A major Los Angeles County Sanitation Districts project to reline an aging sewer trunk line that runs the full length of Hermosa Beach is set to begin March 30, Public Works Director Joe SanClemente told the city's Public Works Commission at its meeting Wednesday night.

The line is over 100 years old. It carries a significant share of the city's sewage outflow and runs from the southern city limit all the way north to the Manhattan Beach border. One short section on Bayview Drive was repaired on an emergency basis about a year and a half ago; this project covers everything else — roughly 8,000 feet of pipe.

What they're doing and why

Rather than digging up and replacing the pipe, crews will install a cured-in-place liner from the inside — a method that rehabilitates the existing line without major excavation. Work proceeds manhole to manhole, with crews typically accessing the pipe at existing manholes along the route. At certain locations, they'll need to cut small trenches into the street surface; where those trenches cross busy intersections, steel plates will cover them to maintain access.

The bigger visible disruption will be the bypass pipe. Because the existing line has to be completely emptied to install the liner, crews run a temporary above-ground pipe down an adjacent street to keep sewage flowing during construction. Think orange pipe, traffic cones, and a lane of your street occupied for a few weeks at a stretch.

What the city negotiated

Director SanClemente noted that staff put considerable work into the phasing agreements. The city required the Sanitation Districts to stay out of the downtown core from April 1 through September 30, which is why Phase 6 is last. The city will also have its own inspector on site throughout the project, alongside the Districts' inspector.

Residents and businesses will receive notifications 14 days, 7 days, and 24 hours before work begins in their area. A small number of properties are directly connected to the county trunk line rather than the city's lateral system; those households will face temporary service disruptions and the Districts will provide portable restrooms and wash stations.

All project costs are borne by Los Angeles County Sanitation Districts. The city pays nothing. Any pavement damaged during construction must be restored to city standards at the Districts' expense — typically a lane-width repair around the trench footprint.

The bigger picture

Commissioners acknowledged that the timing is rough. The southern end of the city — around 2nd Street and Monterey — is already dealing with Cal Water's water main replacement work and the Torrance-led Green Streets project simultaneously. Commissioner Scott Hayes noted that residents trying to navigate the area have been caught between overlapping detours with little coordination between the different crews.

SanClemente acknowledged the frustration but was direct about the urgency. The Bayview emergency repair was a warning sign. "This is over 100 years old," he said. "This carries a lot of flow out of the city. That's why we're trying to break it into manageable pieces."

The project is expected to run close to a year in total. Residents experiencing specific traffic control problems are encouraged to contact the Public Works Department directly rather than wait — staff said they go out daily to enforce compliance with approved traffic control plans and will intervene when contractors aren't following them.

A dedicated project webpage has been set up by the Sanitation Districts. The city's Public Works Department can also be reached directly for issues as they arise.