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' S ~Z~ day of installation, the seismograph was automatically triggered by aground motion apparently created by the detonation of explosives in the nearby Colowyo Coal Company mine. Your monitoring personnel are proficient in seismograph operation and have subsequently made triggering and printout alterations better adapted to site requirements. All containers, instructions, and spare graphical paper and magnetic disks related to the Thomas seismograph were left with your monitoring personnel. We also inspected four structures that were selected jointly by Mr. Bob Trumbly of the Colowyo Coal Company and by Mrs. Naomi Durham, owner of the Durham Ranch. These buildings, the main ranch house, cottage, barn and garage (Building Nos. 1,2,3 and 4 respectively), were selected because of their relative value and importance To the ranch operation. The purpose of inspection was to document the existing "pre-blast" condition of the structures. Evaluation forms, sketches and photographs are enclosed. The evaluation process and documentation was based on a program we have used to establish criteria to monitor potential structural and architectural damage to residences due to underground mine subsidence in Weld, Boulder and EI Paso Counties, Colorado. We found no evidence of recent damage to any structure. The only noticeable structural flaws were apparent settlement of the south portion of the southwest exterior wall of the ranch house, and apparent settlement of the entire northwest exterior wall of the barn. Both situations appeared to be slow movements caused by gradual deterioration of the lowest logs in these walls, or perhaps by settlement of the masonry walls which serve as foundations. These walls are believed to be embedded at a shallow depth. If there are questions regarding this letter or its contents, please call us. Very truly yours, CT OMPSON, INC. Clyd R. nderson Sens En sneering Technician Revi~V 1. l Ronald M. McOmber, P.E. Associate CRA:RMM:kp