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<br />Effects of Underground Coal Mining on the Solitario Ranch Well Page 2 <br />Subsidence Monitoring Plan; and various letters, memos and other correspondence <br />concerning the well. <br />OTHER DATA <br />A copy of a United States Geological Survey aerial photograph was obtained to <br />locate the well and associated windmill, relative to the ventilation abaft and other <br />surface features. From this, the well could be located on a scanned copy of the area <br />of interest of Map 17, which also includes the location of the underground mining. <br />(Map 1). <br />Elevations for the bottom of the ventilation shaft, water bearing horizons, and <br />certain data on the well, were included in a letter from Basin Resources to the <br />Division of Minerals and Geology dated 6/15/94. <br />EVALUATION <br />A drawdown curve is a graphical representation of the effects of dewatering a <br />water-bearing formataon. It usually takes the shape of a hyperbolic cone around a <br />point such as a dewatering well. and can take the same shape along the edges of <br />mine workings. The drawdown cone represents a pressure surface of the water in a <br />rock formation effected by the dewatering. It is generally defined by water level <br />measurements in monitoring wells spaced at distances from the locus of the <br />drawdown. <br />The shape of the curve is effected by the rate of dewatering, and the amount of <br />recharge, and can be unique to a specific mine or even section of a mine. <br />Whenever a mine is dewatered the goal is to limit the effects to only the formation <br />of interest and to avoid pumping unnecessary water or flooding, by not intercepting <br />waters in formations above or below the mine. Whenever caving takes place all the <br />formations above the mine are affected to the limits of subsidence. Drillholes <br />through multiple formations that are not properly sealed can influence the results, <br />as can natural rock breaks called faults. <br />A drawdown curve and the data used to construct it, for the Golden Eagle mine, is <br />included in the hydrology report as Figure 7. This curve was used for this study. <br />According to the data both the shaft and the underground mining activities are <br />close enough to potentially affect the water level in the well. The mining activities <br />involve caving and this action would cross the water bearing zones and this would <br />alter the well's water level (See Chart 1). Subsidence has been reported above the <br />NW #1 workings and subsidence monitoring stations, in this area, are included as <br />part of Subsidence Monitoring Plan. <br />PIONEER ENGINEERING <br />