distributions for CA as for PA.
    Upon reviewing DOE's models and computer codes, the Agency 
questioned a number of important input parameter values and 
distributions used in the PA and in CA. EPA determined that corrections 
were necessary for certain input parameters and conceptual models. 
Because of concerns that the necessary corrections to these parameters 
and conceptual models could have significant effects on the actual 
results of modeling, EPA required DOE to demonstrate that the combined 
effect of all the parameter and computer code changes required by EPA 
was not significant enough to necessitate a new PA. EPA required DOE to 
perform 300 simulations in additional PA and CA calculations as a 
Performance Assessment Verification Test (``PAVT''). 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. 
CA results of the PAVT are discussed below for requirement 
Sec. 194.55(f) and PA results of the PAVT are discussed above in 
Sec. 194.34 of this preamble. The PAVT results confirmed that the 
original PA is sufficiently conservative and indicated that further PA 
and CA analysis is not required.
    After considerable analyses, including the PAVT, EPA was satisfied 
that the parameter values and distributions were adequate for 
determining compliance. See the discussion of the requirements of 
Sec. 194.34 of this preamble. For the reasons discussed in that 
section, EPA also proposes to find the CCA in compliance with 
Sec. 194.55(b).
3. Sampling of Uncertain Parameters
    Section 194.55(c) requires CA to use computational techniques which 
draw random samples from across the entire range of probability 
distributions of uncertain parameters. These computational techniques 
then must be used to calculate the ranges of estimated radiation doses 
to individuals received from all pathways; radionuclide concentrations 
in USDWs; and radiation doses received from USDWs. This requirement is 
parallel to Sec. 194.34(c), which requires techniques for random 
sampling from parameter distributions in the computation of CCDF curves 
for the results of PA.
    The statistical technique that DOE used in selecting parameter 
values in PA, Latin Hypercube Sampling (``LHS''), is also employed in 
the calculations of radionuclide concentrations in ground water (which 
are then used to calculate individual doses) for the CA. The CA 
generated 300 values of contaminant concentrations in ground water (at 
the boundary to the accessible environment) and individual annual 
radiation doses to assess compliance with Sec. 194.55.
    EPA found the LHS technique for drawing samples randomly from 
probability distributions of uncertain parameters to be sufficient, as 
discussed in this preamble for Sec. 194.34. In addition, EPA determined 
that DOE's conceptual model for determining maximum individual exposure 
and the GENII-A computer code used to calculate radiation doses were 
adequate. The Agency found that DOE has used an appropriate 
computational technique, LHS, for sampling widely from the parameter 
distributions described in Sec. 194.55(b), and has used it to generate 
ranges of radionuclide concentrations in USDWs, doses from the 
ingestion of water from USDWs, and all-pathways doses. Therefore, EPA 
proposes to find that DOE has demonstrated compliance with 
Sec. 194.55(c).
4. Sufficient Number of Estimates Generated
    Section 194.55(d) requires that the number of estimates of 
radionuclide concentrations in USDWs, doses from

[[Page 58834]]

the ingestion of water from USDWs, and all-pathways doses must be large 
enough such that the maximum estimates of doses and concentrations 
generated exceed the 99th percentile of the population of estimates 
with at least 0.95 probability. This requirement is similar to the 
requirement of Sec. 194.34(d) for determining if there is a sufficient 
number of CCDF curves in PA analysis. Both requirements have the 
purpose of ensuring that enough simulations are generated so that 
conclusions drawn from their analyses are statistically justified.
    DOE produced 300 CA calculations and used the same statistical 
arguments to justify both the number of calculations for CA and the 
number of CCDF curves. See the discussion for Sec. 194.34 in this 
preamble for a further explanation of DOE's justification and EPA's 
review. EPA found that, for random sampling, 300 individual estimates 
will provide 0.95 probability that at least one of them will exceed the 
population 99th percentile value. Thus, EPA proposes to determine that 
the CCA satisfies the requirement of Sec. 194.55(d).
5. Display full range of CA results
    Section 194.55(e) requires the CCA to display the full range of 
estimated radiation doses and radionuclide concentrations. Section 
194.34(e) has a parallel requirement for displaying the full range of 
CCDFs generated.
    DOE's CA analysis of individual doses started with the findings of 
the PA of contamination that has migrated to the accessible environment 
in the anhydrite interbeds immediately surrounding the repository in 
the case of an undisturbed repository. This analysis generated a full 
range of radionuclide concentrations in the ground water. DOE found 
that only nine of the three hundred estimates were not negligibly small 
(that is, less than 10<SUP>-18</SUP> curies/liter) <SUP>24</SUP>. 
Starting with the concentrations in the interbeds, DOE conducted 
bounding calculations on individual dose, both from the ingestion of 
drinking water and from all exposure pathways combined. These 
calculations adopted assumptions that resulted in upper-bound estimates 
of dose that are much greater than what any individual might reasonably 
be expected to receive. DOE performed this bounding calculation in lieu 
of providing descriptive statistics for the estimates such as mean, 
median and standard deviation, as stated in EPA's ``Compliance 
Application Guidance for the WIPP'' (``CAG''). The criteria and the CAG 
allow the use of a bounding calculation as long as the simplified model 
is more conservative than more detailed and more complex modes. (CAG, 
p. 68)
---------------------------------------------------------------------------

