Laserfiche WebLink
livestock drinking water. In addition, concentrations of manganese and fluoride exceed the <br />agricultural use standazds 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 rechazged from the east north-east and dischazges to the west and along <br />Calamity Draw. The transmissivity varies from 0.92 to 6.0 ft2/day, based on hydraulic conductivity <br />values of 0.04 to 0.34 fUday (average values of 0.19 ftlday), 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/1, averaging 2822 mg/1 at New Horizon Mine. Three <br />wells at the New Horizon Mine 2 exhibit two distinct geochemical chazacteristics. Two wells have <br />calcium/magnesiumsinfate 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 coal 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 rechazged along the <br />Uncompahgre Plateau to the northeast and dischazges towazds the southwest. Transmissivity was <br />measured at six sites and varies from 3.0 to 88 ftZ/day, averaging 38 ft2/day. Hydraulic conductivity <br />values varied from 0.07 to 4.5 fUday, averaging 1.6 fUday. This aquifer is not used locally to any <br />great extent. <br />The water in the underburden is chazacterized as hard, moderately alkaline saline water with high <br />sulfate concentrations (average sulfate concentrations of 695 mg/1). Two wells show a <br />calcium/magnesium sulfate type water while one well shows an alkaline sodium bicazbonate type <br />water. The TDS varies 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 bicarbonate well occasionally exhibits pH <br />levels that exceed the recommended agricultural standard. Another well shows manganese levels <br />that exceed the agricultural standards. All wells meet the recommended water quality standazds for <br />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 />Ground water within 150 feet of the ground surface has been only minimally developed for use in the <br />Nucla area. High salinities and occasionally high sodium or sulfate concentrations preclude its use <br />as domestic, agricultural or stock water. In addition, moderate hydraulic conductivities aze coupled <br />with low sustained well yields (less than 1.5 gpm), discouraging sustained dependence on wells <br />completed within these aquifers. <br />