In the Pipeline : The Underground Life of Water in the Valley

Beneath the floor of the arid San Fernando Valley is a river rushing through 3,000 miles of pipe to reservoirs, holding tanks and homes across Los Angeles. About 225 million gallons of water move daily throughout the Valley in some of the largest and oldest pipelines in the city. Officials worried that breaks, like the one that flooded a Studio City street last week, may become all to common. “We have an aging infrastructure--the pipes underground are not getting any younger,” one Department of Water and Power official lamented. “What we are doing is crossing our fingers and hoping this kind of thing won’t happen again.” New pipes are lined with anti-corrosive and laid on a smooth foundation, evenly distributing pressure over the entire length, eliminating presure points created by rocks or other hard objects. Replacing 70 miles of the larger, older pipes would cost $250 million citywide, water officials have estimated. About $3 million a year is now spent on pipe maintenance in the Valley.

An Aging System

More than 30 miles of truck lines over 50 years old have been identified in the city by the water officials. Many of these pipes, some more than 5 feet in diameter, are buried in highly corrosive soils. Known as “hot soil,” to DWP officials, clay and adobe are good conductors of electricity and speed up the corrosion of pipes. The combination of old pipes and corrosive soil could lead to more breaks.

Unclogging the Arteries

Many pipes installed before 1938 have corroded, diminishing their capacity to carry water, reducing their strength and discoloring water supplies. Since 1955, the Department of Water and Power has cleaned and lined about 4 million feet of pipe with a cement and mortar compound. But another 10 million feet of pipe must be treated.

Water Supply

About 70% of local drinking water comes from the Los Angeles Aqueduct, which mostly carries snowmelt from the Sierra Nevada mountains through the Mono Basin and Owens Valley. Small quantities are also obtained from wells in Los Angeles and from the State Water Project and Colorado River Aqueduct.

Service During Repair

Residential customers are supplied with water through a temporary curbside pipe while the main pipeline undergoes cement lining rehabilitation. The process normally takes about a month per city block.

Source: Department of Water and Power