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Holding Pond #2 <br />The 48 acre feet pond stated in the specifications by Stephan Rogers in TR -18 is a very <br />conservative, worst case scenario, based on a 30 gpm flow for an entire year while driving the <br />9400 L decline. The following conceptual model done by Schlumberger Water Services shows <br />that the 48 acre feet pond is too conservative and describes the basis for the 21 acre feet pond <br />stated in TR -17. <br />Conceptual Model <br />The conceptual model is important to understanding the groundwater occurrence within the <br />study area and provides a basis and rationale for the estimate of dewatering rates. The <br />conceptual model is validated and confirmed by field water level data collected from existing <br />or new monitoring points in the study area, historic data collected in support of previous <br />studies, and review of existing information including water level data, underground mapping <br />of the mine workings, and anecdotal evidence. The following provides the technical support <br />for estimation of dewatering rates presented in Section 3.2 to be encountered during the <br />advancement of the 9400 decline. <br />Meteoric inputs and recharge pathways <br />The Creede area receives approximately 13.47 inches of precipitation per year, half of which <br />falls in the form of snowfall during the winter months. Of the total precipitation, it is estimated <br />that 16 to 17 inches of effective evaporation occurs on average during the summer months <br />(Rogers, 2011). Due to the nature and timing of annual precipitation and evaporation <br />patterns it is surmised that a large amount of snowmelt slowly recharges the Creede <br />Formation from the upper reaches of Windy Gulch. Snowmelt that does not directly recharge <br />the groundwater system runs off into Windy Gulch, and recharges the Creede Formation <br />indirectly via stream bed seepage as Windy Gulch is believed to be a losing reach between the <br />upper watershed and its confluence with Willow Creek. Recharge to the Creede <br />Formation is also supported by the seasonal water level response observed historically at <br />HW -3 (Figure 2.4), along the contact of the Creede and Campbell Mountain Formations. The <br />contrast in conductivity, by several orders of magnitude, of these two formations supports the <br />seasonal flux of water levels in the Creede Formation. The lower conductivity rhyolite of the <br />Campbell Mountain Formation inhibits groundwater flow into this formation, allowing <br />groundwater to mound or accumulate along the contact. Groundwater within the Creede <br />Formation likely discharges downgradient of the Bulldog mine following the natural dip of the <br />rock to the south. <br />Mining influences on groundwater flow <br />Historic mining activities have also influenced the groundwater system at the site and are <br />relevant to the conceptualization of the system. Specifically, the 9360 adit and the <br />underground workings of the Bulldog mine play important roles in the overall site specific and <br />district wide conceptual models, respectively. The district groundwater system is reported to <br />be controlled by various north -south trending fault and fracture systems. Monitoring well <br />HW -4 provides a point for determining the local elevation of the mine pool as it is completed <br />into the 9200 level of the mine. A recent water level measurement of this well indicates the <br />Bulldog Mine pool is currently at an elevation of 9,236 ft msl, approximately 146 feet below <br />the local water level of the Creede Formation. This supports the notion that the Creede <br />TR -1 b' Response to PAR Letter A &S.cloc 9/26/2011 <br />