How to separate voids In a panel

I am designing precast panels, they have a circular void in the panel, the difficulty is that the voids start and stop. Its important that I put the voids in the panel as I estimate the concrete quantities.
Any suggestions?Panel and Void Question Model.skp (1.4 MB)

I attached a model and a picture of the panels, section a and the voids are Plank type 1 Plan

Thanks in advance!!

Create the voids by placing the appropriate geometry inside the group with the back faces orientated outward.
Correctly orientated faces tell the software what is inside and what is out.
A cube with a smaller cube inside can either be two solid cubes or a cube with a void depending on the orientation of the faces.