Audiophile-grade ground rod?

If you lived in North Dakota you could run a ground line out to a fracking well and connect to the 2 mile deep pipework.

Blackest background ever.

My question is what’s the optimum audiophile fill material to surround a pure copper earth rod? This Bentonite clay slurry or something else?

I just got a 6 foot pure copper earth rod and have no chance of hammering it through the rock under the top soil here. So given I will be getting someone in with an long auger to drill a hole down that far it becomes a good opportunity to use a custom backfill to surround the rod. But I do not know what to use.