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<br />1.0 INTRODUCTION
<br />RODUCr ION
<br />As part of their operations, Bowie Resources, LLC currently stockpiles sonie
<br />coverfill on top of gob pile #2 and additional stockpiles are proposed. As part of the
<br />design development process, Huddleston -Berry Engineering and Testing, LLC (HBET)
<br />was retained by Bowie Resources to evaluate the impacts of stockpiling coverfill on the
<br />stability of gob pile #2.
<br />1.1 Referenced Documents
<br />As part of our assessment, HBET reviewed the following documents.
<br />• Alonth1j, Surnrnw), of 1,1br•ating Noire Piezorrreler•s Augusl 2014, Bo1►,ie Aline No.
<br />2, Coal f lasle Disposal Ar'ect No. 2 by Buckhorn Geotecll, file., August 26, 2014
<br />• A/outlrly Sununar.yl of Vibralirrg ffVire Piezoureler•s July 2011, Bowie Aline No. 2,
<br />Coal Waste Disposal rdrea No. 2 by BUCkhorn Geotecll, Irlc., August I, 2014.
<br />• Slabilily Evaluation, Proposed Full Buildout, Gob Pile #2, BoiNe No. 2 Aline by
<br />Huddleston -Berry Engineering & Testing, LLC for Bovvie Resources, LLC, July
<br />30, 2014.
<br />• Stability Eialualion, Technical Relrisiou #SS, Gob Pile #2 Drying Area, Bolvie
<br />No. 2 Aline by Huddleston - Belly Engineering & Testing, LLC for Bowie
<br />Resources, LLC, June 3, 2014.
<br />1.2 Scope
<br />As discussed above, Bowie Resources, LLC currently stockpiles some coverfill
<br />soil on a portion of gob pile #2 and additional coverfill is proposed to be stockpiled on
<br />the gob pile, The purpose of our evaluation was to determine the impacts oil the existing
<br />gob pile #2 associated with stockpiling coverfill on top of time existing pile. The scope of
<br />the work included the following components:
<br />• Reviewing available data to define engineering parameters, piezometric
<br />surface elevation, etc.
<br />• Setting up models which represent the existing gob pile #2, existing coverfill
<br />stockpile, and proposed coverfill stockpile.
<br />• Evaluating the impacts of the coverfill stockpiles to the stability of gob pile #2.
<br />The evaluation was completed by a Colorado registered professional engineer in
<br />accordance with generally accepted geotechnical engineering practices. This report has
<br />been prepared for the exclusive use of Bowie Resources, LLC.
<br />2.0 BACKGROUND
<br />The available reference documentation indicates that the original geotechnical
<br />investigation was completed by Lambert and Associates (Lambert) in 2003 and that
<br />placement of coal mine waste at gob pile 42 began in 2004. Additional evaluation of the
<br />stability of gob pile #2 was completed by Lambert and Buckhorn Geotech, ine.
<br />(Buckhorn) in 2005. Based upon the results of these analyses, maxirnulll slopes of
<br />5f1,1 V were specified for gob pile #2. However, this was based upon the assumption that
<br />undrained (total stress) conditions would exist within the gob pile.
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