Laserfiche WebLink
INTEROFFICE MEMORANDUM <br />Date: 24 June 2015 <br />To: Jason Musick, Lead Specialist <br />From: Marcia L. Talvitie, P.E. <br />Subject: Bowie No. 2 Mine (Permit No. C-1996-083) <br />Review of 4th Qtr 2014 Coal Mine Waste Bank and Instrumentation Report <br />I have reviewed the above -referenced report submitted by J.E. Stover & Associates on Jan. 16, 2015. <br />Approved Placement, Compaction, and Inspection requirements for Coal Mine Waste (Gob) are found in <br />Volume IX, pp. 12-14 and Volume XI, pp. 8-9. The information provided in this report adequately <br />addresses the requirements. 1 have no adequacy comments. <br />Compaction Testing <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). A total of 65 compaction tests were performed between Oct. 7 and Dec. 8, 2014: 45 on Gob <br />Pile #2 and 20 on Gob Pile #3. Coordinates and elevation of each test point are provided in map and <br />tabular form. All locations tested achieved the requisite minimum 90% of Maximum Dry Density. <br />Accurate moisture contents for each sample were measured in the laboratory. <br />In my Nov. 13, 2014 review of the 3rd Quarter 2014 compaction data, I discussed the series of Moisture - <br />Density Relationship Curves that had been developed in the laboratory and were then used to evaluate <br />the relative compaction of coal mine waste. I requested that HBET consider developing additional <br />Moisture -Density curve(s) to represent materials that lay intermediate to curves 14-0195 and 14-0553, <br />and suggested that the inclusion of Gradation, Atterberg Limits, and Description (Classification) for any <br />curve so developed would be highly beneficial. In a Dec. 2, 2014 response, BRL indicated that HBET <br />would collect a new sample for analysis during each site visit. Moisture -density curve, gradation, and <br />Atterberg limits would then be determined in the laboratory, creating a broader representation of the <br />physical properties of the coal mine waste. This practice was implemented during the 4th Quarter; eight <br />new M -D curves were provided in the report, and gradation and Atterberg limits were presented for <br />several of the curves. <br />Instrumentation Reoort <br />Vibrating Wire Piezometers (VWP) are installed at Gob Pile #2 (5) and Gob Pile #3 (also 5). The VWPs <br />were installed and are monitored on a regular basis by Buckhorn Geotech. In a letter dated Apr. 10, <br />2014, the Division directed BRL to increase the monitoring frequency from quarterly to monthly. BRL <br />committed to the increase in a letter dated Apr. 11, 2014. Monthly monitoring was continued through <br />Oct -2014, with an additional quarterly reading taken on Jan. 6, 2015 (representing the 4th Qtr). By Email <br />on Feb. 10, 2015, we approved BRL's reverting to once per quarter through the 1St Quarter of 2015. <br />This concludes my review of the 4th Quarter 2014 Coal Mine Waste Bank and Instrumentation <br />Monitoring Reports. Please let me know if you have any additional questions. <br />cc: Dan Hernandez, DRMS <br />