Panel Report

9.1 The JEB Mill

Following an extensive public review in 1993, [D.G. Lee, J.F. Archibald, J. Dantouze, R. Neal and A. Yassi, Dominique-Janine Extension, McClean Lake Project, and Midwest Joint Venture , Supply and Services Canada, October, 1993.] Cogema was given ministerial approval to construct a mill for refining ore from the JEB, Sue A, Sue B, Sue C and McClean Lake mines at the McClean Lake site about 20 km east of the Midwest mine. This approval contained a requirement to conduct research into methods that could be employed to reduce process chemicals and optimize contaminated water treatment, with the overall objective of reducing environmental loadings. As a consequence of this research, Cogema proposed changing from strong acid stripping to ammonium sulphate stripping. Test work showed that by use of this approach the volume of tailings produced could be reduced by 28 per cent, while holding ammonia concentrations in the effluent at an acceptable level.

The EIS submitted by Cogema [The Midwest Project Environmental Impact Statement, Main Document, Cogema Resources Inc., August, 1995, p. 3-15 to 3-22.] contains a description of the various processes that will occur in the mill: receiving solid mine ore, grinding, two-stage atmospheric leaching, counter current decantation, pregnant solution clarification, solvent extraction, stripping with ammonium sulphate, molybdenum removal, precipitation and calcination of ammonium diuranate to give U₃0₈ (yellowcake), packaging of the yellowcake, barren strip solution clarification, crystallization of ammonium sulphate, and neutralization of the tailings. This process produces two commercial products, yellowcake and ammonium sulphate.

In order to accommodate slurried Midwest ore, produced as described in Section 6.1, the mill design would require three main modifications: the building of a new facility to receive and unload ore slurry; the introduction of a nickel/cobalt recovery system, if economically justified; and the modification of the tailings preparation circuit to produce neutralized paste tailings.[Ibid, pp. 3-38 to 3-60.] The new receiving facility would be required because ore produced from the Midwest mine would be transported as a slurry, whereas the currently approved mill is equipped to receive only solid ore. The nickel/cobalt recovery system would be desirable because the Midwest ore contains substantial quantities of these metals, particularly nickel. Since nickel is a toxic heavy metal, it is important to recover some of it during the refining process; any not removed would be incorporated into the tailings, causing an increased environmental load. Paste tailings must be produced because Cogema proposes to use subaqueous disposal in the JEB pit. Highly radioactive tailings, such as those produced from the Midwest ore, can more safely be placed in the pit under a layer of water.

9.2 The Tailings Management Facility (TMF)

The greatest environmental risks associated with the Midwest project are related to the method selected for tailings disposal. Because of the large volume of tailings produced, it is not practical for mines to consider deep geological deposition, as recently proposed for high-level nuclear reactor wastes. [Environmental Impact Statement on the Concept for Disposal of Canada's Nuclear Fuel Waste, Atomic Energy of Canada Limited Report, C.O.G.-93-1, 1994.] It is of interest, therefore, to note a report which indicates that mill tailings are more toxic in the long term than are high-level wastes.[J.D. Bredehoeft, A.W. England, D.B. Stewart, N.J. Trask and I.J. Winograd, Geologic Disposal of High-Level Radioactive Wastes -- Earth-Science Perspectives: A summary of factors and processes that must be understood for the safe containment of high-level radioactive waste, Geological Survey Circular 779, 1978, p. 10.] For this reason, it is essential that the method proposed for tailings disposal be subjected to careful scrutiny before implementation is approved.

...the hazard from uranium mill tailings which although more than an order of magnitude more toxic than high level waste, have customarily been treated in a much more cursory fashion.

G. Edwards, Transcript of Supplementary Public Hearings for Midwest and Cigar Lake, La Ronge, Saskatchewan, August 28, 1997, p. 69.

Cogema proposes to use the mined-out JEB pit at McClean Lake for a disposal facility. Various configurations (engineered pervious surround, partial engineered pervious surround and natural surround) were considered for the conversion of this pit into a storage facility. After modelling the impacts associated with each configuration, both the proponents and the Atomic Energy Control Board have concluded that the natural surround would provide the best environmental protection.

