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Calcium, potassium, sodium and magnesium are usually not used for trending purposes as they interact with <br />the soil material by adsorption, precipitation and ion exchange reactions. Thallium values have generally been <br />non-detect and therefore no trend analysis/ correlations are possible. <br />Water Elevation Data and Sources of Inflow to C-Pit <br />As discussed at the December 3, 2010 site inspection meeting, CEMEX has compiled all available water <br />elevation data for C-Pit and the nearby bedrock wells, as well as the published flow data for the Boulder <br />Feeder Canal from early 2007 through December 2010. Figure 3 summarizes these data (Note right hand Y <br />axis for flow numbers). Large data gaps were due to data logger failure, and the theft of a laptop computer <br />with pertinent well data (e.g. CEM-001, CEM-003, and C-pit from mid-2008 to mid-2010). In the areas <br />where data points are lacking or where there are few points, the trends are estimated with dashed lines (note <br />where arrows are pointed toward each other indicates a data point). CEM-004 water depth data is not <br />included on this figure because it was demonstrated in the 2007 study that this well is isolated from the C-Pit <br />bedrock. Additionally, CEM 002 is not included in the figure due to the fact that it remains dry and therefore <br />could not to be hydraulically connected to C-pit. See the C-pit Hydrologic Investigations Report 2007 for <br />more detail. <br />Inspection of Figure 3 shows a rapid rise in C-Pit water elevation during the March 2007 through May 2007 <br />period. This rise in water elevation is due to consolidating the water at the north eastern edge of C-pit by <br />filling the south western areas of the pit with subsoil at that time. The corresponding rise in the measured <br />head in well CEM-001 parallels the C-Pit elevation trend, as does the rise in head within the bedrock well <br />CEM-003 (CEM-003 is the shale unit overlying the Fort Hays Limestone). <br />As depicted in Figure 3, there is no obvious direct correlation between the seasonal Boulder Feeder Canal <br />flows, C-pit water, and groundwater elevations. However, there appear to be some delayed correlations. The <br />lack of direct correlations is not surprising, due to the following factors: <br />• The 2008 - 2010 data gaps make interpretation difficult. <br />• It is unlikely to see a direct correlation between the ditch peak flows since water leaking from the ditch <br />would first need to saturate the substrate along the ditch and then move into the C-pit accumulation <br />area. This slow water movement across the substrate would cause a delay in what ever response <br />might be expected. It is nearly impossible to estimate how long it would likely take for the water to <br />move across and through the substrate since the system is influenced by the reclamation fill material. <br />Depicted on the graph there is some indication of a possible delayed correlation between the ditch <br />flow and the depth of water in C-pit. <br />• C-Pit water was pumped for process cooling to lower the potential impacts and that pumped quantity <br />has not been successfully quantified and accounted for on the figure. <br />• Canal losses likely come from more than one location. CEMEX continues to believe that the Feeder <br />Canal is losing water at the location northwest of C-Pit as it curves around the topographic slope, as <br />well as southwest of C-Pit in the reach of the Canal founded on fill (that leaks into the pond southeast <br />of C-Pit). See the discussion in the Conclusions section of the 2007 C-pit Hydrologic Investigations <br />Report regarding leakage from the Boulder Feeder Canal. <br />In response to your request at the December 3, 2010 site inspection, we have gauged the depth of water in C- <br />Pit. The remaining pond was approximately 25 feet deep as measured during the week of February 21, 2011, <br />and perhaps no more than 10 feet deeper immediately adjacent to the eastern C-Pit highwall. CEMEX is <br />presently preparing to start up the C-Pit pump for process cooling purposes, and we expect to remove a <br />significant volume of free water in a relatively short period of time once pumping commences, which in turn <br />will lower the surface of the pond. <br />3