Wearing my geologist's hat, there won't be a problem. The key word is "permeability". Myanmar=tropical=clay=low permeability (I can do geology from 35,000 feet). All you need is a reasonable pump and you will end up with a dryish hole. What's at the bottom of the hole, Lord knows. I'm hoping and wishing for a batch of pristine Spitfires. What I expect is a heap of Fe stained Al oxide.