I live in a partially below-ground finished basement of someone else's house. I have recently tested for radon and found the level to be elevated.
There is a 2-foot deep sump pump pit in the basement that the homeowner says has not been used for over decade and the pump is not even plugged in.
I have discussed radon mitigation with some professionals, who recommend sealing the pit with a cap and running a pipe through a hole in the exterior wall to an outdoor fan for venting out the air. However, the homeowner is wary of putting a new hole in their exterior wall and would prefer to just fill in the sump pump pit.
Would this be a reliable way of mitigating the radon and, if so, what fill-in technique would you recommend? Complete concrete, sand, foam, plastic capping, combination, etc?