2010-03-22_REPORT - C1994082 (2)

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water chemistry (Hem, 1989, pg. 121). Several wells at SCC's Seneca II Mine with high fluoride values also exhibit this type water. Elevated levels of iron may be attributed to natural (i.e., not mining related) conditions, since elevated levels for this parameter are not found in the adjacent Seneca II spoil wells. The high levels of iron displayed in the one alluvial well (YGAL15) may be the result of organic matter and plant debris present in the alluvium (Hem, 1989, pg. 77) This well displayed high levels of iron prior to mining. High manganese values may, in part, be due to recharge from the spoil aquifer, although high values are often common, especially in alluvial material (Hem, 1989, pgs. 86-89). The wells displaying high manganese values this year also did so prior to mining. This standard is used to protect crops grown in soils with a pH value lower than 6.0. In January 2008, CDPHE revised their ground water agricultural standard to reflect this pH qualifier. In soils with a higher pH (as are found in the Yoast region), a more appropriate standard would be 10 mg/l (EPA, 1976). This year, no well displayed a value higher than 1.31 mg/1. Ground Water Points Of Compliance GWPOC's have been established for the Yoast Mine. Attachment 15-1 of the Yoast Mine PAP provides the details. The ground water standards for Grassy Creek Alluvial Well SGAL70 are provided in this AHR on Table 7. No exceedances of those standards were observed on samples collected from this well this year. The ground water standards for Sage Creek Alluvial Well YSAL3 are provided in this AHR on Table 8. No exceedances of those standards were observed on samples collected from this well this year. Ground Water Summar TDS trends are decreasing at three wells, stable at six wells, and . increasing at seven wells, including on upgradient alluvial well. One Ei