I discovered that the previous owner had his main electrical box ground wire connected to a copper pipe that in turn was connected to a plastic source pipe. I think that the copper ground wire must be run to a copper grounding rod buried up to 10 feet in the ground.

The ground around my foundation is hard hard clay and I am worried that I cannot drive it with a sledge hammer. Does the rod have to be driven straight down? Or can it be buried horizontally? If the rod has to go in vertically, what ideas are there for getting it into the ground with the least effort ?

Due to different soil types and other local natural variations, grounding is one of those areas where the local authorities specify what type of grounding electrodes can be used.

Check with your local electrical inspector.