How do I use the pickaxe to remove impediments?
In a few settlements, you will be occasionally rewarded with pickaxes, which can be used to remove Impediments from your settlement, and clear the tiles for further expansion.
Once you have a pickaxe, click on an impediment to be offered the opportunity to use one of them to clear it. It is important to remember there are a limited number of pickaxes available per play through. There are also pickaxes which can be purchased for Diamonds, but these too are of limited quantity.