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these data are presented in Appendix B and statistically summarized <br /> in Table 18. A trilinear plot of the major ions is depicted in <br /> Figure 12. <br /> Because flow is visually estimated at this site, only seasonal <br /> changes in flow can be qualitatively discussed. As one might <br /> expect, the use of the Second Park Lateral irrigation ditch <br /> directly affects the quantity of flow issuing from the coal and <br /> overburden exposed along the highwall . Most of the flow <br /> appears to be issuing along the contact between the overburden <br /> and the upper Dakota Coal . During the winter when the <br /> irrigation ditch is generally dry, there is little if any <br /> visible flow along the highwall . During the summer, flow along <br /> the highwall is continuous and, when the mine is in operation, <br /> the pit must occasionally be pumped out to facilitate the <br /> mining operation. Perusal of the data in Table 18 and Figure 12 <br /> indicates that the quality of this water can be classified as a- <br /> Ca-SO4 type. The relatively high percentage of SO4 reflects the <br /> dramatic difference in quality from that of the proximate <br /> undisturbed surface water system as monitored at SW-N7 on the upper <br /> West Return Ditch. The mean TDS concentration for the period of <br /> record is 1574 mg/l ranging from 780 to 1912 mg/l . <br /> Spoils Spring #1 is located along the south-facing slope of a <br /> west-east flowing reclaimed drainage which enters the <br /> main stem of the West Return Ditch a few hundred feet upstream of <br /> the NPDES 001 pond inlet as shown on Exhibit 7-8. This particular <br /> spring was noted during a MLRD inspection on October 25, 1984 and <br /> has been monitored since the fall of 1984 according to the same <br /> program detailed in Appendix A for the Highwall Spring. Monitoring <br /> of this spring to date (see Appendix B, field remarks in <br /> particular) has indicated that flow is perennial , reflecting the <br /> same seasonal patterns previously described for the surface water <br /> sites along the West Return Ditch. Because this spring is in <br /> essence a series of poorly defined seeps, it is impossible to more <br /> accurately quantify flow than to simply qualitatively estimate the <br /> changes in flow from month to month. <br /> 59 <br />