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Hr. Rob«rr Ov«na <br />CHS Pro3«c^ Jio. 37«4 Octob«r 19, 1992 <br />Ramlta <br />On October a, 1992, vrit«r and an Enqin««rin<| Tachnician obtainad <br />alavationa along thraa aurvay linaa axtanding from tha axiating houaa <br />perpandicular to tna alopa and anding at tha adga of Laka Hinnatonica. <br />Lina 1 waa aatabliahad ipproxiaataiy 20 faat aouth of tha nort.^^ adga of <br />tha houaa; Lina 2 vaa aatabliahad approxiaataly 90 faat aouth of tha <br />north adga of tha houaa; and Lina 3 waa aatabliahad approxiaataly 75 <br />faat aouth of tha north adga ot tha houaa. Attachad ara tha croaa <br />aactiona baaad on thaaa alavationa. Line 2 vaa aatabliahad through ths <br />existing failad cona within tha alopa. <br />As can ba aaan from tha attachad cross sections, tha alopa ia divided <br />into approximately two portiona. An upper zona having a aidaalope of <br />approximately 1.1 to 1.5 horizontal:! vertical; and a lower zona having <br />a flatter slope of approximately 2 to 3 horizontal:! vertical. Based <br />on tha preliminary data, it is our opinion that it is the upper steeper <br />zone that is marginally stable. <br />Based on our anginaering aaseasmant of the cross sections, va <br />three possible remedial schemes: <br />submit <br />1. <br />2. <br />3. <br />Reshape the entire form <br />flatter, more stable configuration <br />a <br />Construct a double ratainir^ wall <br />eliminating tha existing sidaslo,>a <br />Combination slope with reshaping a: t a <br />single retaining wall <br />We ha''a included preliminary drawings outlining these possible remedial <br />measures. After discussing these with you, we understand that <br />reshaping the entire slope is undesirable since this would require <br />losing a large amount of ground an<; trees. If one of the two remaining <br />schemes is chosen for slope repair, it is important that the existing <br />fill soil be removed and replaced in a properly compacted condition. <br />The natural soils should be benched, and the fill placed and compacted <br />in horizontal lifts, thereby eliminating the creation of a potential <br />failure surface between the fill and natural soils. In addition, the <br />use of a geotextile behind the wall would be beneficial for <br />stabilization. It should be noted that alternate 3 would be less <br />costly than alternate 2, since a rough budget estimated cost for tied <br />back timber retaining walls is about $10 per square foot of wall.