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s • GEOTECH <br />January 5, 2015 <br />Huddleston -Berry Engineering and Testing, LLC <br />640 White Avenue <br />Grand Junction, CO 81501 <br />Attention: Mike Berry, PE <br />Civil, Structural +& Geotechnical Engineers <br />222 South Park Ave, • Montrose, CO 81401 <br />Fah,. (970) 249 6828 -FAX (970) 249 -0945 <br />SUBJECT: Quarter 4 Summary, Vibrating Wire Line Piezometers, Bowie Mine <br />No. 2, Coal Waste Disposal Area No. 3 <br />Dear Mr. Berry, <br />Buckhorn Geotech, Inc. (BGI) conducted monthly monitoring of installed vibrating wire <br />piezometers during the period October 31 through December 18, 2014 at Coal Waste <br />Disposal Area No. 3 (CWDA No. 3). A graphic plot of measured pore pressures over <br />time is presented on the attached Figure 1, and numerically in Table 1 below. Table 1 <br />summarizes the initial, last month and current readings and the difference in individual <br />pore pressures since installation and last month's readings. <br />Table 1. Summary of Pore Pressures <br />VWP ID # <br />Initial Pore <br />Pressure <br />10/31/14 <br />(Psi) <br />11/26/14 <br />Pore Pressure <br />(psi) <br />12/18/14 <br />Pore Pressure <br />(psi) <br />Difference <br />Since <br />Installation <br />(Psi) <br />Difference <br />Since Last <br />Reading <br />(Psi) <br />VWP -A Deep <br />10.4 <br />9.4 <br />8.9 <br />-1.5 <br />-0.5 <br />VWP -A Shallow <br />4.7 <br />3.5 <br />3.5 <br />-1.2 <br />0 <br />VWP-13 Deep <br />1 0.2 <br />1 0.1 <br />1 0 <br />-0.2 <br />1 -0.1 <br />VWP-13 Shallow <br />13.9 <br />1 13.5 <br />1 14 <br />+0.1 <br />1 +0.5 <br />VWP -D <br />7.1 <br />1 8.4 <br />1 8.7 <br />+1.6 <br />1 +0.3 <br />If you have any questions regarding this letter or the instrumentation monitoring at <br />CWDA No. 3, please don't hesitate to contact me at (970) 497 -8827 or <br />w, nandorf(&buckhornaeo, com. <br />Respectfully Submitted, <br />BUCKHORN GEOTECH, INC. <br />Wayne Pandorf, P.E. <br />Sr. Geotechnical Engineer <br />Enclosure: Figure 1 — Vibrating Wire Piezometer Data Graph <br />Bowie CWDA 3 Initial Q4 VWP Report 12 -18 -14 PN #13- 231 -002 <br />Page 1 of 1 <br />