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Memo: <br /> To: Mr. Tony Waldron Date: August 23, 2001 <br /> From: Al Amundson <br /> Subject: Inspection of Schwartzwalder Mine,Permit Number M 77-300 August 21,2001 <br /> Concrete Retaining Walls <br /> At the request of the Operator Mr. Tony Waldron and Al Amundson visited the Schwartzwalder <br /> mine August 21, 2001 to discuss a Technical Revision with the mine personnel, which would allow <br /> leaving several concrete retaining walls in place rather than removing them as is presently provided <br /> in their reclamation plan. <br /> The retaining walls are located on the south side of the canyon, east of the bathhouse/office building <br /> which is being demolished. The walls retained the mine portal bench and provided elevated access <br /> to the crusher grizzley and ore sorting building. The walls are substantial reinforced concrete <br /> structures and appear to be sound. They appear to be founded on alluviallcolluvial material that is <br /> well drained. The mine staff proposes to leave the walls in place, and to backfill the free side at a <br /> 2h:ly slope. <br /> This combination of retaining wall with backfill against the wall should be more stable than a slope <br /> alone, and should not present a barrier to either vegetative growth or water percolation as long as the <br /> following conditions are met: <br /> 1 Backfill is to be installed in lifts and compacted as specified in the approved mine <br /> reclamation permit. <br /> 2 Broken concrete may be buried in the fill providing that at least the top four feet of <br /> cover is placed in lifts and compacted as specified in the approved mine reclamation <br /> permit. <br /> 3 Backfill is to be placed and compacted over the top of any remaining concrete to a <br /> minimum depth of two (2) feet. <br /> 4 Both the upslope and the downslope areas are to be sloped and compacted to prevent <br /> standing water accumulating on the fill. <br /> 5 The upslope transition from the natural slope is to be constructed and compacted to <br /> prevent water being conducted into the fill <br /> Please provide me with a copy of the mine's submittal so we can both review their submittal for <br /> completeness. <br />