2013-04-25_REPORT - C1994082 (2)

Home Browse Search

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 /1 (EPA, 1976). This year, no well displayed a value higher than 0.47 mg /1. Ground Water Points of Compliance Two GWPOC's have been established for the Yoast Mine. Attachment 15 -1 of the Yeast Mine PAP provides the details. The ground water standards for Grassy Creek Alluvial Well SGAL70 are provided in this AHR on Table 7. Data from Well SGAL70 may be found in the Peabody Sage Creek Mine AHR, Appendix C. No exceedances of those standards were observed the sample collected from this well this year. The ground water standards for Sage Creek Alluvial Well YSAL3 are provided in this AHR on Table B. Data from Well YSAL3 may be found in Appendix C of this AHR. No exceedances of those standards were observed on the sample collected from this well this year. Ground Water Summa TDS trends are decreasing at five wells and increasing at four wells. No CDPHE agricultural ground water standards were exceeded. In the area surrounding Yoast, ground water is not being pumped for irrigation or livestock watering purposes, nor has the CDPHE classified any aquifer in this region for any use. The above discussion is provided only to serve as a comparative basis to judge ground water quality. In the Probable Hydrological Consequences (PHC, Tab 17, Attachment 17 -5) section of the Yoast Mine PAP, predictions were made as to the expected TDS increases to be observed at various monitoring wells. The following table outlines these predictions along with this year's observed average values (annual average for bedrock wells, May - September average for alluvial wells). 5