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FY2 Task 320 — Geotechnical Investigations Task Objective Provide geotechnical evaluation to support the 17'h Street Interceptor replacement project. HWA GeoSciences Inc. is being retained to perform these services. Consultant Services 1. Review available geotechnical information from and in the vicinity of the project. This will include a review of geologic maps, HWA's library of geotechnical information in the area and data from online databases. 2. Obtain City of Everett Street Use Permit for drilling in the right of way. This includes developing appropriate traffic control plans for the proposed drilling. 3. Develop and coordinate a field exploration program for drilling of five(5)geotechnical borings in support of identifying subgrade soil and groundwater conditions that will affect the proposed improvements. 4. Coordinate and review traffic control with the drilling subcontractor. The subcontractor's certified traffic control supervisor will stamp each traffic control plan. Each plan will be reviewed by HWA prior to distribution to the team. 5. Develop a geotechnical exploration plan for the proposed geotechnical investigation and submit to the City for review and approval. The exploration plan will detail the type, location, and extent of proposed field explorations along with logistics necessary to perform the work such as traffic control plans and staging areas. The work plan will also be used for utility locating clearances and permitting that may be necessary to access the exploration locations. 6. Conduct utility locates for the proposed borings. This will include retaining a private locating service to have underground utilities located in the vicinity of the proposed borings. 7. Conduct geotechnical borings with a truck/trailer-mounted drill rig equipped with hollow- stem auger will be used to drill the geotechnical borings. A total of 5 borings,each drilled to a depth of 20-feet below ground surface. Standard Penetration Test(SPT) samples will be taken at 2-1/2 to 5-foot intervals throughout each boring. Groundwater monitoring wells as a part of the drilling program. All borings will be monitored and logged under full-time observation of a representative of the geotechnical engineer. The boring will be drilled by a licensed geotechnical/well driller under subcontract to geotechnical engineer. 8. Generate boring logs and perform laboratory testing of select samples from the borings. Testing may include moisture content, grain-size distribution and Atterberg limits. Soil and laboratory test information will be presented in summary boring logs that will be generated upon completion of our exploration program. 9. If groundwater is encountered, perform a hydraulic conductivity analysis. Data will be evaluated data derived from our field investigations to develop general recommendations for construction dewatering. Hydraulic conductivity will be estimated using grain size distribution. Field measurement of hydraulic conductivity/flow rate is not included in this scope of work. 10.Evaluate liquefaction potential. City of Everett—17th Street Interceptor Improvements 10 Scope of Services