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Coal Ridge No. 1 Mine C-1984-065: MT-08 April 2, 2019 <br /> <br />Page 5 of 27 <br /> <br />Wheeler Coal. The first three units have been recognized as regional aquifers where the hydrogeologic <br />conditions are suitable. Ground water occurs in both bedrock and alluvial deposits in the vicinity of the <br />mining operation. The potential for groundwater within the area of the mine is greatly limited by the <br />extreme dip of the rock strata which results in prohibitive drilling depths within a short distance . <br /> <br />All water from the three sandstone zones is of a sodium-bicarbonate water type. Total dissolved solids <br />range from 575 to 1,340 mg/l. This water type and range of concentrations are very similar to analyses <br />from the same geologic units taken from other locations along this structure and stratigraphy sequence. <br /> <br />Climatology <br /> <br />The climate is semi-arid with an annual precipitation of 16 inches. Average monthly precipitation varies <br />little throughout the year. Precipitation varies little seasonally, averaging one to two inches per month. <br />Snowfall can reach up to 60 inches in higher elevations. <br /> <br />Summers are hot, marked by very low humidity and cool nights. Winters are cold, generally snow-free, <br />but with frequent blizzard conditions. The mine site has a typical alpine climate, experiencing long, cold <br />winters, averaging from low teens at night to 30 degrees Fahrenheit in the day, and moderate summers. <br />"Mountain top" air flow of cold night air drains from the mountain sides down to the Colorado River <br />Valley. Prevailing winds blow from west and northwest to the southeast with an average velocity of 5.3 <br />mph. <br /> <br />Soils <br /> <br />Soils in the area are characterized as moderately deep to deep, well-drained loams with a dark colored <br />surface layer. Variability in the characteristics of the soil in the area is primarily due to slope and <br />topography. Deeper soils are located in the valley bottoms and at the foot of slopes whi le the shallower <br />soils occupy the steeper side slopes. <br /> <br />Two soil types have been identified at the mine site. These are the Heldt silty clay, found on the lower <br />slopes, and the Nihil stony loam found on the steeper slopes. <br /> <br />The Heldt silty clay occurs on alluvial fans and side slopes of the mountain valleys. The clay is fine, <br />slightly montmorillic and is grayish -brown in color. It varies from 10 to 60 inches in depth and is well <br />drained. <br /> <br />The Nihil stony loam (a loamy-skeletal mixture of sand and clay) occurs in alluvial fans and side slopes <br />of the mountain valleys. It is very pale brown in color. It is a deep (60 inches), well drained soil with <br />rapid permeability and low water retention capability. <br /> <br />Vegetation <br /> <br />Vegetation baseline information is contained on PAP pages 3-124 through 3-142 of Volume I, <br />Appendices 3.6-1 in Volume II, and 3.6-2 and 3.6-3 in Volume VI. The revegetation plan is contained <br />on pages 4-68 and 69, and 4-71 through 74 in Volume I. <br />