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<br />• 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 s~~lected from <br />typical Sections 4 and 5, as they 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 sails. <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 in the analysis is 1.25. This factor of <br />safety corresponds to the mast critical sliver-type of shallow surface <br />failure at this location. This is considered to be an acceG~table safety <br />factor for this type of failure since a potential failure would involve <br />only a limited amount of material and because the out slope 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-t:ype failures <br />of the pile even when water is present within the pile. TFiis indicates <br />that the possibility of a large scale failure through the foundation <br />material is extremely remote. <br />• <br />_ 2~ <br />