John, what was that about NOT using roll flat discharge hose???
Discharge hose will function somewhat, but wants to flatten. There was not enough discharge hose on hand to run both the supply and the discharge so initially small pumps were used for supply. It might have worked with discharge hose but was not tried. My concern with the discharge hose is also "bellys" that could hold material. Bell ended PVC pinned together with screws for easy removal is better.
With proper baffling to direct the material to center, and proper water volume a constant feed is possible. A bent tube "jet" pointed at the valve and fed by garden hose also helps. The bulk of the material was delivered in one day.
Problems encountered: Stones (granite) mixed in probably from residual in the dump truck OR scrapings from the yard can plug the valve. Something I did not expect was that seal of the pipes is critical as well. At one point we lost outflow. We though it was a pipe blockage so we split some pipes. Later found it was gravel in the valve area. When we started again the flow was poor and could not figure out why. Next day started up again and after thinking about it I realized that one of the joints was not pushed in tight and it was sucking air. I gave it a quick tape job and it was off to the races again. I'd guess a solid 2 ton per hr delivery rate which could be sped up with faster loading and maybe more pump speed.
The key we found was to match inflow to outflow and keep the drain making sucking sounds.
