Los Angeles Effluent Outfall Tunnel

The Los Angeles Effluent Outfall Tunnel is a critical infrastructure project to improve wastewater management and protect local waterways. The new 7-mile, 18-foot-diameter tunnel will safely transport treated water from the Hyperion Water Reclamation Plant to the Pacific Ocean, ensuring the long-term reliability of the region’s wastewater system.  

This project addresses three key concerns aging infrastructure, seismic activity along two earthquake faults and overflow risks during heavy rains. Upgrading the system enhances resilience, prevents potential service disruptions and supports future regulatory compliance.  

FlatironDragados is leading tunnel excavation and construction, including launch shaft development, tunnel boring and final pipeline installation. The new tunnel will allow necessary repairs to the existing outfall tunnels, built in 1937 and 1958, while expanding system capacity to support regional population growth.  

An advanced tunnel boring machine will minimize surface disruptions and environmental impact while protecting marine ecosystems. Once complete, the project will strengthen wastewater infrastructure and improve sustainability for millions of residents.