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Page 12 of 59 <br /> <br />City of Everett Merrill & Ring Bridge Replacement <br /> <br />3.3.3 Generate Geotechnical Work Plan Memo: HWA will prepare a Geotechnical Work Plan <br />Memorandum describing exploration means and methods associated with both Phase 1 <br />and Phase 2 of the exploration program. This work plan will be submitted to the design <br />team and the City of Everett for review and approval. The work plans will detail the type, <br />location, and extent of proposed field explorations along with logistics necessary to <br />perform the work such as traffic control plans and designation of staging areas. The work <br />plans will also be used for utility locating clearances and for permitting and right of <br />entries that may be necessary to access the exploration locations. We assume the City of <br />Everett or David Evans and Associates, Inc., in support of this project, will acquire and <br />provide any required permits or right of entries at no cost to HWA <br /> <br />3.3.4 Conduct Phase 1 Explorations (Geotechnical Borings): HWA will conduct a series of 4 <br />geotechnical borings along the bridge alignment to support various aspects of the design. <br />CONSULTANT proposes to drill one truck mounted geotechnical boring near each <br />existing bridge abutment (total of 2 borings). These borings will be drilled to a depth of <br />approximately 100 feet below ground surface near the location of the existing east and <br />west bridge abutments. Instrumented groundwater monitoring wells will be installed <br />within both borings to monitor and record seasonal variations in groundwater levels. <br /> <br />To assess the soil and groundwater conditions at the proposed interior piers, HWA <br />proposes to advance two (2) borings through the bridge deck. At each of the two (2) <br />over-ravine (bridge) boring locations, a nominally 12-inch diameter core will be drilled <br />through the existing pavement and structural deck. The best location for these cores will <br />be coordinated with the design team to account for existing utilities and structural <br />considerations. A very small quantity of water will be used to lubricate and cool the <br />diamond-tipped core barrel; this water will be contained and collected using a shop- <br />vacuum. Both concrete cores will be drilled, extracted, and covered with steel plates the <br />day before drilling is scheduled to commence. <br />Once the core holes are completed, the exploratory borings will be advanced using sonic <br />drilling technique. <br />After each of the boreholes have reached the required target depth of 75 feet below the <br />ground surface, the boreholes will be decommissioned using a bentonite grout slurry in <br />accordance with Washington State Department of Ecology requirements. <br />Once the borings are completed, the core holes in the bridge deck will be patched with <br />high strength concrete. We anticipate that rebar dowels will be installed in the side wall <br />of the core holes to properly adhere the new concrete to the existing bridge deck. HWA <br />will coordinate with David Evans and Associates, Inc. to determine the required doweling <br />protocol for patching the pavement cores. After each core is patched, a steel plate will be <br />placed over the core and surrounding roadway to allow the associated patch to dry.