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t 3.0 GROUNDWATER MONITORING <br />' Table 1 shows the currently approved groundwater monitoring program requirements. There are a <br />total of 31 groundwater monitoring sites at New Horizon. There are 17 sites at New Horizon 1, <br />' including 3 spoil springs. There are 14 sites at New Horizon 2 including 5 new wells drilled in May <br />1993. <br />' 3.1 Monltoring Well Water Levels <br />Appendix A contains the water level measurements taken during this monitoring period. Appendix <br />B contains the water level hydrograph. Appendix C contains the flow data for the spoil springs. <br />' Wells GW-N10, GW-N24, GW-N26 and GW-N28 continued to be dry during the monitoring period. <br />All four of these wells are at New Horizon 1. Of the four wells, 3 are in spoil and GW-N24 is a <br />multiple completion. Two other wells at New Horizon 1, GW-N11 (underburden) and GW-N25 <br />' (multiple completion) were found to be dry in May 1993. Both wells had measurable water levels <br />in the following months. <br />3.2 Monltoring Well Water Quality <br />' Appendix C contains the groundwater and spoil spring quality analysis results. This appendix also <br />contains the flow and water quality data for the spoil springs. Spoil spring 2 did not flow during this <br />monitoring period. All quality parameters at New Horizon 1 ground water monitoring wells were <br />within historic ranges. All quality parameters at New Horizon 2 ground water monitoring wells were <br />within historic ranges with the exception of two wells, GW-N17P1 and GW-N19. <br />' Both GW-N17P1 and GW-N19 are on property owned by others, outside of the permit boundary <br />and beyond the influence of mining activity. Access rights to well GW-N17P1 were acquired in July <br />1993. The September 1993 sample showed a TDS of 2806 mg/I compared to the historic average <br />TDS of 2273 mgfl. It appears that sodium and sulfate are the constituents primarily responsible for <br />the higher TDS. The September 1993 sodium content measured 838 mgfl compared to the historic <br />' average of 662 mgA and sulfate measured 1786 mgfl compared to the historic average of 1500 mgr1. <br />Well GW-N17P1 is located west of New Horizon 2 and is completed in the Dakota coal. During <br />' previous sampling (1986-1988, six samples), GW-N17P1 was exhibiting a rising trend. Continued <br />monitoring may reveal the source of this trend. Wetl GW-N19 is located northwest of New Horizon <br />2 and is completed in underburden. The average 1993 TDS was 1792 mg/I compared to the historic <br />average of 1350 mg/I. It appears that the primary constituents responsible for the higher TDS are <br />sulfate (813 compared to 556 mg/I), magnesium (95.5 compared to 78 mgA) and sodium (192 <br />1 <br />' 9 <br />