    \24\ The Agency agrees with DOE that concentrations of less than 
10<SUP>-18</SUP> curies per liter are negligibly small. Such small 
concentrations found in the analysis could be due to calculational 
error rather than true indicators of radioactive contamination of 
USDWs.
---------------------------------------------------------------------------

    EPA reviewed the CCA and found that DOE performed a full range of 
the necessary calculations to demonstrate compliance with Sec. 191.15 
and Subpart C of 40 CFR Part 191. EPA independently estimated and 
tabulated the all-pathway and USDW doses in a dose verification 
analysis. EPA's results generally agreed with those of the DOE 
analysis, although EPA found DOE's calculations to be conservative. EPA 
calculated descriptive statistics such as the mean and the 95 percent 
confidence interval for doses and concentrations to provide added 
assurance of the adequacy of DOE's methodology. Because the CCA 
presents specific estimates for each of the non-zero simulations or the 
upper bound estimate for those simulations and presents the full ranges 
of radionuclide concentrations and radiation doses, EPA proposes to 
find that DOE has demonstrated compliance with Sec. 194.55(e).
6. Compliance With Radiation Dose and Radionuclide Concentration Limits
    Section 194.55(f) requires the CCA to document that there is at 
least a 95 percent level of statistical confidence that the mean and 
the median of the range of estimated radiation doses and the range of 
estimated radionuclide concentrations meet the requirements of 
Sec. 191.15 and Subpart C of 40 CFR Part 191. This requirement is 
analogous to Sec. 194.34(f), which requires at least a 95 percent level 
of statistical confidence that the mean of the population of CCDFs 
meets the containment requirements of Sec. 191.13. In order to meet 
this requirement, it is necessary to calculate the lower and upper 
limits of the range, the mean, and the median of the estimated doses 
and of the radionuclide concentrations.
    The limit for individual doses in Sec. 191.15 is an annual 
committed effective dose, from all pathways, of 15 mrem/year. The 
limits for doses and radionuclide concentrations in USDWs under Subpart 
C of 40 CFR Part 191 are a total radioactivity concentration for 
radium-226 and radium-228 in any USDW of 5 picocuries per liter of 
water (pCi/L); a gross alpha particle radioactivity (including radium-
226 but excluding radon and uranium) in any USDW of 15 pCi/L; and an 
annual dose equivalent to the total body or any internal organ from 
beta particle and photon radioactivity in any USDW of 4 mrem/year. DOE 
calculated a maximum annual committed effective dose equivalent from 
exposure through all pathways of 0.93 mrem/year. The CCA reported that 
the maximum estimated radium concentration in ground water is 2.0 pCi/
L. The CCA contained the 300 estimated concentrations for the five 
radionuclides \241\ Am, \239\ Pu, \238\ Pu, \234\ U, and \230\ Th, and 
only nine of these were not negligibly small. The CCA reported the 
maximum gross alpha particle concentration as 7.81 pCi/L from \241\ Am, 
\239\ Pu, \238\ Pu, \230\ Th and all isotopes of Ra. DOE used its 
bounding calculation for dose due to all radionuclides from drinking 
USDWs to show that the annual dose equivalent to the whole body from 
beta particle and photon radioactivity would be no more than 0.47 mrem/
year. Supplemental analyses conducted by DOE also showed that the 
maximum beta particle and photon dose equivalent to any internal organ 
was well below the 4 mrem/year regulatory limit; bone surface was 
identified as the critical organ for that calculation. The maximum 
estimate concentration or dose for each of these is less than the 
standard. Because the maximum value for each of these values was less 
than the applicable standard, and because the bounding analysis 
accounted for sources of uncertainty, DOE concluded that the mean, 
median and 95 percent confidence interval values also met the standards 
of Sec. 191.15 and Subpart C of 40 CFR Part 191.
    EPA commissioned an independent analysis to verify DOE's dose 
calculations. In general, EPA's analysis calculated values similar to 
those calculated by DOE. EPA also calculated the mean, median and 95 
percent confidence intervals of concentrations and doses. EPA's 
analysis confirmed that the mean and median values are in compliance 
with the requirements of Sec. 191.15 and Subpart C of Part 191.
    The PAVT computed thirteen simulations with non-negligible 
concentrations of radionuclides in ground water, compared with nine in 
the CCA CA. All of these thirteen simulations computed doses of less 
than 1 mrem/year, compared to the standard of 15 mrem/year for 
individuals. PAVT calculations also demonstrated that the doses to 
internal organs and from beta particle and photon radiation in ground 
water were several orders of magnitude less than the standard. Thus, 
PAVT results indicated that the mean and median dose values and ground-
water concentrations will meet the requirements of Sec. 191.15 and 
Subpart C of Part 191.

