We want to convert a garage to a living space. Can we install drain lines under the slab which is already in place and has been there for 20 years?

Can we install drain lines under the slab which is already in place and has been there for 20 years?
Yes you may! You can cut the slab with a cement saw or jackhammer in the trenches. What do you wish to install? Do you need assistance from us in doing so?
We're here to help if you need us. Good luck, Tom