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-3- <br />1 <br />1 <br /> <br /> <br />2.0 SITE CONDITIONS <br />2.1 GEOLOGIC CONDITIONS <br />Three geotechnical borings were angered and sampled to investigate the <br />geologic conditions in the immediate vicinity of the initial rock waste pile. <br />Locations of borings are shown on Plate 1, and geologic logs of the borings are <br />presented in the Appendix. <br />The borings indicate that the area of lower bench where the initial waste <br />rock pile will be located has approximately 50 feet of soils, probably colluvium <br />and slopewash materials, overlying bedrock. The soils are mostly unsaturated, <br />low plasticity silty and sandy clays. Standard penetration tests indicate this <br />material to be generally very stiff to hard. Sandstone, cobbles and boulders, and <br />Tenses of more sandy soil, are present throughout the colluvium. <br />Bedrock consists of shales, siltstones, sandstones, and coal of the <br />retaceous Mesa Verde Formation. =the top of bedrock was encountered at depths of <br />etweeen 47 and 53 feet below ground surface. Approximately 2} feet of coal was <br />ncountered at the bottom of boring No. Z. A cross section developed from <br />rilling results is presented as Plate 2. <br />No measurable water inflows were noted in any borings during drilling. <br />owever, subsequent water level measurements in boring No. 2 indicated a <br />tanding water TeveT at about 43 feet below the ground surface, which is some 10 <br />eet above the bedrock elevation. <br />Water was measured in boring No. 3 at a depth of 51 feet below the surface <br />levation following the falling head test. This corresponds to the elevation of <br />he bottom of the perforations in the piezometer, and is taken to indicate an <br />bsence of ground water within the depth to which the piezometer extends. <br />No water quality samples were collected for analysis; at the time of our <br />field investigation, it was not apparent that ground water had been encountered <br />in any of the borings. Since the presence of ground water in boring No. Z was <br />indicated by subsequent monitoring, water quality samples should be collected <br />and tested as specified in the section on recommmended monitoring. <br />csoHwao coNw~nr~c. iNC. <br />