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levels of iron displayed in the alluvial wells this year may be the <br />result of organic matter and plant debris present in the alluvium (Hem, <br />1985, pg. 77). <br />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 2.13 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. The secondary standard for iron (0.3 mg/1) was exceeded with a <br />value of 0.61 mg/l. The secondary standard for manganese (0.05 mg/1) was <br />exceeded with a value of 0.051 mg/l. 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 Comuliance(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 twice with values of 9.56 mg/l and 10.80 mg/l. However, see the <br />discussion of iron in the previous section. This well displays an <br />increasing TDS trend, with the peak occurring in May 2009. All values <br />are less than 1700 mg/l. <br />9 <br />