Concrete the revision shaft?

Hello,

my civil engineer is currently installing the manhole (inspection shaft, maintenance shaft) for me.
Instead of using a bottom part that is closed at the bottom, he took a ring at the lowest part and placed it on the ground like that. He then wants to later concrete the lowest ring.
I have already heard in other forums that this is [murks].

I am also currently looking for a building expert who can check this. However, it does not seem to be that easy here in the area.
Furthermore, I have inquired at another civil engineering company and was told that it is possible to do it this way.

Can someone tell me if this is okay?

Best regards
Micha

The problem will be that although the bottom of the shaft is sealed by concreting, the load transfer (weight of the shaft + load on the shaft from above by cars, trucks, etc.) will still only occur through the ring. Since this area is smaller than with a shaft bottom, the risk of settlement under load is higher. The concrete will very likely not form a solid connection with the lower ring and in the worst case will maintain its concreted height while the ring (and thus the shaft) slowly sinks further into the ground.