Refinery Admits Rumble Felt in Concord Emanated From Repair

Officials at the Tesoro Refinery admitted Tuesday that the rumbling disrupting residents of North Concord emanated from the company's compressor.

G.M. Marcy, director of external affairs for Tesoro, said the rumbling was related to a new pipe installation.

“The cause of the rumbling/thumping was the acoustic resonance at a compressor from flaring of excess gases, a safety precaution which is taking place while we conduct repairs to a pin-hole leak which was discovered in a propane transfer pipeline inside the refinery,” Marcy told Patch.

Patch readers reported that the rumbling was audible and could be felt at about 8 p.m. on Monday in North Concord, California. They were concerned that the noise might be related to the fire burning nearby on Mount Diablo. 

Marcy said the company is taking every possible measure to repair the pipe in a safe manner.  He said that the company apologizes for alarming residents with the noise of rumbling or thumping, which may be heard for the next few days. He also said that some of the flares might be visible. 

"Combustion of the gases could be as much as 40-60 feet and the flaming fairly visible off-site, especially after dark," he said. "The paradox with flaring is that, while it may look disconcerting (and occasionally be accompanied by unusual rumbling sound) it is undertaken as a precaution and conducted to depressurize pipelines and process equipment and so ensure a safe working environment for maintenance workers," he added. 

Marcy said Contra Costa County Health Department, local law enforcement and fire agencies have been notified of the repairs, along with The San Francisco Bay Area Air Quality Management District.  

Tesoro’s Eagle Refinery is the second largest refinery in Northern California, capable of producing 166,000 barrels of oil per day. It is located between North Concord and Martinez, California.   

Repairs are expected to conclude within the next few days.