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Home My WebLink AboutDRC-2014-004662 - 0901a06880477db6/3l State of Utah GARY R. HERBERT Governor SPENCER J. COX Lieutenant Governor Department of Environmental Quality Amanda Smith Executive Director DIVISION OF RADIATION CONTROL Rusty Lundberg Director DRC-2014-004662 MEMORANDUM TO: THROUGH: FROM: DATE: SUBJECT: File Phil Goble, Compliance Section Manager Tom Rushing, P.G. v« - "'7 June 5,2014 Review of the Energy Fuels Resources (USA) Inc., White Mesa Uranium Mill, Blanding, Utah, March 18, 2014 Source Assessment Report for Sulfate in Monitoring Well MW-1 and Total Dissolved Solids in Monitoring Well MW-03A, Ground Water Discharge Permit No. UGW3 70004 Summary A March 18, 2014 Source Assessment Report ("SAR") for Sulfate in Monitoring Well MW-1 and Total Dissolved Solids ("TDS") in Monitoring Well MW-3A was submitted to the Director by Energy Fuels Resources (USA) Inc. ("EFR"), received on March 20, 2014. The SAR was submitted for review and approval of proposed revised Ground Water Compliance Limits ("GWCL's") as discussed below. The SAR is broken up into two primary sections: 1) an approach for analysis of potential sources of the contamination, and 2) a discussion and tables of data used for statistical evaluation and generation of proposed modified GWCL's. Figure 1 below depicts a slightly rising sulfate concentration trend in monitoring well MW-1 using all available historical data. DRC notes that four of the most recent five laboratory results for sulfate in monitoring well MW-1 have been above the GWCL (838 mg/L), with the highest historical value being 930 mg/L per the December 4, 2013 sample laboratory results. Figure 1 - Sulfate Data Plot of Historical Data at MW-J ^Slight Increasing Trend MW-1 S04 mg/L 1000 500 Jan-04 Oct-06 Jul-09 Apr-12Dec-14 Date 195 North 1950 West • Salt Lake City, UT Mailing Address: P.O. Box 144850 • Salt Lake City, UT 84114-4850 Telephone (801) 536-4250 • Fax (801) 533-4097 • T.D.D. (801) 536-4414 www.deq. utah.gov Printed on 100% recycled paper EFR 3-18-2014 SAR Report Page 2 Figure 2 depicts a rising concentration trend for TDS using all historical data available for monitoring well MW-3A. The highest historical concentration for TDS in monitoring well MW-3A was 6,020 mg/L, measured on May 22, 2013. Figure 2 - Total Dissolved Solids Data Plot of Historical Data at MW-3 A - Increasing Trend MW-3A TDS Plot 7,000 -, Investigations of Potential Sources of Contamination: /. Sulfate in Monitoring Well MW-1 The SAR Section 3.1 discusses potential sources of sulfate in monitoring well MW-1. The SAR notes that monitoring well MW-1 is located far upgradient from the well and that per a request by EFR (October 2010) to remove GWCL's from the Permit (but continue monitoring all constituents currently required), the DRC sent a letter of preliminary agreement that GWCL's were not necessary given the location and measured ground water elevations in the Burro Canyon Aquifer. DRC advised EFR that the GWCL's would be recommended for removal from the permit pending public notice requirements and formal approval by the Director (signature of a renewed/modified Permit). The Director has agreed with EFR's request to remove the GWCL's from the Permit for all parameters in monitoring well MW-1. Specifically, the Director has proposed to remove all GWCL's from the Permit at Monitoring Well MW-1 per an April 25, 2013 letter (subject to public notification and participation requirements). Therefore, review ofthe proposed modified GWCL for sulfate was conducted to assess the appropriateness only. The review will not result in changes to the MW-1 GWCL's since the previous request to remove all GWCL's supersedes the March 18, 2014 GWPL modification request. EFR notes in the SAR that per the 2009 groundwater background report: 1. Chloride was showing an increasing trend, 2. Fluoride was showing a decreasing trend, and 3. Uranium was showing a significant decreasing trend. Per comparisons with current plots of indicator parameters (shown below) EFR makes the statement in the Report that "groundwater in MW-01 is behaving consistently with background conditions and is not being affected by potential Mill activities:' Q 6,000 5,000 3 -\ i • , ; , Jan-04Oct-06Jul-09Apr-lZ>ec-14 Date MW-1 Cl mg/L 0 Jan-04 Jul-09 Dec-14 EFR 3-18-2014 SAR Report Page 3 MW-1 Fl mg/L 1 T £ 0.5 0 4--- Jan-04 Jul-09 Dec-14 1 2 MW-1 U mg/L 0 -I 1 1 ! 