assuming the pillar is made of concrete, which has a fragmentation value of
6J/cm3
1389 x 6J = 8334 joules
using the violent fragmentation value of 17J/cm3
1389 x 17J = 23613 joules
I'm not quite sure which value would be better to use
also i'm not sure what formula you're using to calculate the hole, i think calculating it as a cylinder would be better