Laserfiche WebLink
April 3, 2012 <br />Bowie Resources, LLC <br />Attn: Bill Bear <br />P.O. Box 483 <br />Paonia, CO 81428 <br />Inclinometers <br />Bowie Gob Pile 2 Instrumentation Monitoring 1st Qtr 2012.doc <br />Project #05- 126 -GEO <br />Page 1 of 4 <br />Civil, Structural & Geotechnical Engineers <br />227 Vnl, <br />Ph • (9 0) i - i `, %• ;Ili <br />RE: BOWIE COAL WASTE DISPOSAL AREA NO. 2 <br />SUBJECT: SUMMARY OF INSTRUMENTATION MONITORING, 1st QUARTER 2012 <br />Dear Bill, <br />Buckhorn Geotech, Inc. (BGI) has conducted on -going monitoring of inclinometers and vibrating <br />wire piezometers previously installed at Coal Waste Disposal Area No. 2 (CWDA No. 2) for <br />Bowie Resources, LLC (Bowie). In 2005, three inclinometers were installed to monitor <br />movement of placed refuse and five vibrating wire piezometers were installed to monitor pore <br />pressures developed within the coal refuse. Installation details of the instrumentation are <br />presented by BGI (2006). Three additional vibrating wire piezometers were installed in June <br />2009. This letter summarizes instrumentation monitoring at CWDA No. 2 through March 31, <br />2012. <br />Three inclinometers, designated BG05 -4, -5, and -7, were installed at CWDA No. 2 in August <br />2005. The inclinometers were installed through the coal refuse and approximately 20 feet into <br />the native foundation soils. Locations of the inclinometers are presented in Table 1 and on the <br />attached site plan. Baseline readings were taken on 8/10/05 and subsequent readings have <br />generally been taken quarterly. Cumulative displacement curves with respect to the baseline <br />readings are presented as an attachment to this letter for each inclinometer. Axis "A" reflects <br />deformation with depth in the direction of anticipated movement, while Axis "B" is orthogonal to <br />Axis A. During our site visit on March 29, 2012 to read the instruments readings were taken at <br />inclinometers BG05 -04, 05 and 07 and are reported herein. <br />Based on our latest readings, no definite indications of deep- seated instability of the gob are <br />observed in the inclinometer monitoring data. As described in previous letters, displacements <br />indicated on the plots for the upper ten feet of the inclinometers are attributed to placement of <br />cover soil on the face of the waste bank in late 2006 /early 2007. Movement previously <br />recorded in the B -axis of inclinometer BG05 -05 has not progressed since the December 2008 <br />readings. The previous movement in the B -axis of BH05 -05 is interpreted to be due to <br />settlement of the coal refuse. <br />