The number of manhole mishaps in the District this year already has eclipsed those in all of 2006, though the severity of the incidents — specifically, 300-pound manhole covers firing violently into the air — appears to be lessened by Pepco’s use of slotted lids.
Between Jan. 1 and June 30, Pepco reported 62 manhole episodes throughout D.C. — 36 smoking, 20 explosions and six fires — up from 58 in 2006.
The number of incidents hovered around 90 per year in 2003, 2004 and 2005.
“Overall, the number of underground incidents is about the same as it has been,” Pepco spokesman Robert Dobkin said. “They just happen to get reported more frequently.”
Beneath the District is the second-largest underground power system in the country, with entrance gained through roughly 60,100 manholes.
When water floods the system, chemicals corrode the cables, wires rub against each other or rats chew through insulation, smoke, fire and explosions are bound to follow, Pepco maintains.
Following a slate of eruptions several years ago in Georgetown and Logan Circle, D.C.’s Emergency Management Agency added manhole-cover explosions to the list of “major hazards” facing the city, along with hurricanes, floods, terrorism and other events.
Pepco responded by installing 7,880 slotted manhole covers, which allow steam, smoke and other gases to vent.
But the new covers also permit debris to flow into and muck up the electrical system, causing the utility to generally restrict them to downtown pedestrian corridors.
As a result, Pepco has suspended its slotted-cover program.
“We’ve covered all the sidewalks and crosswalks and high-density areas,” Dobkin said.
Although Pepco aims to inspect 15,000 manholes per year, the utility rejected the D.C. Public Service Commission’s request to inspect every manhole in the city by 2012, arguing that “inspecting manholes at a rate more than once every 10 years provides no inherent benefit.”
