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~ ii _$_ <br />~~I3.3 CONCLUSIONS <br />' The initial rock pile will be underlain by approximately 50 feet of <br />colluvial soils composed principally of impermeable clays. Ground water has been <br />detected within a bedrock unit up slope of the pile, but has not been detected <br />downslope. For these reasons, we believe that there is an extremely low <br />potential for the contamination of ground water due to the presence of the waste <br />pile. Two monitoring wells located upslope and downslope of the pile will be <br />monitored throughout the period of the operation of the waste rock pile to <br />' confirm that the pile does not affect the ground water. We consider these <br />conditions justify our preliminary recommendation for the elimination of the <br />' subdrainage system. <br />~ Stability analyses using shear strength parameters obtained from testing <br />samples obtained from the general area of the pile, and confirmed using samples <br />obtained from the immediate vicinity of the pile, indicate that there should be <br />no foundation stability problems. Design recommendations based on the assumed <br />j composition of the pile have also been developed based on these stability <br />J analyses to insure the stability of the pile. <br />We consider that the initial waste rock pile can be satisfactorily con- <br />strutted using the preliminary design recommendations of our previous report. In <br />brief, these include the following: <br />l o Tentative design uniform slopes of 1.0 (v): 2.25 (h), to be reviewed <br />subsequent to sampling and testing of waste pile material. <br />o A 15-foot wide near-horizontal bench along the crest of the pile. <br />1 o Adequate surface drainage of the area surrounding the pile and of the <br />7 pile itself after reclamation. <br />o Adequate foundation preparation prior to the placement of the pile by <br />removal of all topsoil and loose, organic, wet, or otherwise objec- <br />tionable materials and grading of the foundation. It is estimated that <br />an average of approximately two feet of soil will have to be removed, <br />although this should be determined during field inspections. <br />~o+noao coHwina~, iHe. <br />