I've been working on a better solution, its quite simple really, same as before, which worked, but was too faffy and slow. with two parallel pipes running, it took about 30mins to drain. The faff involved removing the pump from one pipe, to attach it to the other, and prime that one too. Pipes were too small, which meant an gravel 'hoovered' up could cause a blockage in the pipe, which is what I expect has happened.
Just needs bigger bore pipe, and a bigger pump.
Nearly finished the pump, which has been sat in my garage in bits for years. Been working on it a bit just recently. Based on 6" soil pipe, with two flap valves.
Then we need a 50m coil of 40mm black mdpe pipe, which I dont mind putting my hand in my pocket for.
Pump sits in the sump, permanently, at the deepest bit just before it sumps proper. 40mm pipe runs through the sump and down the FF. All things being equal, pump should be big enough to get the syphon started, and at 40mm bore, once running, it should drain pretty darn fast.
Hopefully, just needs one volunteer, preferably the smallest member of the group to get wet and crawl into the sump, a few strokes of the pump to get it going, then crawl out and wait.
I'll let you know when the pump is finished. Will put a concerted effort in this weekend to get it finished.
Then we'll buy the pipe, and game on. Old pipe and small pump need dragging out. (though perhaps a stash on the FF side of the sump might be useful for emergencies). New pipe will need hauling though the sump . Last time, we had two teams, one team either side, and the pipe got dragged through the sump using the dive line that is in there to pull it though from the FF side. Worked at treat and we had another line tied too, so we could retrieve the dive line back through the sump.
Yes, I'd appreciate it if the Red handled pump made its way back to me. But no biggie.
I've been recovering from a torn tendon in my knee, which is starting to get there now, but somehow a trip down giants still feels like it might be a bit much for it just yet.