1315 PACIFIC AVE 2018-01-01 MF Import

arc not considcred an economical allemativc (significant facc stabilization and longer or post-trnsioned nails would bc required). This report provides recommendations for convrntional cantilever soldier pile walls. If the project rcquires a de�-per excavation than the current proposed depth, recommendations for convcntional soldier pile tie-back walls can be provided. Slh Preparation and Exeava8on Site development will requirc mmoval of cxisting pavements, buildings, buried utilities, and other structums prescnt at the site. Wc understand that the existing 2Q-inch diameter scwer localed under the alley will be abandoncd. Existing fill locatcd under planned(oundations will necd to be removed to expose dense native soils. In addition, a portion of the soils to be excavated con[ain hydrocarbon contaminalion. These soils will need to be disposed ofT site according to Washington State Dcpanment of Ecology Guidelines. Detailed environmental conclusions and recommendations are provided in a separetc rcpoct. Wc expect that the soils encountered within the proposed excavation area can be rcmoued wilh conve�uional excavating equipment. Occasional debris (wood, concretc, or othcr construction debris) may bc cncountered within thc old fill at Ihc site. The fill contains variable fincs content such thal repeatcd construction tralTic in some arcas could resuN in considerable disturbance during wct wcather construction. Wc recommend that, where practical, shoring installation bc accomplishcd by drill equipment working off the existing asphalt. If the asphalt is removcd or if areas of thc si�c show signs of cxcessivc deformations during foundation construction, it may be ncccssary �o conswct a tcmporary fill pad to provide a working surface for construction equipmenl. Thc fill soil for this work pad should consist of crushcd rock, wcll-graded sand and �'avel, quarry spalls, or some combination of thesc materials. We estimatc that thc required thickness of this layer will bc about 12 inches. A thicker laycr (up to 18 inchcs) may be necded whcre rcpcaled heavy loads from cquipment such as concrete wcks occur. A geotextile separator can be uscd between the existing ground and the work pad lo hclp reducc defortnations and possibly dccrcasc thc thickness of thc pad. Wc suggest ulilizing a woven geotextile similar to Amow 2016 or Mirafi 600X for this purpose. Thc decision regarJing whcn and whcrc a u�orking surface is necdcd, iC at all, should be made by the contractor with consultation with GcoLngincers during construction whcn thc bchavior of thc sitc soils undcn c�avy equipmcnt loading can bc bcltcr cvaluatcd. Temponry Cut Slopes I'ar planning pumoses, wc recommend temporary cut slopes in thc dense to vcq� dense glacially consolidated soils bc inclined no stecper than 1H:IV (I�orizontaL•vertical). Temporary cut slopes in the oecrlying looscr fill soils should gcncrally be inclined no stecper than I'hH:l V. A steeper slope, on the order of 1 H:I V,may be used in the fill providcd the slope is tlashcoa�ed with 2 to 4 inches of shotcrete. The above cu� slope recommenda�ions apply to conditions w�here significant secpage is not presrnt. Planer slopes may be necessary if significant secpagc is prcsent on the cut facc or if localized sloughing occurs. Iror open wts at the sitc wc recommend Ihal: • No tramc,construclion equipment,sWckpilcs or b�ilding supplics be allowed a�Ihe top of the cut slopcs w�ithin a dislancc of at Icast 10 fcct Gom thc top of thc wt. • L'xposed soil along the slopc be protected from surface erosion using watcrproof tarps or visqucen or Oashcoating with shotcretc. • Conswction activitics bc schcdulcd so that thc Icngth of time the tcmporary cut is left open is reduced to the extcnt practical. i��tr A'o. 171lSnnl-n0 Page 6 GEOENCIMEE�� Junr b.'P��Y ��