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.
|