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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/l (EPA, 1976). This year, none of <br />the Seneca II -W wells displayed a value higher than 1.4 mg/l. <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. Bottled water is consumed at Seneca II -W. In addition, since <br />the aquifer for the shop well (Trout Creek Sandstone) starts at 280 feet <br />below the Wadge Coal and is separated by confining shale layers, water <br />from this well should not be affected by mining and, therefore, reflects <br />the natural characteristics of the aquifer. <br />Ground Water Points of Compliance (GWPOC) <br />A GWPOC has 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 once with a value of 9.53 mg/l. However, see the discussion of <br />iron in the previous section. This well displays an increasing TDS <br />trend, with the peak occurring in 2009. All values are less than 1700 <br />mg/1. <br />Ground Water Quality Summary. <br />Increasing TDS trends were observed at eight wells. Five wells exhibit <br />stable or decreasing TDS trends. The GWPOC well for the Dry Creek <br />Alluvium, DCAL-02, did not exceed the TDS GWPOC standard, 3195 mg/l, but <br />did exceed the ambient -based iron standard. <br />6 <br />