Quake Repairs of Valley Sewers to Take 2 Years

Workers in the San Fernando Valley will soon begin the massive chore of repairing more than 150 miles of earthquake-damaged sewer lines in a $147-million project that is being called the biggest of its kind in city history.

The work, which may disrupt traffic when crews tear open streets to reach the damaged lines, will take two years to complete.

The city plans to issue more than 100 contracts for repairs in the hardest hit areas of the Valley, particularly in Granada Hills, Chatsworth, Northridge, Reseda and Sherman Oaks. The city normally spends no more than $10 million annually on sewer repairs and maintenance.

The city’s Public Works Commission began awarding contracts for the massive repair program last week and is expected to approve two or three contracts a week until June, 1997, when all the repairs are expected to be completed.

But the amount of damage and the extent of the traffic disruptions are still unclear because city engineers have only identified about 80% of the estimated damage to the city’s 6,500-mile sewer system.

Also, the city will let private firms that are awarded contracts decide whether it is cheaper to repair the lines by digging up city streets or by working underground to reinforce the inside of the cracked lines with special lining.

It is clear, however, that the repair work will aggravate current traffic problems in the Valley.

“We certainly will do everything we can to minimize it, but there will be some disruption,” said J. P. Ellman, chairman of the city’s Public Works Commission.

Los Angeles City Councilman Mike Feuer, who represents Sherman Oaks and adjacent communities, has met with public works officials to try to coordinate sewer repair work and other street projects in his district to minimize traffic headaches.

“What we don’t want to see is them tearing up the street for sewers today and then tear up the streets tomorrow to repair water lines,” said Jane Blumenthal, Feuer’s chief of staff.

All of the repair work will be paid for by the Federal Emergency Management Agency.

The Jan. 17, 1994, quake sent fractures and cracks through the aging system, radiating from the epicenter of the temblor. But there were only a handful of cases where sewage lines collapsed completely. Those repairs were completed soon after the quake.

Although the city’s sewage system continues to run without major problems, Ellman said that unless cracked pipes are repaired quickly, they can eventually erode and collapse, sending sewage into the streets.

“Ultimately, erosion could lead to cave-ins and sinkholes,” she added.

Many Valley residents may have already unknowingly experienced problems due to the damage.

Deputy City Engineer Brad Smith said the quake created small cracks in many of the four-inch-diameter lines that carry sewage from residential homes to the main lines under city streets. Tree roots often squeeze through those cracks in search of moisture and block the lines, he said.

Smith said many residents may have already hired a plumber to clean out the pipes using an electric “rooter.”

Doug Knight, general manager of Roto-Rooter in Sun Valley, said clogs caused by roots poking through cracked lines have become a growing problem in the Valley, particularly around Northridge and other hard-hit areas.

“We have noticed a tremendous number of broken lines,” he said.

Most of the time, Knight said, the lines are cleared by sending in a rooter line with rotating blades to cut back the intruding roots. But the solution is only temporary as the roots eventually grow back, he said.

Since the quake, the city has launched an extensive damage assessment that relies mainly on the use of remote-controlled cameras to travel through about 760 miles of underground lines to videotape damage.

The tiny cameras sent images to workers in a truck on a nearby street who would make note of each crack shown on monitor screens.

“They are literally seeing every inch of the sewer,” Smith said.

The cameras were sent underground mostly at night when sewage use was at a minimum. The lines are up to four feet in diameter, but most of the damage occurred on 12- to 8-inch residential lines.

The videotape recorded by the mobile camera was then examined by city engineers to assess how serious the damage is, he said.

Once the damage was identified, he said city workers designated 118 geographic areas where the problems were greatest. They are now preparing to hire private firms to complete repairs in each area.

When workers decide to repair the lines from the street level, Smith said they will tear out 40- to 50-foot sections along the length of the street, diverting traffic around the gaps in the road.

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Seeking Damaged Sewer Pipes

Over the next two years, the city will repair about 150 miles of quake-damaged sewer lines in the San Fernando Valley. Here is a look at how the damage was assessed and repair options:

1) Workers lower camera down manhole.

2) The camera is pulled through segments of sewer pipes by cable.

3) Engineers monitor the images, assessing the extent of damage.

Repair Options

1. Cut 400- to 500-foot sections in the street to remove and replace cracked segments of lines or;

2. Workers may enter the sewer through a maintenance hole and line the inside of the pipe with a special reenforcing liner.

Repair costs: $147 million to $175 million (estimate)

Type of damage: Cracks and fractured pipe joints.

Projects currently proposed: 118

Completion date: June 30, 1997

Identifying the Damage

Source: Times staff