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Doc Date:12/11/2001 <br />iii iiiiiiiinm iii <br />1997 GEOTECHNICAL DRILLING PROGRAM (MR#218) <br />SYLVESTER GULCH FACILITIES AREA <br />SCOPE: OF WORK <br />ivloun[ain Coal Company (MCC) proposes a geotechnical drilling program to collect the <br />data necessary for the siting and design of future facilities on the main mine site and in <br />Sylvester Gulch. The drilling program is divided into 15 geographic areas which are <br />shown on the enclosed map. Approximately 127 drill hole are proposed for this drilling <br />program. Long-range data adequacy goals have been assessed and planned as much as <br />possible; however, more site-specific data may be necessary as specific structures are <br />designed and built in the future. Additional revisions will be submitted as the additional <br />data needs are defined. The program will begin as soon as this revision application is <br />approved and be completed by October 31, 1997. <br />As the drilling program will occur concurrently with the construction in Sylvester Gulch, <br />it is difficult to specify what earthwork will be needed to construct roads and drill pads. <br />Therefore, all of the road building, pad building, etc. presented in this revision is <br />considered to be worst case. The drilling program will work around the construction in <br />Sylvester Gulch and the drillers may be able to use roads consuvcted for the Sylvester <br />Gulch Facilities Area. <br />• Drilling Program <br />In general, the geotechnical investigation will consist of collecting soil and rock samples <br />to be analyzed for subsurface characterization, installing piezometers to monitor <br />fluctuations in groundwater level, and drilling holes to bedrock to determine the depth to <br />bedrock. <br />No mud pits will be constructed at any of the drill locations. All water used in the <br />drilling process will be contained in a tank and recycled. <br />The soil borings will be drilled with an approximate 6-inch outside diameter, hollow stem <br />augers. Samples will be collected with split-barrel samplers or Shelby tubes. Samples <br />will be collected on 5 to 10-foot intervals. If encountered, water levels at selected <br />locations will be recorded. <br />Some soil boring locations have been selected for the installation of piezometers. The <br />enclosed map shows the location of the piezometers. The piezometer will be constructed <br />of 1-inch schedule 40 PVC casing and factory slotted screen. Coarse-grained sand will <br />be applied to the borehole in the screened interval, and bentonite will be used to backfill <br />the borehole from two feet above the top of the screen to the ground surface. Metal <br />locking protective casing will be installed at the surface of the piezometer to protect it <br />- from damage and to retain its long-term viability. A total of 43 piezometers will be <br />installed. <br />E.rhibit 69 June 1997 <br />esh69mr218.doc <br />