Washington DC - 5 manhole explosions since Feb 18; elect cable malfunctions blamed for some

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Manhole explosion in D.C. Pepco workers at the scene of the latest manhole explosion in the District.

WASHINGTON, D.C., March 9  Pepco is investigating another manhole explosion in the District.

THE MOST RECENT BLAST happened around 8 a.m. Wednesday on 19th Street between K and L streets.

Witness Stacey Muscarella was walking to work when the explosion happened. She says the cover flew several inches out of the sidewalk. It was kind of like a car backfiring, and then I saw flames shoot out at the top, and they lasted maybe three to five seconds, she said. Minutes later smoke was seen billowing from another manhole at the intersection of K and 19th. Officials removed that cover to allow the smoke to clear. No one was injured. Lights and computers lost power momentarily in a nearby building. Pepco says a malfunctioning cable caused this mornings explosion.

Officials have yet to determine what caused three manholes to explode on M Street in Georgetown, February 18th. A similar explosion five days later at 9th and L streets was blamed on an overheated cable. And on March 3 another electrical malfunction caused an explosion that blew an 80 pound manhole cover out of the ground at 3rd and K streets, Northeast. Source: News4, Washington D.C., Jackie Bensen reports.


-- Lee Maloney (leemaloney@hotmail.com), March 09, 2000


Followup article:

Utilities Probing Manhole Blasts; Underground Fire Pops One Downtown

By Petula Dvorak, Washington Post Staff Writer

Thursday, March 9, 2000; Page B03

Utility officials are investigating a cluster of manhole explosions in the downtown area after another lid blew into the air during rush hour yesterday.

About 8 a.m., an underground joint caught fire, sending smoke up through two manhole covers at 19th and K streets NW. The building pressure sent one manhole cover about a foot into the air, said Nancy Moses, spokeswoman for Potomac Electric Power Co.

No one was injured and no vehicles were damaged, Moses said. The fire damaged underground fiber-optic cables and snuffed out a traffic light for most of the morning, officials said.

The copper cable splice was a joint that carries 13,000 volts of power. Something caused the joint to fail, which in turn made the paper and lead insulation around it smolder, Moses said, and that insulation eventually caught fire.

After a series of such explosions throughout the downtown area, including one Tuesday between the east and west buildings of the National Gallery of Art, Pepco officials were investigating the pattern of failures and acknowledging there is an unusual cluster of explosions.

Unless a failure can be traced back to erosion, workmanship or manufacturing errors, Moses said, there are few remaining explanations for the pattern of blasts.

Three manhole lids flew into the air on M Street in Georgetown on Feb. 18. After a two-week investigation, the D.C. fire department and the federal Bureau of Alcohol, Tobacco and Firearms have not been able to determine the cause of the blasts that sent the 80-pound manhole covers skyward.

Five days later, an overheated cable sparked an explosion at Ninth and L streets NW and blew the lid off a manhole. A similar malfunction blew the lid off a manhole again Friday, when the insulation on a 13,000-volt cable smoldered and caused a fire on Second and K streets NE, near Union Station, Moses said.

Tuesday, a lid also popped off a manhole at the corner of Fourth and Madison streets, between the west and east buildings of the National Gallery, Moses said. The cause of that explosion is similar to yesterday's blast, officials said.

Such joint malfunctions are often reported weekly, though it is not a regular occurrence for the faulty joint to explode so violently. Such failures usually are noted only during regular maintenance checks, Moses said.

Manhole Explosions Under Investigation

Utility officials are investigating a cluster of explosions occurring in the city's manholes that have sent manhole covers airborne. Investigators believe yesterday's incident at of 19th and K streets NW was caused when an underground joint caught fire.

Splices: 13,000-volt power cables are spliced together in manholes when repairs to the wires are needed. A "joint" is formed when the wires are connected.

When joints fail: The paper and insulation surrounding the wires can heat up, begin to smolder and catch on fire. The pressure that builds up inside the manhole can force the manhole cover ajar.

There have been five manhole incidents since Feb. 18.


2000, The Washington Post Company

http://www.washingtonpost.com/wp-srv/WPlate/2000- 03/09/295l-030900-idx.html

-- Lee Maloney (leemaloney@hotmail.com), March 09, 2000.

This early report suggests that a natural gas leak may have caused D.C.'s underground explosions.....


Pepco Hints Gas Leak Is Suspected in Explosions

By Linda Wheeler, Washington Post Staff Writer

Saturday, February 26, 2000; Page B03

Pepco issued a report to the D.C. Public Service Commission yesterday that strongly indicated a natural gas leak may have led to the fire and explosions last week that blew three manhole covers in Georgetown, an incident that shut down the 3100 block of M Street NW for 24 hours.

"We may never know what gas caused the fire--whether it's sewer gas, gas emitted by burning rubber cable or natural gas," said Nancy Moses, a spokeswoman for Potomac Electric Power Co.

But the report said sewer gas "has historically not been a significant problem in [Pepco] manholes" and "the strength and location of the manhole explosions . . . raises questions as to whether the explosion could have been caused solely by gasses [caused] by burning of low voltage cable insulation."

Tim Sargeant, a spokesman for Washington Gas, said yesterday that the utility was "disappointed that Pepco speculation and finger-pointing would continue. The report is more innuendo than investigation." Sargeant said gas company investigators who went to the scene of the explosions did not detect natural gas at the time.

Moses said Pepco's investigation discovered that Washington Gas workers responded to an emergency call reporting the odor of gas in the 3100 block of M Street on Feb. 4, "right next to one of the manhole covers where we had a fire."

"We could see they had dug holes in the street and in the tree box," Moses said. "They were dug in spots right over our conduit lines that are about 12 inches below."

She said that a firefighter reported seeing fire and smoke erupting through a hole in the tree box when he arrived on the scene.

Moses said a final report from a forensics company hired by Pepco to examine cable retrieved from M Street is expected in about a month.

Source: The Washington Post Company

http://www.washingtonpost.com/wp-srv/WPlate/2000- 02/26/112l-022600-idx.html

-- Lee Maloney (leemaloney@hotmail.com), March 16, 2000.

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