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ii 999 -'" It • POWDERHORN COAL COMPANY 1993 ANNUAL SUBSIDENCE REPORT ,f /1~~f O ~. ~co~ visual Inspection by: Larry Reschke Report by: Larry Reschke This report is being written in response to Stipulation 12 to Powderhorn's Mining and Reclamation Permit No. C-81-041. The stipulation requires a semi-annual visual inspection of the surface over areas mined or projected to be mined during the current permit term and an annual report. The area projected to be mined during the current permit term is shown on Exhibit 5 of our permit application. At the time of the first visual subsidence survey there was some thought of changing the orientation of mining panels from E-W to N-S; therefore, the survey covered these areas as well. The attached diagram shows the mine at the end of 1992 and 1993, projections for two possible mining patterns, and the inspection path. The projected mining area is an grid mountainous region. The Cameo B seam rests on or near the Rollins sandstone. This massive cliff-forming sandstone creates a bench upon which less resistant formations slope moderately to steeply up to the next massive cliff forming sandstones. The moderately sloping area • generally corresponds to areas of the mine with less than 500' of cover and the steep areas from 500 - 1000' of cover. It is the interval with less than 500' of cover which will be most susceptible to visual subsidence affects. The projected mining area is under federal lease with the federal government owning both surface and coal estates. Mining during this period will be done under multiple small ephemeral drainages but is not projected to be done under the nearby Cottonwood Creek or adjacent water lines. There are no building, structures or known cultural resources within this area. The first inspection in accordance with the stipulation was done on September 22 and 24, 1993. On September 22 the inspection started near the No. 2 West portals and extended south to cover the moderately sloping area on the west end of the projected mining area. Pictures were taken of the mining area from different locations. The enclosed photographs correspond to numbered locations on the attached diagram. There were no specific subsidence related features found, mapped or photographed on this inspection. The September 24 inspection started up Cottonwood Creek where our 5 East Mains cross under the creek and proceeded south and west to cover a steeply sloping area on the northeast corner of the projected mining area. Again pictures were taken from different locations but no subsidence related features were found, mapped or photographed. •