Plan to Resume Tunneling Told

A subway tunneling machine trapped by squeezing earth under the Santa Monica Mountains will have to be partially disassembled, and a fifth of the steel ribs supporting the tunnel behind it must be ripped out or reinforced, to resume work by the end of next week, the Los Angeles County transit agency said Tuesday.

Disclosing its plan to fix a 210-foot section of tunnel weakened by ground that unexpectedly settled over the Fourth of July holiday, the Metropolitan Transportation Authority said its construction contractor must remove and replace 22 steel supporting arches and spray concrete over 22 more.

The MTA’s new reckoning of the number of 21-foot-tall steel tunnel-support segments the company must repair or replace was more than four times greater than the estimate it made last Thursday, when it first announced the problem in the tunnel being dug from Studio City to Hollywood.

A swelling section of soft, crushed shale had contracted the tunnel so severely while workers were away that it bent five of the steel ribs and trapped the subway builder’s 300-foot-long boring machine--”Thelma,” of a pair nicknamed “Thelma and Louise” by construction workers.

To add an extra measure of support, MTA project manager Charles Stark said the 22 four-inch steel ribs that are being torn out will be replaced with six-inch steel ribs.

After the shoring-up operation is complete, Stark said the company will blast away the rock trapping its machine, which weighs more than 500 tons, with powerful jets of water.

Stark said the firm expects to complete the repairs over the next week and start digging again by Aug. 2. Industry experts have estimated the cost of the repair at $1 million.

The contractor is Traylor Bros./Frontier-Kemper of Indiana.

At a news conference and protest staged by state Sen. Tom Hayden at Traylor Bros.’ work site in Studio City, residents of the Hollywood Hills above the tunnel route expressed new frustration about a project they have attacked for environmental reasons for two years.

“If the MTA were subject to the ‘three strikes’ law, they’d be in jail by now,” said Marylane Farris, a Studio City real-estate broker and hillside activist.

Homeowner Patricia Marlatt complained that the MTA had held a lavish community reception to discuss the tunneling project a week ago without mentioning the latest bedevilment.

“They don’t inspire any public confidence when they have one huge, unanticipated mistake after another and don’t talk to us honestly about them,” she said. “Now this happens. What’s next?”

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Adding a bit of Hollywood glamour to the protest over dirt and machines was Callie Khouri, the screenwriter of the hit motion picture “Thelma and Louise.” Declaring that she is an avid hiker in the Hollywood Hills who is concerned that tunneling may lower the mountains’ water table enough to harm plant life, she said she objected “in a good-spirited way” to naming the tunneling machines after her characters.

“I haven’t been offended by almost any use of the names--and that includes a zoo that named its two-headed snake Thelma and Louise,” said Khouri. “But the point of the movie is that my characters never really get mired down or hit bottom--and that’s what these machines have done.”

Hayden, an avid subway critic who wants the entire $5.6-billion project halted, offered a solution.

“Why doesn’t Traylor Bros. just rename them ‘Abbott and Costello?’ ” he asked.

Meanwhile, new questions have emerged about the MTA’s official explanation of how the machine got stuck in the first place.

Stark told MTA board members last week that Traylor Bros. said it was surprised to discover after returning from the holiday that it had parked the machine in a zone of soft, crushed shale that geologists call a “shear zone.” According to Stark, not until July 8 did the company learn that tiny fissures in the rock had opened during the long weekend and, in the parlance of miners, “relaxed” around the tunneling machine and its supports.

Essentially, the company argues, the rock suddenly grabbed the deserted Thelma in a bear hug only 940 feet along its 2.3-mile journey from Studio City to Hollywood.

But one mining industry veteran has told The Times that he believes Traylor Bros.--which is digging its first Metro Rail tunnel--ignored signs that the ground was squeezing its tunnel well before the Fourth of July.

The expert, who spoke on condition of anonymity, said he inspected the tunnel in late June and wondered why the contractor had not taken steps to shore it up.