[[Page 58835]]

    Based on the CCA, supplementary documentation provided by DOE, and 
the Agency's independent studies, EPA has determined that there is at 
least a 95 percent level of statistical confidence that the mean and 
the median of the range of estimated radiation doses and the range of 
estimated radionuclide concentrations meet the requirements of 
Sec. 191.15 and Subpart C of 40 CFR Part 191. Therefore, EPA proposes 
to find that DOE has demonstrated compliance with Sec. 194.55(f). For 
further information on EPA's evaluation of compliance for Sec. 194.55, 
see CARD 55.

XIV. Land Withdrawal Act Section 4(b)(5)(B) Leases

    The 1992 WIPP Land Withdrawal Act (``LWA'') (Public Law 102-579) 
withdrew the geographical area containing the WIPP facility from all 
forms of entry, appropriation, and disposal under public land laws. The 
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. Further, the LWA established 
responsibilities for DOE to manage the land withdrawal area and 
required submittal of a management plan for that purpose. Under DOE's 
management plan, all surface or subsurface mining or oil or gas 
production is prohibited at all times on lands on or under the 
withdrawal area. (LWA, section 4(b)(5)(A)) However, the LWA exempted, 
from the prohibition on oil and gas production, two leases already in 
existence. Section 4(b)(5)(B) states that the existing rights under the 
two oil and gas leases (Nos. NMNM 02953 and 02953C) (hereafter, ``the 
section 4(b)(5)(B) leases'') shall not be affected unless the 
Administrator determines, after consultation with DOE and the 
Department of Interior, that the acquisition of such leases by DOE is 
required to comply with EPA's final disposal regulations at 40 CFR Part 
191, Subparts B and C. Before DOE can emplace waste in the WIPP, DOE 
must either acquire the leases or the EPA must determine that such 
acquisition is not required. (LWA, section 7(b)(2))
    In 1977, DOE purchased the leases in the land withdrawal area 
between the surface and 6,000 feet (1829 meters) below the surface. 
Since DOE owns all land rights down to 6,000 feet, no drilling is 
permitted from the surface of the LWA leases. Any drilling that takes 
place on the LWA section 4(b)(5)(B) leases must therefore be slant 
drilling that is initiated from outside the land withdrawal area. Oil 
and gas resources in the southwest area of the site, where the section 
4(b)(5)(B) leases are located, are expected to occur below 6000 feet 
down to approximately 16,000 feet.
    The EPA's determination of whether the section 4(b)(5)(B) leases 
must be acquired by DOE depends on an evaluation of drilling activities 
very similar to that conducted by DOE for performance assessment 
(``PA'') related to the containment requirements at 40 CFR 191.13. In 
fact, Sec. 194.32(c) of the WIPP Compliance Criteria requires DOE to 
analyze the effects of any activities that occur in the vicinity of the 
disposal system prior to or soon after disposal, including the 
``development of any existing leases.'' Therefore, in its examination 
of the effects of the section 4(b)(5)(B) leases, EPA relied on the 
closely related PA analyses conducted by DOE for the purpose of 
compliance with Sec. 194.32(c).
    For an oil or gas well, the potential life cycle may consist of: 
drilling; resource recovery (production); fluid injection for enhanced 
secondary production (either by waterflooding techniques or injection 
to maintain oil reservoir pressure); reinjection of waste fluids for 
disposal; and abandonment. In the PA for the compliance certification 
application (``CCA''), DOE conducted several analyses to identify the 
potential effects of these activities on the disposal system, with the 
exception of production, which is exempted from consideration by 
regulation (Sec. 194.33(d)). EPA examined each of DOE's analyses in its 
evaluation for the section 4(b)(5)(B) leases.
    In its analyses for the PA, DOE concluded that the drilling of a 
deep well would adversely affect the disposal system only if the 
borehole intersected a waste panel in the underground portion of the 
WIPP. Drilling is of concern if the borehole penetrates the waste, and 
forces it to the surface, or allows a pathway for long-term transport 
of radionuclides. EPA agrees that the effects of drilling a borehole--
and similarly, the effects of resource recovery (oil or gas 
