Senior officials from the U.S. Environmental Protection Agency and the Los Angeles County Sanitation Districts celebrated the influx of $441 million in Water Infrastructure Finance and Innovation Act loans and $127 million in State Revolving Fund loans for the Clearwater underground project.
Construction for the project began in 2019 and is expected to be completed in 2027.

The project begins at the Joint Water Pollution Control Plant (JWPCP) in Carson, CA where two large tunnels to convey water to the ocean. The tunnels are 60 and 80 years old.

The project will begin with the construction of an access shaft. This shaft will be used throughout the project as the entry/exit point for construction workers, tunnel materials (e.g., liner segments and excavates soil), and equipment. A noise barrier, approximately 6 m (20 ft) high, will be erected between the site and nearby sensitive receptors.

At Royal Palms Beach, the new tunnel will connect to the existing ocean outfalls. This work will take a little over two years to complete.

So far, the Clearwater underground tunneling project, which will carry cleaned and treated wastewater, has completed 4 km (2.5 miles).
Robert Ferrante, chief engineer and general manager of the L.A. County Sanitation Districts, told the Daily Breeze that the project addresses several issues that are looming. Most basically, it will replace two existing pipelines from the 1930s and 1950s, respectively, that are operating at near capacity. The path of the pipelines also crosses two earthquake fault lines.

The system handles wastewater for more than 5 million residents and includes seven wastewater treatment plants.

In 2012, the Sanitation Districts’ Board of Directors approved the projects to build a 5.4 m (18-ft) diameter, 11.2 km (7-mile) tunnel with seismic upgrades throughout. At the start of work, the entire project was estimated to cost some $630 million.

The tunneling is being done by a modern tunnel boring machine at depths ranging from 9 m to 137 m (30 ft to 450 ft). Overall construction began in 2019. Actual tunneling started in late 2021.

The tunneling is expected to be finished in 2025, with all construction wrapping up in 2027.