Here's my plan. 4" sch 40 from underwater to over dam. 4" thinwall on drain side. 4" tee underwater, 5 foot horizontal pipes capped and drilled with 1/2" holes. Set at 4' depth. Discharge to have 45 elbow and short riser.
At water edge, pump connected to 4" tee, for filling and priming the 4" pipe. Ball valve on inlet tee and at water edge. All connected using rubber coupler except the underwater tee (I will glue that.)
Operation: Valves open. Start water pump, fill all piping. Turn pump off, simultaneously shutting valve on inlet tee. Drain to desired level then shut off tee at water edge.
Did I miss anything? And do you think the gas powered water pump might break the 4" thinwall-- unless I am really careful (or lucky) to quickly shut it down once the pipe is filled?
