The story is ironic because the people believe they have found an easy solution for all of the terrible and dangerous waste they have created, and yet they don't realize that they're basically just throwing it on their own heads. When they discover the hole seemingly has no bottom, it seems like a great idea to just dispose of unwanted things into the hole where they can't bother anyone. This is a bit like sweeping dirt under the rug, its not getting rid of it, just hiding it. The scientists who are throwing dangerous material down the hole tell the people that the radiation and chemicals will not harm them, and will not seep up into their ground for thousands of years. And in the short run, people benefited from the hole, making profits from those who spent money to dump things into it. However, in the end, what went into the hole eventually is dumped out the other side, which turns out to be right on top of the people who first discovered the hole.