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precipitation and snowmelt. During May and June, flow rates <br /> decreased rapidly from the peak flows of April . Although data are <br /> not available for the months of July through September , flow <br /> rates can be expected to be generally low except during high <br /> energy thunderstorm events. <br /> From May, 1983 to May, 1984, three water samples were taken <br /> at station 1, one from station 2, and four from station 3. The <br /> results of chemical analyses of these samples are presented in <br /> Tables 5, 6, and 7. For the eight samples analyzed, the mean con— <br /> centration of total dissolved solids is 429 mg/1 with a standard <br /> deviation of 107 mg/l. These values are very similar to the mean <br /> and standard deviation of total dissolved solids in the ground <br /> water samples. The highest concentration (578 mg/1) was measured <br /> at station 3 in May, 1983 and the lowest (295 mg/1 ) at station 1 <br /> during April and May, 1984. Values of total dissolved solids are <br /> plotted for the corresponding stations in Figures 4, 5, and 6. <br /> The plots in Figures 4 and 6 - suggest a general decrease in total <br /> dissolved solids during the 1983-84 sampling period. <br /> 4. 0 IMPACT OF THE DISPOSAL PILE <br /> Figure 7 diagramatically illustrates a typical flow system <br /> created by the presence of a disposal pile , with arrows <br /> indicating potential paths of water seepage towards a stream. <br /> Seepage may migrate downward into the ground water, flow system or <br /> emerge from the toe of the waste pile. The volumetric rate of <br /> seepage (S) is given by: <br /> S = P A F (1) <br /> where P is the annual precipitation rate, A the planimetric area <br /> of the pile, and F is equal to that fraction of precipitation <br /> infiltrating the waste materials. Let AC w be equal to the in— <br /> crease in total dissolved solids of seepage and water over that <br /> occurring in natural waters. If S is not large compared to stream <br /> flow rate (Q) , the net increase in total dissolved solids of <br /> water in the stream ( AC.) is approximately given by: <br /> Ocs pcs S (2) <br /> Q <br /> Substitution of (1) into (2) results in the final equation used <br /> to assess impacts to the stream/alluvial system of Coal Creek : <br /> ACs = ACw P A F (3) <br /> Q <br /> 28 <br />