Very, very important, call dig safe and find out where ALL the buried utilities are. Drive a rod through one of those and all hell will break loose in your wallet
Buy good ground rods, bronze if available or heavy copper clad steel for electrical service.
Buy a 10' length of 1/2" galvanized electricians steel conduit pipe, it will be threaded for 1/2" at both ends. Not EMT nor RMC, the other electrical pipe.
Buy a forged 1/2" high pressure Tee, these are made just like a quality pair of pliers, impossible to smash.
Buy a forged 1/2" high pressure steel plug with a hex head, again, impossible to smash.
Buy a 1/2" household water garden hose thread adapter, get a real brass one, not a brass plated aluminum China. In a couple of years, electrolysis eats up the flat seal surface on cheap adapter fittings.
Garden hose and water under pressure, 40 psi is O.K., will be required...
Assemble the Tee, plug and adapter such that the 10' pipe is one of the through sides of the tee and the plug on the other. The adapter is at the right angle. Use Plumbers tape if you wish, should any fitting need replacing. The plugged end will be hit with the hammer.
Select the ground rod location, stay away about a foot to 18" from foundation to avoid hitting the footing some 8' below.
Get the step-ladder and hook up the hose and turn on the water. Set the 10' pipe upright water on and pound on the cap with your favorite 5 pound sledge. Wear gloves, eye protection and maybe boots..The water will clear away most of the small stones and make it real easy going. If a boulder is encountered, all progress will stop. Find another location.
If the pipe hits a tough spot don't go on. One must be able to extract the pipe at any depth. Once the pipe has reached a depth of about a foot shorter than the ground rod. Shut the water off and extract the pipe and promptly insert the ground rod into the hole. The ground rod should be easily pounded to the depth and the final foot or so with small effort. Usually the first four feet the rod can be hand pushed in.
I came up with this method when I was installing TV antennas and used it to install 8' ground rods around my home too.
Hey, if your happy with the galvanized pipe as a ground rod, first cross drill a few 1/16'" holes in the first 2'. Not too many holes, that would spoil the water pressure. When the galvanized pipe is left in the ground, bash up some ice melt or rock salt, dump into pipe add water. The salt electrolysis will lower the resistance, the holes will spread the salt solution around. Cap with a Brass cap with thread tape (it won't rust on) so it can be salt loaded every so often
The ground wire should be as large as one can afford, at lease [You must be registered and logged in to see this link.]
but larger is better.
If you know your property has been back filled with boulders, well what can I say