1 Jan-04 Oct-06 Jul-09 Apr-12 Dec-14 2. Total Dissolved Solids in Monitoring Well MW-3 A a. Ground Water Velocity DRC notes that monitoring well MW-3A is located approximately 2,000 feet downgradient from the White Mesa Mill Facility. Local groundwater velocities in the area south of the facility are very low (pore velocities in the range of 0.55 ft/yr to 0.89 ft/yr) per findings of an EFR 2012 report titled, "Hydrogeology of the Perched Groundwater Zone in the Area Southwest of the Tailings Cells, White Mesa Uranium Mill Site:' Based on these estimated values for groundwater velocity (developed through EFR hydraulic slug testing of installed area monitoring wells) it is unlikely that monitoring well MW-3A has been impacted by potential tailings solution seepage from the facility embankments. Per the SAR "travel times in the perched aquifer at the Mill are estimated to be 0.9 feet per year in the area between the Mill's tailings cells and MW-03A, resulting in a travel time of over 2,000 years" Monitoring well MW-3 A was included in a University of Utah study conducted at the White Mesa Uranium Mill during 2007 (Final Report of Study Findings Dated May, 2008). Tritium concentrations in monitoring well MW-3A were found to be non-detect. If ground water in monitoring well MW-3 A had a surface infiltration source post 1950's (time period of atmospheric injection of tritium during above-ground thermonuclear weapons testing) then tritium concentrations would be expected in ground water samples in monitoring well MW-3 A. The University of Utah ("U of U") Report (Hurst and Solomon 2008) Figure 5 depicts atmospheric concentrations of tritium in the southwest by year. Based on review of the U of U Report and specific data results for monitoring well MW-3 A age dating of groundwater at the well indicates that the MW-3A groundwater predates Mill construction and that uranium concentrations in groundwater at MW-3A does not appear to be from tailings solutions as would be shown with an evaporated stable isotope signal. b. University of Utah Study EFR 3-18-2014 SAR Report Page 4 c. Indicator Parameter Evaluation Per the SAR Part 3.2 "comparing (he current, complete data set for TDS and indicator parameters shows that groundwater behavior in MW-03A has not changed since the time of the Background Reports. Additionally, concentrations of indicator parameters in MW-3 A are exhibiting decreasing trends when plotted over time." Per DRC review of concentration plots for indicator parameters in monitoring well MW-3A (shown below), it appears that concentration trends are essentially flat for indicator parameters (Cl, Fl, U, and S04). MW-3A Cl mg/L 100 00 E u 50 0 Jan-04 Jul-09 Dec-14 1° 1 ^ 0 MW-3A Fl mg/L Jan-04 Jul-09 Dec-14 MW-3A U mg/L "So E = 0 Jan-04 Jul-09 Dec-14 MW-3A S04 mg/L 10000 "S3 E 5000 o to Jan-04 Jul-09 Dec-14 3. Source Assessment Conclusions Based on findings related to indicator parameter analysis and age dating studies conducted by the U of U (Hurst and Solomon 2008), and also supported by the slight decreasing pH trend at monitoring well MW- 31, DRC staff concur with the EFR finding that elevated selenium concentrations in the well do not appear to be due to tailings solution from the White Mesa Mill tailings cells. It therefore appears appropriate to EFR 3-18-2014 SAR Report Page 5 attribute the elevated selenium concentrations to background groundwater sources and modify the current Permit GWCL for selenium in monitoring well MW-31. EFR Proposed Modified GWCL Statistical Evaluation of Data: The following statistical methods were used by EFR to develop the proposed modified GWCLs: Standard Deviation Calculation Shapiro-Wilk Test for Normality Least Squares Regression Analysis Mann-Kendall Trend Analysis A DRC cross-check of the Shapiro-Wilk