Robert H. Neill and Lokesh Chaturvedi
Environmental Evaluation Group
7007 Wyoming Boulevard N.E., Suite F-2
Albuquerque, NM 87109
Tel: (505)-828-1003
Fax: (505)-828-1062
E-mail: lchatur@eeg.org

The Environmental Evaluation Group (EEG) has provided independent scientific oversight of the WIPP project since 1978, and has had a major influence in shaping the project to ensure that the public health and safety of the people of New Mexico is not jeopardized and the environment is not adversely affected. The effect of the EEG's work can be seen, for example, in (1) vastly improved geological and hydrological data base and modeling; (2) relocation of the repository to a more suitable area with respect to long-term integrity; (3) safer operational design and procedures; (4) abandonment of the plans to conduct in situ experiments with waste at WIPP; (5) continuation of performance assessment work after the disposal standards were vacated by the court in 1986, thus not losing time when the standards were re-promulgated in 1993; and (6) a much safer and more cost-effective redesigned transport container (TRUPACT-II), certified by the Nuclear Regulatory Commission, for shipment of contact-handled transuranic (CH-TRU) waste.

The Waste Isolation Pilot Plant (WIPP) is a planned geologic repository for disposal of transuranic (TRU) waste, generated from the production of nuclear weapons in the USA during the past 50 years. The U.S. Department of Energy (DOE) has inherited management of this waste as part of the U.S. defense nuclear complex. Before 1970, such waste was stored in 55 gallon drums and boxes, and buried under a few meter of dirt at several national laboratories. These drums and boxes have been corroded and breached, and the task of removing that waste and cleaning up the ground is a daunting one indeed. It is planned to ship only the post-1970 TRU waste to WIPP, that has been stored in above-ground tension-support structures at the national laboratories. The TRU waste inventory currently in storage at the DOE sites totals about 100,000 cubic meters, or the rough equivalent of half a million 55-gallon drums (1). The WIPP has been designed to contain up to 176,000 cubic meters (approximately 850,000 drum-equivalent) of contact-handled (CH-TRU), and up to 7100 cubic meters (7500 canisters) of remote-handled (RH-TRU) waste. The CH-TRU waste may have a maximum surface-dose rate of 200 millirem per hour. Ninety-five percent of the RH-TRU canisters disposed at WIPP may have a surface dose-rate of up to 100 rem per hour, and five percent by volume may have up to 1000 rem per hour. The TRU waste generated in the future will come from dismantling and cleanup of the nuclear weapons complex and will therefore be different than the existing waste.

The WIPP repository is located in the salt beds of the Permian age Salado Formation, at a depth of 655 meters below the surface in Southeastern New Mexico, 40 kilometers (km) east of Carlsbad, NM. Details of the geologic characteristics of the site and the geologic issues affecting long-term containment are discussed in Chaturvedi, 1993 (2). The 600 meters (m) thick Salado Formation is underlain by the approximately 470 m thick Castile Formation that consists of alternating layers of anhydrite and halite (Fig.1).

Pressurized brine reservoirs have been encountered in the upper anhydrite member of the Castile Formation by a number of oil and gas wells, as well as by two WIPP exploratory wells. Overlying the Salado Formation is the Rustler Formation that contains two confined aquifers of fractured dolomite. The Rustler Formation varies in thickness from 84 m to 130 m in the northern Delaware Basin and is approximately 95 m thick at the center of the WIPP site. The Culebra and the Magenta fractured dolomite aquifers in the Rustler are each approximately 7.5 m thick. The Culebra, having higher transmissivity of the two, is considered a potential pathway for the release of radionuclides to the environment in case of a breach.

Excavation of the WIPP repository began in 1982 and all the surface facilities, four shafts, and all the basic underground facilities, including 1/8 of the repository "rooms", had been excavated by 1988, the year when the DOE had planned to start placing waste in the repository for "experiments" and "operational demonstration". After many years of attempting to do so, the DOE abandoned this plan in 1993 because there was insufficient justification for conducting the in situ experiments with waste and it would have been difficult to ensure retrieval of the waste after several years of emplacement.

