Please Help] Collide Problem

Imagine that I have a excavator. On the end of it, there is the object to remove terrain. This is my player. I am simulating that I am on the seat of the excavator and I want to remove some terrain from one point to other.

I have the object of the player, with its animation, its working perfect... but how to know when the end of the excavator collide with the terrain?

How can I do this?

Thx