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HomeMy WebLinkAboutDRC-2009-004683 - 0901a06880142f19t£6'' .^00^' D0^lcB3 Denison Mines (USA) Corp. 105017th Street, Suite 950 OENlSOhT^MM USA fVl INES Tel : 303 628-7798 Fax:303 389-4125 www.denisonmines.com October 8, 2009 ^ VIA PDF AND FEDERAL EXPRESS Mr. Dane L. Finerfrock Co-Executive Secretary Utah Water Quality Board x <y ^ •• State of Utah Department of Environmental Quality ^\*>.-, -,vt-*''' 168 North 1950 West <?939^T Salt Lake City, UT 84114-4850 Re: Public Notice of a l\/lodification to the Ground Water Quality Discharge Permit No. UGW370004 for the White l\/lesa Mill - Comments of Denison Mines (USA) Corp. Dear Mr. Finerfrock: Reference is made to the Public Notice (the "Notice") of a modification to the ground water quality discharge permit No. UGW370004 (the "Permif) for the White Mesa uranium mill (the "Mill") operated by Denison Mines (USA) Corp. ("Denison") that was published by the Co- Executive Secretary of the Utah Water Quality Board (the "Executive Secretary") on September 2, 2009. Denison has the following comments on the draft modified Permit that was published with the Notice: 1. Part l.B. The latest data used for the October 2007 Revised Background Report for Existing Wells was June 2007, and the latest data used for the April 2008 Revised Background Report for New Wells was December 2007. Therefore, it would be more accurate to change the first part of that sentence to read: "based on groundwater samples collected through June 2007 for existing wells MW-1, MW-2, MW-3, MW-5, MW-11, MW-12, MW-14, MW-15, MW-17, MW-18, MW-19, MW-26 and MW-32 and through December 2007 for new wells MW-3A, MW-23, MW-24, MW-25, MW-27, MW-28, MW-29, MW-30 and MW-31, pursuant to ..." 2. Part I.D.6(c) As discussed with Division of Radiation Control ("DRC") staff, Denison cannot commit to reducing the maximum head in Cell 4A to 1 foot above the FML, nor to commit to a time frame of 6.4 years to achieve a specific head level. The 1 foot maximum head and 6.4 year time frame reflect the design criteria used for the slimes drain system in Cell 4A. These design criteria are theoretical and are based on a number of assumptions and estimates. Denison believes these assumptions and estimates to be reasonable and conservative and that the design criteria are appropriate for Cell 4A. Denison's decision to proceed on this basis was approved by the Executive Secretary. However, Denison cannot guarantee that the system will perform in the future exactly as designed. This attempts to impose a level of accuracy that is unrealistic and that is beyond Denison's control. In order to address these issues, we propose that Part I.D.6(c) be revised to read as follows: c) Slimes Drain Monthly and Annual Average Recovery Head Criteria - after the Permittee initiates pumping conditions in the slimes drain layer in Cell 4A, the Permittee will provide 1) continuous operation of the existing dewatering system, reasonable maintenance excepted; and 2) continuous declining fluid heads in the slimes drain layer, in a manner equivalent to the requirements found in Part I.D.3(b) until such time as the maximum head in the tailings (as measured from the lowest point of the upper flexible membrane liner) is 1.0 feet or less, or otherwise approaches its asymptotic limit as approved by the Executive Secretary. 3. Part I.E.6(h) Paragraph 3.0 of the Mill's Sampling Plan for Seeps and Springs in the Vicinity of the White Mesa Uranium Mill sets out a procedure for dealing with seeps and springs that are effectively dry and cannot be sampled after repeated attempts. Those procedures do not require prior Executive Secretary approval for the omission of samples in those circumstances. Therefore, we suggest that Part I.E.6(h) be revised to read as follows: h. Sample Omission - in the course of each annual sampling event, the Permittee shall sample and analyze, or attempt to sample and analyze, all six seeps and springs identified in Table 1 of the currently approved Sampling Plan for Seeps and Springs in the Vicinity of the White Mesa Uranium Mill. The Permittee shall not omit sampling of any seep or spring during said annual event, without prior written approval of the Executive Secretary, unless the omission is in accordance with such Plan for any seeps or springs that are dry and not capable of being sampled." 4. Part I.E.7(f) The phrase "If a discrepancy is identified . . ." in the last sentence of Part I.E.7(f) is vague and difficult to apply with precision in practice. In order to provide more certainty, we suggest that the phrase "the applicable provisions of the" be added before the word "currently" in that sentence. This will tie the requirements of the Permit to the more specific procedures set out in the Liner Maintenance Provisions, which are capable of being applied with precision in practice. 5. Partl.E.10 The following clarifying changes are suggested: a) Change paragraph 10a to read "One surface impounded wastewater location at each of Tailings Cells 1, 3, and 4A"; DENISO MINES J>M b) Add the words "each of" before the word Tailings in paragraph 10b; c) The subparagraphs in paragraph 10 should be renumberd so that there is not a repeat of subparagraph letters a., b. and c; and d) In subparagraph g.. Prior Notification, delete the words "fieldwork or" and add the phrase "under lO.a, b and c" after the words "sample collection". There is no other "fieldwork" that would require notice to the Executive Secretary under the Plan; therefore, reference to fieldwork should be eliminated. 6. Part I.G.2 The Ground Water Compliance Limits have been set in the Permit to take into account the mean and standard deviations or their equivalent, such that anything less than two consecutive exceedances of the GWCLs would not be considered to be statistically significant. Therefore, if paragraph 2(a)(1) is to be deleted, then paragraph 2(b) should also be deleted. Retaining paragraph 2(b) is confusing, given the way that the GWCLs have been calculated, for the same reasons that retaining paragraph 2(a)(1) would be confusing. Both paragraphs should be deleted. They merely restate the applicable regulations. However, if paragraph 2(b) is to be retained in the Permit, then paragraph 2(a)(1) should also be retained in the Permit. We can see no reason for keeping one of the paragraphs and deleting the other. 