2014-10-10_REPORT - C1982056 - Laserfiche WebLink

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Quarterly Inspection Report - Refuse Pile October 9, 2014 Twentymile Coal Company- Foidel Creel: Mine Page 2 of 3 Job No.: 99 -3983 scattered sandstone fragments (gravels to small boulders) on the regraded slope. Another load of sandstone fragments had been dumped at the top of the regraded slope, but not placed on the slope. Heavy rain events in July, August and September 2014 have caused the regraded slope materials to erode and flow down to the haul road. Tine washed out materials were not blocking the haul road at the time of our visit. It appears that the drainage from tine top of Areas 2, 3 and 4 is concentrating in this area during heavy rain events, causing the washouts. This concentration of drainage to a small area could lead to possible slope instability if not corrected. Photographs taken of this area in September 2013, June 2014 and September 2014 during our site visits are attached. In addition, several shallow small shallow erosion channels were observed in the refuse materials on the cast, north and west sides of Areas 2, 3 and 4. These erosion channels were likely formed during the heavy rain events in 2013 and have increased in number and size during runoff from slnowmelt in Spring 2014 and additional heavy rain events in July, August and September of 2014. We recommend that these erosion channels be re- graded so that the drainage does not concentrate in these areas and cause further erosion and possible slope instability. NWCC recommends the top of Areas 2, 3 and 4 be regraded to drain to the south, away fi•oin the steep faces of the stockpiled materials, similar to the drainage prior to stopping stockpiling and compaction of the refuse materials when the expansion area was opened. If the regrading of the top of this area is not completed and the drainage is continued to flow toward the drainage port, NWCC recommends a properly designed drainage channel be constructed to handle the flow from heavy runoff on drainage events. The design of the drainage channel should be completed by a qualified Civil Engineer. Based on our observations, the surface drainage conditions, with the exceptions noted above, generally appeared to be adequate across the top and sides of the pile. Based oil our observations, we (lid not observe any signs of instability, structural weakness or hazardous conditions at the refitse pile, with the exceptions noted above. We were advised that the wash plants had produced approximately 130,722 tons of waste coal during the 111011th of July 2014, approximately 125,642 tons during August 20t4: and approximately 130,722 tons during September 2014. It is our understanding that the fines being produced at the wash plant, which consists of approximately 10 to 20 percent of the total materials being produced, are being pumped underground into the mine. We were previously informed by Brian Watterson of Peabody that all of the original monitor wells installed in the Refuse Pile were destroyed in July 2012. Two new monitor wells were constructed in Area I of the Refuse Pile in December 2013. NWCC was advised by Mr. Watterson that the water level in the western monitor well (RW# 1) was measured at 61.89 feet below the existing ground surface (bgs) on July 9, at 61.87 feet bgs on August 18 and at 61.67 feet oil September 18 of 2014. The water level in the eastern monitor well (RW #2) was measured at 58.01 feet bgs on July 9, at 57.95 feet bgs on August 18 and at 57.89 feet on September IS of 2014. An additional new monitor well (RW #3) was constructed at the southeast end of the I" bench in new Expansion Area in June of 2014. No water was encountered in the coal refuse NIATC, Inc.