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HomeMy WebLinkAboutDRC-2021-008103 - 0901a06880eb3433June 7, 2021 ENERGY FUELS Div of Waste Management and Radiation Control JUN 0 8 2021 Energy Fuels Resources (USA) Inc. 225 Union Blvd. Suite 600 Lakewood, CO, US, 80228 303 974 2140 D RC —2021— 006 (0 3 www.energyfuels.com Sent VIA OVERNIGHT DELIVERY Mr. Doug Hansen Director Division of Waste Management and Radiation Control Utah Department of Environmental Quality 195 North 1950 West Salt Lake City, UT 84116 Re: Transmittal of Energy Fuels Resources (USA) Inc. ("EFRI") Errata Pages for the Background Report for MW-38, MW-39, and MW-40, White Mesa Uranium Mill, Blanding Utah Dear Mr. Hansen: On May 26, 2021 a teleconference between the Division of Waste Management and Radiation Control ("DWMRC") DWMRC, EFRI, and EFRI's consultant, 1NTERA was held to discuss DWMRC's review of the March 4, 2021 Background Groundwater Quality Report for Monitoring Wells MW-38, MW-39, and MW-40. During their review, DWMRC identified errors in calculation of Groundwater Compliance Limits ("GWCLs") for pH in MW-38, MW-39, MW-40, and gross alpha in MW-40. DWMRC also raised concern about the proposed GWCL for manganese in MW-39 based on recent observations and requested that the GWCL be recalculated using the complete data set rather than removing outliers. DWMRC requested errata pages correcting and adjusting the GWCLs in question. The pages enclosed include changes as described below and are intended to replace the same pages in the hard copies of the March 4, 2021 Background Groundwater Quality Report. Electronic portable data format ("PDF") files of the errata pages and a revised electronic copy of the complete Background Groundwater Quality Report are being provided via email. Changes to the Background Groundwater Quality Report include: • Text pages 5-6 - Section 3.2, modified text to include manganese in MW-39 as a significantly increasing constituent, and - Section 3.3, removed erroneous reference to Appendix G. Letter to Doug Hansen June 7, 2021 Page 2 of 2 Table 8 MW-38: Corrected pH GWCL calculation from mean plus 2 standard deviations ("SD") to mean minus 2 SD. - MW-39: Corrected pH GWCL calculation from mean plus 2 SD to mean minus 2 SD., revised manganese calculations incorporating complete data set. - MW-40: Corrected pH GWCL calculation from mean plus 2 SD to mean minus 2 SD., corrected calculation of gross alpha GWCL from Cohen's mean times 2 Cohen's standard deviations to Cohen's mean plus 2 Cohen's standard deviations. • Appendix C - Page 11: Linear regression plot for manganese in MW-39 was revised using the complete data set. • Appendix F - Outliers previously identified for manganese in MW-39 were removed from Appendix F. DWMRC acknowledged the limited data sets used to calculate GWCLs in MW-38, MW-39, and MW-40, and proposed that EFRI review GWCLs considering all data available to date prior to future Groundwater Discharge Permit ("GWDP") modifications. DWMRC will consider adjustments to the GWCLs incorporated in future GWDP modifications using all available data at