Sorry - from a previous post that noted that the engineers that win govt bids for levees and sewage plants and flood pumps are not Phi Beta Kappa and can barely speak english.
I was commenting on your concern for waterproofing pumps - its done all the time - Motors up high with long shafts to pumps below.
I've got a waterproof 220V pump 150 feet down in my back yard. No long shaft. Power has got to be the problem.