The decision to use the WIPP repository for permanent disposal of TRU waste will be made, in a large part, on demonstration of the facility's compliance with the long-term disposal standards promulgated by the Environmental Protection Agency (EPA) (3). These standards require a probabilistic assessment of the integrity of the repository for 10,000 years into the future. Such an assessment requires a detailed knowledge of the geological and hydrological characteristics of the site, physical and chemical characteristics of the waste, formulation of scenarios for breach of the repository and release of radionuclides to the environment, calculation of the probabilities and the amounts of release during the future 10,000 years, and comparison with the releases allowed by the standards. The DOE completed its performance assessment of WIPP in October 1996 and submitted an application for the EPA certification of the WIPP's compliance with the EPA standards (4). The EPA issued a draft rule in October 1997 proposing to certify that the WIPP meets the EPA standards, and opening a four month public comment period for the draft rule. After considering the comments from the public and the government agencies, the EPA plans to issue a final determination on the DOE application in May, 1998.

The Environmental Evaluation Group (EEG) was established by the State of New Mexico in 1978 as an independent scientific group to conduct scientific evaluation of all aspects of the WIPP project. In addition to the reviews of long-term and operational period safety, EEG has conducted environmental monitoring of air, water and soil at the WIPP site and in the surrounding communities since 1984 to establish a pre-operational environmental baseline against which future suspected contamination episodes may be evaluated. This multi-disciplinary group, with offices in Albuquerque and Carlsbad, is funded with federal money through the DOE. The EEG has had a major influence in shaping the project to ensure that the public health and safety of the people of New Mexico is not jeopardized and the environment is not adversely affected. The effect of the EEG's work can be seen, for example, in (1) vastly improved geological and hydrological data base and modeling; (2) relocation of the repository to a more suitable area with respect to long-term integrity; (3) safer operational design and procedures; (4) abandonment of the plans to conduct "in situ" experiments with waste at WIPP; (5) continuation of performance assessment work after the disposal standards were vacated by the court in 1986, thus not losing time when the standards were re-promulgated in 1993; and (6) a much safer and more cost-effective redesigned transport container (TRUPACT-II) for the CH-TRU waste shipment certified by the Nuclear Regulatory Commission. These examples of the EEG's accomplishments are described below.

The DOE had declared the WIPP site to have been adequately characterized in 1981 on the basis of the Geological Characterization Report (5) and the Environmental Impact Statement (6). The EEG recommended additional field and laboratory studies to resolve several geohydrological questions based on the consensus reached at a scientific conference organized by the EEG in 1980 (7) and a 3 day field conference at the site in June 1980 (8). These recommendations were included in a stipulated agreement between the DOE and the State of New Mexico signed in 1981 as part of the settlement of a lawsuit filed by the State Attorney General. The DOE presented the results of these studies to the EEG during 1982 and 1983 (9). The EEG published its evaluation of the suitability of the WIPP site in 1983 (10) and expressed confidence in the site but also concluded that additional work was needed to improve confidence and for assessing compliance with the long-term standards that were in the process of being developed by EPA at that time. These additional recommendations related to (a) identifying the extent of the underground brine reservoir in the Castile Formation that had been encountered by the borehole WIPP-12 (shown as W12 on Figure 2), one a half km north of the center of WIPP and because of which the location of the repository had been moved 2 km to the south, (b) to address and try to resolve controversial geological issues such as deep dissolution in the Salado Formation, and (c) to better define the hydrological characteristics of the Rustler Formation with its two confined aquifers. Details of how these issues were resolved by the EEG efforts are described in Chaturvedi, 1993 (2). The net result of these efforts is that, although some questions still remain, the assessment of the WIPP's compliance with the EPA standards is on a much sounder footing.

The WIPP repository has been relocated twice. Following the abandonment of the Lyons, Kansas site in 1972, a 3.2 km by 2.4 km (2 mile by 1.5 mile) site was selected by the Oak Ridge National Laboratory on behalf of the then Atomic Energy Commission, 11 km northeast of the present 6.4 km by 6.4 km (4 mile by 4 mile) WIPP site. Cores from two boreholes (AEC-7 and AEC-8, Fig. 2) penetrating through the Salado Formation drilled at the northeast and the southwest corners of that site indicated acceptable geology. Sandia National Laboratories (SNL) was given the responsibility for site characterization of WIPP in 1975. A third borehole (ERDA-6; see Fig.2) drilled by SNL at that site in 1975 encountered a pressurized brine reservoir and intense structural disturbance in the fractured upper anhydrite of the Castile Formation at a depth of 826 m (2709 ft). As a result, the location of the repository was moved to the present site.