7. Part I.H.4 As discussed with DRC staff on May 11, 2009, Denison does not believe that it is necessary to add Part I.H.4 to the Permit. Further, the requirements of Part I.H.4 cannot be complied with as drafted. The Background Reports prepared by INTERA, Inc. demonstrate that the Mill's tailings cells are not leaking to groundwater. The conclusions of those reports were confirmed by the University of Utah Study, which evaluated existing wells that were considered to be the most indicative of any potential tailings cell leakage. There is no need to perform yet another study to verify those conclusions, particularly given the considerations below. There are currently over 40 monitoring constituents in the Permit. These include chloride, fluoride, sulfate and uranium which are all good indicator parameters. As discussed at our meeting and in our June 5, 2009 correspondence with supporting INTERA memorandum, any potential future tailings cell leakage to groundwater will be picked up by these indicator parameters before any other constituents. There cannot be a leak to groundwater of any significance without one or more of these parameters indicating an upward trend. However, although an upward trend in one or more of these indicator constituents is necessary in order to reach a conclusion that the tailings cells are leaking, a rising trend in one or more of these constituents does not necessarily imply that the tailings cells are leaking. Rising trends in indicator parameters could also be due to natural influences. As we discussed in our May 11, 2009 meeting, nothing will be gained from characterizing at this time the chemical composition, noble gas composition, and age of the groundwater in the wells that were not covered by the University of Utah Study. Any potential future exceedance of a GWCL would be evaluated at the time of the exceedance by the most appropriate methods in the circumstances. This would most likely include a spatial and temporal analysis of the constituent in question together with all other constituents in the well, with a primary focus on the indicator parameters. If such an analysis is not conclusive, such as when one or more DENISOI MINES indicator parameters have also risen or have demonstrated an upward trend or trends and natural influences cannot be ruled out, then a further analysis would be performed. This analysis may include an isotopic analysis, depending on the circumstances. If an isotopic analysis were to be performed at that time, then the results of that analysis would be relevant, not the results of an isotopic analysis performed today. In addition to the fact that the analyses contemplated by Part I.H.4 are not necessary and will provide little, if any, information relevant to the analysis of a potential future GWCL exceedance, there are a number of practical problems associated with such an analysis. As we discussed at our May 11, 2009 meeting, the analyses contemplated by Part I.H.4 are not mainstream (i.e., there are no generally accepted methods), they are costly to perform, they are not capable of being performed at commercial laboratohes, and they cannot be performed in the 90-day time frame proposed in Part I.H.4. The required analysis can only be performed at a limited number of university laboratories. Those laboratories are not Utah-certified and there are no EPA-approved methods for such analyses. Further, Denison cannot control the timing and results from such non-accredited laboratories. This is because Denison would not have a choice of commercial laboratories from which to obtain all of the required work. For example, Denison took splits of the samples taken by the University of Utah in July 2007 and engaged one of the few available other university laboratories to perform the tritium/helium analysis. After six months of waiting for the analytical results, and being deferred behind other university projects, Denison finally called off the analysis. Denison cannot be held responsible for failure to meet a schedule when such failure is not within its control. It took the University of Utah approximately one year to complete its study. Planning started in the Spring of 2007, fieldwork was performed in July, 2007 and the final report was issued in May, 2008. It is unrealistic to expect that Denison could have such a study performed in the 90 days contemplated by Part I.H.4. A more realistic time frame would be 365 days, as required by the University of Utah. However even a time frame of 365 days may not be achievable, given Denison's inability to control the schedule of the non-commercial laboratory or laboratories that would be required to perform the analysis. In summary, the evaluations required by proposed Part I.H.4 are not necessary to establish that the Mill's tailings cells have not leaked to date; they will provide little, if any, information that could be of use in evaluating a potential future tailings cell leak; will be costly; will not be performed in accordance with accepted EPA guidance, will take at least one-year to complete; and the timing of completion of the study will not be within Denison's control. As a result, proposed Part I.H.4 should be eliminated from the Permit. 8. Part I.H.5 Once the new decontamination pad is constructed. Mill personnel will be able to check the leak detection system weekly and will be able to take the pad out of service annually in order to inspect the integrity of the steel liner in each of the settling ponds and the visually exposed surface areas of the concrete pad. However, it will not be possible to inspect the integrity of the concrete surfaces below the steel liner in each tank, as it will not be possible to remove the steel liner from each tank. Inspections of such concrete surfaces are not necessary, given the fact that the tanks are lined with steel liners, a leak detection system is checked weekly, and the integrity of the steel liners is checked annually. References to concrete surfaces should DENISOr MINES therefore be removed from Part I.H.5, or it should be made clear that only visually exposed areas of the concrete pad need to be inspected annually and that this does not include areas under the steel tank liners. If you have any questions or require any further information, please contact the undersigned. We suggest that we have a call to discuss the foregoing comments and your responses to them, prior to finalization of the Permit language. Yours truly. F rydenlund P'resiaent Regulatory Affairs and Counsel cc: Ron F. Hochstein Harold R. Roberts Steven D. Landau David E. Turk DENISO MINES r^i