How deep could one man, with a shovel, pickax, a cheap bulldozer, and a jackhammer, dig in 3 months?
I'd say about 35 feet until the sides caved in on him!
a bulldozer is no use to you, they only level ground not dig deep holes. You need an excavator. As you dig the hole you will have to shore the sides. A big excavator can dig a 25/30 feet deep hole
You'd get all the way down to bedrock in no time. Then the only tool that'd keep working would be the jackhammer. You couldn't go but about 3 feet a day with that. And then there's the whole filling up with water thing to consider, and since you don't have a pump, you'd have to hold your breath between each shovel full. So I'd say about 60 feet is all. Now if you had some dynamite...
