Well, I am running out of ideas. Argh. This project should have been pretty simple. I have a concrete slab and want to build a garage on it. Three sides are against a hill, which I will backfill with gravel and earth later. But before I start on the garage, I want to run perf pipe around those three sides for drainage so that water won't ever build up. The slab has floor drains too, so I want to take care of that too. This work area is on a hill, and I started trenching the drain from the slab down about 80 feet by the side of the driveway. I plan to put the perf pipe at the bottom of the trench and cover with gravel to make a kind of downhill leach field. Well, I can get about a foot or two down before my backhoe (Bobcat 910) hits rock and can't go any deeper. So I rented an 880 breaker for a few days to break up the rock in the trench so I can scoop it out. The breaker works nicely on my rock above grade, but for some reason it just does not work below grade in the trench. It really seems to be working, but when I get back to the backhoe, it is like I never used the breaker. So next I rented an auger, figuring that I could dig some holes next to each other so that the backhoe bucket can get in and pull up the rock. This rock is like some kind of cemented red sedimentary rock, and is very tough, but it does fracture and give if you can get underneath it somehow. So that was my idea anyway. This auger is a 15C with a 12 inch bit with carbide teeth, by the way. It takes about 20 minutes to dig a single hole. I counted about 58 RPM, which is about right for my 12GPM 825 on full throttle. The teeth just do not seem to grab and cut the rock, but instead I just get a very fine powder. I am thinking that if the auger could only bite into the rock and bust it up (rather than shaving it), I could do a lot better. I am wondering if the Bobcat rock bit would be a clear improvement over the heavy duty with carbide teeth. My rental place does not rent rock bits, so I can not just rent one and find out easily. Is there maybe some other good way to get my trench done through the rock? Thanks!