By MICHAEL WEISSENSTEIN
MEXICO CITY (AP) — A water-heating system may have leaked natural gas into a tunnel beneath the headquarters of Mexico’s national oil company for more than seven months before it was accidentally detonated by a maintenance crew’s improvised lighting system, officials said Tuesday, adding fresh detail to the narrative of the petroleum giant’s worst disaster in a decade.
Mexico’s attorney general said Monday night that a buildup of an unspecified gas was responsible for the explosion that collapsed three floors of the administrative building in Petroleos Mexicanos’ Mexico City headquarters complex, killing 37 people. He indicated the gas could have been either natural gas, which is used to fuel water boilers, or methane, a product of decomposition found in sewers and landfills.
Assistant Attorney General Alfredo Castillo told reporters Tuesday morning that the likeliest source of the gas was a tunnel that ran beneath the devastated building and carried hot water from a natural-gas heating plant to the 54-story central tower of the complex. He said that explanation appeared likely because the blast blew off manhole covers providing access to the tunnel some distance from the affected building. He added, however, that a methane gas buildup had not been entirely discounted.