SAN FRANCISCO (CBS SF) – The City of San Bruno is suing the California Public Utilities Commission for the release of documents the city claims shows improper conduct between CPUC regulators and Pacific Gas and Electric company in the process to determine fines against PG&E for the 2010 San Bruno explosion.

San Bruno Mayor Jim Ruane, city officials and attorneys were set to announce the lawsuit in a press conference later Tuesday morning on the steps of the CPUC building at Van Ness Ave. and McAllister St. in San Francisco.

The lawsuit demands the release of public records that show what the City of San Bruno alleges is evidence of ongoing cozy relationships among members of the CPUC and PG&E and that would reveal the problems identified by federal investigators as the cause of the San Bruno pipeline explosion.

 The September 2010 explosion and fire killed eight people and destroyed 38 homes. The CPUC is expected to rule on a fine in that case that its safety division has recommended to be $2.2 billion.