For this past weekends event we did a pig roast in the ground. This was the first time we had tried something like this, and it was a team effort between our Food and beverage staff and our Maintenance staff.
First the "pit" was dug about 4 ft deep and filled with scrap metal
Then rocks were layered over the metal.
Then charcoal, mesquite briquettes, and a fire to top it off
The fire burned for about 3 hours and heated up all the metal and rocks, which would then hold the heat in for the next 36 hours while the pig cooked.
36 hours before meal time the hot coals were spread out and the pig was prepped. This meant we were having the fire in the middle of the night and putting the pig in the hole at 4 AM.
On top of all the hot coals we placed "trimmings", which included banana leaves and grass clippings. You can see the heat of the coals below and the steam being created that will "roast" the pig. The pig was wrapped in chicken wire, placed on top of a cedar board with handles and straps to pick it up after it was cooked.
More grass clipping and banana leaves on top.
Then a canvas tarp over the trimmings and bury it all in soil to keep the heat and steam in for the next 36 hours.
36 hours later uncover the pig and start the feast.
Hot rocks were also placed inside the pig to add more heat.