I’m not surprised by last year’s assault on a California power station — just by the lack of media coverage until now:
The attack began just before 1 a.m. on April 16 last year, when someone slipped into an underground vault not far from a busy freeway and cut telephone cables.
Within half an hour, snipers opened fire on a nearby electrical substation. Shooting for 19 minutes, they surgically knocked out 17 giant transformers that funnel power to Silicon Valley. A minute before a police car arrived, the shooters disappeared into the night.
To avoid a blackout, electric-grid officials rerouted power around the site and asked power plants in Silicon Valley to produce more electricity. But it took utility workers 27 days to make repairs and bring the substation back to life.
The country’s roughly 2,000 very large transformers are expensive to build, often costing millions of dollars each, and hard to replace. Each is custom made and weighs up to 500,000 pounds, and “I can only build 10 units a month,” said Dennis Blake, general manager of Pennsylvania Transformer in Pittsburgh, one of seven U.S. manufacturers. The utility industry keeps some spares on hand.
Mr. Wellinghoff said a FERC analysis found that if a surprisingly small number of U.S. substations were knocked out at once, that could destabilize the system enough to cause a blackout that could encompass most of the U.S.
Overseas, terrorist organizations were linked to 2,500 attacks on transmission lines or towers and at least 500 on substations from 1996 to 2006, according to a January report from the Electric Power Research Institute, an industry-funded research group, which cited State Department data.
This attack wasn’t the work of bored teenagers or drunk hunters:
At 12:58 a.m., AT&T fiber-optic telecommunications cables were cut — in a way that made them hard to repair — in an underground vault near the substation, not far from U.S. Highway 101 just outside south San Jose. It would have taken more than one person to lift the metal vault cover, said people who visited the site.
Nine minutes later, some customers of Level 3 Communications, an Internet service provider, lost service. Cables in its vault near the Metcalf substation were also cut.
At 1:31 a.m., a surveillance camera pointed along a chain-link fence around the substation recorded a streak of light that investigators from the Santa Clara County Sheriff’s office think was a signal from a waved flashlight. It was followed by the muzzle flash of rifles and sparks from bullets hitting the fence.
The substation’s cameras weren’t aimed outside its perimeter, where the attackers were. They shooters appear to have aimed at the transformers’ oil-filled cooling systems. These began to bleed oil, but didn’t explode, as the transformers probably would have done if hit in other areas.
About six minutes after the shooting started, PG&E confirms, it got an alarm from motion sensors at the substation, possibly from bullets grazing the fence, which is shown on video.
Four minutes later, at 1:41 a.m., the sheriff’s department received a 911 call about gunfire, sent by an engineer at a nearby power plant that still had phone service.
Riddled with bullet holes, the transformers leaked 52,000 gallons of oil, then overheated. The first bank of them crashed at 1:45 a.m., at which time PG&E’s control center about 90 miles north received an equipment-failure alarm.
Five minutes later, another apparent flashlight signal, caught on film, marked the end of the attack. More than 100 shell casings of the sort ejected by AK-47s were later found at the site.
At 1:51 a.m., law-enforcement officers arrived, but found everything quiet. Unable to get past the locked fence and seeing nothing suspicious, they left.
A PG&E worker, awakened by the utility’s control center at 2:03 a.m., arrived at 3:15 a.m. to survey the damage.
Grid officials routed some power around the substation to keep the system stable and asked customers in Silicon Valley to conserve electricity.
In a news release, PG&E said the substation had been hit by vandals. It has since confirmed 17 transformers were knocked out.
Mr. Wellinghoff, then chairman of FERC, said that after he heard about the scope of the attack, he flew to California, bringing with him experts from the U.S. Navy’s Dahlgren Surface Warfare Center in Virginia, which trains Navy SEALs. After walking the site with PG&E officials and FBI agents, Mr. Wellinghoff said, the military experts told him it looked like a professional job.
In addition to fingerprint-free shell casings, they pointed out small piles of rocks, which they said could have been left by an advance scout to tell the attackers where to get the best shots.
“They said it was a targeting package just like they would put together for an attack,” Mr. Wellinghoff said.