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<br />configuration of the pile is sloped between 2.0:1 and 2.5:1 for the <br />entire height of the pile. <br />2. The existing coal processing waste pile is judged to be stable for the <br />various slope face configurations, strength properties and water <br />conditions modeled, with calculated safety factors between 1.4 and <br />2.5. <br />INVESTIGATION <br />Our field investigation was conducted in November of 1995. At that time, our <br />scope of work was for the Ciruela Canyon RDA. Subsurface conditions were <br />investigated by drilling 5 exploratory borings in the Ciruela Canyon RDA area and <br />one boring in the existing coal processing waste pile. The boring drilled in the coal <br />processing waste pile allowed us to sample the waste material and determine the <br />current depth of the waste pile. Our picture of the subsurface conditions is limited <br />due to the fact that only one boring was drilled in the waste pile area. We reviewed <br />data obtained from our previous investigations and from the 5 borings drilled in the <br />Ciruela Canyon RDA area and have assumed the subsurface conditions below the <br />existing coal processing waste pile to be similar. Information from our previous <br />investigation "Supplemental Stability Investigation, Refuse Disposal Area," Job No. <br />22,478, dated May 10, 1995, was considered in performing our evaluation. <br />The field investigation for the stability evaluation included a site visit and <br />drilling of one exploratory boring. The boring was drilled on top, near the center of <br />the coal processing waste pile. The approximate location of this boring is shown on <br />Fig. 2. Bulk samples of the coal waste were obtained off the augers and from the <br />surface of the waste pile. Groundwater was not encountered in this boring at the <br />time of drilling. <br />Samples obtained during the field investigation were returned to the <br />CTL(Thompson, Inc. laboratory for testing which included grain-size analyses on <br />three samples of the coal waste. Moisture-density relationship (ASTM D 698) and <br />direct shear tests were performed on a composite sample. The coal waste contained <br />significant percentages of large particles which cannot be included in conventional <br />Bla51N RESOURCES, INC. <br />CTL? 2],79] 2 <br />