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High manganese values may, in part, be due to recharge from the spoil <br />aquifer, although high values are often common due to naturally <br />occurring geochemical conditions, especially in alluvial material (Hem, <br />1989, pgs. 86 -89). This standard is used to protect crops grown in soils <br />with a pH value lower than 6.0. In January 2008, CDPHE revised their <br />ground water agricultural standard to reflect this pH qualifier. In <br />soils with a higher pH (as are found in the Seneca II -W region), a more <br />appropriate standard would be 10 mg /1 (EPA, 1976). This year, none of <br />the Seneca II -W wells displayed a value higher than 1.57 mg /1. <br />At the Seneca II -W shop well, Well 201TC, CDPHE drinking water standards <br />were used to determine its suitability. No human health standards were <br />exceeded. The secondary standard for iron (0.3 mg /1) was exceeded with a <br />value of 5.69 mg /1. The secondary standard for manganese (0.05 mg /1) was <br />exceeded with a value of 0.076 mg /1. However, bottled water is consumed <br />at Seneca II -W. Also, since the aquifer for the shop well (Trout Creek <br />Sandstone) starts at 280 feet below the Wadge Coal and is separated by <br />confining shale layers, water from this well should not be affected by <br />mining and, therefore, reflects the natural characteristics of the <br />aquifer. <br />Ground Water Points of Compliance(GWPOC) <br />A GWPOC have been established in the Dry Creek alluvium for the Seneca <br />II -W Mine. Appendix 15 -3B of the Seneca II -W PAP provides the details. <br />The ground water standards for Dry Creek Alluvial Well DCAL -02 are <br />provided in this AHR on Table 7. One exceedance of these standards <br />occurred this year. The ambient -based standard for iron (8.06 mg /1) was <br />exceeded with a value of 10.2 mg /1. However, see the discussion of iron <br />in the previous section. This well displays an increasing TDS trend, <br />with the peak occurring in May 2009. All values are less than 1700 mg /1. <br />Ground Water Quality Summary. Increasing TDS trends were observed at <br />eight wells downgradient of mining. Six downgradient wells exhibit <br />stable or decreasing TDS trends. The GWPOC well for the Dry Creek <br />7 <br />