2012/08/08 Council Agenda Packet

2 Task 603 Geotechnical Investigation. Geotechnical information will be obtained to support the detailed design. Geotechnical work will be completed by a subconsultant, GeoEngineers. Assumptions: • Traffic control will be provided based on City of Everett standards o Traffic Data will not be required for pavement thickness design, standard City design pavement sections will be utilized Activities: Soils Exploration • Review previous geologic and subsurface information. • Prepare a brief exploration plan as a Technical Memorandum, including locations, duration, name of driller and backhoe subcontractor, and schedule. • Submit traffic control plans and obtain permits for the field exploration program. • Conduct.a visual pavement survey to evaluate the existing pavement surface conditions to aid in selection of exploration locations. • Complete the one-call utility-locate service and coordinate with City of Everett Utilities to locate utilities in exploration areas. • Retain and supervise driller and backhoe subcontractor. • Maintain field supervision of driller and backhoe subcontractor, prepare exploration logs, collect and monitor soil samples. • Restore bore holes and test pits and dispose of cuttings. • Complete twelve initial and four additional optional soil borings with laboratory testing. • Complete 6 to 8 backhoe test pits in alleys where mutually agreed. Import crushed rock to backfill test pits where appropriate. Geotechnical Engineering Analysis • Characterize soil conditions and identify ground water depths for the purpose of planning utility trenching, trench backfill, pipe loading, subgrade preparation, and development of subgrade repair strategies for pavement support where unsuitable subgrade soils are encountered. • Evaluate and provide recommendations for alternative pipeline installation methods, such as pipe bursting. • Prepare geotechnical report including: a. Descriptions of site conditions and detailed subsurface. soil conditions encountered based on results of the above tasks. b. Provide recommendations for earthwork and site preparation including suitability of on-site soils for reuse in trench backfill, placement and compaction of trench backfill, and mitigation of unsuitable soil conditions. This will include an evaluation of the effects of weather and/or construction equipment on site soils. c. Perform engineering analyses and provide conclusions and recommendations for conventional trenching techniques including the following: • Geotechnical parameters for trench shoring design including lateral pressures, and partial shoring considerations; July 2012 r6.0 Page 9 of 19 Jacobs Engineering Group 19