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October 9, 1985 <br /> To Mr. Greg Sparks <br /> Mr. Doug Murray <br /> From Dave Moody, Minerals Consultant <br /> Subject : American Tunnel Sludge Disposal <br /> I have reviewed the geotechnical investigation of Tailings Pond No. 3 <br /> dated April 28, 1976, authored by F. M. Fox and Associates, Inc. , and <br /> directed that an updated survey be conducted to show final constructed <br /> configuration. The tailings embankment factor of safety is currently <br /> in excess of 1.15 and up to 5.47 feet can be added to the embankment and <br /> still maintain this factor of safety. <br /> The Tailings Pond No. 3 site appears to be the best short term disposal <br /> area; however, several issues still need to be addressed prior to temporary <br /> disposal, including <br /> 1. Methodology of removal of standing water (pump 5 days) . <br /> 2. Analysis of sludge to assess a permanent disposal <br /> site (due October 19) . <br /> 3. Methodology of removal of sludge if it is required <br /> disposed on a geo-membrane liner (see 3.0 below) . <br /> Summary of Observations <br /> 1.0 Current configuration of embankment <br /> March 1978 April 1976 Surveyed <br /> Location Data Points Assumed 10/2/85 Added <br /> 1.1 Dam Crest #7 9455.90 9457.90 9464.20 6.3 ft <br /> 1.2 Dam Crest #5 <br /> and #6 9457.97 9459.97 9460.50 0.53 ft <br /> 1.3 Water Elevation 9453 Est -- 9454.0 1.0 ft <br /> 1.4 The current embankment at Sections AA and BB (10/2/85 survey) <br /> is at 1.58 to 1 and 1.67 to 1 respectively (horizontal to vertical) , <br /> and F. M. Fox recommends that this should be at a 2.5 to 1 slope. <br /> Physical inspection and review indicate that Section AA can achieve <br /> a slope of 2.26 to 1 and BB can achieve a 2.76 to 1 slope without <br /> highway relocation by earthen construction. <br />