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and exist in the south pit area downgradient of the last mining area at <br />this mine. <br />Most aquifers at Seneca II-W exhibit a typical seasonal fluctuation. <br />Water levels are highest after the spring runoff, which recharges the <br />aquifer. Often, bedrock aquifers exhibit a lag time between spring <br />runoff and highest water levels. Water levels then decrease as late <br />summer or fall approaches. <br />Ground Water Quality. Table 3, Summary of Ground Water Monitoring Wells, <br />describes the wells that have been sampled in the past and site <br />characteristics. Table 4a and 4b show the new (2010) ground water <br />parameter lists. Analyses have been performed by ACZ Laboratory in <br />Steamboat Springs, Colorado since May 31, 1983. ACZ Laboratory performs <br />all analyses by EPA or equivalent methods. Samples are delivered the day <br />of collection to the lab in an iced cooler. Monitoring frequencies for <br />ground water quality may be found in Table 1 of Appendix 15-3a in the <br />Seneca II-W PAP. 0 <br />The following discussion of the analytical data collected during the <br />reporting period is arranged by strata being monitored and coincides <br />with the format (by aquifer type) in which the analytical data are <br />presented in Appendix D. The following discussion of water quality will <br />limit itself to a description of total dissolved solids (TDS). A <br />separate section, Comparison of Ground Water Quality to Water Use <br />Standards, will list those samples that exceed water use standards. <br />Data for each well in Appendix D begins with a listing of the water <br />quality data collected during the past two years, followed by remarks <br />explaining the sampling procedure. This is followed by a plot of TDS <br />versus time for the entire period of record. The regression line on this <br />plot is generated by a method known as LOWESS (Locally Weighted Scatter <br />plot Smoothing). Unless otherwise noted, a smoothness factor (SF) of 1 <br />(on a scale of 0 to 1) was used, which gives maximum smoothing. This <br />plot is followed by a table listing historic TDS values and percent <br />milliequivalents for major ions. Finally, a statistical report <br />4