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II. Tie Camp Waste Rock Dumn "10400 -10100" Levels Site Description: The Tie Camp Waste Rock Dump was regraded in 1994 following procedures approved in the February, 1994 Technical Revision. Visual observations indicate that the repairs to the minor azeas of slope instability (surficial "slips") that were performed in 1995 were successful and no new areas of surficial instability were observed from 1996 through 2001. 2001 Observations: The 2001 observations aze similaz to those provided in past reports. Piezometer TC10375 monitors the Tie Camp Creek Waste Rock Dump. The water levels aze stable at approximately 171.6 feet bgs, with seasonal fluctuation of approximately 2.4 feet for 2001. III. Piezometers - 2001 General Comments (response to comment #1 & 2) The 2001 water level measurements continue to confirm the normal seasonal vaziations in the depths to water, and therefore, the thickness of the saturated zone at the base of the Waste Rock Dumps. The saturated zone under the dumps remains thin and similaz to past yeazs. Therefore, there continues to be no evidence of concerns with stability. The depth to groundwater in the piezometers has held fairly stable during the yeazs of monitoring for most of the sites, even with the yeazly fluctuations. Site IC1030Q however, seems to indicate a consistent pattern of increasing depth (decreasing water elevation) each successive year. Normalized over the 70-month period from November 1996 to December 2001, the piezometric surface at IC10300 has decreased by 1.7 feet annually. This occurrence has not been of concern since the piezometric surface and resultant pore pressures within the waste rock dump aze decreasing. This decreasing piezometric elevation is probable the result of several conditions, each of which indicates increased stability within the dump: • The Indian Creek Dump drain is located down-gradient from this piezometer, which facilitates drainage at the toe of the dump, • In general, annual precipitation in the region has been below average for the last 6-years, and • Increased revegetation success on the dump increases evapo-transpiration and retains moisture in the thin, slowly developing soil horizon Piezometer IC10300 also has anomalous annual fluctuations, when compazed with the fairly consistent fluctuations of all other piezometer in the azea. This could be a result of the type of fill around the IC10300 piezometer. When the waste rock] was placed in the dump, there was very little control. The material near IC10300 is probably coarse, poorly graded material that readily allows downwazd migration of metoric waters. The Indian Creek Dump drain is also directly down-gradient from this piezometer, which is likely facilitating drainage in the azea. This has not been a concern for Homestake since the average piezometric surface is decreasing.