Sunday, September 16, 2001 Copyright © Las Vegas Review-Journal

Threats to Hoover Dam assessed

Experts: Kamikaze attack unlikely to succeed

By KEITH ROGERS REVIEW-JOURNAL

Since 1942, the concrete-and-steel bunker has baked in the sun high atop an Arizona hill overlooking Hoover Dam.

Although the guns that it housed are gone, the "pillbox," as it was called, is a reminder of the security concern defense officials had then for the dam's vulnerability to a kamikaze-style attack in the aftermath of Japan's aerial assault on Pearl Harbor.

Built by a military police battalion soon after the attack, the 24-foot-long bunker and its rock facade had six gun ports. It is the last standing of several gun-emplacements that were built to protect the dam from being attacked, since it was a major hydroelectric power supplier for the defense industry.

Fifty-nine years later, the dam is still a military target but for different reasons. Because it is an essential structure for agriculture and drinking water supplies in the Southwest, Hoover Dam ranks among the top five targets in the West that experts believe would be in the cross hairs of a long-range missile attack, from as far away as 5,000 miles.

Experts have taken into account many scenarios that could cause a structural failure, but little thought has been given to what might happen in the case of an attack similar to that waged last week on the World Trade Center and the Pentagon.

Shortly after Tuesday's strikes, the solid, concrete structure that holds back the nation's largest man-made reservoir was closed to all traffic and visitors. Passenger traffic on U.S. Highway 93 across the dam resumed the next morning but commercial vehicles and trucks with trailers continue to be detoured.

Bureau of Reclamation officials said last week the impacts from a hijacked jetliner slamming into the dam haven't been analyzed.

"That's something we never thought about," said Jim Bayne, dam safety program manager for the Boulder City region.

But trying to navigate a commercial jetliner through the canyon would be a difficult task, he said. The canyon walls or the transmission towers and lines "would probably tear the wings off before you hit."

Even if a plane were able to make a direct hit, "I don't think it would do anything to (the dam)," Bayne said.

"It's very massive," he said.

Unlike the hollowness of high-rise buildings constructed of steel and concrete such as the fallen World Trade Center towers, Bayne said Hoover Dam is made of solid layers of concrete and is essentially as thick as it is tall. It is 726-feet tall, 45-feet wide across the top, 660-feet wide at the bottom and weighs 6.6 million tons.

The worst-case scenario that experts analyze takes into account what would happen if the dam structure suddenly was demolished -- either by a natural or other event. "It's like saying you'd have to yank the whole dam out instantaneously," he said.

But there's no way that would happen, Bayne said. Portions of the dam would remain and massive fragments from the structure itself would impede water flow to some degree through the narrowness of the canyon. In addition, Davis Dam is a mile north of Laughlin, which would further negate a massive flood.

A commercial airline pilot from the Las Vegas Valley, who flies the same type of jetliners as those involved in last week's terrorist strikes, said he too has doubts that a fully fueled Boeing 757 or 767 would compromise Hoover Dam's structural integrity.

"I'm not sure if an airplane hit it, it would breach it. It's pretty thick," said the pilot who spoke on the condition of anonymity.

"Breaching a building is a lot easier than breaching a solid, concrete dam. Whether it would hit wire and cause it to hit a canyon wall first would be another question," the pilot said.

He said he doubts that the resulting explosion would penetrate the face of the dam. "It's so solid right there the blast would be reflected back."

Then again, he said, before Tuesday's terrorist hijackings, "A lot of people didn't think a lot of things were possible."

Experts say the dam would need an anti-ballistic missile system to knock out nuclear-bomb-tipped missiles. So would four other targets listed in 1999 by the California-based Claremont Institute think tank as being the highest risks for attack in the West.

Those are: Los Angeles, because of its population; Prudhoe Bay, Alaska, where one-quarter of U.S. oil reserves are kept; chemical weapons depots in Oregon and Washington, which could release deadly toxins; and Port Valdez, Alaska, a key location for delivery of Alaskan oil.

Bureau of Reclamation officials said while contingency plans are in place, and periodically rehearsed, for the unthinkable event that the dam would fail, there would still be a three- to five-hour window to evacuate Laughlin and downstream communities before the area is deluged. The leeway is attributable to a wide flood plain that begins 12 miles downstream, which would slow down the spread of water.

Bob Walsh, a spokesman for the bureau's Boulder City office, said there's "no black-and-white" answer to what would happen if, for example, a powerful earthquake struck.

"It depends on the epicenter, how much water is in the reservoir and the wave action," he said.

"In the event of a massive failure, an extremely unlikely event, there would be several areas downstream underwater," he said. "We have emergency action plans and guidelines for the kinds of actions we would take to notify emergency agencies in the communities."

Currently, Walsh said, Lake Mead contains more than 20 million acre-feet of water and is 78 percent full. An acre-foot is 326,000 gallons or the amount of water that would cover an acre to a depth of 1 foot.

-- Anonymous, September 16, 2001

Answers

Sis (a resident of downtown Vegas) is prepared to see the economy collapse, but no way I can convince her to do some basic preps.

-- Anonymous, September 16, 2001