Laserfiche WebLink
INTEROFFICE MEMORANDUM <br />Date: 13 November 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 3rd Qtr 2014 Coal Mine Waste Bank and Instrumentation Report <br />At your request, I have reviewed the above - referenced report submitted by J.E. Stover & Associates on <br />October 22, 2014. Approved Placement, Compaction, and Inspection requirements for Coal Mine Waste <br />(Gob) are found in Volume IX, pp. 12 -14 and Volume XI, pp. 8 -9. <br />Compaction Testi <br />During this quarter, coal mine waste placement and compaction activities alternated between Gob Pile <br />#2 and Gob Pile #3. All compaction testing was performed by Huddleston -Berry Engineering & Testing, <br />LLC (HBET), at a frequency of approximately once per week. <br />A total of 100 compaction tests were performed, including one re -test for a site that initially failed to <br />obtain the required 90% of Maximum Dry Density (MDD). Moisture contents of the emplaced coal mine <br />waste were noticeably lower than results reported in previous quarters. This favorable condition was <br />achieved even without BRL's needing to incorporate as much coverfill material as they have in the past. <br />HBET's detailed report of materials testing for the 3rd quarter included a series of Moisture - Density <br />Relationship Curves that were developed in the laboratory and are used to evaluate the relative <br />compaction of coal mine waste. The eight curves are summarized in Attachment 1 to this memo. <br />In Table 1 of Attachment 1, the curves are arranged by "Sample No. ". Gradation, Atterberg Limits, and <br />Description fields are filled in where this information was provided with the curve(s) by HBET. At the far <br />right, columns have been added to show how many times each curve was used as a reference during the <br />2nd and 3rd quarters of this year. In Table 2, the same curves have been re- arranged in order of <br />decreasing "MDD ". <br />As shown in Table 1, the curve being used with the greatest frequency is Sample No. 14 -0195. Aside <br />from the source being identified as "Gob #3 Borrow Blend ", no other properties are provided <br />(Gradation, Atterberg Limits, or Classification). The Division has reviewed the 2nd and 3rd quarter <br />compaction results where this curve was used. That data is compiled in Attachment 2, which shows the <br />Compaction achieved, among other results. As highlighted in yellow, the compaction fell slightly <br />below 90.0% with some regularity (although all tests would be at least 90 if rounding is employed). <br />