Sealing a sump pit? The Radon venting standards require a sump pit, if it is drafting air (the only reason to really seal a pit) to be air tight. If the pit is the suction point, it of course has to be sealed, and of course the pit would have to be air tight.
But what if the suction point is through the slab, on the other side of the basement? With homes that have interior drain tile and or gravel it is likely that communication will be quite good (which is what you want). When this happens the sump pit needs to be sealed. Otherwise the system can pull air from the basement which can combat your own system and possibly raise Heating and Cooling bills.
Only submersible pumps can be used when sealing a sump pit. Doing a smoke test to determine air drafting after a system is operational is the best way to know if a pit has to be sealed, if the pit is not the suction point and there are no interior drain tiles. So, sealing sump pit is very important.
While draft testing you need to check cracks, open holes through the slab and cold joints for leaks. Cold joints are where the slab and foundation wall meet. If drafting caulk with a polyurethane caulk. Clear silicone on the pit lid.
The video shows the suction/drafting of a pit. The Radon system is on the other side of the basement, routed through the slab and then up through garage and roof. Imagine if the pit was not sealed or this was a cold joint leaking. This is why smoke tests must be performed with every system.