I drilled a couple of test holes so far. I bought a couple of different ship auger bits. It looks like the Warrior Harobor Freight 1 inch diameter 18 inch long bit is the one. They have a better Hercules bit, but you can't back it out. The thing is so aggressive it just pulls you in more and more, until it is stuck. I also had to buy a better drill of HF. I had to step up to their D handle heavy duty. My regular dewalt electic and 20v drills did not have enough torque. So, I am now using a 9 amp drill and that works. So, I will drill a bunch of holes and some horizontal holes to intersect, then apply potassium nitrate and we will burn it later in the week.