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1 <br />' EXPLANATION REGARDING VOLUME DISCREPANCY <br />AND PROPOSED RESOLUTION FOR THE LONG-TERM STORAGE PILE, <br />COORS ENERGY COMPANY, KEENESBURG MINE FACILITY, <br />WELD COUNTY, COLORADO <br />The Coors Energy Company (CEC) Keenesburg Mine Facility (facility) is a former coal mine <br />located in Weld County, Colorado. In accordance with Colorado Revised Statute (C.R.S.) <br />' 34-33-101, the facility has a mining permit C-81-028 (permit) to conduct surface mining and <br />reclamation activities. In 1996, CEC completed the dismantling of all on-site coal handling <br />facilities. Although coal is no longer mined on the CEC property, there are on-going <br />' reclamation activities including ash disposal, other noncoal waste disposal, and road and <br />facility maintenance conducted in accordance with the permit Reclamation Plan. As part of the <br />reclamation activities, B-Pit is used for the disposal of mixed fly and bottom ash obtained from <br />the coal-combustion power plant located on Coors Brewing Company property in Golden, <br />Colorado. The long term spoils pile (LTSP) is located to the east of B-Pit and contains <br />overburden that is used to provide daily cover on the ash and to provide fmal cover (6 feet <br />' thick) on B-Pit. <br />CEC has contracted BE&K/Terranext (Terranext) to provide reclamation evaluation and <br />' tracking work for the Keenesburg facility. During completion of the 2000 Annual Hydrology <br />& Reclamation Report (AHR), a discrepancy was observed between the 1999 reported LTSP <br />overburden volume (approximately 331,000 bank cubic yards [bcy]) and the 2000 reported <br />' volume (approximately 527,000 bcy). Regarding this discrepancy, the following footnote was <br />added to the AHR (p. 122): <br />' Previously reported values appear to have been a calculation error carried forward in past <br />Reports and discovered in this year's cut and fill modeling. Terranext is reviewing past files <br />and current computations but is satisfied in their ability to reproduce this number [527,000 bcy] <br />' Based on a review of the project file, the LTSP overburden volume discrepancy is attributed to <br />two factors: <br />' 1. Previously reported LTSP overburden volumes were based on an assumed final <br />reclamation grade equal to the 4,800-foot elevation contour rather than the final <br />' reclamation grade provided in the permit (Appendix Q-1, Reclamation Contour antl <br />Drainage Plan Map) and <br />2. Previously reported volumes were calculated using the Average End Area method. <br />' This method is not as precise as other available volumetric methods such as the Grid <br />method (a more advanced volumetric calculation method). <br />' These two issues are discussed below. <br /> <br /> <br />' ` BEAK/TerraNeKt <br />