the time of the next permit modification. If you should have any questions regarding this report please contact me. Yours very truly, ENERGY FUELS RESOURCES (USA) INC. Kathy Weinel Quality Assurance Manager CC: David Frydenlund Logan Shumway Scott Bakken Terry Slade 2 3.0 RESULTS OF ANALYSIS AND DETERMINATION OF GROUNDWATER COMPLIANCE LIMITS MW-38, MW-39, and MW-40 are Class III wells based on their TDS concentrations (all three of the wells have mean concentrations of TDS that are greater than 3,000 milligrams per liter ["mg/L"]) according to the rules set forth in UTAC R317-6-3. 3.1 Indicator Parameters Chloride, sulfate, uranium, and fluoride have been identified as the best indicator parameters of potential tailings cell seepage at the site, as described in Section 9.0 of the Existing Wells Background Report (INTERA, 2007a). Review of the results for indicator parameters in each well demonstrate that concentrations of indicator parameters in MW-38, MW-39, and MW-40 are not exhibiting significantly increasing trends (Appendix C, Table 8). Chloride, sulfate, and uranium in MW-38 are not trending, and fluoride in MW-38 is decreasing slightly, though the trend is not significant. Chloride, fluoride, and sulfate concentrations in MW-39 are stable to decreasing slightly. Uranium in MW-39 is significantly decreasing. Chloride and uranium in MW-40 are decreasing, and fluoride and sulfate in MW-40 are increasing slightly, but these trends are not significant. Evaluation of indicator parameters in MW-38, MW-39, and MW-40 supports the findings of previous investigations at the Site, which conclude that there has been no impact to groundwater from potential tailings cell seepage. 3.2 Trending Constituents Trending constituents were identified by one of two trend test methods, according to the Flow Sheet (Figure 2). Linear regression analysis was performed for normally or lognormally distributed constituent data sets (Appendix C), and the Mann-Kendall trend test was performed for the data sets which are not normally or lognormally distributed and contained 15% - 90% NDs (Table 8). Statistically significant increasing trends include TDS in MW-38, potassium and manganese in MW-39, and selenium in MW-40. Constituents that appear to exhibit increasing trends that are not statistically significant include bicarbonate, and nitrate + nitrite, in MW-38; gross alpha, and in MW-39; and fluoride and sulfate in MW-40. In addition to the constituents listed here, and despite the generally decreasing trend in pH observed sitewide, pH in MW-38 and MW-40 is exhibiting an increasing trend. As described in Section 2.0, the strength of statistical tests will increase with larger data sets, resulting in the potential for trending concentrations in the future. Background Groundwater Quality Report for MW-38, MW-39, and MW-40 White Mesa Uranium Mill Page 5 Blanding, Utah March 4, 2021 (revised June 4, 2021) 3.3 Groundwater Compliance Limits GWCLs were determined based on the DWMRC-approved Flow Sheet (Figure 2) and in a similar manner to the previous Background Reports. GWCLs for constituents in