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<br />Mountain Coal Company <br />West Elk Mine <br />Post Ofriee Box 597 <br />Somerset, Colorado 87434 <br />Telephone 970 9235075 <br />Fax 970 9235595 <br />July 11, 1997 <br />RECEIVED <br />JUL 14 1997 <br />Dr. Jim Pendleton <br />Colorado Division of Minerals & Geology Division of rvunerais a Geology <br />Office of Mined Land Reclamation <br />1313 Sherman Street, Room 215 <br />Denver, CO 80203 <br />Re: Geotechnical Report -Sylvester Gulch Site Development <br />Ref: Permit Revision 07 and Technical Revision 79 to Permit No. C-80-007 <br />Dear Dr. Pendleton: <br />~II ~I~~II~~~~~~~ ~I~ <br /> <br />The following presents Mountain Coal Company's (MCC) current summary of geotechnical <br />issues for the Sylvester Gulch Site Development Project, as required by Permit Revision 07. <br />Although not required, similar related information pertaining to the Refuse Pile Expansion (RPE) <br />project (TR79) and various Minor Revisions aze also included. The following information covers <br />the time period from July 4, 1997 -July 11, 1997. <br />General Construction Summary <br />Construction of the RPE Pond (TR79) is 95% complete. Excavation of Phase 1C and creation of <br />structural fill via screening operations is in progress. Construction of the Pond SG-1 berms <br />began. Excavation of the Substation pad and cut slope aze nearing completion. Installation of the <br />96" X 57" azch culvert for the west fork of Sylvester Gulch is approximately 50% complete. <br />Installation of the foundation of the Plate Arch culvert for the main Sylvester Gulch crossing was <br />completed. Weather was dry throughout the period. <br />Field Monitoring and Observations <br />RPE: Completed slope excavations (south slope) for Phase lA and 1B are stable at <br />approximately Z:1. Site lines were observed and no movement was detected. No soft spots <br />or water was observed from the known springs uphill (south) of the excavation. <br />~Ivester Gulch Main Road: A major slope failure has occurred in a fill section of the Main <br />Road from Station 62+00 to 67+00. Failure was first observed on July 4th, 7 AM, as an <br />approximately 1 foot wide by 1 foot drop at Station 63+75. Additional cracks along the <br />section (Station 62 to 67) appeared over the next 24 hours. Daily monitoring was initiated on <br />July 5th using survey lathe to measure vertical and horizontal offsets. Offsets are now in <br />excess of six feet in some locations and are continuing to move. The toe of the fill also <br />appears to have moved east and northeast and is impinging on Sylvester Gulch. Two different <br />