Someone upthread mentioned (as part of a joke) a wood chipper or paper shredder. While something like that has the potential to spark, if they had a way to break them up (maybe soaking them in water and then using some sort of shredder) and burn them in an uncontained vessel, away from the public, I’d think that would be the safest.
Whatever they do, I assume they detonated them in an enclosed container. That’s was probably the biggest problem. What should have been a loud, sparkly fire with some projectiles was turned into a bomb.
Moving non-passivated explosive devices, and particularly improvised explosive devices which do not incorporate any safety or anti-ignition features, is a hazardous operation, and transporting them on public surface streets is extraordinarily risky, especially in large volume for reasons that should be evident. I would assume that they were dealing with assembled pyrotechnic devices which they did not want to attempt to disassemble and passivate, and a large enough volume that it would not be feasible to transport it in just a few trips to a suitable location for disposal even if it were considered safe to do so.
Presumably someone consulted the specifications of the blast containment chamber in the truck and calculated the allowable energetic mass but either dropped a factor in their calculations or (likely) underestimated the energetic yield of the device. Why they did not remove vehicles from the street and evacuate the neighborhood I do not have any explanation, but it seems likely that the City of Los Angeles is going to be paying out on a lot of claims.
From the picture in that article these look like they may be commercial aerial mortar shells (the kind used for large commercial displays); one of the boxes clearly says “Against All Odds” which, if is as linked is just a barrage pyrotechnic system. It is difficult to read the DoT hazard class placards but the boxes on the right look like they are listed as 1.4, which shouldn’t contain any detonatables or blasting agents that could potentially produce high explosive effects. Unless they just overloaded the blast containment chamber or there was something unexpected in those boxes, I’m at a loss for why this produced such an unexpected large blast. If these are commercial pyrotechnics and not homemade IEDs as was originally indicated, I’m not sure why they wouldn’t just transport these for disposal at a designated site because they’ve doubtless been transported as commercial products. There is either something not being addressed in the news stories or somebody seriously miscalculated the effects of on-site disposal.
@Stranger_On_A_Train pretty much hit the nail on the head. They may have siezed 5,000 lbs (or 35,000 lbs) but containment vessels are only really rated to 10-15 lb TNT-equivalent shots. We didn’t have one at my shop, so I’m admittedly unfamiliar with their specs. However, if the Bomb Disposal Team (sorry to nitpick Stranger, but there was no ordnance involved) did not account for double base propellants, they probably stacked far more than what they thought they were–thus, “unintended kablooey.”
All that being said, I dispute the claim that “Clearly protocols were followed and pursued.” FIrst point of evidence is the yield. I would question whether a proper interview of the IED manufacturers was conducted, or a search of the premises was made to accurately identify what they are dealing with. But, I’m armchair quarterbacking this, after being ninja’d by @Stranger_On_A_Train. Second, I’d like to see the maintenance records for that containment vessel. Yep, all tools need maintenance and inspection.
ETA: I just read the article linked by @Darren_Garrison. My sigline still stands.
Armchair QB: I would have transported them off-site before “kablooey.”
Heh…everything I deal with is ordnance so I tend to use it as a synonym for explosive.
Whatever was in that truck definitely went beyond what I would consider a recreational pyrotechnic. I’m curious to see that blast containment vessel; those things are usually a couple of inches thick steel, and whatever they detonated in there didn’t just crack a weld.
I don’t know anything about this stuff but is there any chance they simply didn’t latch the vessel opening properly?
Or, similarly, some water got inside?
This Beyond the Hydraulic Press vid shows some similar testbeds but with minor differences. I’ll spoil it and say they do blast a meaningful hole in the wall and you should watch to see how. The vid shows it in a very entertaining and funny manner.
“Yea, they sell these in grocery stores.” @40s lol
The conflicting reports are normal, but… they’ve said both that the trailer was being used for ‘transport’ and for ‘disposal’. If somebody packed that thing full of fireworks, then tried to do a controlled explosion inside a protected sub-unit …
If the hatch were just unsecured the hatch would have flown open and there would have been a directional blast but in this case it seems to have consumed (or at least, scattered) the entire chamber. You can see the blast chamber in this video. If you back the video up to 1:00 you can see the detonation and then aerial footage of the aftermath. I’m guessing that car that is on its side may have actually been hit by a segment of the chamber.
A little bit of water inside the chamber wouldn’t have caused any kind of problem. The reason the charge in the demonstration video you linked to below is more effective with the water tank backing is because the speed of sound of the initial shockwave in mass of water is much faster that the bulk of the water can move (because water is incompressible and has much greater inertia than air), so once the shockwave hits the outward facing side of the tank it is reflected back toward the wall creating a concentrating effect which blew out the far side of the wall (spallation). If there were a high speed camera on the tank itself you’d see it rupture and pieces fly off while the mass of the water more slowly expands outward. So, unlike the grenade or shaped charge where at least half of the energy is wasted on the air, much of the energy is reflected back into the wall. It’s a common technique in demolition of concrete or rock removal to minimize the amount of explosive used.
From that news clip above it does sound like there were improvised devices as well as the boxes of commercial fireworks, so they probably wanted to dispose of the IEDs rather than take the risk of moving them through occupied neighborhoods; this was at East 27th and San Pedro, smack in the middle of what used to be called South Central, in the middle of a massive residential neighborhood about a quarter mile east of USC, south of Staples Center, and just down the street from an elementary school. If you map it you’ll find that there are no empty lots or open fields anywhere nearby, and no route to transport it that it wouldn’t be a potential danger even if they could clear the streets. That being said, it boggles my mind that they didn’t evacuate the neighborhood and at least clear the street of vehicles, even for just a few pounds of explosives. I’m guessing some of those procedures are going to be revised most soonest while city lawyers negotiate settlement agreements with the entire neighborhood.