Somewhat moot point but official website insists it is NOT a fire

https://chiquitacanyon.com/odor-mitigation/recent-updates/

>>Any odors coming from the Chiquita Canyon Landfill are related to an abnormal biotic or abiotic process (also known as a landfill reaction) taking place deep within a lined, but older and inactive portion of the Landfill waste mass. This reaction is not a fire or subsurface oxidation event within the waste mass, and is not related to waste disposal operations at the Landfill.