How far under the slab do you have to go? Is there anything like a cabinet that you can remove to cut a hole that wont be noticed in the concrete?
The picture is of a drain line that I put in for a new bathtub in a bathroom that I did. I also moved the toilet and sink, plus added a seperate shower on that job. All the drain lines had to be moved. Water lines were easy and I was able to run them throught the walls.
I figured out where the lines needed to be and cut out the concrete with a masonary blade in my 7 1/4 saw. Then I chip out the concrete with my air chisel and didg down into the dirt about six inches.
Then I measure real good on the outside to where it will line up with the hole in the concrete. I dig a hole on the side of the house and connect a 3/4 inch PVC schedule 40 pipe to a water hose. Then I start pushing the pipe into the dirt until I get to the hole in the concrete. For the drain lines, I had to do this a few times to get the drain lines through, but for a small copper line, that would be all you need to do.
If you can't hide the hole with a cabiner, you can always fill it back in with concrete and finish off the floor with tile, linolium, carpet or ????
If tunneling isn't an option, you can cut a trench through the concrete with a masonary saw blade the full lenght and about 2 inches wide. Then chip it out and dig down into the dirt. Refill with sand and soak with water to get compaction. Finish with cement and hide with flooring.
The saw blades that I like the best have notches in them with diamond, smooth cutting edges. It's loud, dusty work, but it works good and goes fairly quickly.
Sorry to hear about those pipes. I've never seen a galvanized pipe that wasn't at least 80% blocked.
Eddie