Project:
Effluent Outfall Tunnel Project, San Pedro, California
Overview
The A.K. Warren Water Resource Facility, previously known as Joint Water Pollution Control Plant (JWPCP), in Carson currently provides primary and secondary treatment for a design capacity of 400 million gallons of wastewater per day, and serves over 4.8 million residents, businesses and industries. The project consisted of a 7-mile-long, 18-foot diameter tunnel from the JWPCP to a new ocean diffuser along the San Pedro shelf.
Location:
Los Angeles County
Owner / Client:
Los Angeles County Sanitation Districts
Performance Period:
2006-2016
Services:
- Seismicity and Faulting Studies
- Geotechnical and Hydrogeological Characterization
Scope of Services Provided by AES
AES, as a subcontractor to Fugro West, provided geotechnical consulting services for the feasibility and preliminary design phases of the JWPCP Tunnel and Ocean Outfall project.
The onshore portion of the project area has been divided by the Sanitation Districts into a series of 13 potential tunnel sub-alignments. Once the tunnel has passed beneath the coastline, it will continue out across the adjacent San Pedro Shelf. Several potential diffuser locations near the edge of the shelf are being evaluated. Those locations are in areas extending from Whites Point on the west to the Beta Oil Filed on the east where the water depth is between 165 and 330 feet. The diffuser will be about 10,000 to 12,000 feet in length.
All of the tunnel alignments crossed the active Palos Verdes fault zone. With the exception of one eastern alignment, the other alignments crossed the Palos Verdes fault zone beneath San Pedro or Terminal Island. With the exception of the one eastern alignment, the other alignments also crossed the potentially active Cabrillo fault zone.
In addition to an offshore field program to collect marine geophysical and geotechnical data on the San Pedro Shelf, AES personnel were responsible for implementing onshore subsurface investigations during the feasibility phase. The onshore investigations included drilling, sampling and logging borings to investigate subsurface conditions near potential shaft locations and at sites where Tertiary bedrock units were relatively close to the ground surface. The borings were drilled to depths varying from 250 to 450 feet. In addition to the collection of continuous core from several of the borings, downhole geophysics including velocity, natural gamma, caliper, borehole acoustic televiewer and electrical logs were conducted in the borings. Vibrating wire piezometers were also installed to measure groundwater pressures and temperatures at various depths and packer testing was conducted in selected borings to evaluate the hydraulic conductivity of the Tertiary bedrock.
The results of these investigations were provided to the Sanitation Districts for use by their Design Consultants for tunnels and pipelines designs.