Martinez Refining Company, or MRC, on Sunday morning reported a "level 1 community awareness message" to Contra Costa County Health.
MRC said on yesterday the message was related to a steam release that began at approximately 7 a.m. and lasted about 30 minutes. It added that was release was due to a startup of equipment, which was loud enough to be heard offsite.
The county health agency's website listed a level 1 community awareness message from Sunday.
The refining company said the department issued a message warning residents that they may hear, smell, or see signs related to this event. however no action is required.
The health agency's site says calls a level 1 community awareness message means an incident consisting of "odor or audible impact; flaring lasting longer than 20 minutes; or other non-flaring visual impact."
Martinez Refining Company has scheduled a maintenance project that will run through early April and will result in more traffic in the area, periodic noise and increased flaring, the company announced.
Three months ago, the company was fined five-million dollars for alleged air quality violations — the second largest penalty the district has ever handed out.