Crews failed to relocate pressure-sensing lines from an old cast-iron distribution main during a mid-September Columbia Gas pipeline replacement, igniting a series of explosions and fires north of Boston, according to a preliminary report by federal investigators.
In Woburn, Mass., National Grid shut off gas to 339 homes after a worker inadvertently over-pressurized a line Oct. 8. A similar occurrence Sept. 13 in a Columbia Gas line in the region apparently triggered explosions and fires that burned 80 structures in three localities.