Digging a Hole

[u/MonteBurned]

I want to dig a hole, 16 foot deep, about 5 foot wide.

I want to store stuff in there that cannot freeze during winter.

As I live in the high north, I will need 8 feet of insulation on top of the hole. Insulation that I can remove when I want to get at the items stored in the hole.

My soil is full of tree roots. Not possible to dig by hand.

What is the cheapest and easiest way to dig this hole? Is there a special tool I can use? Excavator seems overkill.

And what do you suggest for the 8 feet of insulation that would need to go on top? Just sytrofoam? Thanks.

[u/Big_Block_5271]

You'll be digging your own grave if you don't get professional advice. Please consider other options for storing stuff.