1999-06-10_REPORT - M1977378 (2)

Home Browse Search

1999 Annual Update Sunnyside Mine Bulkheads Page 3 Mine Pool: The American Tunnel bulkhead valve was closed in September 1996 and the Terry Tunnel bulkhead valve was closed in July 1996. Since September 1996 the mine pool has been allowed to rise towards physical equilibrium. As of the end of the report year (March 30, 1999), the mine pool had reached 11,506 feet M.S.L.. Included in Appendix B is monitoring data and a graph of the mine pool pressure readings Although the mine pool surface is in the zone of predicted equilibrium, it does not appear that physical equilibrium was reached during the 1998 report year. The bulkheads and resulting mine pool within the Sunnyside Mine has not had any detectable impact on the dissolved zinc concentrations (used for comparison due to chemical mobility) in Cement Creek. Included in the Appendix, B-18, is a graph of Cement Creek dissolved zinc concentrations from the monitoring station at the American Tunnel (above the water treatment discharge). Study Update: Attached in Appendix B is the data collected through March 1999 for the seep, spring, and flowing adit inventory and monitoring required by TR-14. During the report year no new monitoring sites were added and no sites were deleted. Sunnyside visited all identified sites twice during the report year, collected field data, and sampled for lab analysis more than the 20 percent of the sites the monitoring program (attached in Appendix B) requires. Data summary sheets are included in Appendix B. Data Analysis: Seep, spring and flowing adit samples were taken in early summer, when the sites became accessible and snow-melt would not bias the samples, and fall before snowfall was expected to shut off site access. The sampling efforts were spread over approximately a month for each round. Early July was an approximate mid-point of the summer sampling round and late-September for the fall sampling round. The mine pool elevation rose 20 feet between rounds. It was approximately 11,460 feet MSL in early July and 11,480 feet MSL in late-September. Included in Appendix B is a table of the monitoring sites sorted by elevation and monitoring data for these sites ordered by drainage. Since the mine pool could not have affected these sites through 1996, a data analysis (i.e. sample count, average, standard deviation, maximum value, and minimum value) is provided for pre-1997 data.