Successful application of this technology requires that the tailings be produced and deposited in such a way that they consolidate over time to give a material that has a hydraulic conductivity at least ten times less than that of the surrounding host rock. The essential difference between this approach and the technology pioneered at the Rabbit Lake in-pit TMF is that it is the tailings, rather than the surround, which would be engineered to produce the required difference in hydraulic conductivity. Several potential advantages of this approach, as noted by the proponents, are described in the following paragraphs:

• Natural surround technology allows the tailings to be deposited under water. The ability to use subaqueous deposition is important for tailings produced from high grade ore because it provides for greater worker protection. As described in the EIS, [The Midwest Project Environmental Impact Statement, Main Document, Cogema Resources Inc., February, 1996, pp. 3-60 to 3 - 81.] deposition of the tailings under a few metres of water protects the people working around the pit from exposure to radiation. It is, therefore, proposed that the tailings would be laid down, using a tremie pipe, [See Figure 3.] under a cover of water that would be deep enough to absorb most of the radiation emanating from the deposit.
• Subaqueous deposition would also prevent the formation of ice in the tailings before they had consolidated.
• The approach proposed for the JEB pit would allow the tailings produced from the milling of the ore from several mines (JEB, McClean, Sue A, Sue B, Sue C, Midwest and Cigar Lake) to be deposited in a single pit, thereby decreasing the number of sites requiring long-term monitoring.
• The use of a natural surround would permit the maximum quantity of tailings to be placed in the pit; i.e., the amount of environmental disturbance associated with pit construction, per tonne of tailings stored, would be minimized.
• The use of natural surround technology would avoid the use of engineered barriers, such as dams or liners, which might fail in the long term.
• Eventual capping of the pit with several metres of rock and till would avoid the weathering problems that are likely to compromise aboveground storage facilities in the long term. Capping the pit would also protect wildlife and humans from direct exposure in the postdecommissioning era.
• Tailings deposited in a pit, below ground level, would be protected when glaciers from the next ice age scarify the landscape of northern Saskatchewan.

Despite these potential advantages, many concerns associated with the use of the proposed tailings management facility were raised during the hearings. Among these are the closeness of the JEB pit to Fox Lake (about 125 m) and the failure of the proponent to provide convincing evidence that the lake is not likely to become contaminated in the long term. Modelling studies indicate a good possibility that arsenic levels, for example, could eventually exceed both Saskatchewan Surface Water Quality Objectives (SSWQO) and Canadian Water Quality Guidelines (CWQG) in Fox Lake.

Part of the uncertainty relates to the predicted concentrations of arsenic in the porewater of aged tailings. Estimates for the arsenic source term ranged from as low as 1 mg/L or less, to as high as 100 mg/L or more. Company-employed consultants with distinguished credentials suggested theoretical ways of reducing porewater concentrations by creating conditions in the tailings pit that would result in the formation of secondary minerals.[D. Langmuir, Transcript of Supplementary Public Hearings for Midwest and Cigar Lake, La Ronge, Saskatchewan, August 26, 1997, p. 39-47.] On the other hand, an engineering firm reviewed published data and experimental results from existing tailings facilities which indicated that arsenic concentrations in the porewater, instead of decreasing with time, have actually increased at a rate of about 500 per cent per year. [R. Swider, The Cigar Lake and Midwest Projects Tailings Disposal, Richard C. Swider Consulting Engineers Limited, Toronto, Ontario, August 21, 1997, p. 23.] When the hearings closed on August 28, 1997, the issue of the value to be assigned to the arsenic source term remained unresolved.

Figure 3: JEB TMF - Subaqueous Tailings Disposal

It is clear, however, that the proponent should not be given a licence to use the JEB pit as a TMF until it can demonstrate that arsenic and other contaminants in the porewater can be maintained at levels sufficiently low to minimize the chance that Fox Lake would be polluted in the long term.

It is at this point that the regulatory process must take over from the panel process. We find the concept of in-pit tailings disposal using a natural surround to be acceptable, but we are not able to assess all of the required site-specific conditions. In fact, we believe that our involvement at that level would be inappropriate. We are, therefore, making a favourable recommendation with respect to the concept of using the JEB pit as a TMF, but wish to temper that recommendation by attaching the following list of site-specific conditions that must be dealt with satisfactorily before a licence is given:[As mentioned elsewhere in this report, we have confidence in the regulators' ability to undertake this task, provided they are given adequate resources to do so.]

