bathtub in basement question

Hello All,
I recently bought a 15 years home. After moving in, the motor in the basement Jacuzzi tub died.
When I opened the access panel to the bath tub, I noticed that the bath tub sit in a basement concrete cut-out.
Below the Jacuzzi bath tub is the gravel/dirt.
1. is that normal? will there be radon or any toxic gas rising from the dirt?
2. should I just pour concrete and cover up the gravel/dirt? That will also partially cover the pipes for the tub.
3. any recommendation where to buy a replacement motor for the jacuzzi?

thank you all,

Go to any big box or hardware store (and many others) and buy a radon test kit if you're worried. Radon is the decay product of (most frequently) granite. This is more prevalent in places like NH where the whole place sits on granite rock (one reason why its nickname is the Granite State!). Not sure how much of a problem it is around Chicago. The harder it is to find a test kit, the less likely it's a local problem. Unless your water table is high and that area gets wet (and you'd likely notice evidence of that), it probably isn't a big deal.

Most of those motors tend to be proprietary designs and you may need to go to Jacuzzi for a replacement. Someone here may know of an aftermarket supplier, but I don't.