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WEST HOLLYWOOD — The special cement used to backfill the massive sinkhole on Sunset Boulevard caused by the rupture of a 36-inch-wide water main that unleashed a deluge July 16 is in the midst of the 24-hour hardening process.
“Crews have placed 300 cubic yards or 30 truckloads of concrete slurry into the trench following thorough pressure testing and verification that all identified leaks were fully resolved,” the Los Angeles Department of Water and Power announced July 21.
While the slurry cures, pipe disinfection, water quality testing, and regulatory approvals are also taking place to ensure water quality requirements are met, before returning the pipeline to service. The DWP expects street reopening and full pipe restoration by end of week.
Sunset Boulevard remains closed between Sherbourne Drive and San Vicente Boulevard, with limited local access on nearby streets including Cynthia and San Vicente, as repairs continue.
Work on repairing the broken main, which dates to 1916, involved more than 250 DWP workers toiling around the clock after the rupture was reported at about 3 a.m. July 16 on Sunset Boulevard at Holloway Drive, pushing around cars and flooding garages while shifting massive chunks of asphalt and concrete slabs.
By 7 a.m. that morning, the rushing water, which sent debris downhill to Santa Monica Boulevard, had been stopped.
“No water service interruptions are expected while DWP finishes the repair work,” the department reported. “The water supply to the affected neighborhood continues through an 8-inch distribution pipeline and drinking water remains safe. Until the repaired 36-inch pipe is returned to service, customers are still urged to conserve water to avoid residents and businesses on upper floors from experiencing lower pressure during periods of high demand.”
Repairs of the broken main were completed July 20 as a new 25-foot section was welded into place.
The DWP was working with the Metropolitan Water District of Southern California, Los Angeles County Public Works and other utilities to protect underground infrastructure during the repairs.
Some businesses in the area remain closed, including Book Soup, and many residents suffered property damage in the disaster.
Customers with questions regarding the pipe rupture may call 800-342-5497. Claims information is available at LADWP.com/Claims.
West Hollywood has launched a website with regularly updated information about the response and recovery effort. The site, weho.org/watermainbreak, includes repair updates, street closures, traffic information, bus line detours, parking enforcement changes, claims information, hotel discounts for affected residents and other resources.
Officials said the 10-mile Sunset Trunk Line that ruptured had already been designated for replacement. The department said design work is underway on a project to replace nearly 6.4 miles of large-diameter pipeline and 3.5 miles of distribution pipe, with construction expected to begin in 2031.
The utility said it replaced more than 246,000 feet of water pipeline during 2024 and 2025 and is on track to replace another 246,000 feet this year.
The department also said its leak rate is 36% below the national average, averaging 16.1 leaks per 100 miles of pipe compared with 25 leaks per 100 miles nationwide.
The specific cause of the break is still under investigation, but Anselmo Collins, the LADWP’s chief operating officer and senior assistant general manager of the water system, said pressure in water delivery lines is highest at night when demand drops.
