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uncensored, that is, the number of exceedances above the Method <br />Detection Limit (MDL) / the number of exceedances between the MDL and <br />the Practical Quantitation Level (PQL) / censored, that is, the number <br />of sample values below the MDL but the MDL was higher than the standard <br />/ the total number of samples. Below is a summary of standards that were <br />exceeded. Given in parenthesis is the source and use of each standard. <br />Parameter <br />of Wells / # of excursions <br />Manganese (CDPHE, irrigation) 1/1 <br />pH (CDPHE, irrigation) 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, 1989, pgs. 86 -89) . The well 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 0.237 mg /1. <br />Ground Water Points of Compliance <br />Two GWPOC's 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. No exceedances of those standards were observed the sample <br />collected from this well this year. <br />The ground water standards for Sage Creek Alluvial Well YSAL3 are <br />provided in this AHR on Table 8. Data from Well YSAL3 may be found in <br />Appendix C of this AHR. No exceedances of those standards were observed <br />on the sample collected from this well this year. <br />5 <br />