Toxic chemical leak at a manufacturing facility in Orange County

I know it changed its meaning over time, but that was the original meaning.

Leaking is any unintended oozing, sweating, transfer of tank contents to outside tank.

With increased temperature and pressure, gauges red lining, etc. it's very probable there's been leakage and / or venting.

The creation of dikes and dams to contain greater spillage from a potential low level rupture is in anticipation of more than just a leak and ideally less than a full thermal run away and explosion.

You design equipment, procedures, monitoring, training etc to account for the possibility of human error. Like computer security, you build systems with layers of fault tolerance and ways of minimizing risk or consequences.

Go watch the CSB youtube channel for a few hours and you'll see that basically none of these are "accidents" and most of them involve severe facepalm you-gotta-be-kidding-me situations.

From watching a lot of the videos, the causes seem to boil down to:

- poor training, either in the dangers of what workers were working with, signs of things going wrong, or how to handle things going wrong

- management / supervisors either tolerating or outright encouraging corner-cutting for the sake of productivity

- lots of looking-the-other-way especially in communities where the plant in question is the biggest, or only, employer around. If you're seen as someone who complains about safety issues, and you get fired - you don't have many other options for other places to work. If you complain and cause a work stoppage and people lose income, you're going to be mighty unpopular, fast.

- poor maintenance and upkeep

- badly designed, insufficient, flaky, or outright failed monitoring equipment that is ignored/tolerated

- poor emergency response planning

- people trying to "save" a situation, or waiting to act, because the corrective action would cause a lot of downtime, or wrecked material/product

- improper materials used for storage/handling (I exaggerate, but think: plastic seals on valve of a tank that someone pumps acetone into. acetone leaks through valve into another tank full of stuff that acetone Reacts Poorly To. Material incompatibility is featured in a lot of CSB videos)

Often it's multiple of the above. Say - something that should have been minor wasn't caught because Bob was poorly trained. It would have been OK if the monitoring system alarm rang at the security desk, but they moved the desk and the alarm is now in an accountant's office. Even then, if they had been checking the pressure relief pipe as part of their regular maintenance, they would have found it was blocked by an Eastern Spotted Wombat's nest, and the blockage meant the tank couldn't drain, and kaboom. That's basically how a lot of the CSB investigations play out. The US chemical industry is a barely-regulated clown show and the rest of us pay the price.

The hazards of the chemical overheating are well known. So was the tank's size, and the radius in terms of a catastrophic failure, and the number of people inside that radius. There was no reason they couldn't have had a deluge standpipe to douse the exterior of the tank.

There's a chemical that can bring the stuff under control by injecting it into the tank. It sounds like it wasn't stored on-site but was brought in by a "response team" that arrived well after the whole mess started. Given the danger level to the surrounding population people on-site should have been trained in emergency response, and that chemical should have been readily accessible if not part of a connected system where a button push or valve opening would disperse the counteragent.

The valves they could have used to inject the chemical were stuck shut. I saw someone claim it was because of the pressure, but it feels pretty laughable that the pressure in the tank was high enough to cause the valves to stick, but not high enough to cause the tank to rupture. From watching a lot of CSB videos, I can almost guarantee that if it gets investigated (Trump has wiped out almost all of the CSB) investigators will find the valves were poorly maintained.

There's also no excuse for them not having a contingency plan to do something like using a self-piercing device to pierce either the tank or a pipe that connects to the tank, and inject it. Self-piercing taps/valves/whatever are used for all sorts of things - it's not some uber complicated technology.

Again: if 40,000 people are within the radius of harm if Easily Angered Chemical goes exothermic, then you need to have solid plans with multiple ways to address it and people ON SITE who can address it.