opening in one-way slab

huangyhg

opening in one-way slab
i've been asked by a contractor if it's ok to cut a opening in a one-way spanning slab. details are on the attachemnt and are as follows:
- 125mm thick, rebar not known
- spanning 3300mm from wall onto steel beam
- opening is 310x260mm at corner
i'm aware of rules governing the positioning and size of openings for 2 way spanning slabs however there seem to be very little on 1 way spanning slabs. my thoughts are rebar will be hit and the slab will lose some of its strength however due to the size and the location adjacent to 2 walls the slab will be ok with needing secondary steelwork or strengthening.
any thoughts?
it is only 260 (10.5") in the direction that the slab is spanning, run a covermeter over it, the opening hopefully only  cuts 1 bar maximum, it is in a low moment region so hopefully the slab with still have enough capacity in that region.
is the wall running left to right along the page loadbearing?
i would not hesitate to cut the hole in this location.  a crack could propagate from the corner, but it would be of no consequence.
i would prefer a circular hole for easy of coring, even so i wouldn't hesitate, just make sure they don't over cut too much.
when in doubt, just take the next small step.