• Before the JEB pit is approved for deposition of tailings from Midwest ore, the proponents should demonstrate, using actual experimental data from aged tailings, that porewater contaminant concentrations can be controlled at acceptable levels. Theoretical solutions should not be accepted in lieu of experimental data for these purposes. The chemistry of tailings depositories is so complex that theories can be used only as a rough guide for the design of processes.

Well, in fact, we did not carry out leaching tests because when you have to carry out some tests, you have to be very cautious, you know.

M. Roche, Cogema Resources Inc., Transcript of Supplementary Public Hearings for Midwest and Cigar Lake, La Ronge, Saskatchewan, August 28, 1997, p. 23.

• If approval is given subsequent to the completion of the specified research, the contents of the pit should be monitored carefully to determine if the concentration of contaminants in the porewater is increasing or decreasing over time. We suggest a detailed survey every five years to examine porewater chemistry and to check for the development of secondary minerals. If conditions can be found which promote formation of secondary minerals, as suggested during the hearings, the pit would gradually begin to resemble a thermodynamically stable geological deposit. On the other hand, if porewater contaminant concentrations are found to increase with time, as predicted by the data presented by Richard Swider, deposition should cease. Licence approvals should continue to be for a limited time only. Renewal of approvals should be conditional on the ability of the operator of the TMF to prepare tailings that do not result in highly contaminated porewater.
• Procedures for mitigating all potential unacceptable impacts should be identified before deposition begins.
• New Canadian Water Quality Guidelines with lower arsenic levels have recently been introduced. Modelling should acknowledge the adoption of these more stringent levels. For the purposes of Fox Lake contamination, these levels should be treated as requirements, not merely as targets that may or may not be achieved.

The panel should be aware that the CWQG for arsenic has recently been revised to 0.005 mg/L (10 times lower than the SSWQO).

B. Fallis, Department of Fisheries and Oceans, Transcript of Supplementary Public Hearings for Midwest and Cigar Lake, La Ronge, Saskatchewan, August 27, 1997, p. 87.

• Fox Lake should not be considered to be a mixing zone. The discharge from the pit should meet the more stringent of the SSWQO and CWQG, as it enters the lake. Use of the concentrations of contaminants that would be present upon complete dilution in the entire lake allows for the existence of small localized zones of highly polluted water that could endanger the health of wildlife and humans.
• The sediments in the bottom of Fox Lake should be monitored periodically to assess their condition and the need for any possible mitigative measures. Sediment monitoring methodologies were discussed in a previous panel report. [D.G. Lee, J. Archibald and R. Neal, McArthur River Uranium Mine Project, Minister of Public Works and Government Services, February, 1997, p. 35.]
• Control of contaminants during deposition will require the use of a well-functioning underdrain. However, one rock fall has already occurred in the area where the construction of the portal to this drain is proposed. A detailed geotechnical assessment should, therefore, be undertaken to ensure that the drain can be properly constructed and that it will function adequately for as long as it is required. This geotechnical review should utilize the most current geologic mapping, rock mass characterization and rock physical property data in its assessment of portal and underdrain stability conditions.
• The tailings, when consolidated, should not be above the top of the sandstone formation.
• The migration of contaminants in the ground water should be carefully monitored and mitigation procedures deployed if necessary. Establishment of a hydraulic cage should be used as the initial mitigative procedure if contaminant migration exceeds acceptable levels; raising the water level in Fox Lake could be considered as a secondary mitigative procedure. Both of these procedures should be defined in greater detail and subjected to the scrutiny of SERM, AECB, DFO and Environment Canada before deposition begins.
• In light of recent problems at Ontario Hydro's nuclear generating stations, which seem to have been caused more by poor management than by inferior technology, the regulators should make a careful assessment of Cogema's ability to manage the potentially dangerous JEB tailings management facility. The current management of this company appears to be chaotic. News releases have reported numerous resignations and changes at the senior management level; one of the Midwest partners has been openly contemptuous of Cogema's competence; [Correspondence to Alain Marvy, President, Cogema Resources Inc., from Dr. Hikmet Akin, President and Chief Executive Officer, Uranerz Exploration and Mining Limited, June 4, 1997.] most of Cogema's technical assessment has been done by consultants, some of whom fly in only to make a presentation and then depart without contributing to or learning from other presentations; [For example, Dr. Langmuir left the public hearings almost immediately after his presentation on August 26, 1997, and was not present to discuss the contradictory information presented by Richard Swider on August 28, 1997.] and the chairman of Cogema Resources Inc. admitted that the company did not have the scientific staff required to critically assess the advice given to it by consultants. [M. Poissonnet, Transcript of Supplementary Public Hearings for Midwest and Cigar Lake, La Ronge, Saskatchewan, August 26, 1997, p. 110.] A company that proposes to operate a waste dump, among the potentially most dangerous in Canada, should have greater competence and stability than Cogema has demonstrated. Before a licence to operate the JEB TMF is given to Cogema, the public and the regulators must be confident that the company has sufficient managerial and scientific strength and integrity within Saskatchewan to provide assurance that environmental damage would not result from incompetent operation of the facility.
• At times during the review, we observed that Cogema had a dismissive attitude toward the regulators and their concerns. They did not always appear to take seriously the issues raised by SERM and the AECB.