Test for normality and standard deviation was conducted. The DRC calculation results were essentially the same as the EFR conclusions. EFR proposes a modified GWCL based on the mean value of historic data plus two standard deviations. The EFR proposed GWCL appears to be in conformance with the Director approved statistical flow chart which outlines a decision making process when calculating background GWCL's (Intera 2007). The table below summarizes the EFR calculations and background rationale for the proposed TDS GWCL. Summary of EFR Proposed Revised GWCL for TDS at Monitoring Well MW-3 A: Well Number Parameter Location Current GWCL (mg/L) EFR Proposed GWCL Revision (mg/L) Mean + 2a EFR Background Rationale EFR Method to Determine GWCL DRC Finding - Is Proposed GWCL in Conformance with the Statistical Flow Chart? MW-3A TDS Downgradient from White Mesa Mill Facility 5,805 6,028 Well Location Downgradient of Facility Indicator Parameters Consistent with Background Report U of U Study Showing Old Ground Water Mean + 2(SD) Yes Mean + 2a Conclusions: Based on DRC staff review of the SAR it is recommended that a correspondence letter which summarizes the DRC review of the proposed modified GWCLs for sulfate in monitoring well MW-1 and TDS in monitoring well MW-3A be sent to EFR. The letter will provide the information in this memo above and a recommendation that the proposed modified GWCL (MW-3A TDS 6,028 mg/L) be included in the Permit renewal. Notification that the modification is subject to public notice requirements and that proposed EFR 3-18-2014 SAR Report Page 6 revised GWCL's will not be effective until formal issuance in an updated Permit will be included in the letter. References 1 Denison Mines (USA) Corp., October 2007, Revised Background Groundwater Quality Report Existing Wells for Denison Mines (USA) Corp. White Mesa Mill Site, San Juan County, UT 2 Energy Fuels Resources (USA) Inc., March 18, 2014, Source Assessment Report for Sulfate in MW-Oland TDS in MW-03 White Mesa Uranium Mill. 3 Energy Fuels Resources (USA) Inc., June 6, 2012, While Mesa Uranium Mill Ground Water Monitoring Quality Assurance Plan (QAP), Revision 7.3 4 Energy Fuels Resources (USA) Inc., October 12, 2012, Source Assessment Report, Prepared by Intera 5 Energy Fuels Resources (USA) Inc., November 9, 20\2, pH Report, Prepared by Intera 6 Hurst, T.G., and Solomon, D.K. University of Utah, 2008, Summary of Work Completed, data Results, Interpretations and Recommendations for the July 2007 Sampling Event at the Denison Mines, USA White Mesa Uranium Mill Near Blanding, Utah, Prepared by Department of Geology and Geophysics 7 Hydro Geo Chem, December 7, 2012, Pyrite Investigation Report 8 Intera, 2007, Groundwater Data Preparation and Statistical Process Flow for Calculating Groundwater Protection Standards, White Mesa Mill Site, San Juan County, Utah 9 Utah Department of Environmental Quality, August 24, 2012, Utah Division of Radiation Control, Ground Water Discharge Permit, Permit No. UGW370004, Energy Fuels Resources (USA) Inc. Appendix - DRC Cross Check Shapiro-Wilk (TDS MW-3 A) Shapiro Wilk (n<50) Method DRC Cross Check Data Entered 5/29/14 TR Energy Fuels Monitoring Well MW-3A TDS Shapiro Wilk x(i) x(n-i+1) x(n-i+1)Ax(i) a(n-i+1) bi 5070 6020 950 0.4254 404.13 5330 5940 610 0.2944 179.584 5360 5860 500 0.2487 124.35 5410 5860 450 0.2148 96.66 5470 5810 340 0 187 63.58 5490 5770 280 0.163 45 64 5520 5770 250 0.1415 35.375 5540 5760 220 0.1219 26.818 5560 5750 190 0.1036 19.684 10 5570 5730 160 0 0862 13.792 11 5580 5720 140 0.0697 9.758 12 5600 5720 120 0.0537 6 444 13 5610 5700 90 0 0381 3.429 14 5630 5690 60 0.0227 1 362 15 5660 5690 30 0.0076 0 228 16 5690 5660 17 5690 5630 18 5700 5610 19 5720 5600 20 5720 5580 21 5730 5570 22 5750 5560 23 5760 5540 24 5770 5520 25 5770 5490 26 5810 5470 27 5860 5410 28 5860 5360 29 5940 5330 30 6020 5070 total= Standard Deviation Calculation: Mean = 5639.67 Variables = 1095896.667 Standard Deviation = 179.5334367 1025.815 W Statistic = 0 989312421 DRC Calculated Limit Energy Fuels Calculated Limit 5999 6028 .01 Critical n(30) = 0.927