MW-38, MW- 39, and MW-40 that were not exhibiting any increasing trends were determined by following the Flow Sheet without any modifications. Table 8 contains a summary of the results of the Flow Sheet along with the proposed GWCLs based on that analysis. The GWCLs included in Table 8 include mean + two standard deviations (mean + 2 SD), Cohen's adjusted mean + 2 SD, highest historical values (HHV), fractional, and Poisson Prediction Limits. The fractional approach follows Utah Administrative Code ("UAC") R-317-6-4.6 B(2), Cohen's adjustment calculation follows that outlined by the USEPA (2009) and the Poisson Prediction Limit is from USEPA statistical guidance (1992). 3.4 Modified Approach for Groundwater Compliance Limits for Trending Constituents According to the DWMRC-approved Flow Sheet (Figure 2), if an increasing trend is present, a modified approach should be considered for determining GWCLs for parameters listed in the GWDP. Significant increasing trends in MW-38 (TDS) and MW-40 (selenium) can be attributed to natural background conditions and are consistent with similar trends in other monitoring wells at the Mill. The UAC R317-6-4.6 recognizes that "contaminants" may be present as part of naturally occurring background conditions: When a contaminant is present in a detectable amount as a background concentration, the concentration of the pollutant may not exceed the greater of 1.5 times the background concentration or 0.5 times the ground water quality standard or background plus two standard deviations... In this rule, background concentration is defined as the "concentration of a pollutant in ground water upgradient or lateral hydraulically equivalent point from a facility, practice or activity which has not been affected by that facility, practice or activity." Therefore, to be conservative, the mean concentration was used for the purposes of this calculation. The mean concentration assumes all data to date for calculation steps in the Flow Sheet. UAC R317-6-4.6 also states that TDS may not exceed the greater of 1.25 times the background concentration or background plus two SDs. For this reason, the modified-approach GWCL for TDS in MW-38 was calculated by multiplying the mean by 1.25. The modified-approach GWCL for selenium in MW-40 was calculated by multiplying the mean by 1.5. Background Groundwater Quality Report for MW-38, MW-39, and MW-40 White Mesa Uranium Mill Blanding, Utah Page 6 March 4, 2021 (revised June 4, 2021) TABLE 8 Summary of Flow Sheet GWCL Calculations Based on UDEQ-Approved Flow Sheet Normally or Lognormally P4140#014R4 Linear Regression Significant Trend Mann-Kendall Cohen Poisson Fractional Significant Prediction Approach Tmnd ..., Mean St. Dev. HHV Llrn1t,96% , (Class III) Proposed Modified Flowsheet Flowsheet GWCL Modified GWCL GWCL Rationale GWCL Rationale MW-38 Nutrients (mg/L) MW-38 Ammonia 25 10 70% No 2 0.45567 0.0658 12 5 12.50 Fractional MW-38 NitrateNitrite 10 10 0% Yes 0.59229 0 07121 0.3508 14.18 0.93190367 15.7 5 16.04 mean + 2SD MW-38 Heavy Metals (pg/L) MW-38 Arsenic 50 10 100% Not Tested 5.71 25 25 Fractional MW-38 Beryllium 4 10 100% Not Tested 1.39 2 2 Fractional MW-38 Cadmium 5 10 100% Not Tested 1.39 2.5 2 5 Fractional MW-38 Chromium 100 10 100% Not Tested 19.47 50 50 Fractional MW-38 Cobalt 730 10 100% Not Tested 9.47 365 365 Fractional MW-38 Copper 1300 10 100% Not Tested 9.47 650 650 Fractional MW-38 Iron 11000 10 100% Not Tested 22.62 5500 5500 Fractional MW-38 Lead 15 10 100% Not Tested 2.04 7.5 / 5 Fractional MW-38 Manganese 800 10 100% Not Tested 9.47 400 400 F actional MW-38 Mercury 2 10 100% Not Tested 1.39 1 1.39 Poisson Prediction Limit MW-38 Molybdenum 40 10 80% No 9 0.15018 13.3 20 20 Fractional MW-38 Nickel 10 10 100% Not Tested 16.25 5 16.25 Poisson Prediction Limit MW-38 Selenium 50 10 0% Yes -0.4462 0.19612 0.1991 163.2 7.77174369 175 25 178.74 mean + 2SD MW-38 Silver 100 10 100% Not Tested 9.47 50 50 Fractional MW-38 Thallium 2 10 100% Not Tested 1.39 1 1.39 Poisson Prediction Limit MW-38 Tin 17000 10 100% Not Tested 63.76 8500 8500 Fractional MW-38 Uranium 30 10 0% Yes -0.0386 0.91571 0.001 6.39 0.38464991 6.78 15 7.16 mean + 2SD MW-38 Vanadium 60 10 100% Not Tested 12.94 30 30 Fractional MW-38 Zinc 5000 10 80% No -15 0.03496 15.1 2500 2500 Fractional MW-38 Radiologics (pCi/L) - MW-38 GrossAlpha 15 9 67% No 8 0.18828 1.3 7 5 7.50 Fractional MW-38 Vola Ile Organic Compounds (pg/L) MW-38 Acetone 700 10 100% Not Tested 16.25 350 350 Fractional MW-38 Benzene 5 10 100% Not Tested 2.04 2.5 2.5 Fractional MW-38 Methyl ethyl ketone 4000 10 100% Not Tested 16.25 2000 2000 Fractional MW-38 Carbon tetrachloride 5 10 100% Not Tested 2.04 2.5 2.5 Fractional MW-38 Chloroform 70 10 100% Not Tested 2.04 35 35 Fractional MW-38 Chloromethane 30 10 100% Not Tested 2.04 15 15 F actional MW-38 Methylene chloride 5 10 100% Not Tested 2.04 2.5 2.5 F actional MW-38 Naphthalene 100 10 100% Not Tested 2 04 50 50 Fractional MW-38 Tetrahydrofuran 46 10 100% Not Tested 2.04 23 23 Fractional MW-38 Toluene 1000 10 100% Not Tested 2.04 500 500 Fractional MW-38 Xylenes, Total 10000 10 100% Not Tested 2.04 5000 5000 Fractional MW-38 Other MW-38 Chloride (mg/L) 10 0% Yes -0.1428 - 0.69391 0.0204 43.54 2.57992248 46.5 48.70 mean + 2SD MW-38 Fluoride (mg/L) 4 10 0% Yes -0.5199 0.12345 0.2703 0.7027 0.1362653 1.03 2 0.98 mean + 2SD MW-38 Field pH (s.u.) 10 0% Yes 0.62471 0.05349 0.3903 7.138 0.23006279 7.45 6.68 mean - 2SD MW-38 Sulfate (mg/L) 10 0% Yes 0.09486 0.79436 0.009 2670 228.375908 3090 3126.75 mean + 2SD MW-38 TDS (mg/L) 10 0% Yes 0.69321 0.02623 0.4805 Increasing 4007 147.048745 4240 4301.10 mean + 2SD 5008.75 1.25x mean =INITERA Background Groundwater Quality Report for MW-38, MW-39. and MW-40 - White Mesa Uranium Mill, Blanding, Utah Page 1 of 3 TABLE 8 Summary of Flow Sheet GWCL Calculations Based on UDEQ-Approved Flow Sheet LinaiL Normally or Lognormally Well Constituent GWQS N %ND Distributed? giression Mann-Kendall Cohen Poisson Fractional Proposed Modified Significant Significant Prediction Approach ., Flowsheet Flowsheet GWCL Modified GWCL Trend S p Trend Mean St. Dev. HHV LinOt. .4., WRY, GWCL Rationale GWCL Rattapale MW-39 Nutrients (mg/L) MW-39 Ammonia 25 10 0% Yes -0.6114 