Tunnel Stabilization & Sewer Pipeline Phases 1-4

In the 1950s, a gravity-fed sewer line and tunnel stretching two miles were constructed in Laguna Beach. Over time, the structure deteriorated and increasingly lacked support, so its current owners and operators, the South Coast Water District, contracted Drill Tech to implement a four-phase plan to rehabilitate the existing tunnel, install a new sewer pipe, and reconnect the 80+ lateral services. The project required 10,000 linear feet of concrete pipeline encasement and concrete invert placement, as well as a 24” sewer main. The shaft itself was 20 feet in diameter and 100 feet long.

Several environmental accommodations were required throughout the duration of the project, including limited beach access due to the grunion run, paleontologist inspection for fossils every 1,000 feet of tunneling, and monitored vibration and noise levels. Because excavation occurred next to a live sewer main, operations were held to a high degree of care and scrutiny, as well as regular gas testing. Drill Tech partnered with the South Coast Water District, regulating authorities, and third-party stakeholders to identify issues and manufacture solutions in real time.