I was looking forward to seeing some german bunds, but it looks like they were pretty confident in their ability to remove the fuses. Not the first bombs these gents have seen!

Pictures indicate that the bombs have been found in a more open area by the river, which would would factor into the EOD team's decision to attempt to defuse the bombs in place.

You know a machine is fun when it gets its own lab and a big interlocked cage. Testing this week at @sheffunieng.bsky.social's Thermomechanical Compression (TMC) facility: 500kN at up to 1200C!

Hi, I'm Andrew. I research blast loading and dynamic material behaviour, enabling the development of effective systems to protect lives and infrastructure. (I blow stuff up to stop stuff blowing up.) 💥

The sheet piles that formed supported the sand on the enclosure roof are perforated with holes from the bomb casing fragments. These fragments were then captured by the sand in the walls and roof - no fragment damage has been reported.

The blast is channelled upwards through the sand on top of the enclosure, resulting in the jets of sand visible in this image. Kinetic energy in the sand is kinetic energy that isn't available to the air shock, so full marks there. What about fragments?

An attempt was then made to destroy the explosive by controlled burning, which is riskier as there is a chance of a transition to detonation. This did indeed happen, but luckily we have drone footage to see the sand enclosure in action! 💥

The design of the enclosure will vary depending on factors such as the type of explosive device and the proximity of other structures: in this case it looks like an extra L-shaped wall has been added to protect nearby houses.

Hesco MIL units are like a conventional gabion steel mesh, but lined with a geotextile material that allows them to be filled with finer soils like sand. Machinery can be used to do all the heavy lifting, then some compaction by foot and you're done.
So easy even I can do it...

Instead, the EOD team made use of Hesco MIL units and excavators to rapidly build a hefty sand enclosure around the bomb, with more sand on the roof supported by steel sheet piles.

That brings us to sand. Sand is fantastic at slowing down fast-moving projectiles and absorbing shocks, thanks to friction between the sand particles and the energy required to move it around (it's heavy).
Of course, sandbags are not a recent invention!

SC 250s have a total mass of 250kg of which 130kg is a high explosive such as TNT.
Detonating 130kg of TNT in an urban area is a bad idea [citation required] due to the risks of death/injury and damage from:
💥Fragmentation of the bomb casing
💥Shock waves in air
💥Ground shock

In February 2023 a WW2 bomb was discovered during dredging work in the River Yare. It's common to unearth old bombs during construction work in the UK, and they still pose a real danger 80 years later.
This appears to have been a German SC 250.

How do you dispose of a huge WW2 bomb in the middle of a town while keeping everyone safe? Sand!
The discovery of a 250kg bomb in #GreatYarmouth provided a great example of how the Army responds to these threats. 🧵