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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 are representative of <br />water within the lower Dakota Sandstone. This confined aquifer is recharged along the <br />Uncompahgre Plateau to the northeast and discharges towards the southwest. Transmissivity was <br />measured at six sites and varies from 3.0 to 88 ft2/day, averaging 38 ft2/day. Hydraulic <br />conductivity values varied from 0.07 to 4.5 ft/day, averaging 1.6 ft/day. This aquifer is not used <br />locally to any great extent. <br />The water in the underburden is characterized 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 bicarbonate type <br />water. The TDS varies from 960-2648 mg/l, averaging 1619 mg/l. Dissolved iron levels vary <br />from 0.02 to 2.51 mg/1 and average 0.63 mg/l. The sodium bicarbonate well occasionally exhibits <br />pH levels that exceed the recommended agricultural standard. Another well shows manganese <br />levels that exceed the agricultural standards. All wells meet the recommended water quality <br />standards for livestock watering. The underburden aquifer does not produce acceptable water for <br />domestic purposes; TDS, sulfate and ammonia standards are exceeded. Measurable trace element <br />concentrations in the underburden aquifer include aluminum, arsenic, boron, cadmium, copper, <br />fluoride, iron, lithium, manganese, mercury, nitrate, vanadium and zinc. <br />Ground water within 150 feet of the ground surface has been only minimally developed for use in <br />the Nucla area. High salinities and occasionally high sodium or sulfate concentrations preclude <br />its use as domestic, agricultural or stock water. In addition, moderate hydraulic conductivities are <br />coupled with low sustained well yields (less than 1.5 gpm), discouraging sustained dependence on <br />wells completed within these aquifers. <br />E. Soils <br />There were three major soils types in the original 220 -acre NHM area: Progresso -Bond Complex, <br />2 to 15 percent slopes; Barx — Barx, scalped — Barx, buried complex, 1 to 4 percent slopes; and <br />Lithic-Typic Haplaquolls, 1 to 3 percent slope. The Progresso -Bond complex is comprised of 40 <br />percent Progresso, 40 percent Bond, 10 percent Barx (see below), 5 percent Travesilla, and 5 <br />percent Bowdish series soils. The Progresso series is classified as a fine -loamy, mixed, mesic, <br />Ustollic Haplargid. The Bond series is a loamy, mixed, mesic Lithic Ustollic Haplargid. The main <br />difference between these two is the distance to bedrock; Bond soils are shallow (17 to 19 inches <br />to bedrock) while Progresso soils are fairly deep (36 inches to bedrock). Barx soil is found in the <br />southeast corner, primarily within Mapping Unit D70B. It is classified as a fine -loamy, mixed, <br />mesic Ustollic Haplargid. It is a deep, well -drained sandy loam formed in sandstone derived <br />alluvium. <br />The ephemeral drainages contained three families of Haplaquoll soils: Lithic, Lithic/Typic, and <br />Typic Haplaquolls. The loamy, mixed, mesic, Lithic Haplaquolls are found in the upper reaches <br />of the swales in the area and are the shallowest of the three series (bedrock at 11 inches). <br />Lithic/Typic Haplaquolls (coarse -loamy, mixed, mesic, moderately deep Typic Haplaquolls) are <br />found in the mid to lower reaches of the swales and exhibit good quality soil to a depth of about <br />14 <br />