I have a 18in by 18in area in my basement floor that is open dirt. The house is measuring high for radon so I need to seal this up as it is a major source for radon getting into the house.
There are some water pipes coming out of the dirt area, and something else that you can just see the top of... not sure what it is. Can I cover this all with concrete and seal it up? That's what the radon mitigation company said to do. Would I ever need to access these pipes again?
If you are going to concrete this, you need to extend the sewer cleanout or you'll be taking a hammer to the concrete when you need that (if you even remember where it is, then), and you'll need to sleeve the copper waterline with something to protect it from the concrete, or you'll be having a massive leak and needing to hammer the concrete to fix that. Both of those penetrations will want an appropriate sealant / caulk for the radon containment job, as well.
At 18x18 inches you could possibly also adapt a standard radon-sealing sump cover to cover the hole and attach a radon vent pipe to, though this looks like the sort of overly finished basement where that might be difficult as you're built right up to the hole.
My basement is quite tightly sealed (it's a newer house), and the cleanout hatch like yours is screwed down piece of plywood, which is caulked all around.
I suggest you do something like that, too. Remove the hinges, apply a generous amount of silicone caulk, and screw it down shut. If you ever need to open it, it's easy to do, and if you don't, that seal will last a long time.
All these openings around pipes need to be sealed as well, of course. Depending the size, you might need to add a backer rod or some kind of a flange, to make these openings smaller so you can caulk them properly.
In any case, do not cover any cleanouts with concrete.
