Is it good to install a Radon mitigation system through the sump pump pit? The answer is, yes, it can be a good way to install a Radon system. But, it can also be the 2nd or 3rd choice in a home.
It all depends on how the home is constructed and how old it is. Also, the sump pit area can sometimes have other mechanical items in the area that could be an issue.
If there is gravel under the basement slab it doesn’t really matter if there is a drain tile or not. If there is gravel and an interior drain tile system with a sump pit then you get the best of both worlds. But, you do not have to use the sump pit for the system.
The best way to go is a sub-slab system where we core through the slab to install the Radon system. The sump pit is only sealed so the system does not pull conditioned air from the home. By installing a sub-slab Radon system you have more choices to route the system for aesthetics. Normally through the garage and roof (the best way).
So, venting off a Radon mitigation system sump pump pit for a Radon system is fine. To me it is the easy way out. Nothing wrong with it, but when able it would be the 2nd or 3rd choice for location. On older homes where there is clay or sand under the basement slab and a sump pit is present, then it might be the way to go.