0.06035 0.3738 0.2718 0.02923012 0.319 12.5 0.33 Imean + 2SD MW-39 NitrateNitrite 10 9 33% No l - 3 0.00962 Decreasing 0.166 5 5 Fractional MW-39 Heavy Metals (pg/L) MW-39 lArsenic 50 10 100% Not Tested 5.71 25 25 Fractional MW-39 Beryllium 4 10 0% Yes -0 7746 0 00852 0.6 Decreasing 4 987 0.48958145 5.94 2 5.97 mean + 2SD MW-39 Cadmium 5 10 0% Yes 0 08191 0.82201 0.0067 2.718 0.14366628 2.97 2.5 3.01 mean + 2SD MW-39 Chromium 100 10 100% Not Tested 19.47 50 50 Fractional MW-39 Cobalt 730 10 0% Yes -0.2147 0.55146 0.0461 68 24 5.46487776 79.8 365 79.17 mean + 2SD MW-39 Copper 1300 9 0% Yes -0.6573 0.05436 0.4321 29.733 2.90989691 35.4 650 35.55 mean + 2SD MW-39 Iron 11000 9 0% Yes 0.00339 0.9931 1E-05 14700 403.112887 15300 5500 15506.23 mean + 2SD MW-39 Lead 15 10 100% Not Tested 2 04 7.5 7 5 Fractional MW-39 Manganese 800 10 0% Yes 0.72496 0.01768 0.5256 Increasing 2204 120.11106 2440 400 2444.22 mean + 2SD MW-39 Mercury 2 10 100% Not Tested 1.39 1.39 Poisson Prediction Limit MW-39 Molybdenum 40 10 100% Not Tested 20 Fractional MW-39 Nickel 100 10 0% Yes -0.0184 0.95976 0.0003 33.59 39.25 mean + 2SD MW-39 Selenium 50 10 100% Not Tested 5.71 25 25 Fractional MW-39 Silver 100 10 100% Not Tested 9.47 50 50 Fractional MW-39 Thallium 2 10 0% Yes 0.49431 0.14642 0.2443 3.444 0.18762847 3.83 1 3.82 mean + 2SD MW-39 Tin 17000 10 100% Not Tested 63.76 8500 8500 Fractional MW-39 Uranium 30 10 0% Yes -0.6393 0.04656 0.4087 Decreasing 12.02 0.96701143 14.2 15 13.95 mean + 2SD MW-39 Vanadium 60 10 100% Not Tested 12.94 30 30 Fractional MW-39 Zinc 5000 9 0% Yes -0.4667 0 20537 0.2178 243.89 7.55718937 257 2500 259.00 mean + 2SD MW-39 Radiologics (pCi/L) MW-39 GrossAlpha 15 9 0% Yes 0 52762 0.14432 0.2784 j 3.2189 1 12645955 5 11 J 7.5 5.47 mean + 2SD MW-39 Volatile Organic Compounds (pg/L) MW-39 Acetone 700 10 100% Not Tested 16.25 350 350 Fractional MW-39 Benzene 5 10 100% Not Tested 2.04 2.5 2.5 Fractional MW-39 Methyl ethyl ketone 4000 10 100% Not Tested 16.25 2000 2000 Fractional MW-39 Carbon tetrachloride 5 10 100% Not Tested 2.04 2.5 2.5 Fractional MW-39 Chloroform 70 10 100% Not Tested 2.04 35 35 Fractional MW-39 Chloromethane 30 10 100% Not Tested 2.04 15 15 Fractional MW-39 Methylene chloride 5 10 100% Not Tested 2.04 2.5 2.5 Fractional MW-39 Naphthalene 100 10 100% Not Tested 2.04 50 50 Fractional MW-39 Tetrahydrofuran 46 10 100% Not Tested 2.04 23 23 Fractional MW-39 Toluene 1000 10 100% Not Tested 2.04 500 500 Fractional MW-39 Xylenes, Total 10000 10 100% Not Tested 2.04 5000 5000 Fractional MW-39 Other MW-39 Chloride (mg/L) 10 0% Yes -0.2481 0.48948 0.0616 38.73 2.47568172 41.7 43.68 mean + 2SD MW-39 Fluoride (mg/L) 4 9 0% Yes 0.02712 0.94479 0.0007 0.692 0.06310903 0.805 2 0.82 mean + 2SD MW-39 Field pH (s.u.) 9 0% Yes 0.07202 0.85392 0.0052 4.17 0.16889346 4.53 3.83 mean - 2SD MW-39 Sulfate (mg/L) 10 0% Yes -0.4015 0.25018 0.1612 3079 221.532541 3570 3522.07 mean + 2SD MW-39 TDS (mg/L) 10 0% Yes -0.41 0.2393 0.1681 4216 248.739042 4560 4713.48 mean + 2SD laMINNITERIX Background Groundwater Quality Report for MW-38, MW-39, and MW-40 White Mesa Uranium Mill, Blanding, Utah