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• FIELD INVESTIGATION <br />The field investigation for the project was conduced in two phases. The first phase was completed on <br />September 9, 1997 and consisted of the excavation of three test pits in the north end of the RDA. The <br />second phase of dle investigation was completed on October 23, 1997 and consisted of dle drilling of two <br />test holes along the east edge of the RDA, in the location of the firs[ (lower) bench. The approximate <br />[es[ pi[ and [es[ hole locations are shown on Figure #1. Locations of the tes[ pits and holes were located <br />in the field by a representative of Northwest Colorado Consultants, Inc. and the actual locations and <br />elevations of the test pi[s and holes were determined by the client using an instrument survey. The test <br />pits and holes were logged by a representative of Northwes[ Colorado Consultants, [nc. <br />The first phase was conduced to determine the condition of the waste coal materials in the upper 10 feet <br />of the embankment, after they were placed and compacted. The tes[ pits were excavated with a Cat 436 <br />backhoe so tha[ the compaction of the fill materials could be determined using a nucleaz density gauge <br />and the subsurface profile could be visually observed. In addition, large disturbed bulk samples of the <br />waste coal materials were obtained from the test pits as they were excavated. The test pits ranged from 8 <br />[0 10 fee[ in depth. Graphic logs of the test pits are shown in Figure #2. The tes[ pit logs indicate the <br />• depth of [he compaction tests, as well as the results of the laboratory tests taken on the samples obtained <br />from those depths. <br />The second phase of the field investigation was conducted so that the deeper subsurface conditions could <br />be determined in the lower portions of the first bench. The test holes were drilled in[o the waste coal <br />materials, natural clays and underlying claystone bedrock with atrack-mounted drill rig utilizing 4-inch <br />diameter con[inuous High[ power augers. The [es[ holes ranged from 38 to 40 feet in depth. The test <br />holes were also cased with slotted, l.5-inch diameter PVC pipe so that groundwater levels could be <br />moni[ored aher the drilling was completed. Samples of the waste coal materials were taken from the test <br />holes with a 2-inch I.D. California liner sampler and a 1-3/8 inch I.D. standard split spoon sampler. The <br />samplers were driven in[o the various stra[a with blows from a 140-pound hammer falling 30 inches. <br />This tes[ is similar to the s[andazd penetration test described by ASTM Method D 153-86. Penetration <br />resistance values, when properly evaluated, indicate the relative density or consistency of the soils. <br />Depths at which the samples were taken and the penetration resistance values are shown on the logs of <br />the exploratory holes in Figure #3. The Legend and Noes associated with the test pit and hole logs aze <br />shown in Figures #4 and #5, respectively. <br />• <br />lob No. 97-3216 NoMwesl Colorado Cotuvllanu, Inc. Page 3 <br />