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GeolechniCal En( in�,err�r, P.r��s'? <br />1313 f�adrona Ave,�.�.� <br />Everett, 1/��ashinytc: <br />March 11, 2013 <br />RN File No. 2793-CG?:. <br />Page 6 <br />Some aeration and/or addition oi n��o�sture may al=o b= r�ecessary VJe expect ti�at cornpacticr <br />of the native soils to structural fill specifica[ions would be drfficult, d not impossible, during wet <br />weather. <br />Fill Placemen:.: Following subgrade preparation, placement of the structural (ill may proceed <br />Fill should be placed in 8- to 10-inch-thick uniform bfts, and each lift should be spr2ad evenly <br />and be thoroughly compacted prior to placement of subsequent lifts All structural fill <br />underlying building areas, and within a depth of 2 feet below pavement and sidewalk subgrade, <br />should be compacted to at least 95 percent of its maximum dry density. Maximum dry densiry, <br />in this report, refers to that density as determined by the ASTM D1557 compac;ion test <br />,,rocedure. Fill more than 2 feet beneath sidewalks and pavement subgrades sf��ould be <br />compscted to at least 90 percent o( the maximum dry density. The moisture content o( the soil <br />to be compacted should be within about 2 percent of optimum so that a readily compactable <br />condition exists. It may be necessary to overexcavate and remove wet surficial soils �n cases <br />where drying to a compactable condrtion is not feasible. All compaction should be <br />accomplished by eau,pment of a type and size sufficient to attain the desired degree of <br />compaction. <br />Temporary and Permanent Slopes <br />Temporary cut slope sta6ility is a function of many factors, such as the type ard consisiency of <br />soils, depth of the cut, surcharge loads ad�acent to the excavation, length of time a cut remains <br />open, and the presence of surface or groundwater. II is exceedingly difficuit under these <br />var�able conditions to estimate stable temporary cut slope geometry. There(ore, it should be <br />the responsibility of the contractor to maintain safe slope configurations, since the contractor is <br />continuously at ihe job site, able to observe the nature and condition of the cut slopes, and able <br />to mor�rtor the subsurface materials and groundwater conditions encountered. <br />For planning purposes, we recommend that temporary cuts in the ste soils be no steeper than <br />1 5 Horizontal to 1 Vertical (1.5H:1V) I( groundwater seepage is encountered, we would <br />expect that (latter inclinations would be necessary. <br />We recommend tha[ cut slopes be protected from erosion. Measures taker, may include <br />covering cut slopes with plast�c sheeting and drverting surface runoff away (rom the top of cut <br />slopes. We do not recommend vertical slopes for cuts deeper than 4 feet. if worker access is <br />necessary. We recommend that cut slope heights and �nclinations conform to local and <br />WISHA/OSHA standards. <br />Final slope inclinations for granular structural fill and Ihe native soils should be no steeper than <br />2H:1V. Lightly compacted fills, common fills, or structural fill predominately consisting of fine <br />grained soils shculd be no steeper than 3H:iV Common fills are defined as fill material with <br />some organics that are "Irackrolled" inro place. They would not meet the compaction <br />specificaUon o( strucwral fill. Final slopes should be vegetated and covered with straw or jute <br />netting. The vegetatron should be maintained until it is established. <br />Robinson Noble, Inc <br />