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<br />CTL/THOMPSON. INC. <br />• COr+SULT~~G GEC°~-wiC.aL a,wC ;::~-_;- ,.~ S =NGir~EERS <br />May 21, 1982 <br />Empire Energy Corporation <br />6900 South Yosemite Street <br />Suite 160 <br />Englewood, Colorado 30112 <br />Attention: Mr. Rick Mills <br />Subject: Observation of Foundation Preparation <br />and Subsurfiace Drain Installation <br />Coal Processing Waste Bank <br />Empire Energy Mines No. 5 and 9 <br />Craig, Colorado <br />Jab Na. 8003 <br />Gentlemen: <br />At your request, we visited the subject Coal Processing Waste Bank area <br />during March, April and May of 1982. The purpose of our visits was to <br />observe preparation of the site far placement of coal processing waste, and <br />installation of the subsurface drainage system. This letter summarizes our <br />observations. <br />We made a preliminary geotechnical evaluation of the processing waste <br />disposal area in October 1979 (Job No. 5843). The report presented <br />recommendations far the configuration of the pile, subsurface drainage <br />recommendations, and general recommendations for the construction of the <br />waste bank. <br />Our preliminary investigation was completed prior to the development of <br />processing waste from the mining operation. In December of 1980, a sample <br />of processing waste was obtained, and Proctor compaction and direct shear <br />tests performed to confirm the strength parameters assumed for the <br />stability analysis made in our preliminary investigation. The results of <br />our testing, presented in a letter dated January 16, 1981 (Job No. 6918) <br />indicated that the waste bank would be stable to its planned maximum height <br />of 50 feet with 4:1 (horizontal to vertical) slopes. <br />Due to some variance between large scale topography used for initial design <br />and more recent topographic maps, some revision in the original design was <br />• necessary. The revised construction plans were completed August 12, 1981 <br />(Job No. 7372). We understand that the plan was accepted and approved for <br />construction by the Colorado Mine Land Reclamation Board (MLRB). <br />