CSB claims Tesoro is blocking investigation of sulfuric acid incident

Washington – The Chemical Safety Board on Feb. 26 issued an open letter expressing disappointment with Tesoro Corp. for allegedly hindering the agency’s investigation of a Feb. 12 sulfuric acid release at a Tesoro refinery in Martinez, CA.

The letter states that Tesoro management and legal counsel claim CSB does not have jurisdiction and have refused to allow CSB investigators to enter the site and conduct interviews. It further states that Tesoro – which experienced a fatal explosion at a refinery in Anacortes, WA, in 2010 – failed to preserve the site, and has indicated the company would not comply with a document subpoena.

Further, CSB maintains that Tesoro presented false information to the public by claiming two workers suffered “less than serious injuries,” when in reality they were sent to a hospital with first- and second-degree burns from sulfuric acid.

CSB claims that despite a lack of help from Tesoro, the agency has determined that the sulfuric acid release resulted from a mechanical integrity failure, and being sprayed by caustic substances while operating the machine was a “common occurrence.” Until the release was stopped, sulfuric acid was leaking at a rate of 5 gallons per minute, according to CSB, and workers have since told investigators they feared losing their jobs if they raised safety concerns.

The letter notes that CSB’s investigation into the 2010 explosion uncovered safety culture problems, and investigators would like to examine whether the same problem exists at the Martinez facility.