The original configuration called for the repository to be in the northern part of the site and the experimental area (for rock mechanics and container integrity experiments) to be south of the center of the site. In 1981, the EEG recommended deepening the borehole WIPP-12 to explore the structure in the upper Castile Formation. WIPP-12 had been drilled to the bottom of the Salado Formation in 1978. The borehole was deepened from its 834.5 m depth to a total depth of 1197.4 m in November- December 1981. Pressurized brine associated with hydrogen sulfide gas was encountered at 919.5 m depth. The location of the repository was shifted again, this time at the recommendation of the EEG, from its location near WIPP-12 to a location 2 km south. The repository design was rotated so that the experimental area is now located north of the center and the repository to the south. The EEG considers this to be an accomplishment because, even though the brine reservoir appears to extend under the present repository, the area to the south is less geologically disturbed.

While EPA has been assigned the responsibility to regulate off-site radiation exposure to the general public from operations at WIPP, the DOE has the responsibility and the authority to regulate on-site worker radiation exposure. EEG is the only full-time oversight organization providing reviews of operational design and procedures to the DOE. To that end, in 1984, the EEG evaluated the radiation shielding in the hot cell facility for RH-TRU waste, which can have a maximum dose rate of 1,000 R/hour (11), analyzed the classification of system, structures and components in 1985 (12), assessed the continuous air monitoring equipment for radiation detection in 1988 (13), and the impact of salt buildup on the filters in 1996 (14). The benefits and risks of conducting experiments with CH-TRU waste in WIPP were evaluated in 1989 (15). The hoist system to lower the waste 655 m for emplacement underground is a critical link in accident analyses and EEG has published four reports in this area beginning in 1990 (16,17,18 and 19). As a result of the EEG review and recommendations, the DOE has modified the valves used in the system, changed the design and increased annual inspections to a daily frequency.

The stability of the underground excavation was addressed in 1996 (20) since the Panel 1 room may be open 13 years or longer from excavation to the completion of waste emplacement. Supplementary roof support system have been emplaced in the ceilings of these room to enhance stability. The EEG plans to continue to monitor the safety of all operations at WIPP. Only the EEG provides detailed reviews of the DOE's Safety Analysis Report for WIPP. The EEG has actively participated in the Operational Readiness Review exercises in the past and plans to do so in another such exercise planned in 1998.

From 1982 to 1993, the DOE planned to emplace some TRU waste at WIPP before assessing its suitability to be a permanent geologic repository. Both the amount and the purpose of the planned waste emplacement varied over the years. The purpose varied from "research and development" to "operational demonstration" or both. The amount changed from 200,000 CH-TRU drum in 1982 (21) to 100 drum in 1993 (22).

The 1992 land-withdrawal act for WIPP (P.L. 102-579) required the DOE to demonstrate the data from experiments with CH-TRU waste at WIPP would be directly relevant to demonstrating compliance with the EPA standards for radioactive waste (40 CFR 191) and the Solid Waste Disposal Act (42 U.S.C. 6901 et seq.). After submitting two drafts of a test phase plan to the EPA in early 1993, the DOE found itself supporting the following contradictory positions:

• Defending underground bin tests while stating in the Supplementary Environmental Analysis Report that they can be performed elsewhere;
• Undertaking an elaborate and expensive waste characterization and bin preparation program while admitting that the waste used for these tests will not be representative of the total WIPP inventory;
• Having designed an elaborate and expensive seal for the alcoves that may be rendered ineffective by rock fracturing soon after installation;
• Planning to rely on the alcove test results for compliance with the RCRA regulations when the VOC concentrations in the alcoves may be below detection and also far below the EPA allowable limits;
• Having installed an elaborate and expensive supplementary roof support system in Room 1 of Panel 1, designed to keep the roof stable through 1998, although this time period is not long enough to assemble characterized waste, conduct a 5 to 7 year test and retrieve the waste safely;
• Committing monetary and time resources for the tests with waste while not identifying through the performance assessment process, the need to refine the gas generation rates and species.

After urging by the EEG and other reviewers, DOE decided in October 1993 to abandon the concept of the "test phase" for WIPP. This was a major and a very significant milestone for the WIPP project. For the first time since the project's inception, the DOE planned to demonstrate compliance with all applicable regulations before shipping waste to WIPP. This has resulted in the completion of the CCA(4) and other documents.

The EPA promulgated the standards for 10,000 year performance of nuclear waste repositories, 40 CFR 191, originally in 1985 (3). Those standards were vacated by a court order in 1987 following a legal challenge concerning the lack of sufficient public comment opportunities, and inconsistency with the Safe Drinking Water Standards. Immediately after the court order, at the urging of the EEG, the State of New Mexico entered into an agreement with the DOE that the DOE would "continue its performance assessment planning as though the provisions of 40 CFR 191 effective November 19, 1985 remain applicable." (23). This foresight on the part of the EEG and the DOE allowed the DOE to be prepared with preliminary performance assessment and focused gathering of additional data needed for performance assessment, when the EPA re-promulgated 40 CFR 191 in 1993 (3).

The EEG calculated hypothetical doses from transportation accidents and documented the importance of decontamination of actinides following such a release, in 1980 (24).

Problems in transporting high curie Pu-238 CH-TRU waste from the Savannah River Project, due to the expected generation of flammable hydrogen from radiolysis of organics, were identified by the EEG in 1983 (25). The issue has not yet been addressed by the DOE, although NRC certification requires that the hydrogen gas concentration be less than 5% for 60 days during transportation.

The failure of the rectangular TRUPACT to meet both NRC and DOE requirements for double containment of shipments containing more than 200 curies of plutonium as well as pressurization problem with a sealed shipping container were documented in 1986 (26). After maintaining for several years that double containment would reduce the payload, increase the number of shipments, increase traffic fatalities and increase the cost, DOE eventually abandoned the rectangular design in favor of a right circular cylinder. The new design accommodates 42 drums per shipment vs. 36, is less expensive to manufacture and maintain, and fewer shipments are required.

A risk analysis of the EPA point source dose model (RADTRAN) was published in 1990 (27), which showed the normal doses from transportation were low.

DOE submitted a design for a cask to transport RH-TRU waste from NRC certification at the beginning of 1997. Certification of the shipping container by NRC has not been completed. Although the RH-TRU comprises only 5% by volume of the TRU waste, it contains 30% of the initial radioactivity and 25% of the total $19 billion cost. The plan is to place RH-TRU waste canisters in 1 meter diameter horizontal holes in the walls of the underground rooms and drifts, prior to stacking the CH-TRU waste drums. Thus, the longer it takes to start shipping the RH-TRU waste to WIPP, after stacking of the CH-TRU waste begins, the less space will be available for the RH-TRU.

EEG has conducted a radiological environmental monitoring program at and near the WIPP facility since 1985. Results have been published in seven environmental data reports (28, 29,30, 31, 32, 33, and 34). EEG expects to continue monitoring the environmental impact of WIPP operations through the disposal phase.

A capability for analytical radiochemistry was developed in EEG's Carlsbad office in 1993. In 1996 EEG co-founded a new laboratory quality assurance program, the National Institute of Standards and Technology (NIST) Radiochemistry Intercomparison Program (NRIP), to certify traceability of measurements to national standards, maintained at NIST. EEG received certification of its measurements of plutonium and americium in water in June 1997 and the air filters in August 1997.

EEG has also conducted extensive analyses of WIPP effluent air monitoring system using spectral data and computational models. The EEG investigations were published in EEG-37 (34), EEG-38 (13), EEG-52 (35) and EEG-60 (14). EEG staff presented AAn Evaluation of the Adequacy of Effluent Air Monitoring System at the Waste Isolation Pilot Plant@ at the Health Physics Society annual meeting in 1993. EEG staff presented AMeasurement of Transuranic Radionuclides in a Salt Matrix by L X-ray Spectrometry at the Health Physics Society's annual meeting in 1992 and AThe Influence of Salt Aerosol on Alpha Radiation Detection by WIPP Continuous Air Monitors.@ An article was published in Health Physics AIssues in Establishing a Radiological Baseline for the Waste Isolation Pilot Plant@ (Health Physics, February 1997, Volume 72, Number 2).

