The advantage to our house being built on bedrock is that, if we ever get water in the basement, it is time to call Noah. The disadvantage is the possibility of radon gas. When we moved in 12 years ago, the readings were well below a problem level. But over the years I think we’ve made the house tighter against air infiltration, and we’ve had to install a radon pump in order to sell.
This pipe goes through the basement floor, and is connected to a fan outside that draws air (and the radon it contains) out from under the slab, instead of building up in our basement.