PG&E: One-quarter of high-risk gas lines running through dense cities not yet fully inspected

PG&E: One-quarter of high-risk lines not assessed

The company whose ruptured gas pipe sparked a deadly explosion in a San Francisco suburb has not finished fully inspecting all its high-risk lines.

A spokeswoman for Pacific Gas & Electric Co. says the utility has yet to assess about a quarter of the 1,021 miles of pipeline ranked as “high consequence areas.” That type of line requires more stringent inspections.

Spokeswoman Katie Romans says the utility found four leaks and five failures since officials started inspecting their high-risk transmission lines in 2005. She says the company is on track to finish by 2012, but that leaves 270 miles across California that haven’t been fully inspected.

Investigators are still trying to determine why the San Bruno pipeline ruptured and ignited a gigantic fireball, killing at least four.