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Table 14 Total Dissolved Solids Concentration Statistics in Temporary Site Monitoring WellsColowyo Mine, Meeker, ColoradoDrainage Well NameNo. of Samples(1)Unit Average Minimum MaximumGroundwater Standard using Upgradient Well Background(2)Standard TypeUpgradient Well Site Background Value(3)Downgradient Well Site Background Value(4)% Exceeding Groundwater Standard% Exceeding Upgradient Well Background% Exceeding Downgradient Well BackgroundGood Spring NGSW 21 mg/L 1934 1720 2190 1700 Drinking Water 1360 1840 100% 100% 71%Good Spring POC-8 7 mg/L 1080 440 1570 1700 Drinking Water 1360 1840 0% 14% 0%Good Spring POC-9 2 mg/L 1060 640 1480 1700 Drinking Water 1360 1840 0% 50% 0%Good SpringPOC-10 7mg/L1331 750 15601700 Drinking Water 1360 1840 0% 57% 0%Good SpringPOC-11 7mg/L1596 900 1790 1700Drinking Water1360 184043% 86%0%Good SpringPOC-12 7mg/L3093 2600 34801700 Drinking Water 1360 1840 100% 100% 100%Good SpringPOC-13 7mg/L 2313 1780 2750 1700 Drinking Water 1360 1840 100% 100% 86%Good SpringPOC-14 7mg/L3213 2590 53701700 Drinking Water 1360 1840 100% 100% 100%TaylorMT-95-02 21mg/L2303 2080 26001700 Drinking Water 1360 1840 100% 100% 100%Taylor POC-3 7 mg/L 2391 2310 2500 1700 Drinking Water 1360 1840 100% 100% 100%Wilson GOSSARD WELL 21 mg/L 1839 1640 2200 1700 Drinking Water 1360 1840 90% 100% 33%WilsonPOC-1 7mg/L1436 830 15901700 Drinking Water 1360 1840 0% 86% 0%Wilson POC-2 7 mg/L 1427 1290 1500 1700 Drinking Water 1360 1840 0% 86% 0%Wilson POC-5 7 mg/L 1920 1020 2400 1700 Drinking Water 1360 1840 86% 86% 86%Wilson POC-16 7 mg/L 3753 3360 4130 1700 Drinking Water 1360 1840 100% 100% 100%Wilson POC-6 7 mg/L 2694 630 5110 1700 Drinking Water 1360 1840 86% 86% 86%WilsonPOC-15 7 mg/L 1577 1400 2000 1700Drinking Water1360 184014% 100%14%Notes:mg/L = milligrams per liter(1) The period of record used to calculate statistics was January 2015 through March 2020 for the existing permanent monitoring wells, and October 2019 through November 2020 for the temporary wells.(2) Groundwater standard obtained from Colorado Department of Public Health and the Environment (CDPHE) Regulation No. 41, The Basic Standards for Ground Water (BSGW), adopted May 11, 2020, and effective June 30, 2020. Per Regulation 41, the standard for total dissolved solids (TDS) was calculated as 1.25 times the Upgradient Well Site Background Value.(3) Site Background Value represents the 95 percent Upper Tolerance Limit for total dissolved solids reported at upgradient wells A-6 and A-8.(4) Site Background Value represents the 95 percent Upper Tolerance Limit for total dissolved solids reported at NGSW and Gossard Well using Pre-1994 data.(5) Non-detect sample results were assigned one-half of the reporting limit.Total Dissolved Solids ConcentrationPage 1 of 1