I have drilled under several driveways over the years, usind a 100 diameter hand post hole digger. It is slow and tedious but it can be done but you get drop in the hole the further you go as rotating to the right all the time makes the auger drop towards the right. This means if you start at 500 below the ground on one side by the time you get across an 8 foot driveway you will probably be about 700 deep on the other side and then you have to dig a hole to find where you are. Can be done but as I said it is tedious
