2012-11-27_REPORT - C1994082 - Laserfiche WebLink

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Ground Water Level Summary. This year, water levels at all wells fell within their historic ranges, with the following exception. Sage Creek alluvial wells YSAL1 and YSAL3 and Annand Draw alluvial well YAAL14 all experienced their highest water level ever this year. This is due to the high snowpack runoff seen this year. In addition, at Well YSAL3, an adjacent beaver dam in most likely the cause of high water levels. All alluvial wells are showing distinct seasonal water level fluctuations in response to periods of precipitation recharge or the lack of precipitation. Overburden and coal well water levels are fluctuating in response to the precipitation recharge, induced ground water flow to the reclaimed mine pits. Ground Water Quality. Table 3 provides a summary of ground water monitoring sites at the Yoast Mine. Table 4a and 4b show the new (2010) ground water parameter lists. Appendix C provides all ground water quality data collected during the past two years, along with sampling remarks. This is followed by a plot of TDS versus time for the entire period of record. The regression line on this plot is generated by a method known as LOWESS (Locally Weighted Scatter plot Smoothing). Unless otherwise noted, smoothness factor (SF) of 1 (on a scale of 0 to 1) was used, which gives maximum smoothing. A statistical report representing baseline (i.e., premining) data for each well (when available) is presented in Appendix Cl of the 2010 AHR. On this statistics report, "censored data" refers to analytical values that were below the detection limit, which were censored from the min /max /mean calculations. The time frame for baseline conditions is listed under "conditions specified" at the bottom of each page. - Alluvium. One well, YAAL14, monitors water quality in the Annand Draw alluvium. TDS values for this well display an increasing trend. However, the peak value occurred in May 2008. 3