Los Angeles Department of Water and Power crews successfully completed pressure testing of the system of the ruptured water main in West Hollywood and Tuesday will prepare the site for the next steps of backfilling with a concrete slurry mix the massive sinkhole that closed portions of Sunset Boulevard.
Once the site is prepared and materials are in place, crews will begin backfilling the excavation area. Approximately 300 cubic yards of concrete mix slurry will be placed into the trench, requiring about 30 truckloads, according to the LADWP.
The slurry will be filled to roughly two feet below the surface and will cure for 12 hours. After required work in the shallow portion of the trench is finished, the slurry will cure for an additional 24 hours to ensure full stabilization.
“As repairs continue into this week, we remain aware of the difficulties and disruptions experienced by residents and businesses throughout West Hollywood,” said DWP. “LADWP continues to collaborate closely with the City of West Hollywood and all partner agencies to ensure that the restoration process meets all City requirements and completed to the highest standards of safety and quality.”
Crews will next install the base layer and apply new asphalt, ensuring all street restoration materials and methods have been approved by the city of West Hollywood. Water quality crews will disinfect the repaired section of pipe with chlorine, followed by comprehensive water quality testing to ensure full compliance with all drinking water standards.
The water will then be dechlorinated and discharged to the storm drain system.
The pipe will not return to service until every regulatory and internal safety benchmark are fully met, according to the DWP.
As of Monday evening, crews have successfully resolved all issues identified during pressure testing and completed thorough testing on every section of the pipeline, the DWP reported.
Repairs of the 36-inch main were completed Sunday night as a new 25-foot section was welded into place.
A section of the circa-1916 water main broke open at 3 a.m. Thursday on Sunset Boulevard at Holloway Drive, pushing around cars and flooding garages while shifting massive chunks of asphalt and concrete slab. A number of vehicles were visibly damaged and others were flooded nearly to their roofs in subterranean parking.
By 7 a.m. Thursday, the rushing water, which sent debris all the way to Santa Monica Boulevard, had been stopped.
A stretch of Sunset Boulevard will remain closed until the sinkhole created by the leak can be filled in.
Sunset Boulevard remains closed between Sherbourne Drive and San Vicente Boulevard, with limited local access on nearby streets including Cynthia and San Vicente.
There is no set completion date, but the DWP said crews “remain dedicated to finishing the repairs as quickly and safely as possible.”
The DWP is working with the Metropolitan Water District of Southern California, Los Angeles County Public Works and other utilities to protect underground infrastructure during the repairs.
The utility said customers in the area continue to have reliable drinking water, but are being asked to continue conservation practices because the area is receiving water through an 8-inch pipe.
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 1-800-DIAL-DWP. Claims information is available at LADWP.com/Claims.
The city of West Hollywood also 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, Metro 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 Thursday’s break was under investigation, but Anselmo G. Collins, the DWP’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.