Page 2 of 3 TABLE 8 Summary of Flow Sheet GWCL Calculations Based on UDEQ-Approved Flow Sheet ' „Regression Significant Trend Mann-Kendall Significant p Trend Mean St. Dev. .,1141/,: , Poisson Prediction Limit 95% Cohen Fractional Approach Flowsheet (Class III) " SD GWCL Flowsheet GWCL Rationale Proposed Modified GWCL Modified GWCL Rationale MW-40 Nutrients (mg/L) MW-40 Ammonia 25 10 80% No -5 0.30229 0.2 12.5 2.5 Fractional MW-40 NitrateNitrite 10 10 0% Yes -0.8252 0.00329 0.6809 Decreasing 2.822 0.29483705 3.52 5 3.41 mean + 2SD MW-40 Heavy Metals (pg/L) MW-40 Arsenic 50 10 100% Not Tested 5.71 25 25 Fractional MW-40 Beryllium 4 10 100% Not Tested 1.39 2 2 Fractional MW-40 Cadmium 5 10 100% Not Tested 1.39 2.5 2.5 Fractional MW-40 Chromium 100 10 100% Not Tested 19.47 50 50 Fractional MW-40 Cobalt 730 10 100% Not Tested 9.47 365 365 Fractional MW-40 Copper 1300 10 100% Not Tested 9.47 650 550 Fractional MW-40 iron 11000 10 90% No 9 0.08187 41 5500 5500 Fractional MW-40 Lead 15 10 100% Not Tested 2.04 7 5 7.5 Fractional MW-40 Manganese 800 10 0% No -22 0.02966 206 400 400 Fractional MW-40 Mercury 2 10 100% Not Tested 1.39 1 1.39 Poisson Prediction Limit MW-40 Molybdenum 40 10 100% Not Tested 9.47 20 20 Fractional MW-40 Nickel 100 10 100% Not Tested 16.25 50 50 Fractional MW-40 Selenium 50 10 0% Yes 0.70593 0.02253 0.4983 Increasing 160.5 25.8639603 196 25 212.23 mean + 2SD 240.75 1.5 x mean MW-40 Silver 100 10 100% Not Tested 9.47 50 50 Fractional MW-40 Thallium 2 10 90% No -5 0.24312 0.603 1 1 Fractional MW-40 Tin 17000 10 100% Not Tested 63.76 8500 8500 Fractional MW-40 Uranium 30 10 0% Yes -0.3451 0.32869 0.1191 25.29 1.81625378 27.8 15 28.92 mean + 2SD MW-40 Vanadium 60 10 100% Not Tested 12.94 30 30 Fractional MW-40 Zinc 5000 10 80% No -17 0.01916 Decreasing 66.1 2500 2500.00 Fractional MW-40 Radiologics (pCi/L) MW-40 GrossAlpha 15 9 22% Yes -0.2394 0.53492 0.0573 1.3778 0.38005848 1.92 7.5 1.339 0.429 2.20 mean + 2SD (Cohen Adjustment) MW-40 Volatile Organic Compounds (pg/L) MW-40 Acetone 700 10 100% Not Tested 16.25 350 350 Fractional MW-40 Benzene 5 10 100% Not Tested 2.04 2.5 2.5 Fractional MW-40 Methyl ethyl ketone 4000 10 100% Not Tested 16.25 2000 2000 Fractional MW-40 Carbon tetrachloride 5 10 100% Not Tested 2.04 2.5 2.5 Fractional MW-40 Chloroform 70 10 100% Not Tested 2.04 35 35 Fractional MW-40 Chloromethane 30 10 100% Not Tested 2.04 15 15 Fractional MW-40 Methylene chloride 5 10 100% Not Tested 2.04 2.5 2.5 Fractional MW-40 Naphthalene 100 10 100% Not Tested 2.04 50 50 Fractional MW-40 Tetrahydrofuran 46 10 100% Not Tested 2.04 23 23 Fractional MW-40 Toluene 1000 10 100% Not Tested 2.04 500 500 Fractional MW-40 Xylenes, Total 10000 10 100% Not Tested 2.04 5000 5000 Fractional MW-40 Other MW-40 Chloride (mg/L) 9 0% Yes -0.5608 0.116 9 0.3146 41.433 3,88458492 47.1 49.20 mean + 2SD MW-40 Fluoride (mg/L) 4 10 0% Yes 0.55728 0.09421 0.3106 0.6905 0.08394211 0 805 2 0.86 mean + 2SD MW-40 Field pH (s.u.) 10 0% Yes 0.47601 0.16432 0.2266 6.762 0.24822928 7.06 6.27 mean - 2SD MW-40 Sulfate (mg/L) 10 0% Yes 0.31499 0.37535 0.0992 2196 242.175327 2600 