Gas Leak's Ignition A Mystery
Georgetown Pipe Was Damaged
Reference to the newspaper

By Monte Reel and Clarence Williams
Washington Post Staff Writers
Friday, February 21, 2003

The blast that launched one manhole cover into the air and upended another in Georgetown this week was likely unrelated to previous manhole eruptions in the neighborhood, utility officials said yesterday, although specific causes of an underground gas leak and its subsequent ignition remained speculative.

Inspectors discovered cracks in a small ventilation pipe under the 3200 block of M Street, where Wednesday afternoon's traffic-jamming explosion occurred. Two weeks ago, Washington Gas finished upgrading pipes in the vicinity as part of an ongoing project to overhaul Georgetown's underground utilities, and the damaged ventilation pipe was part of a branch of the system that was replaced. However, that branch retained gas, according to a company spokesman.

The remaining gas eventually was to be vented, said spokesman Tim Sargeant, but the procedure has not been scheduled. The abandoned branch would remain underground.

"We have not determined the cause of the damage to that pipe," said Sargeant, adding that a review is pending.

Some utility officials said that salt and other chemicals applied to icy roads can exploit weaknesses in underlying pipes and casings, but Sargeant declined to comment on possible causes.

Exactly what ignited the leaking gas also remained a mystery yesterday. When a series of manhole explosions rattled Georgetown three years ago, a consulting firm hired by the D.C. Public Service Commission determined that overloading of the neighborhood's electrical grid during peak demand was a key factor. But Pepco, which maintains the underground electrical lines, said an examination of cables near the site of Wednesday's explosion suggested that the electrical system didn't provide the spark.

"We found no obvious defects, no damage to any cables in any of the seven manholes we checked in the immediate vicinity of where this happened," Pepco spokesman Charles Taylor said.

He said that because there are small holes on the manhole covers, almost anything -- including sparks from tire chains or a smoldering cigarette butt -- could have ignited the leaking gas.

Although Georgetown has been the site of memorable manhole explosions -- including three that shattered storefronts on Feb. 18, 2000 -- Pepco officials suggested that such incidents happen throughout the city. This year, Pepco has reported 13 manhole explosions or displacements, including two last week in the 700 block of 12th Street NE, which were caused by underground electrical shorts. Last year, 39 manhole explosions were reported in the District, down from 62 in 2001 and 48 in 2000, according to Pepco.

"Rarely is there a common cause in any of these," Taylor said.

This week's explosion on M Street will not affect the progress of the Georgetown Project, the $40 million effort to upgrade the underground network of gas, electrical, water and communications lines and improve the streetscape, said Skip Newcombe, project manager for Pepco. Unlike other areas of the city that underwent infrastructure overhauls when Metrorail was introduced in the 1970s, much of Georgetown's substructure has remained essentially unchanged since the 1880s. Though the age of the underground systems wasn't positively identified as the direct cause of any of the manhole explosions in 2000, those blasts cast a spotlight on the antique systems and spurred the overhaul.

The project, which began in October 2001, is split into two geographical sections: M Street and Wisconsin Avenue. The M Street upgrades are scheduled to be completed next spring, and the Wisconsin Avenue portion in summer 2005.

Those target dates were pushed back from initial projections after business groups and residents struck a deal to keep traffic flowing in both directions on Wisconsin Avenue. Work on the project is done at night, when flaggers wave vehicles through a maze of cones and uneven pavement to prevent congestion on residential blocks.

"It's not as productive as we'd like, but we're working with it," Newcombe said.

Wednesday's manhole explosion, which occurred at 4:40 p.m., caused the evacuation of three M Street businesses and clogged traffic throughout Georgetown during the evening commute. Police closed M Street between Wisconsin Avenue and the Key Bridge and stopped incoming traffic from the bridge. Two-way traffic on M Street wasn't restored until 9:30 p.m. There were no related traffic problems yesterday.

Staff writer David A. Fahrenthold contributed to this report.