2014-09-08_REPORT - C1996083 - Laserfiche WebLink

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= OTECN August 26, 2014 H udd leston- Berry Engineering and Testing, LLC 640 White Avenue Grand Junction, CO 81501 Attention: Mike Berry, PE Civil, Structural 8 Geotechnical Engineers 222 South Park Ave. • Montrose. CO 81 4U t Ph.. (970) 249 -6828 - FAX. {970) 249 -0945 SUBJECT: Monthly Summary of Vibrating Wire Piezometers August 2014, Bowie Mine No. 2, Coal Waste Disposal Area No. 2 Dear Mr. Berry, Buckhorn Geotech, Inc. (BGI) has conducted monitoring of vibrating wire piezometers (VWP) previously installed at Coal Waste Disposal Area No. 2 (CWDA No. 2) at Bowie Mine No. 2. This letter summarizes VWP monitoring at CWDA No. 2 through our site visit on August 22, 2014. Per your email correspondence of August 20, 2014, we understand that DRMS has asked that only vibrating wire piezometers, designated VWP -06 and VWP -08 be read in the future. Pore pressures measured to date are presented on the attached Pore Pressure Plot Charts, Figures 1 and 2, and in Table 1 below. Table 1 summarizes the initial and current readings and the difference in individual pore pressures since installation and since their last readings for VWP -06 and VWP -08. Table 1. Summary of VWP -06 and VWP -08 Pore Pressures VWP ID Initial Pore 7/25/14 8/22/14 Difference Difference # Pressure Pore Pore Since Since Last (psi) Pressure Pressure Installation Reading (psi) (psi) (psi) (psi) VWP -06 11.3 16.8 17.4 +6.1 +0.6 VWP -08 8.2 9.4 9.6 +1.4 +0.2 The physical locations of the piezometers are shown on the attached Instrumentation Site Plan, Drawing 1. The graph of historical data through 5 -21 -14 is presented for reference as Figure 1. A graph of pore pressures for active piezometers only is presented as Figure 2 with readings for VWP -05, 09 and 10 terminated as of 7- 25 -14. August 2014 VWP report-8-26-14 PN #13- 231 -001 Page 1 of 2