2011-01-06_REPORT - C1982056 - Laserfiche WebLink

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ortnWest Colorado Consu Geotechnical / Environmental Engineering • Materials Testing January 5, 2011 Twentymile Coal Company 29515 RCR #27 Oak Creek, CO 80467 Attn: Mr. Jerry Nettleton Job Number: 99-3983 Subject: Quarterly Observation Report, Refuse Pile, Foidel Creek Mine, Routt County, Colorado. Mr. Nettleton, As requested, NWCC, Inc. (NWCC) has prepared this report outlining our observations made during the fourth quarter of 2010 at the Refuse Pile, which is located at Twentymile Coal Company's (TCC) Foidel Creek Mine in Routt County, Colorado. During this quarter, Tim Travis of NWCC visited the project site on December 28, 2010 to provide the quarterly inspection/observations of the Refuse Pile. In addition, a representative of NWCC visited the refuse pile on October 29 and December 23, 2010 to take compaction tests in the new Expansion Area of the refuse pile. On October 29, 2010, a total of five compaction tests (#447 to #451) were taken in Expansion Area near the newly constructed underdrain during this visit. On December 23, 2010, a total of two compaction tests (#452 and #453) were taken at the western end of the new Expansion Area. All of the tests taken on these dates met the minimum compaction requirement of 90% of the maximum standard Proctor density. Copies of the compaction test results and the daily field reports are attached. It should be noted that the abbreviations given in the Nuclear Density Test Results (Proctor Data) are as follows: Maximum DD = Maximum Dry Density and OMC = Optimum Moisture Content. Both of these values have been determined in accordance with ASTM D698. At the time of our site visit on December 28, 2010, we completed a cursory site inspection of the existing refuse pile. Based on our observations made during this visit, it appeared that the contractor was presently stockpiling the refuse coal in western portion of the new Expansion Area over the west end of the recently constructed underdrain. The surface drainage conditions generally appeared to be adequate across the top and sides of the existing pile. However, the shallow erosion channels located on the lower bench on the east side of the refuse pile, as noted in our previous inspection report, did not appear to have been repaired. We recommend that these erosion areas be re-graded so that the runoff does not concentrate in these areas and cause further erosion. (970) 879-7888 a Fax (970) 879-7891 2580 Conner Ridoe T)rive. • RtPamhnnt Cnrinac (`r) RCIA97