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Table 6 Dissolved Iron Concentration Statistics in Temporary Site Monitoring WellsColowyo Mine, Meeker, ColoradoDrainage Well NameNo. of Samples(1)Unit Average Minimum MaximumGroundwater Standard(2)Standard TypeUpgradient Well Site Background Value(3)Downgradient Well Site Background Value(4)% Exceeding Groundwater Standard% Exceeding Upgradient Well BackgroundGood Spring NGSW 21 mg/L 0.025 0.025 0.025 0.3 Drinking Water 1.48 - 0% 0%Good Spring POC-8 7 mg/L 0.678 0.025 2.950 0.3 Drinking Water 1.48 - 57% 14%Good Spring POC-9 2 mg/L 6.555 0.110 13.000 0.3 Drinking Water 1.48 - 50% 50%Good SpringPOC-10 7 mg/L 0.025 0.025 0.0250.3 Drinking Water 1.48 - 0% 0%Good SpringPOC-11 7 mg/L 0.060 0.025 0.270 0.3Drinking Water1.48 -0% 0%Good SpringPOC-12 7 mg/L 0.194 0.025 1.2100.3 Drinking Water 1.48 - 14% 0%Good SpringPOC-13 7 mg/L0.030 0.025 0.060 0.3 Drinking Water 1.48 - 0% 0%Good SpringPOC-14 7 mg/L 0.073 0.025 0.3600.3 Drinking Water 1.48 - 14% 0%TaylorMT-95-02 21 mg/L 0.025 0.025 0.0250.3 Drinking Water 1.48 - 0% 0%Taylor POC-3 7mg/L0.025 0.025 0.025 0.3 Drinking Water 1.48 - 0% 0%Wilson GOSSARD WELL 21mg/L0.025 0.025 0.025 0.3 Drinking Water 1.48 - 0% 0%WilsonPOC-1 7 mg/L 0.084 0.025 0.4400.3 Drinking Water 1.48 - 14% 0%Wilson POC-2 7 mg/L 0.031 0.025 0.070 0.3 Drinking Water 1.48 - 0% 0%Wilson POC-5 7 mg/L 0.124 0.025 0.720 0.3 Drinking Water 1.48 - 14% 0%Wilson POC-16 7 mg/L 0.025 0.025 0.025 0.3 Drinking Water 1.48 - 0% 0%Wilson POC-6 7 mg/L 0.094 0.025 0.350 0.3 Drinking Water 1.48 - 14% 0%WilsonPOC-15 7 mg/L 0.047 0.025 0.180 0.3Drinking Water1.48 -0% 0%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.(3) Site Background Value represents the 95 percent Upper Tolerance Limit for dissolved iron reported at upgradient wells A-6 and A-8.(4) No pre-1994 iron data were available to calculate background for Gossard and NGSW.(5) Non-detect sample results were assigned one-half of the reporting limit.Dissolved Iron ConcentrationPage 1 of 1