My muddy and chunky clay well got a 4" pvc liner that we slotted. Raised the pump 20' [about 220' deep hole] seems to be working, especially by pumping at low volume to a tank.
Since I dig big holes, I know what this goop is - I find veins of a white clay, that are perfectly wet in totally dry soil - just like modeling clay you buy. In my case the deep pumping would likely suck in a mile of this weird stuff.
would it pay to fill the gap between the 4" pipe and the 6" borehole with pea gravel?