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n - v ---+- - r <br /># of Wells / # of excursions <br />Manganese (CDPHE, irrigation) 1/1 <br />PH 1/1 <br />High manganese values may, in part, be due to recharge from the spoil <br />aquifer, although high values are often common, especially in alluvial <br />material (Hem, 1985, pgs. 86-89). The wells displaying high manganese <br />values this year also did so prior to mining. This standard is used to <br />protect crops grown in soils with a pH value lower than 6.0. In January <br />2008, CDPHE revised their ground water agricultural standard to reflect <br />this pH qualifier. In soils with a higher pH (as are found in the Yoast <br />region), a more appropriate standard would be 10 mg/l (EPA, 1976). This <br />year, no well displayed a value higher than 1.13 mg/l. <br />Ground Water Points of Compliance <br />Two GWPOCs have been established for the Yoast Mine. Attachment 15-1 of <br />the Yoast Mine PAP provides the details. The ground water standards for <br />Grassy Creek Alluvial Well SGAL70 are provided in this AHR on Table 7. <br />Data from Well SGAL70 may be found in the Peabody Sage Creek Mine AHR, <br />Appendix C. The cadmium standard is 5.0 ug/1, however the MDL is 10 ug/l. <br />All cadmium values this year were less than the detection limit. <br />Therefore, no exceedances of standards were observed in the sample <br />collected from this well this year. <br />The ground water standards for Sage Creek Alluvial Well YSAL3 are provided <br />in this AHR on Table 8. Data from Well YSAL3 may be found in Appendix C <br />of this AHR. No exceedances of those standards were observed in the sample <br />collected from this well this year. <br />Ground Water Summa <br />TDS trends are decreasing at two wells and increasing at seven wells. <br />CDPHE agricultural ground water standards were exceeded for pH at well <br />YWCU33 and for manganese at well YAAL14. In the area surrounding Yoast, <br />ground water is not being pumped for irrigation or livestock watering <br />1.1 <br />