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Homestake 2015 Geotechnical Observations Pitch Reclamation Project Indian Creek and Tie Camp Creek Rock Dumps Between June and November the water level in IC10370R dropped 2.44 feet, but didn't fall back to its normal winter range until December. Similar to IC10630, it appears that heavier than normal rainfall during the summer months prevents this piezometer from dropping completely to its January level by December. Piezometer 1C10360 is also located in this area. Water levels in this piezometer rose by 6.9 feet in spring 2015 compared with a rise of 17.90 feet in 2014. The 2015 rise was similar to the rise of 5.6 feet in 2012. The average depth to water in 2015 was 223.65 feet bgs compared with 223.0 feet bgs in 2014. In 2015 the water level in IC10360 increased by 6.53 feet compared with a 7.7 feet rise in 2014. This condition is similar to other piezometers in the Indian Rock Dump, and reflects the seasonal snow pack in the area. Between June and October the water level in IC10360 dropped 5.09 feet to elevation 10147.72 feet amsl. Unlike other Indian Rock Dump piezometers, the water level in IC10360 did not fall back to its January 2015 level, remaining about 1.5 feet above the level measured earlier in the year. "10300 — 10100" Level Site Description: The Indian Rock Dump was re -graded in 1994 following procedures approved in the February 1994 Technical Revision. During 1995, several minor, localized areas of slope instability were noted, corrected, and reported in the 1995 Annual Geotechnical Report. 2015 Observations: Field observations indicate that the repairs performed in 1995 were successful and no new areas of surficial instability were observed from 1996 through 2015. Due to problems in Piezometer IC10300 over several years with sediment buildup in the casing, in 2011 it was abandoned and replaced by Piezometer IC10300R located approximately 30 feet to the west of IC10300. The piezometer was terminated at a depth of 210 feet and completed with 20 feet of screen and an 8 -inch steel well protective casing set in concrete. In 2014, the water level in Piezometer IC10300R rose by 17.9 feet compared with 11.1 feet in 2013 and 0.2 feet in 2012. In 2015, the water level increased by 6.96 feet between January and June. The average depth to water for the past three year period increased by 3.1 feet, reflecting an increased snow back and heavier summer precipitation in the area in 2014 and 2015, compared with the 2012-2013 period. However, the water levels dropped back to acceptable levels in the early fall each year. Homestake Pitch Reclamation Project 2015 Annual Geotechnical Report M-1977-004HR Page 4 January 9, 20165 2015 AnnualGeotechnicalReportText_Final.doc