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SUNDAY MINE COMPLEX-HYDROGEOLOGIC REPORT <br /> required by the DRMS to supplement the Environmental Protection Plan, a document that was <br /> approved by the DRMS for a Designated Mining Operation (DMO). The report will also support <br /> permitting with the BLM with regard to an Environmental Assessment and associated Plan of <br /> Operations. <br /> The hydrogeologic study of the SMC involved a review of existing regional and local geologic <br /> and hydrologic literature, related reports and documents prepared by previous mine operators, <br /> and the compilation and interpretation of recently acquired hydrogeologic data obtained from a <br /> groundwater monitoring program. The findings of this research are summarized below followed <br /> by a summary of the interpreted hydrogeologic site conceptual model. <br /> Groundwater Occurrence <br /> • Groundwater elevations measured in the Top Rim unit in monitoring wells in the SMC area <br /> are divergent and do not portray a uniform hydraulic gradient. Elevations indicate an <br /> unconfined Top Rim unit just upgradient of the West Sunday Mine workings and a confined <br /> unit downgradient of the SMC. <br /> • Ground water elevations at the upgradient well (MW-SUN3), and downgradient well (MW- <br /> SUN1) are 5,494 and 5,571 ft amsl and trending upward. <br /> • Groundwater elevations in the underground workings, as indicated by vent shaft water level <br /> measurements, have risen approximately 85 ft since 2009, and are continuing to rise at a rate <br /> of approximately 0.7 ft/month. Current elevations are approaching an elevation of 5,500 ft <br /> amsl in the mine workings. <br /> • The elevation of the Dolores River, a suspected hydraulic divide and potential discharge area <br /> of the Salt Wash Member, is between 5,400 and 5,500 ft amsl. <br /> • The implied hydraulic gradient in the Top Rim unit is relatively flat in the SMC area; this is <br /> supported by work done by Weir in 1983. <br /> • Hydraulic testing of well MW-SUN1 indicates a low hydraulic conductivity of 5.06 x 10"3 ft/d. <br /> This and the very slow recovery rates observed during well sampling, indicate that the Top <br /> Rim water-bearing unit is an aquitard. <br /> • It is hypothesized that groundwater elevations are continuing to rise in wells and within the <br /> mine workings in response to attaining static potentiometric equilibrium in these structures. <br /> • The calculation of average linear velocity using conservative values for hydraulic conductivity <br /> of 0.31 ft/d and the hydraulic gradient of 0.01 parameters indicates a velocity of 0.019 ft/d. <br /> This results in a travel time from the SMC to the Dolores River to the west of 2,740 years. <br /> Western Water& Land, Inc. 53 <br />