I'm unaware of any examples of subterranean carbon monoxide storage. However, underground helium storage has been done successfully for a while. Helium is one of the best gases at leaking because of its small size, which should provide some reassurance as to the storage of larger gases underground.

I agree that greed and corporate malfeasance are a thing, but it's kind of a separate problem. The government is either going to enforce environmental regulations and manage our resources properly or it's not.