I am trying to make a copper pipe which is placed in a natural park capacitive. It is placed in the soil meaning that it is already grounded. I am using a basic arduino and their capacitive sensing library to quickly experiment with, but the issue I am having is that the arduino itself needs to be grounded in order to have a decent value output. But grounding the arduino to the copper pipe (or anywhere) doesn't work. Because than the ground and the capacitive sensor are directly connected.
tl;dr: How can I make a grounded object capacitive?