Just for some pitchers, to borrow a term from johnbridge, here is an update. We bought a $80 1" SDS rotary hammer from harbor freight. I would have rather bought american-made, but you gotta choose your battles. The drill and chisel worked well enough, but if you need to clear some area, a demolition hammer would be the way to go. This is a small bathroom, and I'd rather not use a jackhammer unless I had to. If you'll check the map below, we're working in the master bathroom right beside the toilet drain. Note how the water heater is towards the front of the house.
I debated with my Dad to do the tear out in the front bathroom, but there's a cabinet above the problem area and he didn't want to tear it out. It looks like we'll tear it out anyways, since we'll only be able to see the elbow of the hot water supply joint, no matter how deep we go. They didn't suspend the rebar when they poured the slab - the rebar lies at the bottom of the concrete. I'm going to drill into the slab horizontally and epoxy some rebar when we patch it up. We needed a hole in the master bathroom anyways, since the toilet drain has a 1.5" hole in it.
There's a lot of gravel in the leak area. Here are a few questions now....
1) Soft copper is used under slabs if I understand correctly. Since the leak is on the hot water line, there's a joint where it goes below the soil, correct? I've heard not to solder soft copper, so I assume I'll have it brazed. Since there's so much gravel, we'll try to be careful about knocking the pipe around. Is it easy to estimate the extent of a leak with compressed air? Should we only hope that there's a leak at the joint, and not pinholes through the length of the run?
2) I'm gonna check half price books for slab repair/foundation repair texts. Any tips for backfilling? Maybe some terms or manufacturer's to google search? I read a blurb about engineered backfill from a concrete supplier, so I suppose I could stop by one in Dallas. There was a stringy black material in the area of the pipes. Is this oakum? I'm still surprised at the amount of gravel.