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= <br />August 1, 2014 <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. C�) 8140 t <br />Ph.. (970) 249 -6828 • FAX. (970) 249 -0945 <br />SUBJECT: Monthly Summary of Vibrating Wire Piezometers July 2014, <br />Bowie Mine No. 2, Coal Waste Disposal Area No. 2 <br />Dear Mr. Berry, <br />Buckhorn Geotech, Inc. (BGI) has conducted monitoring of functional vibrating wire <br />piezometers (VWP) previously installed at Coal Waste Disposal Area No. 2 (CWDA No. 2) <br />at Bowie Mine No. 2. This letter summarizes VWP monitoring at CWDA No. 2 through our <br />site visit on July 25, 2014. <br />Five vibrating wire piezometers, designated VWP -05, 06, 08, 09, and 10 are currently <br />functional and are located on the attached Location Plan. <br />Pore pressures measured to date are presented on the attached Pore Pressure Plot <br />Charts, Figures 1 and 2, and in Table 1 below. Table 1 summarizes the initial and current <br />readings and the difference in individual pore pressures since installation and since their <br />last readings. <br />Table 1. Summary of Functional VWP Pore Pressures <br />VWP ID <br /># <br />Initial Pore <br />Pressure <br />(psi) <br />6/29/14 <br />Pore <br />Pressure <br />(psi) <br />7/25/14 <br />Pore <br />Pressure <br />(psi) <br />Difference <br />Since <br />Installation <br />(psi) <br />Difference <br />Since Last <br />Reading <br />(psi) <br />VWP -05 <br />6.8 <br />2.0 <br />2.1 <br />-4.7 <br />+0.1 <br />VWP -06 <br />11.3 <br />16.0 <br />16.8 <br />+5.5 <br />+0.8 <br />VWP -08 <br />8.2 <br />9.2 <br />9.4 <br />+1.2 <br />+0.2 <br />VWP -09 <br />2.8 <br />2.8 <br />2.9 <br />+0.1 <br />+0.1 <br />VWP -10 <br />-1.9 <br />-1.9 <br />-1.8 <br />+0.1 <br />+0.1 <br />The physical locations of the piezometers are shown on the attached Instrumentation <br />Site Plan, Drawing 1. The graph of historical data through 5 -21 -14 is presented for <br />reference as Figure 1. A graph of pore pressures for active piezometers only is presented <br />as Figure 2. <br />July 2014 VWP report-7-31-14 PN #13- 231 -001 <br />Page 1 of 2 <br />