Storage of Pallets of Coal

I want to store several tons of bagged coal on pallets over several years. If I cover the pallets of coal under a tarp do I need to put down treated wood under the pallets? I also have landscape fabric I could put over the dirt and then the pallets on top of that. Or would I be wasting my time since the tarp will keep the wood of the pallets dry. I also bought a special tarp to block out UV's and the bagged coal will be in the shade. I hope this will keep the bags from detoriating. They are made from fabric but the sun will detoriate them.

Thanks in advance

If the pallets are on gravel I think they'll be fine. Even if the bottom board rotted in 4 or 5 years you will still be able to pick up the pallet. It would be many many years before the risers sank into the earth.

Takes some time for the wood to rot, ~3 years as Freddy says, recommend putting them on some sort of blocks or whatever to keep them off the dirt if you want them to last longer than above. No matter how well you try to cover them, if stored outside, you may get a small amount of condensation in the coal, the Blashak bags do have preforations in them, this has been discussed in other threads, Not a big deal for hand fed through with stokers using rice coal, some parts of a stoker can rust if the coal is placed in the stoker wet. You can always dry the coal first in some sort of bin system. Many on this site know more than me about this sort of thing. Good luck with coal, the neighbors will semi-hate you.