Lack of maintenance--not nearby sewer construction--is the main factor in the September 2011 San Bruno natural gas explosion, according to attorneys for the city. An independent investigation \u201cfails to address\u201d pipeline owner Pacific Gas & Electric\u2019s \u201cserious corporate and engineering failures,\u201d according to the attorneys on July 14. Some of the conclusions in the panel\u2019s report to the California Public Utilities Commission are \u201cdiversionary,\u201d noted attorneys. They encouraged regulators to develop a historical review of pipeline system pressures and called the theory that a 2008 sewer project in the area contributed to the explosion \u201cwholly speculative.\u201d PG&E responded it \u201cagrees in full spirit with the panel\u2019s overall conclusions\u201d in its filing. A day later, the commission ordered PG&E to, among other things, provide the state with inspection records on shut off valves and give fire agencies maps of pipelines and valves.