MTA to Begin Blasting for Subway Extension Under Mountains

The Metropolitan Transportation Authority is hoping to start off the new year with a bang.

Hundreds of bangs, actually.

The transit agency is preparing to set off 100,000 pounds of explosives deep inside the Santa Monica Mountains as part of its construction of the Hollywood-to-San Fernando Valley subway extension.

To no one’s surprise, residents on the surface already are a bit shaky.

This is, after all, the MTA--and it’s more or less under their houses, with bombs.

The agency’s explosives expert has assured everyone concerned that the blasting--which will occur four times a day, day and night except Sunday over several months--will be barely perceptible. Blasting is expected to begin next week.

“When you get in a Chevy pickup truck, your body is subjected to a hundred times the motion levels that we expect from these blasts,” said Gordon F. Revey of Geotek & Associates.

A test blast with 80 pounds of explosives was staged Friday. A muffled “boom-boom-boom”--sounding like distant thunder--could be faintly heard on the surface. But it was nowhere as noisy as the leaf blowers and weed whackers in use nearby.

A resident of the house closest to the blast heard the bang and thought her 2-year-old was banging the floor. Her 6-month-old baby slept through the explosion, she said.

“For me, it wasn’t that bothersome, but it might be worse at nighttime,” said the woman, who declined to give her name.

Although tunneling machines recently finished digging a path for the subway through the mountains, explosives are needed to cut through the hard granite rock and hollow out a series of cross passages and a space between the pair of tunnels where trains will be able to switch tracks.

No blasting will occur directly under homes; it will take place 500 feet to 800 feet under Runyon Canyon Park, the former retreat of swashbuckling film star Errol Flynn.

A bigger challenge than the geology, officials say, is allaying the fears of a citizenry that remembers the lawsuits alleging that damage followed subway construction in Hollywood.

“Contrary to the image of a bunch of wild miners packing thousands of pounds of explosives, lighting it and running around the corner, yelling, ‘Fire in the hole,’ it’s a carefully controlled process,” Revey said.

Underground teams will drill 50 or so holes in the rock, then pack one-pound sticks of an emulsion gel explosive in each hole. Each blast is divided into a series of small charges fired with separate detonators, exploding like a string of firecrackers. Each blast will last about 10 seconds.

Construction crews expect to remove about 5,000 truckloads of rock from the blasting. Smoke may be visible at the tunnel shaft off La Brea Avenue.

MTA officials have distributed information to 35,000 homes explaining the blasting. If residents have concerns, officials promise to visit homes with a seismograph to measure the ground motions.

The MTA planned more extensive blasting, but scaled back plans in response to a lawsuit filed by environmental and neighborhood groups and demands from county Supervisor Zev Yaroslavsky, an MTA board member.

Transit officials say they expect a high level of public anxiety. To protect themselves against lawsuits, they took photos showing the condition of houses before subway construction began.

“There are already people complaining about blasting, and we haven’t done any,” said Gary Kramer, assistant resident engineer of JMA, which is supervising the tunnel construction.

The subway extension is scheduled to open in 2000.