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r <br />Mr. Dale Gustafson <br />October 11. 1994 <br />Page 3 <br />on the fine grained shore materials prior to placing the riprap. This filter layer is attended to <br />For this tvoe of wall system, several conditions must be evaluated to determine the wall system <br />geometr^required so adequate lateral support is attained. Those conditions and mmimum <br />factors of safety we have considered are as follows: <br />Bearing Capacity FaUure - Safety Factor = 2.0 <br />Base Sliding - Safety Factor — 1.5 <br />• Wall Overturning - Safety Factor — 2.0 <br />Overall Slope Failure - Safety Factor 1.5 <br />Geogrid Overstress - Safety Factor — 1.2 <br />Geogrid Pullout - Safety Factor = 1.5 <br />Your proposed wall system has three general geometrical cross-sections. <br />Walls separated by relatively large distance with a slope upward away from the lower <br />wall of 2.5:1 to 3:1 (horizontal:vertical). <br />Up to four terraced walls at spacings of as little as about 6 <br />elLation away from the shoreline of about 2.5:1 (honzontahvenical). with backfill <br />between individual walls relatively level. <br />Two-tiered wall system with relatively level grades between and above the walls. <br />Adequate bearing capacity of the wall system will require replacement <br />witll the area of *e walls. This includes all soil materials which shifted “ “ <br />slope faUure several years ago. For access to the planned <br />ex^g trees and shrubs along the shoreline will have to <br />should be grubbed and cleared from the area. We tecotmne^ T <br />areas by an experienced soils engineer or technician prior to fill placement. <br />Supporting earth materials beneath the wall system must be <br />comV'e* fiU- The fill material should preferably be fine gravel with a maxunum largest <br />1 <br />imcaLjit.