My modified Brotek ripper did pretty well. The hardpan (technically Duripan) we have is almost water impermeable, but if you keep it covered with water for several weeks, a trace amount of water will seep in and give it the slightest hint of humidity inside the stuff. While it is still very hard, this seems to make a bit of a difference in being able to penetrate the stuff. I gave the section a few days for the water on top that I had been irrigating it with to evaporate. The modified ripper was able to penetrate about 1" and as I curled the ripper back towards the tractor, it very slowly ripped the pan into chunks averaging about 10" x 6" x 1". These were still about the strength of concrete, even with the trace humidity inside them. I got down about 25" in depth yesterday, but there is about 47" more to go. The auger can wiggle a bit from side to side now, but the Woods BH6000 didn't have the strength to yank it upwards even a millimeter. As I get deeper, the pan seems ever so slightly not quite as hard and I may switch to the 9" bucket (modified with tiger teeth). Excavating the spoils with a shovel is a pain. The bucket has more difficulty than the ripper because the pressure is spread out over more area, while the modified ripper concentrates the force into one small point.
Even though I could have done without the time loss this is taking, it is still fun to use the tractor and a little innovation to problem solve.
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Post Script, an afterthought
I was thinking about what Jabroni said about the strength and also the soil not getting removed. Some of the big rigs have buckets with teeth patterns of teeth not all the same length. Some have the teeth long on one end, descending in length to the other. Some buckets have a long center tooth, very short teeth to the outsides, snd medium in between. I wish I could get a bucket that is about 7" wide and 14" from front to rear (excluding teeth). There would be 3 bolt on teeth. The outer teeth would be 2.5" single spike mini-tigers. The center tooth would be a 1/2 scale version of a Brotek ripper, with the tooth being a small single tiger point, and the shank would have the sharpened curved cutting edge like the Brotek. The teeth points and the cutting edge on the curled center shank would all be carbide and relatively sharp. I think that would give Jabroni a better chance to be able to slice through roots and remove the equivalent of 2 shovelfulls of soil. It would give me the ability to slowly rip my hardpan and then go back to scoop and excavate the spoils.