Following these studies, the original L X-Ray type continuous air monitors (CAM) were replaced by alpha CAM, filter collection heads were redesigned, the pitot tube array used for effluent air sampling was replaced with the shrouded probe sampling device, and the air flow turbulators and air flow straighteners were removed from the exhaust duct. The CAM which cause automatic shift to High Efficiency Particulate Air (HEPA) filtration were recently relocated from Station A at the top of the exhaust shaft to the exhaust air duct in the room with active emplacement operations.

During the 20 years of its existence, the EEG has succeeded in helping to improve the safety at WIPP, and the EEG efforts have resulted in providing a sounder basis for making decisions concerning the long-term integrity of the repository.

1. U.S. DEPARTMENT OF ENERGY, OFFICE OF ENVIRONMENTAL MANAGEMENT, "Closing the Circle on the Splitting of the Atom", DOE/EM-0266, 106 p. (1995).
2. L. CHATURVEDI, "WIPP Related Geologic Issues", New Mexico Geological Society Guidebook, 44th Field Conference, Carlsbad Region, New Mexico and Texas (1993).
3. U.S. ENVIRONMENTAL PROTECTION AGENCY, "Environmental Radiation Protection Standards for Management and Disposal of Spent Nuclear Fuel, High-Level and Transuranic Radioactive Wastes", 40 Code of Federal Regulations Part 191 (1993).
4. U.S. DEPARTMENT OF ENERGY, "Title 40 CFR Part 191 Compliance Certification Application for the Waste Isolation Pilot Plant, October 1996", DOE/CAO-1996-2184 (21 Vols.), U.S. Department of Energy (1996).
5. D. POWERS, S.J. LAMBERT, S.E. SHAFFER, L.R. HILL, W.D. WEART, "Geological Characterization Report, Waste Isolation Pilot Plant Site, Southeastern New Mexico", Sandia National Laboratories Report, SAND78-1596, 2 Vols. (1978).
6. U.S. DEPARTMENT OF ENERGY, "Final Environmental Impact Statement, Waste Isolation Pilot Plant", DOE/EIS-0026, 2 Vols. (October 1980).
7. ENVIRONMENTAL EVALUATION GROUP, "Geotechnical Considerations for Radiological Hazard Assessment of WIPP: A Report of a Meeting Held on January 17-18, 1980", EEG Report #EEG-6 (1980).
8. L. CHATURVEDI, "WIPP Site and Vicinity Geological Field Trip: A Report of a Field Trip to the Proposed Waste Isolation Pilot Plant Project in Southeastern New Mexico, June 16 to 18, 1980", EEG Report # EEG-7 (1980).
9. ENVIRONMENTAL EVALUATION GROUP, "EEG Review Comments on the Geotechnical Reports Provided by DOE to EEG Under the Stipulated Agreement Through March 1, 1983", EEG Report #EEG-22 (1983).
10. R.H. NEILL, J.K. CHANNELL, L. CHATURVEDI, M.S. LITTLE, K. REHFELDT, P. SPIEGLER, "Evaluation of the Suitability of the WIPP Site", EEG Report #EEG-23 (1983).
11. KNOWLES, H. B., "Radiation Shielding in the Hot Cell Facility at the Waste Isolation Pilot Plant: A Review", EEG Report #EEG-28 (1984).
12. F. DOUGHERTY, Tenera Corporation, "Evaluation of the Waste Isolation Pilot Plant Classification of System, Structures and Components", EEG Report #EEG-30 (1985).
13. J.C. RODGERS and J.W. KENNEY, "A Critical Assessment of Continuous Air Monitoring System at the Waste Isolation Pilot Plant", EEG Report #EEG-38 (1988).
14. W. T. BARTLETT and B.A. WALKER, "The Influence of Salt Aerosol on Alpha Radiation Detection by WIPP Continuous Air Monitors", EEG Report #EEG-60 (1996).
15. L. CHATURVEDI, "Evaluation of the DOE Plans for Radioactive Experiments and Operational Demonstration at WIPP", EEG Report #EEG-42 (1989).