“I could see that the ground, left alone without putting in bigger steel, would be a problem,” said the miner, who has built tunnels around the country. “If it had been my tunnel, I would have put in bigger steel. It was obvious. You could see it. The only question would have been how much bigger: 6-inch or 8-inch?”

Using the thicker steel could cost up to $2 million more, he noted.

Stark said the first 730 feet of the tunnel is supported by arcs of 6-inch steel ribs. Only the last 210 feet is supported by 4-inch steel, he said.

Another industry veteran who declined to be identified scoffed at the notion, however, that the contractor did not know that its crews were working in a zone of what miners call “squeezing” ground. He said the operators of the boring machine, at least, should have noticed that it took a lot more pressure to push forward in the area of soft, crushed shale.

“When you’re going through good rock, the machine just pushes real smooth, like a cookie cutter through dough,” said the miner. “But when you’re in squeezing ground, you can pump and pump and pump and finally the machine lurches forward.”

A determination of when Traylor Bros. first became aware of the hazard will help decide whether the contractor or the MTA will pay for repairing the tunnel and digging the machine out.

In an interview Monday, Stark disputed the mining experts’ assertions. “The contractor did not know, nor did we know, that we were in squeezing ground until after the July 4th holiday,” he said.

The MTA’s solidarity with the contractor may be strained next week, however, when the transit agency’s top tunneling consultant says he will tell Traylor Bros. that it should have known it could encounter squeezing ground in that section of the mountains and taken precautions.

The consultant, University of Alberta civil engineering professor Dan Eisenstein, said in an interview from Edmonton that he expects the meeting to be “confrontational.”

The reason: Eisenstein and the MTA contend that the shear zone is described in a report of the area’s geology that was made available to all construction firms who bid for the tunneling contract. Traylor Bros. won the job in 1994 with a bid of $124 million.

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The professor asserted that the firm should have been alert for the zone and used 6-inch-wide support beams there. He also said the company should not have stopped for four days in an area of potentially unstable ground.

“When you enter a shear zone, you might not notice that the fissures are tightly closed. But if you leave a tunnel open for a period of time, the fissures open, the ground loses its strength, your support gets overloaded and then it becomes deformed,” Eisenstein said. “There is a domino effect of negative factors.”

Eisenstein, who downplayed the event as the equivalent of a flat tire, said he did not expect any more such shear zones, but added: “Mother nature is unpredictable.”

Traylor Bros. is prohibited under the terms of its contract from commenting to the news media.

Stark said, however, that the contractor had sent a letter to the MTA blaming the agency’s subway design team--a private consulting consortium called EMC--for failing to accurately describe the type of rock its miners would encounter.

Also irate about the situation is Los Angeles County Supervisor and MTA board member Mike Antonovich, who asserted that the transit agency’s staff had attempted to cover up the tunneling snafu for a week and a half.

In an interview, he also complained that the organization lacked the money to pay for such errors--if Traylor Bros. ultimately proves that it was not at fault.

Indeed, last week the transportation subcommittee of the U.S. Senate’s Appropriations Committee recommended just $55 million for Metro Rail construction in the federal government’s fiscal 1998 budget--less than a third of the $158 million that the MTA had requested. The House Appropriations Committee last month recommended $90 million for Metro Rail. Legislative conference committees will reconcile the versions later in the summer.

MTA chief executive Joseph E. Drew said in a statement issued Tuesday afternoon that the squeezing ground never threatened the integrity of the tunnel or endangered workers. “We are committed to building a world-class subway system,” he said.

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Stuck in the Mud

A machine digging a passage for the Metro Rail Red Line subway through the Santa Monica Mountains got stuck in a section of soft shale that miners call “squezzing ground.” The machine, nicknamed Thelma by miners, is 225 feet below Fredonia Drive, Workers will have to disassemble part of the machine, back it up slightly and replace 22 of the four- inch tunnel ribs with six- inch ribs.

Relieving Pressure

A. Steel ribs supporting the ground behind the machine’s cutter head bent over the Fourth of July weekned, slightly weakening the tunnel.

B. Miners will free the machine by jetting away the dirt with high- pressure water hoses.

Source: Tunnel staff