I had a 50 foot black olve cut down. The stump and surrounding area
were ground with a stump grunder. I am doing sprinkler work and have
so thick root masses. 4 inches thick 10 inches wide and some are just
flat. Trying to hit them with a hatchet or hand ax is like hitting
concrete.

I want to try to break them up at least to decompose faster. I
driilled holes with stump rot in some holes, sugar in others and high
nitrogen fertilzer in others.

I am thinking just cover em over and hope the decompose with the holes.
Alternatively, I was thinking of a maul or big ax to break up these
roots. Any suggestions? Forget fire as these roots seem impervious
to fire. .