2680.35 mean + 2SD MW-40 TDS (mg/L) 10 0% Yes -0.2445 0.49593 0.0598 3470 189.326291 3760 3848.65 mean + 2SD Notes: %ND = the percent of non-detected values in a data set. pg/L = micrograms per liter. GWCL = groundwater concentration limit. GWQS = Ground Water Quality Standard (R317-6-2 UT Administrative Code). HHV = Highest historical value. mg/L = milligrams per liter. N = number of data points in a data set. p = probability, where a value <0.05 is significant. M,INITERIX pCi/L = picocuries per liter. r = strength and direction of the linear relationship, where a negative value indicates decreasing trend. r2 = The measure of how well the trendline fits the data where r2=1 represents a perfect fit. S = Mann-Kendall statistic indicating how strong the trend is and which direction the data are trending (i.e. A large positive S value indicates a strong increasing trend, where a small negative value indicates a weaker decreasing trend). SD or Std. Dev. = standard deviation. s.u. = standard units. Background Groundwater Quality Report for MW-38, MW-39. and MW-40 White Mesa Uranium Mill, Blanding, Utah Page 3 of 3 Ma n g an e s e ( u g /1) Ma ng ane se ( u g /1 ) Ma ng an es e ( u g /1 ) Appendix C: Time Series Plots for All Constituents Showing Linear Regressions for Normal and Log-Normal Distributions (Non-Detected Values are Substituted with the Minimum Detection Limit) Manganese in MW-38 14 — 12 — 10 — 8 — 6 — 2019 2020 Sample Date Manganese in M -39 r 0.725 p = 0.0177 r = 0.5256 2400 — 2300 — 2200 — 2100 — 2000 — 2019 2020 Sample Date Manganese in MW-40 200 180 160 140 120 100 2019 2020 Sample Date Detect Non-detect — Regression tne I TERA Background Groundwater Quality Report for MW-38, MW-39, and MW-40 White Mesa Uranium Mill, Blanding, Utah Page 11 of 38 Appendix F: Data That Have Been Removed or Modified Prior to Statistical Analyses Field_Sample •cation_ . -• ate_ 'm•144 Parameter_ ,. Name Report_ esult .... . ”” Report_U nits , ........_ . lifi ,., mple_ Reason Removed .. , , MW-38_07182019 MW-38 7/18/2019 1Gross Alpha minus Rn and U 4.07 pCi/L GW Extreme Outlier MW-39_07172019 MW-39 7/17/2019 Gross Alpha minus Rn and U 17.9 pCilL GW Extreme Outlier MW-40_07162019 MW-40 7/16/2019 Gross Alpha minus Rn and U 5.24 pCi/L GW Extreme Outlier MW-40_05032018 MW-40 5/3/2018 Chloride 53.9 mg/L GW Extreme Outlier MW-39_05032018 MW-39 5/3/2018 Copper 51.1 ug/L GW Extreme Outlier MW-39_10292019 MW-39 10/29/2019 Fluoride 1.11 mg/L GW Extreme Outlier MW-39_05032018 MW-39 5/3/2018 Iron 12900 ug/L GW Extreme Outlier MW-39_05032018 MW-39 5/3/2018 Nitrate + Nitrite as N 0.182 mg/L GW Extreme Outlier MW-39_07102020 MW-39 7/10/2020 pH 5.08 pH Units GW Extreme Outlier MW-38_11062019 MW-38 11/6/2019 Potassium 41 mg/L GW Extreme Outlier, non-regulated constituent MW-39_05032018 MW-39 5/3/2018 Zinc 293 ug/L GW Extreme Outlier Notes: pg/L = micrograms per liter mg/L = milligrams per liter pCi/L = picocuries per liter U = result not detected above the laboratory reporting limit Background Groundwater Quality Report for MW-38, MW-39, and MW-40 White Mesa Uranium Mill, Blanding, Utah Page 1 of 1