http://www.azcentral.com/arizonarepublic/news/articles/0131bordertunnels0131.html

Technology not effective at finding border tunnels

Associated Press Jan. 31, 2006 12:00 AM

SAN DIEGO - A U.S. government effort to find drug-smuggling tunnels underneath the Mexican border with ground-penetrating radar and other high-tech gear has had little success.

Human intelligence has proved the most effective method of finding the passageways. A case in point: The longest tunnel ever found along the border was discovered last week after a tip.

The Homeland Security Department said Monday that a Mexican man, Carlos Cardenas Calvillo, was arrested in connection with the 2,400-foot tunnel, which went as deep as 90 feet and was about 5 feet high and 5 feet wide. He appeared in federal court Monday on charges of conspiracy to import more than a ton of marijuana. A bail hearing was set for Wednesday.

"The problem is the technology picks up some kind of anomaly or variation of soil," said Lauren Mack, a spokeswoman for U.S. Immigration and Customs Enforcement. "We go in with big backhoes and bulldozers, we spend all day doing it, and all we hit is rock or water tables."

That was what happened earlier this month when high-tech gear alerted authorities to a possible tunnel near Boulevard, a hamlet about 60 miles east of San Diego along the Mexican border.

A full day of digging turned up nothing.

The technology is "not there yet," Mack said. "What we've seen so far just hasn't proven itself to be effective."