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3.2.1 Excavation for Tiebacks - A trench will be <br />excavated perpendicular to the existing wall at each <br />tieback location. The trench length will be field <br />determined, but should be approximately 15 feet long. <br />The back portion of the trench will be excavated as <br />deep as the hydraulic excavator can reach to allow <br />installation of tieback beams. Eight tiebacks will be <br />installed. <br />3.3.1 Installation of Tieback Beams - The tieback beams <br />will be placed vertically at the back of the trench <br />and will be driven into the ground as far as possible <br />with the hydraulic excavator. The beams will be cut <br />to a point to aid in driving. The trench will be <br />vackfilled with compacted fill. All fill will be <br />compacted to 958 maximum dry density. <br />3.4.1 Installation of Tieback Cables - Tieback cables <br />consisting of 1 inch wire rope will be installed <br />between the tieback beams and the wafers used at the <br />wall termination of the cable to provide some tension <br />on the cable. <br />3.5.1. Existing Wall Extension - The existing retaiing <br />wall is 56 feet long and consists of 6" x 8" steel <br />beams on 8 foot centers. The beams are lagged with <br />treated wood to retain the soil. It is planned to <br />extend the height of the wall 4 feet by welding an <br />additional 6" X S" beam to each existing beam. Beam <br />joints will be gusseted to provide maximun strength. <br />Additional treated wood laggig will also be installed. <br />Walers consisting of 6" X 8" steel beams will be <br />welded to the back (uphill) side of the wall. the <br />walers will run the full length of the wall. Waler <br />attachment will alternate 1 foot above and 1 foot <br />below extension joint. Individual waler lengths will <br />be either 8 or 16 feet as determined during <br />construction. <br />