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III IIIIIIIIIIIII III 999 w BASIN RESOURCES, wc. a subsidiary of ENTECH, Inc. Mr. Ken[ Gorham State of Colorado Division of Minerals & Geology 1313 Sherman Street, Roam 215 Denver, Colorado 80203 ~N~` ` Q ak ir.~,lv~t'~ cwt m ~ ~~~ l/u' ~~ ~ 5~~,,,, - Re: Golden Eagle Mine Permit No. C-81-013 Technical Revision 48 -Subsidence Monitoring Dear Mr. Gorham: RECEIVED AUG 2 6 1998 DIV. OF MINERALS 8 GEOLOGY Enclosed is an application for a technical revision to modify the subsidence monitoring plan for the Golden Eagle Mine. The currently approved plan, originally designed for continuous operations throughout the permit term, was modified in 1997 by technical revision 46. This revision eliminated a number of monitoring stations where subsidence had either ceased, or where mining operations were terminated prior to mining approaching their location. The proposed revision updates the subsidence data within the permit and requests approval for the termination of subsidence survey requirement for the remaining active stations. The remaining active stations were monitored quarterly through the remainder of 1997 and the first two quarters of 1998. Tables 26 and 27 of Exhibit 24 have been updated to include this most recent data. (It should be noted that due to weather conditions and scheduling conflicts, not all of the survey stations were occupied during each calendar quarter; however, each station was surveyed four times during the calendar year.) Eleven (11) stations within [he Zamora Canyon survey line were destroyed by Oil and Gas right-of--way construction in 1998. However, thirty-three adjacent stations indicate that the area has stabilized and no subsidence has occurred for at least the last twelve months. Further, the remaining stations will provide _ adequate information to evaluate any future affects of subsidence. For these reasons, Basin requests approval to not reestablish these stations. Remaining stations will be protected and remain in place V_ through final bond release. Table 27 presents an analysis of the cumulative data for each station. The lust four columns provide the station name, survey date, and raw data from each survey. Successive columns provide the cumulative change from the basin line survey, change from the previous survey, and finally the change over the last twelve months. Table 26 lists the horizontal and vertical displacement and compares the maximum displacement to the displacement over the last 12 months for each station. The observations show that none of the remaining active subsidence monitoring stations has experienced significant movement during the last l2 months. Further, most of these stations have had no significant movement over the last 24 months. • • 14300 Highway 12 Weston, Colorado 81091 (719)868-2761 Purchasing (719) 868-2768 Fax (719)868-2275 ~y} ~ 0.I 5j~' i Q1 "' ~ ~I d 15~ ?ttgtt1? 24, 1998