REP39118 - Laserfiche WebLink

Home Browse Search

~c~~ rthWest Colorado Consults Geotechnical /Environmental Engineering • Materials Testing September 9, 2002 Twentymile Coal Company 29515 RCR #27 Oak Creek, CO 80467 Attn: Mr. Rick Mills Job Number: 99-3983 Subject: Quarterly Observation Report, Refuse Pile, Foidel Creek Mine, Routt County, Colorado. Gentlemen: RECEIVED ocra~~~ Division of Minerals and Geology As requested, NWCC, Inc. (Northwest Colorado Consultants, Inc.) has prepared this letter outlining our observations made during the third quarter of 2002 at the Refuse Pile, which is located at the Foidel Creek Mine in Routt County, Colorado. During this quarter, we visited the project site on August 8 and September 24, 2002 to provide our quarterly observations, as well as to test the compaction of the materials being placed and compacted. At the time of our site visit on August 8, 2002, we conducted five (5) compaction tests (#220 [o #224) across the portion of the refuse pile in which the failing tests were recorded during our last visit on June 26, 2002. It appeared that the contractor had scarified and recompacted these areas prior to our site visit. A copy of the compaction test results and daily report are attached. Based on the compaction test results, it appeared that the areas that had been scarified and recompacted met the project specifications for compaction. I[ 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/AASHTO T99. At the time of this site visit, we also observed that the majority of the refuse materials (waste coal) being produced were being stockpiled in the south end of Area 2. At the time of our site visit on September 24, 2002, we met with Mr. Rick Mills of Twentymile Coal Company to observe the conditions at the Refuse Pile. At the time of our visit, it appeazed that the majority of [he refuse materials (waste coal) chat were being produced were being stockpiled in Area 1. At the time of this visit, we also noted that the contractor had wind rowed the materials that had been previously stockpiled in the south half of Area 2. It should be noted that we observed [hat a fairly large erosion channel with several other smaller channels had developed below the first bench (east facing slope) in Area 1. It appeared that sediment had washed down into the back of the bench and the sediment was directing the surface drainage along the bench to the slope face. We recommended to Mr. Mills that they regrade the bench above the erosion and periodically monitor the condition of the bench to reduce the risk further erosion in the future. (970) 879-7888 • Fax (970) 879.7891 • nwcc@cmn.net 2580 Copper Ridge Drive • P.O. Box 775226 • Steamboat Springs, CO 80477