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INTEROFFICE MEMORANDUM <br />Date: 17 July 2014 <br />To: Susan Burgmaier, Lead Specialist <br />From: Marcia L. Talvitie, P.E. <br />Subject: Bowie No. 2 Mine (Permit No. C-1996-083) <br />Review of 2nd Qtr 2014 Coal Mine Waste Bank and Instrumentation Report <br />I have received and reviewed the 2nd Quarter 2014 report described above, and I do have some <br />comments. My first set of comments relate to the compaction testing as it is currently being done. A <br />discussion of the data and methods is provided here, for your consideration. <br />Compaction Testing was conducted in the past by Buckhorn Geotech. It is my understanding that <br />Buckhorn collected a gob sample with each field test, and transported it to their lab, where the <br />Maximum Dry Density (MDD) and Optimum Moisture Content (OMC) for that particular sample were <br />established. Thus, for each compaction test location, field results were compared with custom results <br />obtained in the lab, and the percent compaction was determined. <br />The values below are derived from Buckhorn's test results, generated between January 2012 and March <br />2014, and depicted in the graph which follows: <br />Statistical Average (Mean): 100.0 pcf <br />Maximum MDD to date: 117.0 pcf (Test No. 33 on 05 -Mar -2014) <br />Minimum MDD to date: 82.7 pcf (Test No. 593 on 26 -Apr -2012) <br />120.0 <br />115.0 <br />U <br />Q- 110.0 <br />a <br />41c <br />105.0 <br />0 100.0 <br />0 95.0 <br />E <br />90.0 <br />m 85.0 <br />Coal Mine Waste - Max Dry Density <br />Comparisons <br />75.0 <br />0 100 200 300 400 <br />Chronological Test Sequence <br />BGI MDDs <br />MDD-Avg <br />MDD - Max <br />X MDD - Min <br />HBET 14-0195 <br />HBET 14-0373 <br />HBET 14-0375 <br />500 <br />