A massive steam explosion, a crater, a five-alarm fire send Midtown into chaos; terrorism ruled out, but asbestos cloud is new concern. At least one person is dead and dozens were injured when a steam explosion ruptured the intersection at 41st Street and Lexington Avenue, right next-door to Grand Central Station, at the height of the Manhattan evening rush hour.
Eyewitnesses described a plume of steam, rocks, mud and flames, followed by a massive shower of debris–concrete shrapnel from the blown-out street surface.
The scene by nightfall was eerily reminiscent to New Yorkers who remember the Sept. 11 terrorist attacks.
“I heard repeated reverberating explosions,” said Sandy Brown, a 34-year-old Web site producer who witnessed the blast.
In the throws of a failing economy and amidst the ever present and growing energy crisis, lurks an even bigger culprit than your father’s old gas guzzler.
Although some may view steam as a fleeting source of energy and an unlikely candidate for concern in world energy conservation, the fact remains that steam is still a living necessity in a vast majority of U.S. hospitals, power plants and manufacturing facilities, and in spite of it’s environmentally “green” disposition, is also single handedly responsible for billions of dollars in fuel consumption every year.
The U.S. Department of energy reports that over 45% of all the fuel burned by U.S. manufacturers is consumed to make steam. Making these losses critical not only to the companies involved but the U.S. economy as a whole.
Eric Honan, Chief Engineer of American Plant Maintenance, Inc., an energy conservation corporation dedicated to the survey and repair of steam and compressed gas systems, claims the problem stems mainly from a lack of awareness and preventive maintenance.
The deadly steam pipe explosion that shook Midtown Manhattan on July 18 was caused by a combination of heavy rainfall, leaks in underground water and sewer pipes and debris that clogged two critical devices designed to let water out of the steam main, according to an extensive investigation whose findings Consolidated Edison released on Thursday.
In response to the findings, the result of a $1.3 million independent study by two consulting firms hired by the utility, Con Edison promised major changes on Thursday in how it operates the Manhattan steam distribution system. By far the country’s largest, the 105-mile system dates to 1882 and provides about 7 percent of the company’s $12 billion in annual revenue.
Among other changes, Con Edison recently replaced all 1,654 steam traps — the devices designed to release water from steam mains — and required its safety patrols to remove manhole covers and check for water in areas traditionally prone to flooding. Previously, the crews merely drove by the manholes to check for vapor. Vapor is a telltale sign — but not the only sign — of water accumulation around steam pipes. The utility is also exploring ways to improve the design of the steam traps and better inspect and test them.
“Our goal is to ensure this does not happen again,” Ronald H. Bozgo, vice president for engineering at Con Edison, said in an interview on Thursday at the company’s headquarters near Union Square. “We’re going to learn from this. It’s a horrible thing. There are no words to express how saddened we are by this event.”
The late afternoon explosion, in the intersection of East 41st Street and Lexington Avenue, sent a boiling geyser shooting upward, rained debris and mud onto the street and left a crater 37 feet wide and 20 feet deep. A fleeing woman suffered a fatal heart attack, two other people were severely burned and Midtown businesses sustained millions of dollars in economic damages.
Critics of Con Edison were not mollified by the investigation. “This report shows that Con Ed’s poor maintenance contributed to this deadly explosion — that their own repair job clogged valves and kept vital backup systems from functioning,” said City Councilman Eric N. Gioia, a Queens Democrat whose constituents lost electric power during a blackout in 2006.
Under normal circumstances, small amounts of water gather in steam pipes as steam condenses from the loss of heat to the surrounding environment. The condensation is normally drained and then discharged into the sewer system through devices known as steam traps.
But in the hours before the steam pipe rupture on July 18, two traps malfunctioned after becoming clogged by debris, most of it from a chemical resin that had been used to seal leaks in a nearby joint connecting two sections of pipe. The finding that the resin had blocked the steam traps was reported on Thursday in The Daily News.
The pipe that exploded was 20 inches in diameter and had been installed, about 20 feet below street level, in 1924. Surprisingly, the investigation found that the pipe, despite its age, was in good condition, with minimal corrosion. The pipe was strong enough to withstand a total applied pressure of about 1,200 pounds per square inch, well above the normal pressure of the steam flowing through it, which was about 160 pounds per square inch.
The pipe itself was not the problem, but rather the equipment around it, according to the investigation.
In the early hours of July 18, water began to accumulate around the steam main, cooling the pipe and causing condensation to form, as often occurs when it rains.
Images from a security camera near the site of the explosion showed vapor rising from a manhole at the intersection from 9 a.m. until about 10:05 a.m. on July 18. After that, vapor was no longer visible.
A Con Edison safety patrol visited the site around 11:30 a.m. looking for vapor. Seeing none, the crew drove off.
Meanwhile, a perilous situation was developing underground. So much water had gathered around the steam main that the pipe itself cooled, no longer sending off the telltale vapor.
Condensed water had collected inside the pipe as well. Normally, that water is drained away from a low point in the main and pushed upward and through steam traps, which release the water while containing the steam. But the two traps near the steam main had become clogged by the resin, known as an epoxy, which a contractor had used on March 14 to seal a leaking joint.
That set the stage for the accident.
Just before the explosion, at 5:56 p.m., a routine adjustment in steam flow caused some steam to enter the cooled water that had collected inside the main, creating a steam bubble.
Upon contact, the steam bubble condensed very rapidly, creating a vacuum and causing water to rush in and fill the void. Water rushing from one direction slammed into water rushing from another, creating a phenomenon known as a “water hammer,” a “large momentary pressure pulse,” according to the investigation.
The pressure from that water hammer most likely exceeded 1,200 pounds per square inch, causing the steam main to burst. It was the greatest disruption of the city’s steam network since a steam main exploded near Gramercy Park on Aug. 19, 1989, killing three people.
The main findings in the investigation came from ABS Consulting Group of Stratham, N.H., a risk management company that is part of the ABS Group of Houston. A second company, Lucius Pitkin Inc. of Manhattan, conducted metals testing, a key element of the investigation.
The two reports were completed on Dec. 18 and presented to the state’s Public Service Commission and aides to Mayor Michael R. Bloomberg the next day.
Bob McGee, a Con Edison spokesman, said the utility planned to announce the findings, along with the company’s action plan for averting future accidents, in early January, but the company made all three documents available on Thursday after The Daily News reported the findings about the resin.