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Erica Cosby 23Mar95 <br />Environmental Protection Specialist <br />Division of Minerals and Geology <br />State of Colorado <br />1313 Sherman St., Room 215 <br />Denver, CO 80203 <br />Dear Erica, <br />Attached is Cyprus Empire Corporation semi-annual subsidence report <br />monitoring report. The report is a result of regular quarterly surveying of the <br />longwall monument lines made on Sep94 and Nov94. The subsidence results <br />match permitted predictions and plans. As noted on the attached sheets, the last <br />surveys were done using the more accurate and weather proof GPS methodolgy. <br />In a related matter, Empire has been undermining a 6" Amoco pipeline since <br />1Jan95. This activity was approved under a previous TR and with Amoco's <br />written legal permission. The longwall face as of 22Mar95 has passed beyond the <br />pipeline. The actual maximum measured subsidence to date at trough center has <br />been 5.7 ft. Additional trailing and stabilizing subsidence is anticipated at an <br />additional 0.3 ft which will match exactly the total pre-mining forecast of 6.0 ft. <br />The pipeline has not had to be re-leveled as the strain induced on the pipeline by <br />subsidence has not even approached 50% of the design trigger point of 0.001 "per <br />1" of strain. The project has been a resounding success. You are most welcome to <br />come visit the site. <br />If you have any questions or comments please don't hesitate to call Marcus <br />Middleton or me at (303)824-8246. Please forward a copy of this report to Jim <br />Pendleton. <br />Sincerely, <br />~~, ~ ~"~° <br />Andrew P. Schissler, P.E. <br />Manager of Engineering <br />Cyprus Empire Corporation <br />cc. <br />Art Palm, General Manager, Empire. w/o attachments <br />Marcus Middleton, Em~ironmental Engineer <br />