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3.15 — Conduct Subsurface Explorations <br /> Upon approval, HWA shall conduct the proposed field exploration program, which includes a <br /> total of six borings. For the bridge structure HWA shall drill three geotechnical soil borings. The <br /> first boring will be drilled at the top of the existing slope in the vicinity of the proposed eastern <br /> bridge abutment. This boring will be drilled and sampled to approximately 150 feet below the <br /> ground surface in order to categorize the soils along the steep slope. It will be drilled with a <br /> track mounted drill rig utilizing mud rotary drilling techniques. Upon completion of this boring a <br /> ground water monitoring well will be installed. <br /> A boring approximately 25 feet deep will be located at the base of the existing slope to <br /> characterize the soils and available bearing capacity at the location of a possible temporary <br /> construction support associated with bridge launching procedures. This boring will be drilled <br /> with a hand portable drill rig to limit impacts associated with BNSF. <br /> The third bridge boring will be drilled at the location of the proposed western bridge abutment. <br /> This boring will be drilled to a depth of 100 feet below ground surface in order to provide deep <br /> foundation design recommendations. This boring will be drilled with a track mounted drill rig <br /> utilizing mud rotary drilling techniques. Upon completion of this boring a ground water <br /> monitoring well will be installed. <br /> 3.16 — Generate Boring Logs and Assign Laboratory Testing <br /> HWA shall prepare summary boring logs and perform laboratory testing to evaluate relevant <br /> physical properties of the site soils. Laboratory testing will include moisture contents, grain-size <br /> distribution, Atterberg Limits, one-dimensional consolidation, direct shear testing and <br /> consolidated undrained triaxial tests. All laboratory testing will be performed in general <br /> accordance with the corresponding ASTM procedures. <br /> 3.17— Conduct Steep Slope Reconnaissance <br /> A geologist and a geotechnical engineer from HWA shall conduct a detailed reconnaissance of <br /> the steep slope located directly to the west of the proposed eastern bridge abutment. This <br /> reconnaissance shall include a detailed evaluation of existing slope features and the <br /> advancement of strategic hand explorations to facilitate identification of soil conditions along the <br /> slope. This effort shall be focused on evaluating the stability of the near surface soils along the <br /> existing steep slope. <br /> 3.18 — Evaluate Field and Laboratory Data <br /> Based on the borings and the laboratory test results of selected samples, HWA shall generate <br /> estimates of the soil strength and other properties needed to evaluate the effects the subsurface <br /> conditions will have on seismic performance of the proposed structure. <br /> 3.19 — Generate Geologic Cross-Section <br /> HWA shall construct a geologic profile along the bridge alignment based on the information <br /> obtained from the above described geotechnical borings and slope reconnaissance. This profile <br /> shall be provided in the geotechnical report and shall be used for global stability and shoring <br /> analyses. <br /> KPFF Consulting Engineer November 10, 2014 <br /> Grand Avenue Park Utility Bridge, Phase 1A Page 12 of 55 <br />