16. M. A. GREENFIELD, "Probabilities of a Catastrophic Waste Hoist Accident at the Waste Isolation Pilot Plant", EEG Report #EEG-44 (1990).
17. M. A. GREENFIELD and T.J. SARGENT, "A Probabilistic Analysis of a Catastrophic Transuranic Waste Hoist Accident at the WIPP", EEG Report #EEG-53 (1993).
18. M. A. GREENFIELD and T.J. SARGENT, "An Analysis of the Annual Probability of Failure of the Waste Hoist Brake System at the Waste Isolation Pilot Plant (WIPP)", EEG Report #EEG-59 (1995).
19. M.A. GREENFIELD and T. J. SARGENT, "An Analysis of the Annual Probability of Failure of the Waste Hoist Brake System at the Waste Isolation Pilot Plant WIPP", EEG Report #EEG-65 (1998).
20. H. MALEKI and L. CHATURVEDI, "Stability Evaluation of the E140 Drift and Panel 1 Room at WIPP", EEG Report #EEG-63 (1996).
21. R.V. MATALUCCI, C.L. CHRISTENSEN, T.O. HUNTER, M.A. MOLECKE, and D.E. MUNSON, "Waste Isolation Pilot Plant (WIPP) Research and Development Program: In Situ Testing Plan," SAND81-2628, Sandia National Laboratories (March 1982).
22. U.S. DEPARTMENT OF ENERGY, "Test Phase Plan for the Waste Isolation Pilot Plant," DOE/WIPP/89-011 Revision 1, U.S. Department of Energy (March 1993).
23. STATE OF NEW MEXICO AND U.S. DEPARTMENT OF ENERGY, "Second Modification to the July 1, 1981 Agreement for Consultation and Cooperation on WIPP by the State of New Mexico and U.S. department of Energy", Signed by the Governor of New Mexico and the DOE Manager of Albuquerque Operations Office, August 4, 1987 (1987).
24. J.K. CHANNELL, "Calculated Radiation Doses From Deposition of Material Released in Hypothetical Transportation Accidents Involving WIPP-Related Radioactive Wastes", EEG Report #EEG-5 (1980).
25. R. H. NEILL and J. K. CHANNELL, "Potential Problems From Shipment of High-Curie Content Contact-Handled Transuranic (CH-TRU) Waste to WIPP", EEG Report #EEG-24 (1983).
26. J.K. CHANNELL, J.C. RODGERS and R.H. NEILL, "Adequacy of TRUPACT-I Design for Transporting Contact-Handled Transuranic Wastes to WIPP", EEG Report #EEG-33 (1986).
27. GALLEGOS and J.K. CHANNELL, "Risk Analysis of the Transport of Contact Handled Transuranic (CH-TRU) Wastes to WIPP Along Selected Highway Routes in New Mexico Using RADTRAN IV", EEG Report #EEG-46 (1990).
28. P. SPIEGLER, "Environmental Evaluation Group's Environmental Monitoring Program for WIPP", EEG Report #26 (1984)
29. J.W. KENNEY, J.C. RODGERS, J.B. CHAPMAN, and K.J. SHENK, "Preoperational Radiation Surveillance of the WIPP Project by EEG, 1985-1988", EEG Report #EEG-43 (1990).
30. J.W. KENNEY, and S.C. BALLARD, "Preoperational Radiation Surveillance of the WIPP Project by EEG During 1989", EEG Report #EEG-47 (1990).
31. J.W. KENNEY, "Preoperational Radiation Surveillance of the WIPP Project by EEG During 1990", EEG Report #EEG-49 (1991).
32. J.W. KENNEY, "Preoperational Radiation Surveillance of the WIPP Project by EEG During 1991", EEG Report #EEG-51 (1992).
33. J.W. KENNEY, "Preoperational Radiation Surveillance of the WIPP Project by EEG During 1992", EEG Report #EEG-54 (1994).
34. J.W. KENNEY, P.S. DOWNES, D.H. GRAY, and S.C. BALLARD, "Radionuclide Baseline in Soil Near Project Gnome and the Waste Isolation Pilot Plant", EEG Report #EEG-58 (1995).
35. J.C. RODGERS, "Exhaust Stack Monitoring Issues at the Waste Isolation Pilot Plant", EEG Report #EEG-37 (1987).
36. W. T. BARTLETT, "An Evaluation of Air Effluent and Workplace Radioactivity Monitoring at the Waste Isolation Pilot Plant", EEG Report #EEG-52 (1993).

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