After a couple years of neglect, I am trying to refurb a shallow well that feeds my irrigation system. It's a 2" jet well, 45 feet deep, with the water column rising to 9 feet deep. I am fairly sure there is a sand point on the end.

Removing the seal, I was surprised to find the 1" suction tube to be about 6 feet shorter (39 feet).
I was also surprised that instead of having a foot valve, the suction side went down to an injector/venturi fitting(?), slightly bulbous area for a lower seal, then ended with a check valve.

While this design seems to work, I was left wondering if there might have been something in that gaped 6 feet, or is this a "typical" configuration? And if it is typical, what would the normal range for the check valve's height above the base?