Can you provide at least one complete sentence and the context?
The fragment you have posted doesn't provide much information.
I can see that this text appears to be from a set of construction specifications but without more information I can't offer more than guesses.
"Cut out" or "cut-out" can refer to cutting into an existing floor or substrate to create a trench for a structural element or a drain or a conduit, that appears to agree with "the existing trench."
A "cutout" can also refer to automatic power switches.
The numbers might be dimensions.
These are all guesses.