Situation: An immortal has been dumped into a hole (about 2 meters long, 1 meter wide, 3 meters deep) onto a level surface of concrete (1 meter deep) then covered with wet concrete (buried and entombed). A 1.5 meter depth of concrete is poured over the body, and once cured for a few days is covered with gravel then dirt and sod.
Once rescue arrives, they can take care of the dirt and gravel, and are left with a block of concrete weighing roughly 10.8 metric tons (3x1x1.5 at 2,400 kl/sq meter) their guy is in the middle of. They're in the wilderness, so electricity will require generators, and they need to maintain a certain level of discretion, so they can't bring in a huge team or a crane. They don't want to use any method that will risk either completely pulverizing the body or separating limbs/head. They can get explosives, jackhammers, heavy truck winches, and maybe one or two modest sized construction vehicles, etc. plus expert help for any skills they lack. Once they get the weight down to a few metric tons they can transport it.
Question one: What would be the easiest/fastest/most effective ways of dealing with the concrete? They need to at least get enough removed that they'll be able to lift and transport the chunk that has him in it, to do the final clean-up and un-entombment elsewhere.
Question two: Drowning in concrete is primarily cause by compression - once you exhale, the weight of the concrete prevents you from inhaling again - but how much concrete (if any) would be in his mouth/throat simply from being pushed in by compression force as more was poured over him? Or would his throat and lungs be completely collapsed from the weight?
ETA: He's laying down and tied up, and is pleading with his captor as the concrete is being poured. Also, he won't be in a container of any sort - that's established.
Son of ETA: And I think I've got what I needed! Thank you all SO MUCH!
Grandson of ETA: Children of Eden spoilers in comments.