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IIIllllllllllllllll °~~~~~=~~ "~ ~'-~ <br />uPR 2 1 19$9 <br />Proposal <br />WASTE PILE AND WEST PORTAL CUT STUDIES a~.::'•'_^ .'_!,;.,~~ <br />FOR CYPRUS ORCHARD VALLEY COAL CORPORATION^C~ ~11f,F~; sU~L ~';J:':;e)i~, <br />INTRODUCTION <br />During the week of March 27, 1989, Messrs. Joe Green-Heffern <br />and Mike Bukovansky visited the Cyprus Orchard Valley Mine <br />at Paonia, Colorado. The purpose of their visit was to observe <br />the conditions of the existing waste pile and the recent <br />failure of the north side of the west portal cut. <br />Following this site visit, a meeting was held at the Colorado <br />Mined Land Reclamation Division on March 30, 1989. At this <br />meeting, possible improvements of the waste pile and investi- <br />gation of the west portal cut failure were discussed. <br />This proposal presents a brief description of the existing <br />conditions at both these sites, recommendations for geotech- <br />nical investigations, and recommendations for subsequent <br />design activities to correct or to mitigate the problems at <br />the waste pile and at the cut portal failure. <br />WASTE PILE EXISTING CONDITIONS <br />The existing waste pile (waste rock disposal site) was designed <br />and permitted by Colorado Westmoreland Inc. (CWI), assisted <br />by Geo-Hydro Consulting, Inc. in 1983. Slopes were designated <br />at 2(H):1(V), with terraces 20 feet wide at vertical intervals <br />of 50 feet. Compaction of the waste pile material was specified <br />to be at least 90 percent of the maximum standard dry density <br />(AASHTO T99-74). <br />At present, only the west ridge pile has been constructed. <br />According to Cyprus3records and recent surveying, slightly <br />more than 60,000 yd have been deposited in the waste pile. <br />Recent inspections and surveys performed by Cyprus and their <br />consultant, Lambert and Associates, indicated that the existing <br />waste pile, at certain locations, does not fully comply with <br />the design specifications. The waste pile slopes are, at <br />several locations, steeper than 2(H):1(V); slopes as steep <br />as 1.7(H):1(V) were measured. Relative compaction of less <br />than 90 percent was identified at several locations by Lambert <br />and Associates. This evaluation was based on measuring dry <br />densities at different depths in the pile and comparing them <br />to the maximum dry density of one reference sample compacted <br />in accordance with AASHTO T99-74. <br />DEN/40Y/020 1 <br />