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<br />Preliminary West Pit Remediation Cost Estimate <br />Battle Mountain Resources Inc. <br />San Luis Mine <br />October 30,1999 <br />This preliminary cost estimate has been prepared evaluating potential capital and annual <br />operating and maintenance (O&M) costs associated with the various West Pit <br />management options as presented with the Colorado Division of Minerals and Geology <br />Technical Revision (TR) 26 submittal and/or technical responses presented in the <br />Colorado Department of Public Health and Environment Cease and Desist Order <br />Response Plan for the Battle Mountain Resources Inc. "San Luis West Pit Project". This <br />cost estimate presents potential costs associated with slurry wall containment <br />construction, passive in-situ water treatment, agriculture beneficial use, enhanced <br />mechanical evaporation, and active water treatment. Presented cost estimates reflect <br />costs assumed to be incurred for capital construction and the operation and maintenance <br />of these facilities by third-party contractor personnel. These costs include expenses <br />associated with operating and maintaining the particular systems which includes <br />operating equipment maintenance and replacement, labor and all necessary materials <br />required. In addition to the costs presented for the operation and maintenance of these <br />systems, costs are included to install a slurry wall or hydraulic barrier along the eastern <br />and southern perimeters of the West Pit. This installation is included to preclude or <br />minimize groundwater inflow volumes from the upgradient Rito Seco alluvial aquifer <br />which is estimated to be approximately 70 gpm of the total 110 to 120 gpm of <br />maintenance phase groundwater required to be extracted. Thus reducing the volume of <br />water required to be managed during the maintenance phase of the project to <br />approximately 40 to 50 gpm. <br />Estimated costs are presented in a two phase presentation as described and detailed in the <br />Technical Revision (TR) 26 conceptual hydrological model. This two-phase presentation <br />is made to account for annual costs associated with both the initial reduction phase and <br />[he following maintenance phase. The first phase of this process (i.e., [he reduction <br />phase) requires the extraction of higher pumping rates [approximately 400 gallons per <br />minute (gpm)] for 60 to 70 days to reduce the local groundwater elevation within the <br />West Pit. This reduction in the groundwater elevation acts to control the hydraulic <br />gradients out of the West Pit area into the adjacent Rito Seco alluvial aquifer, thus <br />eliminating groundwater movement from the West Pit. The second phase (i.e., <br />maintenance phase) of this process will require the pumping of approximately 110 to 120 <br />gpm of West Pit groundwater to maintain the reduction phase groundwater elevation and <br />hydraulic gradients throughout the remainder of the remediation project until flushing <br />and collection of the secondary mineralization is completed. As stated above this <br />maintenance phase pumping rate would be reduced to approximately 40 to 50 gpm with <br />the installation of the slurry wall barrier. <br />