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i <br />ii 1 with a measurably higher silt content and lower gravel content <br />in the near surface soils located in the upper 5 to 10 ft of <br />~ ~ the profile. The laboratory test results indicate that these <br />silty soils can be readily amended using relatively small <br />percentages by weight of powdered bentonite, and thereby made <br />suitable for use in a compacted soil liner. The permeability <br />of the compacted soil liner will be 1 x 10-b cm/sec. Natural <br />clay content is generally low in all of the native soils with <br />' the majority occurring in discontinuous pockets o1'topsoil and <br />as scattered lenses interbedded with sands at depth. Relatively <br />clean sands and gravels exist locally where intermittent stream <br />action has occurred. Higher up on the slopes, the Santa Fe <br />Conglomerate is exposed. Hard, non-rippable bedrock materials <br />were not encountered in any of the boreholes or test pits. <br />Groundwater was encountered in boreholes BH-6, BH-7, and <br />BH-8 at depths of approximately 22 ft, 77 ft, and 52.5 ft, <br />respectively, however, the water is believed to b? from small <br />' perched aquifers. <br />Some aeolian (wind-blown) deposits were identified <br />locally during the exploration program although mast of these <br />' materials were encountered in the potential borrow area located <br />to the south and west of the heap leach facilities. Nuclear <br />' density testing indicated law density and, therefore, high void <br />ratio (up to 1.0) for some of these deposits. Nuclear density <br />test results are included in Appendix D. Due to thf~ relatively <br />shallow depth and infrequency of occurrence, these aeolian <br />deposits are expected to be excavated during site grading and <br />' are not anticipated to be hazardous to the integrity of the <br />proposed facility. <br />D.7.3 Material Characteristics <br />' Simulated San Luis heap leach ore was tested for <br />geotechnical and geochemical characteristics. The sample was <br />D-40 (Revised 4/20/89) <br />