production)--would be highly localized, for several reasons. Current 
oil and gas production drilling in the area near the WIPP site includes 
well casing procedures and borehole plugging practices that would 
mitigate the potential impact of future drilling activities. Wells 
drilled in the Delaware Basin (which encompasses the entire land 
withdrawal area) include at least two sets of steel casing lining the 
borehole (deeper wells use three sets of steel casing). Also, 
production and injection wells contain an additional set of tubing used 
to produce the oil or gas, or to inject fluid into the well. Present 
day practice would require multiple failures in these steel casings and 
tubings to cause any flow from the oil-or gas-producing zone towards 
the disposal system.
    Borehole plugging practices near the WIPP site also employ multiple 
levels of protection that mitigate the potential impact of oil and gas 
operations in the immediate area. The State of New Mexico regulates 
borehole plugging practices with a robust series of requirements that 
control the flow of fluid in the subsurface (New Mexico Oil 
Conservation Division, Order R-III-P). The use of these measures reduce 
the chance of any fluid flow toward or into the repository using 
current methods and technology.
    Fluid injection for brine disposal, waterflood, or pressure 
maintenance could affect the disposal system if the injected brine were 
to reach the waste area by way of migration through Salado anhydrites 
(calcium sulfate rock) (markerbeds 138 or 139). DOE analyzed this 
scenario in two different modeling studies (Docket A-93-02, Item II-G-
1, Reference #611, and Item II-I-36) as well as in a study that 
identified well construction and operating practices in the vicinity of 
WIPP. The results of the modeling studies showed that little or no 
brine would be expected to reach the WIPP waste area through the 
anhydrite interbeds. The amount of brine that is modeled to reach the 
repository in the initial study (Docket A-93-02, Item II-G-1, Reference 
#611) is within the amount that is already accounted for in PA, and 
does not cause the WIPP to violate the disposal regulations.
    An examination of current practice for fluid injection techniques 
confirms that the effects of fluid injection can also be expected to be 
highly localized. All injection operations in the vicinity of the WIPP 
site are controlled by the underground injection control requirements 
of the EPA. (40 CFR Parts 144 and 146) The requirements limit the flow 
rates of injection fluids and the maximum pressures that can be used in 
all injection wells. In addition, the injection well operator is 
required to evaluate the area of influence of any injection well before 
injection operations can be approved, and the State of New Mexico 
monitors the performance of injection operations periodically by 
requiring stringent reporting procedures.
    Regarding abandonment, DOE indicated (Appendix SCR.3.3.1.4.2 of the 
CCA) that abandoned deep boreholes that do not intersect waste panels 
have been eliminated from the PA calculations on the basis of low 
consequence to the performance of the disposal system. This is because 
the rate of fluid flow through a borehole located

[[Page 58836]]

more than a meter away from the waste panels is so small that it would 
have an insignificant impact on releases.
    EPA's review of DOE's modeling studies and analyses of well 
construction and operating practices found that the parameterization 
(e.g., injection rate and volumes) and model representation (e.g., 
incorporation of stratigraphy) used in DOE's modeling are consistent 
with those characteristics identified independently by EPA for the 
region in the southwest part of the land withdrawal area (the location 
of the section 4(b)(5)(B) leases). (Docket A-93-02, Item III-B-27) 
DOE's analysis of drilling for the PA indicated that deep wells drilled 
into the controlled area, but away from the waste disposal rooms 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 (and in turn, on compliance 
with the disposal regulations). Based on EPA's findings that DOE 
adequately modeled human intrusion scenarios in PA, and on the 
additional analyses described above, EPA concludes that potential 
activities at the section 4(b)(5)(B) leases do not cause the WIPP to 
violate the disposal regulations. 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.

