EPA “Worst Case Scenario” Maps Understate Dangers of Modified Hydrofluoric Acid (MHF)

The EPA requires refineries using modified hydrofluoric acid (MHF) to prepare an “Offsite Consequence Analysis” report estimating the effects of a “worst case” release of MHF.  Upon MHF release, a dense ground hugging cloud of hydrofluoric acid (HF) will form.  The two black circles on the area map below represent the official EPA reports “scenario maps” from by the Torrance and Valero, Wilmington refineries.  The HF cloud would originate at the refinery, in the middle of a zone.  It would spread in an elongated plume in the direction of the breeze.  Wind direction determines which area inside a risk zone will get the most HF exposure.  The cloud’s HF concentration, highest near the refinery, gradually declines as it drifts.  


The EPA uses Emergency Response Planning Guidelines (ERPGs) to measure toxicity.  The scenario map radius (black circles) is an estimate of how far the HF cloud would travel with a concentration greater than ERPG-2 (20 parts per million [ppm]).  Inside this risk zone, short-term exposure to the HF cloud (defined as one hour) could cause serious and irreversible health effects.  Closer to the refinery, for the first 1.8-2.0 miles, HF concentration would exceed ERPG-3 (50 ppm).   Inside this smaller zone, “life threatening” health effects (death) could occur with short-term exposure to the cloud.

These official scenarios are horrifying.  A total of 615,524 residents within these zones live with the constant fear of death or irreversible and serious health effects if such an MHF release were to occur.   The cities most affected are Torrance, Redondo Beach, Lawndale, Gardena, Carson, Manhattan Beach, Hermosa Beach, West Carson, Los Angeles, Lomita, Long Beach, and Hawthorne.  The residents of cities outside the zones could also suffer health effects as the plume moves beyond, such as choking, burning eyes and respiratory tract, pain, and panic.  So-called “sensitive receptors,” such as grandparents, cancer patients, asthma sufferers, and our babies and toddlers, are not included in determining ERPG levels and would suffer health effects at lower concentrations than these levels indicate.

But it gets worse, because industry data show that these risk zones are grossly understated. It took a year-long investigation, but TRAA unearthed the data despite trade secret rights, redacted official reports, and a complete lack of cooperation or assistance from local government and regulators.   The two black circles on the area map below represent TRAA’s estimate of what the scenario maps should be for MHF as it actually is, 90% HF, barely modified and barely different in cloud formation upon release.


This is too horrifying to believe.  Yet HF-using refineries around the US report toxic distances just like this and worse.  That is why Torrance residents demanded HF be eliminated.  In 1997 we were told HF was gone and “very significantly safer” MHF in place.  MHF “remains on ground,” the City of Torrance still tells us.  But that is just a lie.  

Valero admits MHF “toxic distance” is a mere 7.9% shorter than for HF.   (A 10-mile toxic distance for HF would decline to 9.2 miles for MHF, for example.)  That’s no safety advantage.

The Torrance refinery’s risk zone reaches downtown LA, and includes LAX.  This accident nearly happened on 2/18/2015 during the Torrance refinery explosion, which was a near miss on 50,000 lb. of MHF.  This is not “just” a Torrance problem, or a South Bay problem.  But we are most at risk.   A release of MHF far less than “worst-case” could still cause death, injuries, and panic.  Even if deaths don’t occur, thousands could require immediate treatment for possible HF exposure.  Property values would plummet.  Business losses would mount.  

The safer alternatives sulfuric acid (used by all CA refineries other than Torrance and Valero) or solid acid catalyst would eliminate the toxic airborne threat. Demand a ban on MHF.


ExxonMobil’s Official EPA Risk Management Program scenario map, which greatly understates the risk:


Valero, Wilmington’s official Risk Management Program EPA scenario map, which greatly understates the risk: