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<br />site and regrade the problem spot. An existing access road <br />which parallels the stream channel can be used to reach the site <br />without disturbing any vegetated areas. Measures would be <br />taken to prevent soil erosion from the newly regraded area. <br />The stream will also be monitored for quantity and quality <br />before and after any coal is excavated from the area below, <br />as described in the section on surface water monitoring. <br />The contributing flow from this channel to Raton Creek and <br />the Purgatoire River is so small, and the water use is far <br />enough downstream that the impacts from the proposed profile <br />change would be minimal. <br />Possibility of Surface Water Entering the Ground Alono Fractures <br />• It is unlikely that any significant amount of surface water will <br />enter the ground through fractures for the following reasons: <br />(1) Average rainfall is inly 13.2 inches per year, <br />and the surface stream channels of the area only <br />flow a few times per year during storm events. <br />(2) The immediate roof the upper and lower seams is weak <br />and is expected to break up and fill the voids. pro- <br />duced shortly after mining. Studies in Europe have <br />shown that caving continues until the voids are <br />filled, which is usually about twice the seam <br />height. After this point, the main roof settles <br />on top of the broken material and compresses it <br />to cause surface subsidence, but does not break in <br />shear. Core descriptions of~the immediate and main <br />roofs indicate that the main roof will subside due <br />• <br />569 <br />D. H. EMLING COMPANY <br />