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~~, <br />© MWH <br />MONTGOMERYWATSON HARZA <br />Date: <br />To: Michael G. Altavilla <br />From: Thomas E. I.eidich <br />Subject: Haul Road D Outslope Stabilization Plan <br />On Monday June 18, 2001, MWH inspected the minor slope failures on the outslopes of Haul <br />Road D at the Seneca Yoast mine between stations 42+00 and 44+00. The Haul Road stationing <br />is shown on the Haul Road D As-Built Drawing (Exhibit 13-16). The slope failures appear to be <br />minor surficial slides. In addition, the surface water drainage from the road appears to be <br />directed to the outslope side of the haul road. After our site visit, MWH reviewed the latest aerial <br />topography dated May 8, 2001 that is shown on the Haul Road D As-Built Drawing (Exhibit 13- <br />16). The topography indicates that portions of the outslope between stations 42+00 and 44+00 is <br />steeper than I.SH:1 V. <br />The steep slopes and the surface water drainage is probably what led to the minor su>fcal slides. <br />To reclaim and control the minor surfacial slope failures, MWH recommends that Seneca <br />relocates the haul road approximately 20 feet into the hill between stations 42+00 and 44+00 and <br />than regrade the outslopes to less than 1.SH:1 V. The slopes should be reduced by removing the <br />loose material from the top of the slopes. Additional material should not be placed at the base of <br />the slope because this would load the top of the old pond 12 slide and could destabilize the area. <br />The material from the slope could be placed in the existing pit or spoil areas. In addition, the <br />relocated haul road should be graded to drain into the slope to divert all surface water run-off to <br />the inside of the road. <br />,_... <br />~~ <br />.._ <br /> <br />