Domains
Tunnel & Underground;Water / Wastewater treatment
Client
Dragados (USA)
Final client
LA County Sanitation Districts
Time frame
Construction cost
$630'000'000
Services
- Support to contractor
- Consulting / Expertise
- Design
- Inspections & Assessment
Phases
- Preliminary design
- Construction
The Project
This tunnel will transport secondary effluent from the Joint Water Pollution Control Plant in Carson, California to the existing ocean outfalls at Royal Palms State Beach, on the Palos Verde Peninsula. Its goal is to provide redundancy for the existing effluent tunnels and to increase the overall conveyance capacity of the system. The tunnel will have a length of approx. 7 miles (11.265 km) and a finished internal diameter of 18 feet (5.49 m). It will be excavated by a TBM designed to cope with water pressure up to 10 bar.
A Tunnel for the City of Angels
Much of the sewage produced by inhabitants of Los Angeles ends up at the Joint Water Pollution Control Plant (JWPCP) in Carson. From there, the treated water reaches the ocean through two tunnels that have been in operation for more than 60 years but are no longer meeting demand. This new 7-mile tunnel will ensure continued protection of the environment and public health. The work ranges from 30 to 450 feet below ground, following the route of existing roads. This solution was chosen for its two distinct advantages. Firstly, working several meters underground reduces disruption to surface activities as it affects road traffic only marginally. Secondly, tunneling below streets utilizes the public right of way, minimizing authorization and bureaucratic involvement. It is expected to be completed in 2027, when the tunnel will join the existing ocean drains at Royal Palms Beach in San Pedro, California.
The new Los Angeles, California JWPCP effluent outfall tunnel is designed to provide relief and redundancy to the existing tunnels built almost a century ago
When the project was advertised, it was immediately obvious that this wasn’t going to be an easy one. And because of that, without hesitation, ARX fought to become the primary geotechnical consultant. The ground conditions are so diverse and extreme that our assumptions and plans are challenged daily. It’s the perfect place to learn tunneling, and we’re trying to get as many of our engineers exposed to it as possible. A job like this defines what we do and who we are as a Group.