XV. Administrative Requirements

A. Executive Order 12866

    Under Executive Order 12866, (58 FR 51,735; 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 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 will be 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 proposed rule would 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 
Unfunded Mandates Reform Act of 1995 (UMRA) (Pub. L. 104-4), 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 
specifically set forth by the Congress in the Waste Isolation Pilot 
Plant Land Withdrawal Act (Pub. L. 102-579).

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 and minority communities. EPA has complied with this 
mandate. 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 assist 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. 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. 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. EPA also developed a vast mailing list, which includes many 
low-income and minority groups, to systematically provide interested 
parties with copies of EPA's public information documents and other 
materials. EPA will continue its efforts toward open communication and 
outreach during the development of the final rule.

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: October 23, 1997.
Carol M. Browner,
Administrator.
    For the reasons set out in the preamble, 40 CFR Part 194 is 
proposed to be amended as follows.

[[Page 58837]]

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: The Waste Isolation Pilot Plant Land Withdrawal Act 
of 1992, Pub. L. 102-579, 106 Stat. 4777, as amended by the 1996 LWA 
Amendments, Pub. L. 104-201; Reorganization Plan No. 3 of 1970, 5 
U.S.C. app. 1; Atomic Energy Act of 1954, as amended, and Nuclear 
Waste Policy Act of 1982, 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. 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 Seal 
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 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 Item II-G-1) 
instead of fresh water concrete.
    Condition 2: Sec. 194.22, Quality Assurance. (a) 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.
    (b) Upon submission by DOE of site-specific quality assurance 
program plans, EPA will evaluate the relevant quality assurance program 
at the relevant waste generator site by conducting a quality assurance 
audit or an inspection of a DOE quality assurance audit. EPA will 
publish a notice in the Federal Register announcing its intent to 
evaluate the relevant quality assurance program, and soliciting public 
comment on the quality assurance program plans and appropriate audit 
documentation. A public comment period of at least 30 days will be 
allowed.
    (c) EPA's written approval that the requisite quality assurance 
requirements have been met at a waste generator site will be conveyed 
in a letter from the Administrator's authorized representative to the 
Department. No such approval shall be granted until after the end of 
the public comment period described in paragraph (b) of this condition. 
A copy of EPA's approval letter will be placed in the public dockets in 
accordance with Sec. 194.67. The results of any audits or inspections 
conducted by the Agency to evaluate the quality assurance programs 
described in paragraph (a) of this condition will also be placed in the 
dockets described in Sec. 194.67.
    (d) EPA will conduct inspections, in accordance with Secs. 194.21 
and 194.22(e), to confirm the continued compliance of the programs 
approved under paragraphs (2)(b) and (c) of this condition. The results 
of such inspections will be made available to the public through the 
Agency's public dockets, as described in Sec. 194.67.
    Condition 3: Sec. 194.24, Waste Characterization. (a) The Secretary 
may allow shipment for disposal at the WIPP of retrievably stored 
(legacy) debris waste streams, at the Los Alamos National Laboratory 
(``LANL''), that can be characterized using the systems and processes 
documented in Docket A-93-02, Item II-I-70. The Secretary shall not 
allow shipment of any waste from any other LANL waste streams or from 
any other waste generator site for disposal at the WIPP until the 
Agency determines that the site has:
    (1) provided information on how process knowledge will be used for 
waste characterization of the waste stream(s) proposed for disposal at 
the WIPP,
    (2) 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 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.
    (b) The Agency will conduct an audit or an inspection of a DOE 
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 audit or inspection in the Federal Register. In 
that notice, the Agency will also solicit public comment on all 
appropriate audit 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.
    (c) EPA's written approval of the waste characterization programs 
described in paragraph (a) of this condition 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 approval shall be granted until after the end of the public 
comment period described in paragraph (b) of this condition. A copy of 
EPA's approval 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 
(a)(1) and (2) of this condition will also be placed in the dockets 
described in Sec. 194.67.
    (d) The Administrator's authorized representative(s) will conduct 
inspections, in accordance with Secs. 194.21 and 194.24(h), to confirm 
the continued compliance of the plans approved under paragraphs (b) and 
(c) of this condition. The results of such inspections will be made 
available to

[[Page 58838]]

the public through the Agency's public dockets, as described in 
Sec. 194.67.
    Condition 4: Sec. 194.43, Passive Institutional Controls. (a) Not 
later than the final re-certification 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 a 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 DOE 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, EPA will place such documentation in the public dockets 
identified in Sec. 194.67. The Agency will determine if a modification 
to the 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. 97-28647 Filed 10-29-97; 8:45 am]
BILLING CODE 6560-50-P