To get an idea how dangerous hydrogen fluoride is, consider just half an ounce — one tablespoon or ⅓ of a whiskey jigger — released into a large 10×10 meter conference room with a 3-meter ceiling (33′×33′×10′). A simple calculation, which a high-school chemistry student could easily verify, shows that the room would be raised above the Emergency Response Planning Guidelines’ ERPG-3 level of 50 parts per million, resulting in life-threatening health effects. Now consider that each of the two alkylation-unit settler tanks at the Torrance Refinery contains up to 50,000 lbs of hydrogen fluoride, or 1.6 million of the 1/2-oz samples. That’s nearly twice the population of the entire South Bay. It’s important to note that MHF is just as toxic as HF.
The TRAA Science Advisory Panel made an important discovery about toxicity of sulfuric acid that reveals a fatal flaw in the Consent Decree, which settled the lawsuit between the City of Torrance and Mobil. The Consent Decree was modified in the mid-1990s to allow MHF if Mobil’s Quantitative Risk Assessment (QRA) could show MHF was no more dangerous than sulfuric acid. However, QRAs are notoriously infamous for wildly varying over orders of magnitude in predictions depending on the numerous assumptions made. Mobil’s QRA is kept from public disclosure by claims of “proprietary and sensitive” information. It’s a mystery to the public that defies common sense how Mobil’s QRA could predict that very-low-volatility sulfuric acid, which doesn’t require an EPA Risk Management Plan, could be as dangerous as highly volatile hydrofluoric acid.
However, we do know a thing or two about Mobil’s QRA from the Consent Decree’s Safety Advisor in his 1995 Report, where he writes (page V-36),
“The quantitative risk comparison uses ERPG-3s, which can be regarded as thresholds for potentially fatal effects, as a basis for comparison of the two substances. The Safety Advisor considers that this is a reasonable choice because the ERPGs have been carefully developed and peer reviewed”.
We discovered that the ERPG-3 used in Mobil’s Quantitative Risk Assessment overstates the toxicity of sulfuric acid by a factor of four. The 1995 Safety Adviser Report shows that 30 mg/m3 for the EPRG-3 value for sulfuric acid was used in Mobil’s QRA (see Table V.4 on page v-36). Today’s accepted value is 120 mg/m3. An unbiased competent engineer would immediately recognize that such a large change in a primary parameter likely invalidates Mobil’s QRA. Thus, there is no legal basis for Mobil Refining Company to be using MHF. This will be a moot point if the SCAQMD follows through and bans MHF. Otherwise, the substantial EPRG-3 change, along with today’s understanding of MHF behavior and sulfuric acid behavior, is the basis for a lawsuit to ban MHF.
The U.S. Chemical Safety Board (CSB) reported on an accidental release of 84,000 pounds of sulfuric acid over two-and-a-half hours from an alkylation-unit settler tank at the Tesoro Refinery in Martinez, California, on February 12, 2014. The release was onto the refinery grounds and into a process sewer system. There was no vapor cloud or offsite consequences to the community. The spill burned two workers, who were transported to the nearest hospital burn unit by helicopter. They survived and returned to work after five months.
A Modified Hydrofluoric Acid (MHF) release of this magnitude would have had cataclysmic consequences not only for refinery workers, but also for the surrounding community. A ground-hugging toxic cloud would be lethal for more than eight miles downwind. (For comparison, there are 50,000 pounds of MHF in one Torrance refinery settler tank.) This full-scale incident is further dramatic evidence that sulfuric acid alkylation is far safer than MHF alkylation, contrary to the claims of ExxonMobil and the Torrance Refining Company.
A leader in sulfuric acid alkylation, DuPont offers a cost-effective alkylation conversion from volatile and toxic hydrofluoric acid (HF) alkylation units to safer sulfuric acid alkylation technology.
Click the image above to watch TRAA’s short two-minute video where Dr. Sally Hayati, former TRAA President, refutes the claim of Torrance Refinery manager that alternative emerging technology may never be available.
These elected officials have written letters to the South Coast AQMD in support of a Rule 1410 banning MHF:
LA County Board of Supervisors Congresswoman Maxine Waters
Congressman Ted Lieu Congresswoman Nanette Barragán
The Office of California Attorney General Xavier Becerra
President pro tempore of California Senate Kevin de León California State Senator Ben Allen California Assemblyman Al Muratsuchi
Torrance City Council Member Tim Goodrich
Redondo Beach City Council Member Christian Horvath
Redondo Beach City Council Member John F. Gran
Redondo Beach Mayor William Brand
— on behalf of the Redondo Beach City Council
Hermosa Beach Mayor Jeff Duclos
— on behalf of the Hermosa Beach City Council
Manhattan Beach Mayor Amy Howorth
— on behalf of the Manhattan Beach City Council
Carson Mayor Albert Robles
Carson City Councilman Elito M. Santarina
View the letters of support on the TRAA website from these elected officials as well as other prominent community-minded individuals and organizations by clicking here
“When the Torrance refinery exploded in February 2015, showering residential neighborhoods with industrial ash, the event ignited a three-year public debate over hydrofluoric acid that continues to this day.