Neither the federal nor the provincial government should permit a company displaying such an attitude to be in charge of constructing and operating a radioactive waste disposal facility. Without a major attitudinal adjustment on the part of the proponent, there is a risk to the environment that supersedes the ability of scientists and engineers to design and construct a safe facility. Before approval is given, Cogema should be required to give more than superficial attention to the concerns of the regulators. It is, after all, the regulators who have been charged with the responsibility, on behalf of the people of Canada, to ensure that this facility would, if approved, be properly constructed and operated.

While fulfilling their responsibilities as regulators, AECB and SERM should be strongly supported by the federal and provincial governments and should not be subjected to undue pressure from conflicting government interests.

The panel is aware that an adequate response to many of these concerns will take considerable time. To reassure the public that this facility can be operated properly may therefore mean a substantial delay in the licensing process. Such a delay is the price the proponent must pay for its failure to provide convincing evidence that the facility can be operated safely and without adverse impacts on the environment. The regulators should not allow the fiscal consequences of such a delay to compromise their responsibility to ensure that the facility is properly designed and that there is a high probability it can be operated in such a way that the environment will be protected now and in the future.

I find myself totally amazed at the narrow view that suggests that we should ravage our northlands, contaminate its waters, only to produce even more deadly waste which we still haven't figured out how to handle.

K. Weingeist, Transcript of Midwest Public Hearings, Saskatoon, Saskatchewan, May 29, 1996, p. 85.

9.3 Conclusions and Recommendations

The proposed JEB TMF, constructed using natural surround technology, provides an opportunity to realize several potential environmental benefits. Among these are the ability to use subaqueous deposition, to store tailings from several mines in one site, to avoid the use of engineered barriers, to minimize weathering problems that are likely to compromise aboveground facilities, and to protect the contents of the pit from scarification by glaciers during the next ice age. Because of these potential advantages, the concept for tailings disposal represented by the JEB TMF proposal is recommended. However, there are also a large number of site-specific concerns associated with this particular site. The closeness of the JEB pit to Fox Lake, the failure of the proponent to provide convincing evidence that the lake will not become contaminated over time, and a lack of confidence in Cogema's ability to manage this facility must be taken into consideration. Consequently, it is necessary to attach several critical conditions to this recommendation. In summary, these conditions are:

• the proponent must demonstrate experimentally that porewater contaminant concentrations can be maintained at acceptable levels in aged tailings;
• if approval is eventually given, the chemical and physical properties of the deposited tailings must receive careful monitoring and the porewater quality must be periodically assessed;
• Fox Lake should not be used as a mixing zone;
• sediments in Fox Lake should be monitored;
• the more stringent of the SSWQO or the recently amended CWQG should be used when modelling the expected contamination of Fox Lake;
• a better geotechnical assessment of the underdrain portal should be provided, and design improvements made if required;
• tailings, after consolidation, should not be above the top of the sandstone formation;
• procedures for mitigating all potential unacceptable impacts should be identified before deposition begins. The construction of a hydraulic cage or raising the water level in Fox Lake should be more completely described and approved in principle by appropriate federal and provincial departments before deposition begins;
• the operator should be required to demonstrate that it possesses adequate managerial and scientific competence before responsibility to construct and operate this highly dangerous facility is approved;
• the operator should demonstrate that it is capable of, and intent upon, giving thoughtful, sincere and professional attention to the concerns of the regulators, SERM and AECB; and
• arrangements should be made to provide for perpetual monitoring of this and other tailings management facilities, if approval is given.