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W.W. Wheeler & Associates, Inc. <br /> June 5, 1996 <br /> Page 2 <br /> After reviewing the embankment material types and the geometry and height of the proposed <br /> cut, the undersigned advised you on June 3, 1996, that the temporary excavation slope could <br /> probably be as steep as 1:1 without us performing any stability analysis, provided we were <br /> there to observe the conditions exposed. Based on the location of the bypass conduit shown <br /> in a drawing provided to us, 1:1 excavation slopes up to approximately 35 feet in height would <br /> have been required. <br /> The undersigned met with Mr. Kenny Sheesley, ASI RCC's Project Superintendent, on the <br /> morning of June 4, 1996. The bypass conduit had already been excavated back to the 450 <br /> bend. However, the location of the bend was actually approximately 30 feet south of the <br /> location shown on the drawing provided to us, resulting in the excavation depth being less than <br /> originally envisioned. The excavation slopes were nearly vertical, and were judged to range <br /> from about 10 to nearly 20 feet in height. The soils exposed in the excavation sides were a <br /> very stiff to very dense mixture of clay, sand and gravel, with occasional cobbles. <br /> Water was flowing several inches deep in the 24-inch CMP and flowing to the southwest in <br /> a ditch along the original conduit alignment. The bypass conduit bedding and backfill up to <br /> approximately 1 to 2 feet above the pipe consisted of silty sand and gravel with an <br /> approximate maximum size of 2 inches, similar in appearance to base course. No seepage was <br /> w observed in the excavation, although the base course pipe backfill appeared very moist to wet <br /> below the elevation of the top of the pipe. Mr. Sheesley said that he planned to excavate the <br /> slope back to an inclination between 1:1 and 1.5:1 prior to allowing personnel to work in the <br /> vicinity of the toe of the excavation slope. The undersigned told Mr. Sheesley that, <br /> considering the apparent absence of seepage and the stiffness of the soil exposed, the slope <br /> should remain stable at a 1:1 to 1.5:1 slope for the relatively.short duration proposed (e.g., <br /> approximately 1 week). The undersigned further recommended that the flow from the pipe <br /> should be stopped and the excavation slopes allowed to dry sufficiently to confirm the absence <br /> of seepage at the toe of the slope prior to allowing personnel access. <br /> The undersigned and Mr. Sheesley also discussed the general approach for preparing the <br /> subgrade prior to backfilling the conduit excavation and the overall breach excavation. It was <br /> agreed that wet/loose/disturbed material should be removed to a firm, properly compacted <br /> subgrade, particularly on the south side of the outlet conduit, where standing water and soft, <br /> wet soils were observed. Mr. Sheesley agreed with this approach. <br /> Kumar & Associates, Inc. <br />