We built a sub soiler when I was a 'kid' (maybe 15). We called it a ripper, heavy duty. We ran 2in pvc pipe through our pasture by capping the end with an eye bolt drilled into it, hooking a small chain to the eye and around the tooth of the ripper (which only had one tooth installed in the center) and dragging it through the dirt. Drive it forward until the end gets to about the start, glue on the next pipe and signal the drive to drive forward another 20 feet or so. We did about 20 acres this way. If the pipe broke or we hit a rock, then we would dig it up and repair, start again. It was awesome and still in use today!
Where the sprinklers came up, before we drug the pipe though the ground, we bored holes at each sprinkler location, if memory serves, 4in holes using an auger. Drug the pipe though the holes, cut the pipe to install a T with the part going up threaded, sleeved the hole with 2in pipe and back fill the little bit around it, threaded in metal 1in risers. It was something like that. We wanted the ability to remove the risers for mowing, which I dont think we ever did as we just mowed around them one or twice a year. System works(ed) very well. Simply turn a valve at the buried main line and turn an entire line on. Come back that night and turn it off, move up or down one line and turn that one on. Irrigation was easy.
But I digress, we used a sub-soiler to pull small pipe through the ground very easily. We didnt trench the line first, just drug it down.
