2010-03-22_REPORT - C1994082 (2)

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Technical Revision 39 was approved on March 19, 2009. This TR established ground water points of compliance (GWPOC) for the Yoast Mine. Attachment 15-1 of the Yoast PAP provides details of thi s TR. Well SGAL70 (GW-S70-A) is the GWPOC in the Grassy Creek alluvium. Well YSAL3 is the GWPOC in the Sage Creek alluvium. An analysis of these two GWPOC's is provided in the ground water section of this AHR. Meteorological Data No meteorological data is collected at the Yoast Mine. SCC maintains a weather station (wind speed and direction, temperature and precipitation) at its adjacent Seneca II-W Mine. The reader is referred to that AHR, Appendix B. SCC also maintains a precipitation gage at its adjacent Seneca II Mine. Data from that gage for this year are included on Table 1. A summary of all data collected at that gage is provided here in Table 2. • Data from the National Climatic Data Center's Hayden Station is used here to evaluate the precipitation trend. These data are provided in Appendix B of the Seneca II-W AHR. For this year, 20.03 inches of precipitation was measured, which is 2.69 inches (160) above the 1971- 2000 average. The months of December, January, March, April, May and June were above average. Snowpack runoff, as estimated by totaling November through March precipitation values, was 10.17 inches, which was 2.99 inches (42%) above the 1971-2000 average. Ground Water Water Levels. Table 3 provides a summary of ground water monitoring sites at the Yoast Mine. Water level data are provided in Appendix B. Water level reports for the past six years are presented immediately after the water level hydrograph of all data since 1991. Water level measurements are collected with an electrical water level indicator or a steel tape. Pressure readings (in psi) obtained from flowing wells with pressure gages are multiplied by 2.31 to obtain head in feet. The 2