• 2006 - 2018 Planning and Design 

• 2019 - 2027 Beginning in Carson, construction is currently underway and progressing through Royal Palms Beach.

• 2027 The project will be finalized and all construction sites will be restored to their original conditions.  

*Note: These dates are all subject to change

The tunnel will be built using a state-of-the-art, multimillion-dollar tunnel boring machine (TBM) specifically designed for this project. It will mostly run under public streets and will not pass under any homes. At depths of 30 to 450 feet, tunneling will produce no noticeable vibration or noise at the surface. An extensive geotechnical monitoring system with over 1,000 locations along the alignment will track ground movement. If any movement is detected, tunneling will be slowed or stopped, and the TBM adjusted.

The project is designed to minimize community impacts by limiting construction to two sites for tunnel access shafts. At the Warren Facility shaft, the TBM and materials will be lowered into the ground, and excavated soil removed, with barriers to reduce visibility and noise. A smaller exit shaft at Royal Palms Beach will remove the TBM and connect the new tunnel to existing ocean outfalls, with visual and noise barriers in place. Work will be confined to a small area, and the beach will remain accessible.

The project’s Environmental Impact Report/Statement (EIR/EIS) identified potential impacts and required mitigation measures, which the Sanitation Districts will implement, including using modern, clean-engine trucks.

The new tunnel alignment follows public streets as much as possible to avoid passing under homes and businesses. It will start under the west side of the Warren Facility (formerly JWPCP), then run beneath Figueroa Street, Harbor Regional Park, North Gaffey Street, Capitol Drive, and Western Avenue (through South Dodson Avenue), ending at Royal Palms Beach. The tunnel must pass under some commercial properties to make the turns from Gaffey to Capitol and from Capitol to Western.

At depths of 30 to 450 feet, impacts at street level are expected to be imperceptible. As a safeguard, an extensive geotechnical monitoring system along the alignment will track parameters such as vibration and settlement to ensure safety.

Most above-ground construction activity will occur at the Warren Facility and Royal Palms Beach shaft sites. Some locations along the tunnel alignment will also have short-term visible activity, such as installing the geotechnical monitoring system. In addition, three underground maintenance blocks needed for TBM cutting head maintenance will be constructed. Each block will take about three months to build using a drill rig that injects cement into the ground at the TBM’s depth.

Once completed, the project will have no impact on traffic. During construction, trips will be needed for workers, supplies, and removal of tunnel soil. At the Warren Facility shaft site, trucks will follow a route along Figueroa Street and Sepulveda Boulevard to the Harbor Freeway, avoiding residences. The EIR/EIS found these impacts to be less than significant. The Sanitation Districts will also coordinate with the cities of Carson and Los Angeles to further minimize the impact to the community.

The tunnel will be constructed entirely underground, except for the shafts at each end. Limited street work will be needed to install and later remove the geotechnical monitoring system, and this work will occur during off-hours to minimize impacts. No road closures are required.

Modern tunnel boring machines (TBMs) provide a highly controlled tunneling process and are widely used in urban areas. They construct the tunnel in 5-foot segments, immediately supporting the surrounding soil as they advance. Settlement is continuously monitored, and tunneling operations are adjusted if limits are approached. For most of the Palos Verdes Peninsula, tunneling will occur deep below the surface, further reducing any risk to buildings.

Over 1,000 monitoring points will be installed along the tunnel alignment to ensure safe tunneling. This extensive geotechnical monitoring program includes:

• Ground Surface Monitoring Points (GMPs): Reference points installed every 300–1,000 feet to detect any ground deformation or settlement.

• Utility Monitoring Points (UMPs): Fixed vertical rods touching subsurface utilities, spaced every 25–100 feet along the tunnel-overlying section, to detect movement.

• Multiple Position Extensometers (MPXs): Monitor settlement at multiple depths from 5 feet above the tunnel to the surface, installed every 500 feet, providing early warnings for potential impacts to structures or buried utilities.

• Displacement Monitoring Points (DMPs): Monuments or fixed points on structures used to determine whether ground movement is from the project or another source.

• Vibrating Wire Piezometers (VMPs): Track groundwater level changes during excavation to guide TBM operations.

• Inclinometers: Measure lateral ground movement near the surface.

• Vibration Monitoring: Placed near homes and businesses to detect ground-borne vibration and noise from tunneling.

In addition, pre- and post-construction inspections will compare conditions before, during, and after tunneling to determine any project-related changes.

Surface impacts from tunneling are expected to be imperceptible. A $7 million geotechnical monitoring system will ensure safe tunneling. The Sanitation Districts are committed to safely and responsibly serving the public and are accountable for any damage caused by construction. Concerns can be reported via the project email (ClearwaterProject@lacsd.org), hotline (877-300-WATER), or website (www.clearwater.lacsd.org), and will be addressed promptly.

The vibration at the surface from this tunneling is expected to be less than the vibration from a large truck driving down the street. Further, it is important to note that the geology and circumstances that led to the landslide at White Point are not present at Royal Palms Beach. For a landslide to occur, all of the following factors are required:

• Unfavorable bedding - This condition occurs when the thin layers that separate the rock layers, called bedding planes, are angled or tilted downward towards the ocean.

• Weak bedding plane - A weak bedding plane occurs when the bedding plane is made of weak material, such as bentonite clay.

• Wetted bedding plane - This condition occurs when water has passed through the rock formation and wetted the bedding planes. In the case of bentonite clay, water turns the clay into a slippery surface.

Landslides can also occur without a wetted bedding plane if the base of a bluff is undermined, such as by ocean erosion. These factors were identified as causes of the nearby White Point Landslide by the City of Los Angeles’ geotechnical consultant. At Royal Palms Beach, these conditions do not exist. The bedding planes are angled upward, highly folded, and the bluff base is protected from ocean erosion, making the geology stable.

The existing tunnels, built in the late 1930s and 1950s by blasting through bedrock, did not cause landslides. Modern tunnel boring machines (TBMs) generate much less vibration, well below levels that could trigger a landslide.

As a safeguard, tunneling will be closely monitored using over 1,000 geotechnical monitoring points along the alignment. In the unlikely event that surface movement is detected, tunneling will be slowed or stopped, and TBM settings adjusted.

The tunnel in this area will be about 50 feet deep, well below the depth of utility lines. The Sanitation Districts have coordinated with local governments and utility companies along the tunnel route, sharing engineering drawings and incorporating their feedback. All utility lines crossing the tunnel alignment will be monitored for settlement, and if movement approaches strict safety limits, tunneling operations will be adjusted to avoid causing damage.

Once completed, the project will produce no air emissions. During construction, trucks and equipment will generate some emissions, and mitigation measures will be implemented to minimize these impacts. Mitigation measures include using haul trucks powered by modern, clean engines and routing construction traffic away from congested streets and sensitive areas whenever feasible.