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53 ft'lday, averaging 13.3 ft'lday. The McWhorter analysis of pit inflow conservatively estimated <br />that the hydraulic conductivity of the overburden was 0.61 fUday. Hydraulic conductivity <br />calculations from field tests of the overburden showed a range of 0.39 to 1.05 ft/day, indicating <br />moderate permeability. <br />The water Found in the overburden is characterized as very hard, saline, calcium magnesium sulfate <br />water with neutral pH. TDS levels vary from 1494-10074 mgll and average 4613 mgl1. Sulfate <br />concentrations are very high, varying from 875 mg/l to 6872 mg/1 and averaging 3176 mg/1. In some <br />of the overburden wells, sulfate, TDS, manganese and fluoride exceed recommended standards for <br />livestock drinking water. Tn addition, concentrations of manganese and fluoride exceed the <br />agricultural use standards in some wells. <br />The Dakota coal has been described as an aquifer. Wells completed in the Dakota show water level <br />fluctuations of 1.3 to 14.6 feet. The water table exhibits seasonal fluctuations with high water levels <br />in late fall. The aquifer is recharged from the east north-east and discharges to the west and along <br />Calamity Draw. The transmissivity vazies from 0.92 to 6.0 ftZ/day, based on hydraulic conductivity <br />values of 0.04 to 0.34 fUday (average values of 0.19 fUday), reflecting moderate flow capabilities. <br />The water quality of the Dakota coal is unacceptable for most uses. The saline, sulfate-based water <br />has TDS levels varying from 1050-4444 mg/I, averaging 2822 mg/1 at New Horizon Mine. Three <br />wells at the New Horizon Mine 2 exhibit two distinct geochemical characteristics. Two wells have <br />calcium/magnesium sulfate water with the pH averaging 5.4. One well, 17-P1, is an alkaline sodium <br />sulfate water with the pH averaging 9.2. Iron, manganese, aluminum, fluoride and pH levels exceed <br />recommended water quality criteria for agricultural use, and concentrations of aluminum and fluoride <br />exceed recommended water quality criteria for livestock. <br />The aquifer underlying the coat is identified as the underburden aquifer. The wells in the <br />underburden have been completed 17 to 64 feet below the coal, and samples aze representative of <br />water within the lower Dakota Sandstone. This confined aquifer is recharged along the <br />Uncompahgre Plateau to the northeast, and dischazges towazds the southwest. Transmissivity was <br />measured at six sites and vanes from 3.0 to 88 ftZ/day, averaging 38 ftZ/day. Hydraulic conductivity <br />values vazied from 0.07 to 4.5 fUday, averaging 1.6 ft/day. This aquifer is not used locally to any <br />great extent. <br />The water in the underburden is chazacterized as a hazd, moderately alkaline saline water with high <br />sulfate concentrations (average sulfate concentrations of 695 mg11). Two wells show a <br />calcium magnesium sulfate type water while one well shows an alkaline sodium bicarbonate type <br />water. The TDS vanes from 960-2648 mg/1, averaging 1619 mg/1. Dissolved iron levels vary from <br />0.02 to 2.51 mg/1 and average 0.63 mg/1. The sodium bicazbonate well occasionally exhibits pH <br />levels which exceed the recommended agricultural standard. Another well shows manganese levels <br />which exceed the agricultural standards. All wells meet the recommended water quality standazds <br />for livestock watering. The underburden aquifer does not produce acceptable water for domestic <br />purposes; TDS, sulfate and ammonia standazds aze exceeded. Measurable trace element <br />concentrations in the underburden aquifer include aluminum, azsenic, boron, cadmium, copper, <br />fluoride, iron, lithium, manganese, mercury, nitrate, vanadium and zinc. The highest concentrations <br />of arsenic, mercury and copper were measured in the underburden aquifer at the New Horizon 2 <br />mining azea. <br />s <br />