“A Fatal Flaw in the Consent Decree” by Jim Eninger, Ph.D.

Jim EningerTo 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 very-low-volatility sulfuric acid, which doesn’t require an EPA Risk Management Plan, could be as dangerous as highly volatile hydrofluoric acid. And it is especially troubling that Quest Consultant’s excellent 1995 paper, Effectiveness of Mitigation Systems in Reducing Hazards of Hydrogen Fluoride Leaks by David W. Johnson and John B. Cornwell, which directly contradicts Mobil’s assertion that MHF is as safe as sulfuric acid, was not mentioned in reports to the Court by the Safety Advisor, who was handpicked by Mobil.

Johnson and Cornwell’s assessment was that for the major release they considered, the worst-case toxic distance (to ERPG-3)  was 300 feet for sulfuric acid, compared to 14,000 feet (2.7 miles) for MHF with 50 wt% sulfolane additive (see Table 2 — Acid Dispersion Analysis for Alkylation Unit in the paper referenced above). Note that Quest’s 1995 assessment of sulfuric acid’s behavior was confirmed in the 84,000-pound sulfuric-acid release from an alkylation-unit settler tank at the Tesoro Refinery in Martinez, California on February 12, 2014. There was no offsite consequence to the community.

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 Advisor 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 invalidates Mobil’s QRA. Thus, there is no legal basis for Mobil Refining Company to be using MHF.

Dramatic Large-Scale Demonstration that Sulfuric Acid Is Vastly Safer than MHF for Alkylation and Two Other Alternatives

Loss of containment, from a tubing separation (yellow oval) after the valve (red square) was opened, released 84,000 pounds of sulfuric acid at the Tesoro Refinery in Martinez, California. There were no offsite consequences.

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 vastly safer than MHF alkylation, contrary to the claims of Exxon-Mobil and the Torrance Refining Company.

The DuPont™ ConvEx℠ HF Alkylation Conversion to Safer Sulfuric Acid Alkylation Technology

A leader in sulfuric acid alkylation, DuPont offers a cost-effective alkylation conversion  from hydrofluoric acid (HF) alkylation to a modern, vastly safer sulfuric acid alkylation technology.

Two U.S. Refineries Currently Undergoing Conversion from HF to New Safer Alternatives

Two U.S. refineries are are in the process of conversion to other vastly safer alkylation technologies.

In Oil and Gas Engineering, see:

Ionic Liquid Alkylation Technology Receives Award
Chevron is converting its hydrofluoric acid (HF) alkylation unit at their Salt Lake City refinery to ISOALKY technology, which will be operational in 2020, when the refinery’s HF equipment and its inventory of hydrofluoric acid will be removed.

In Chemical Engineering see:

KBR to Provide Solid-Acid Alkylation Technology for Wynnewood Refinery in Oklahoma
KBR, Inc. has entered into a contract to convert the existing Hydrofluoric acid (HF) alkylation unit at the Wynnewood Refinery to its K-SAAT solid-acid alkylation technology.


Elected Officials’ Support for MHF Ban

TRAAThese 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

“Developments in the debate over hydrofluoric acid” – Daily Breeze


Nearly 300 residents march in protest to the PBF Energy refinery in Torrance on Saturday, Feb 17, 2018. It has been three years since the refinery explosion rocked the neighborhood and now residents are calling for a ban on the use of hydrofluoric acid at the refinery. (Photo by Scott Varley, Contributor)

“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.

“Here are the major developments we’ve seen since then: