An 80-Year-Old Sewer Line Threatens Metrolink Tracks And Power Lines

Tiles have fallen and voids formed in a 48-inch high sewer line, part of the North Outfall Sewer line in the Hyperion Sanitary Sewer System. It's part of the largest sewer system in the nation, and the location of this deteriorating pipe makes it very difficult to repair. (Los Angeles Sanitation)

It would be hard to find a worse place for an 80-year-old sewer line to threaten to collapse.

It's near the 110 and 5 freeways, right next to the L.A. River. It's 10 feet from an LADWP transmission tower, and it runs under the Metrolink train tracks.

"It's very complicated because it's impossible for us to actually dig down to the sewer over those locations and repair it," said Barry Berggren, the Los Angeles Sanitation division manager who oversees the city's wastewater and stormwater systems. (L.A. has separate systems for sewage and stormwater.)

Workers will construct a temporary detour pipeline to route sewage around the repair sites. The sewage bypass will run from about the Riverside Drive/Figueroa Street bridge over the L.A. River to around Avenue 19 near Humboldt Street. Then they'll dig a deep pit, pierce the old sewer pipe and fix it from the inside by sliding a liner into it. Grout will be pumped between the new liner and old sewer pipe to secure it in place, Berggren said.

Map showing the location, near Avenue 19 and Humboldt Street, where a sewer line is deteriorating. (Los Angeles city Sanitation map)

The repairs on about a half-mile of 48-inch-wide pipe were planned for next year, but the risk of a sinkhole under the railroad meant the $17 million project got moved up.

The first phase of the repair proposal goes before the Los Angeles Board of Public Works on Friday.

This line is part of a system that moves wastewater from the San Fernando Valley, Burbank, Glendale, L.A., and Culver City to the Hyperion wastewater treatment plant near LAX. From there the water is used to replenish underground aquifers or dumped offshore into the Pacific.