I assume that this is your own private drive and these are the phone and electric that feed only your house? If so, don't even worry about the phone. If you cut it, and you want it later. Just call the phone company to hook you up. When they come out to do so and test the line, they will find something wrong and install a new faster better quality line at their dime. Just play dumb.
Now as far the electric. Do you know if it is primary or secondary? Do you have a big metal box up by the house that has a little hum to it? If so that is a transformer and that means that is a primary (i.e. roughly 7200 volts). DON'T HIT THAT ONE!

It should be 3'-4' deep if it's not real rocky. Regardless it should be in conduit and at least 24" deep, secondary and 36+" for primary and you should be able to grind the stump with no concern.
Removing the stumps is possible, but it will be like removing a brain tumor. Slow and careful and lots of hand digging. Good luck.:thumbsup: