I've been back on this project for the past month and have made a bunch of progress, though it's been very slow. Getting all the rock out of the excavation site has been a real challenge. There are days when I think I'll make it, and days when I think I'll be forced to move the building.
It's really hard to capture it in pictures, but here's a try. In the picture below I have highlighted a paint mark showing my target elevation for excavation. You can see where I have been busting out rock to reach that grade, and to push it back towards the rear of the building site. The whole area to the left is still 2-3' high, and is pretty much solid granite. I'm continually generating piles of rocks like the one on the right. For reference, from the red mark up to the ground level is about 8'
This next pictures tries to show what the rock formations are like. The horizontal line is the target grade, and I have circled two veins of granite that slope up and towards the back of the site. These are solid granite, however if you dig around them enough, they are separable chunks - just gigantic in size. I have circled two veins/chunks, but there are actually 4 or 5, each overlapping the next. So it's a bit like a game of pickup sticks to figure out what sections are pinned in my other sections, and what order they need to be removed in to get it all out.
I realized that anywhere it's possible to dislodge and remove a section whole, that's much easier and faster than trying to break it up with the hammer. So removing them is very much like digging out a stump, finding and following the perimeter, and digging out all the material and tentacles that are holding the section in place. This is a much better use of the hammer, and much easier on the hammer. Eventually I'll see the rock move a little bit, and then I know I have it. Here is one of those big ledge sections after I have broken it loose, but before dragging it out of the hole. This one was actually two pieces which is a blessing given their size and weight. This whole section was a solid 20' long. My excavator can lift about 6000 lbs, and it could barely lift one end of the bigger section at a time. So that's probably a 10,000 to 15,000 lbs rock. I have pulled close to a dozen such sections out so far.
Speaking of the hammer, this project has been really rough on it. The vibration and pulsing of the hoses snapped the hose end fitting of the pressure line right off. Not once, but three times. I finally switched to a much higher pressure hose than is required, solely because the fittings are much bigger. Now, after $600 in hoses, it seems to be holding up OK.
I also developed a leak in one of the hard pipes for the aux hydraulics on the excavator. The machine is 7 years old, but just now a pin hole opened up at one of the weld joints, probably because of the vibration and pulsing. That was another $500 for a new pipe.
And granite is very hard on the chisel tools. I completely blunted my original chisel and had to buy a new one. There goes another $700. I checked around a bunch of places to see if anyone could re-point the old one, but nobody would take it on. It's apparently too hard for a milling machine, so the only solution is grinding, and that's a lot of material to removed to repoint it. Maybe someday I'll give it a try, but for now I need to just keep working. Oh, and I just replaced the chisel AGAIN. There goes another $700.
