Los Angeles Sewer Tunnel

Joint Outfall “C”, Unit 1, Relief Trunk Sewer

Carson & Wilmington, California

Geotechnical investigation and engineering support for construction of a 10-foot-diameter 1.5-mile long tunnel for 8-foot-diameter RCP sewer. Geotechnical exploration were performed for the tunnel crossing within the Alameda Transportation Corridor, Port of Los Angeles railroads, Tesoro Oil Refinery, numerous oil pipelines, and landfills. Geotechnical scope included three phases: 1) Drilling, soil/weak rock sampling and logging of 50 exploratory borings and advancing Cone Penetration Test (CPT) soundings, assessment of pipeline alignment stratigraphy, material property characterization and Geotechnical Data Report (GDR) preparation; 2) Preparation of a Tunnel Feasibility Report (TFR) for a 3,500-feet-long section of 10-foot-diameter tunnel; with evaluation of primary subsurface constraints along the pipeline alignment, prospective tunneling methods, ground settlement analyses, tunnel threshold limits and action levels, potentially gassy conditions; and 3) Engineering support during tunnel construction as part of CM team. Tasks included: a) collecting soil/rock samples from tunnel face; b) detailed logging of tunnel rib and lagging systems; c) tunnel ground settlement measurements; d) performance evaluations of existing nearby refinery infrastructure foundations and pipelines, relative to tunneling operations. Assisted in negotiations with Tunneling Contractor.