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Hydro Investigation Results <br /> Santa Fe Formation-West Pit Battle Mountain Resources Inc. <br /> 3.1 Analytical Methods <br /> Drawdown and recovery data collected from the pumping well during the hydrologic testing were <br /> graphically analyzed to assess aquifer properties of the alluvial aquifer. As previously indicated, <br /> there was no measurable response in any of the observation wells during the test. The methods of <br /> analysis for the drawdown/recovery data were Theis (1935)and Neuman(1972). <br /> Theis (1935)derived a solution for unsteady flow to a fully penetrating well in a confined aquifer. <br /> The solution assumes a line source for the pumped well and therefore neglects wellbore storage. <br /> Theis modified the original solution to allow for estimation of aquifer properties from recovery <br /> data. The procedure involves fitting a straight line on a residual drawdown plot of s' (residual <br /> drawdown)versus log t/t' (ratio of time since pumping began to time since pumping stopped). <br /> Neuman derived an analytical solution for unsteady flow to a fully or partially penetrating well in <br /> a homogeneous,anisotropic unconfined aquifer with delayed gravity response.The Neuman model <br /> assumes instantaneous drainage at the water table and can also be used to analyze recovery data. <br /> These analytical methods are based on several inherent assumptions, including: <br /> • The aquifer has infinite extent; <br /> • The aquifer is homogeneous and isotropic; <br /> • The aquifer has uniform effective thickness over the area influenced by pumping; <br /> • The piezometric surface is horizontal prior to pumping; and <br /> • The well diameter is small, so well storage is negligible. <br /> Although these assumptions are typically not fully satisfied, these analytical methods generally <br /> provide a reasonable approximation of the transmissivity of the pumped aquifer under the given <br /> conditions. However, in this case, the low volume of water that was extracted relative to the <br /> volume of water in the casing (casing storage) makes analyses of the drawdown data of limited <br /> value. Therefore,analyses were limited to the recovery data following the termination of pumping. <br /> An additional complication to the data analyses was whether the Santa Fe Fm is a confined or <br /> unconfined aquifer. The initial depth to water measured in WP-6 was similar to surrounding wells <br /> (although the well has not been surveyed yet to provide a more accurate assessment of water level <br /> elevation). During the test, the water level in WP-6 dropped below the top of the screen and the <br /> alluvium/Santa Fe Fm contact, indicating that, at least during the latter portion of the test, <br /> unconfined conditions were imposed at the well. To address this issue, both a confined, Theis <br /> (1935), and an unconfined,Neuman(1972), analytical solution were used to evaluate the recovery <br /> data. <br /> The software used to graphically analyze the WP-6 hydrologic test data was Aqtesolv Professional, <br /> Version 4.5 (HydroSOLV, 2007). The program is capable of analysis of drawdown and recovery <br /> data, unconfined and confined aquifer conditions, partially penetrating wells, and variable <br /> pumping rates. <br /> February 2023 5 Engineering Analytics,Inc. <br />