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I I <br />Subsurface Conditions <br />The subsurface conditions described below are based on the boring drilled <br />in the waste pile area, the 5 borings drilled in the Ciruela Canyon RDA area and the <br />borings drilled for the previous investigations. The approximate location of the <br />boring drilled iri the waste pile area is shown on Fig. 2. <br />Subsoils encountered in the boring were 23 feet of coal waste over 6 feet of <br />clayey sands underlain by claystone bedrock. The depth of the coal waste <br />correlated reasonably well with pre-construction topographic information. The <br />engineering properties of the coal waste are discussed in detail in following sections. <br />A very dense clayey sand or possible weathered bedrock layer was logged <br />below the coal waste. This layer was comparatively thin, typically 5 to 6 feet thick. <br />The layer was primarily identified by drilling resistance and vibration, essentially the <br />drilling "smoothed out" over this interval just prior to encountering very hard <br />bedrock. We interpret this layer as a combination of a disturbed soil zone created <br />during stripping and weathered bedrock. The bedrock found in the boring consisted <br />of hard to very hard, interbedded sandstone and sandy shale. <br />Groundwater Conditions <br />Groundwater was not encountered in the boring drilled at the waste pile at the <br />time of drilling. Since this boring was primarily for sampling purposes, the boring <br />was backfilled after drilling and additional water level measurements could not be <br />made. The presence of water within the pile is a significant stability concern and <br />water conditions were evaluated in the stability analysis. <br />Coal Refuse ProAerties <br />The results of laboratory testing for this investigation are shown on Figs. 4 <br />through 7. The results of laboratory testing from previous investigations were also <br />BASIN RESOURCES, INC. <br />CTL'f 27,79] 4 <br />