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designing for the 50-year flood. <br /> The results of the stability analyses for various pile configur- <br /> ations (existing conditions, future conditions, and the reclaimed con- <br /> figurations) are presented in the following paragraphs. <br /> 4.3 Existing Configurations <br /> For the stability evaluation of the existing waste piles, three <br /> typical sections were selected and analyzed. They were selected from <br /> typical Sections 4 and 5, as t'•ey are presented on Plates 10 and 11 . <br /> These three cases are described below: <br /> CASE I <br /> Stability analysis of the west pile (Section 4) . This case com- <br /> prises a large waste pile located mostly on the flat part of the alluvial <br /> valley, with a side slope on the order of about 33°. The pile is <br /> assumed to be underlain by colluvial soils. <br /> The results of the analysis of this section are presented on Plate <br /> 12, Results of Stability Analysis - Existing Waste Piles, Plate 1 . The <br /> lowest factor of safety found 'n the analysis is 1.25. This factor of <br /> safety corresponds to the most critical sliver-type of shallow surface <br /> failure at this location. This is considered to be an acceptable safety <br /> factor for this type of failure since a potential failure would involve <br /> only a limited amount of material and because the outslope of the pile <br /> will be flattened for final reclamation. Substantial safety factors in <br /> excess of 2.5 are indicated for deep-seated and foundation-type failures <br /> of the pile even when water is present within the pile. This indicates <br /> that the possibility of a large scale failure through the foundation <br /> material is extremely remote. <br /> - 22 - <br />