If you are approving the use of the cable. You should be able to do this calculation yourself. Or you need someone to review it, peer, supervisor, or outside consltant.
You also need to look at the protection for the circuit to ensure that it is suitable first. The cable size is then based on the protective device and not the load.
Is it 2 core 70mm2 or 2 single cores. I haven't ever come across 2 core 70mm2 cable before and I would think it is expensive.
All this information regarding current carrying capacity voltage drop should be on the cable datasheet.
Anixter have a great cable handbook if you ask your local rep for it.
Here is the 600/1000V XLPE single core informatin from it,
Assuming that it is 2 single cores installed on cable tray.
Current carrying capacity is 310A, though you wil neet to derate for , ambient conditions, no of conductors in the vicinity , Installation method etc.
You then need to compare that to your protective device. If the upstream device will let 300A flow in the cable then it unlikely to be sufficent. I souwl suggest that something inthe 63A range might be a good place to start
Volt drop is .68V/Am so for you is 111m x 58A x .68V/Am = V
I'll let you do that bit yourself