Utilities Search for Buried Danger

Tuesday, July 31, 2007

By DAVID B. CARUSO, Associated Press Writer

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NEW YORK —

For years, scientists at utilities around the country have tried to peer deep into the guts of their cities without jackhammers.

They've experimented with robotic probes, ground-penetrating radar and thermal cameras _ all ways to identify dangers like frayed electrical wires or leaking pipes before they turn into disasters like the steam eruption that caused chaos in Manhattan nearly two weeks ago.

Engineers in New York and elsewhere have tested a variety of space-age contraptions, but good solutions have been elusive in trying to pinpoint the danger that lurks below.

"We're looking all over the world for the best technology," said Fred Coppersmith, a research director at Consolidated Edison Co., a power provider.

After a morning of downpours on the day of the Manhattan steam blast, Con Ed resorted to an old-fashioned method for identifying spots where hot pipes had come into potentially dangerous contact with cold rainwater: It sent employees out in trucks to look for manhole steam.

That system didn't detect anything amiss. Hours later, a steam main near Grand Central Terminal exploded, creating a colossal geyser that swallowed a truck, tore a 25-foot-deep crater in the street, burned bystanders and showered the neighborhood with toxic debris. One person died of a heart attack and more than 40 people were injured.

Con Edison isn't the only utility turning to higher-tech methods of trying to find problems in the country's aging infrastructure.

The Trigen Companies, which operates steam systems in 11 cities, including Boston, Philadelphia and Las Vegas, said it occasionally flies thermal cameras over its networks, looking for heat plumes that might indicate a steam leak, or pooling groundwater in the area of a pipe.

Bill Schutt, president of MATCOR, a Pennsylvania-based corrosion control company, said engineers can use sensors that analyze electrical fields to determine whether there are flaws in the protective coatings on buried pipelines.

Oil and gas companies check the integrity of their larger lines with mechanical probes called intelligent pigs, named for the squealing sound they make as they travel through the pipe.

Con Ed has been trying for years to adapt robotic probes to its steam lines. The devices, which resemble metallic snakes, crawl through pipes to look for problems. Some models can even do basic welding. So far, though, they haven't been able to withstand the searing heat inside steam mains.

"In a steam line, you may need to wait days for it to cool down enough for you to put in a camera," Coppersmith said.

Con Ed has also experimented with peering into its pipes and cables using ground-penetrating radar, like the kind the military uses to uncover land mines, and with a device that projects sound waves into the tubes to look for defects.

Another contraption lets inspectors listen for the whistle of escaping steam or gas.

None of these systems are ready yet for widespread use, but Coppersmith said he believes the technology will improve.

Con Ed used to have a hard time trying to pinpoint leaks in underground power cables that rely on pressurized fluids to operate. At one point, the utility even tried using scent dogs to detect fluids leaking from the lines.

But after years of study, and some key help from a Department of Energy laboratory, power companies began injecting cables with chemical compounds that could be traced with sensitive air sampling equipment if a line broke.

Con Ed made similar progress developing ways of detecting stray voltage from electrical equipment. Corroded and frayed circuits in lampposts and underground utility boxes occasionally deliver painful jolts to unsuspecting pedestrians. One such accident delivered a fatal jolt to a Manhattan woman in 2004.

Now the utility routinely uses roving vans equipped with special sensors to hunt for leaking current.

"Certainly, some things have gotten easier," Coppersmith said. "Ultimately, you'll be able to wear a pair of goggles connected to something on your belt and be like Superman and look into the ground, although maybe not in my lifetime."