2010-03-22_REPORT - C1994082 (2)

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What is important is what the long-term trend indicates, and not what the individual values observed are. More data will be needed to determine the long-term TDS trend at this well. The GWPOC well for the Grassy Creek Alluvium, SGAL70, did not exceed the TDS GWPOC standard, 5038 mg/1. At Grassy Creek alluvial well YGAL15, the average TDS value observed this year was 4975 mg/l (4635 mg/l calculated). This value exceeds the predicted value of 3548 mg/1. However, the average TDS value observed this year upstream at Well YGAL16 (Pond Oil alluvium), was only 1440 mg/l. Also, the May-September maximum TDS from Pond 011 discharges was only 1310 mg/l. Since Pond 011 is the only discharge coming from the Yoast Mine into this portion of Grassy Creek, the elevated TDS values at Well YGAL15 must have a source other than Yoast Mine discharges. The GWPOC well for the Grassy Creek Alluvium, SGAL70, did not exceed the TDS GWPOC standard, 5038 mg/1. At Sage Creek alluvial well YSAL1, the average TDS value observed this year was 1420 mg/l (1345 mg/l calculated). This value exceeds the predicted value of 798 mg/l. However, the average TDS value observed this year upstream at Well YSAL3 (directly below Pond 012), was only 1160 mg/1. The GWPOC well for the Sage Creek Alluvium, YSAL3, did not exceed the TDS GWPOC standard, 2675 mg/l. This years TDS value at Wadge coal well YW30 was 6570 mg/1, which was over ten times the value observed in 2007, 590 mg/1. The PHC predicted value for this well is 2570 mg/l. More data from this well will be needed to determine if this year's value was an anomaly. Surface Water A summary of surface water sites is provided in Table 9. Stream monitoring occurs on Sage Creek at Sites YSSF3 and YSS2, and on Grassy Creek at Sites YSGF5 and YSG5. These surface water sites are monitored triannually for flow and field parameters (pH, temperature, and electrical conductivity [EC]). NPDES Discharge Points 013 and 014 are 13