Need unconventional plumbing help

[asylumdown]

Hi folks, this is sort of a long story that I will skip most of for now, but the end result is this:

My backyard has been one massive FUBAR disaster since the moment we moved in to our house. The festering sore that has been the source of now 15 months of misery for me is a giant, completely messed up water feature that is built in to a very large, expensive, and permanent system of concrete retaining walls. The short version of the story is that the people who designed and built it are so negligently incompetent, it didn't hold water, and when they realized how badly they'd messed up, they vanished for months and torpedoed any chance we had of doing landscaping last year.

Because I'm apparently a masochist, our home builder convinced us that they had finally gotten the company who designed it back on board and that the water feature was going to be addressed first thing this spring. Long story short, it's now almost August and they've been yanking our chain all summer, but I'm well past the point where I can get another company in to do the work.

In essence, this water feature is like a massive, concrete, outdoor fish tank with multiple tiers. The plumbing is 90% done, but the way the slack-jawed gopher who was working on it plumbed it, when the power is cut to the pump, 50% of the middle basin of the water feature (about 150 gallons of water) drains in to the lower basin and floods my back yard. Yes, the level of incompetence is that serious.

I have completely fired these people, and at this point I'm *pretty* sure I know how to fix his hack job of a plumbing set-up, but I've only ever plumbed one large tank myself before. What I really need is someone who's plumbed a few different large aquariums and understands siphons, back flow and all the things that can lead to disaster well enough so that I can fix this once without having to mess around with it for hours and hours trying to get it working right. If this describes you, and you live in Calgary, and are willing to come to my house in the near future and help me solve something that I have been losing a massive amount of sleep over for the past year, I would be happy to feed, drink, and pay you a generous consulting fee. I would try and do this all through the forum, but the plumbing on this water feature is quite a bit more complicated than I think I can convey in a few pictures and words, it really should be seen in person.

Again, I know what the problem is, I just don't think I can get to the exact solution without playing around with it for hours, and the plumbing pieces I might need are considerably more robust than something you can get at home depot - it was built using swimming pool plumbing. I'd like my first fix to be the right fix, if you know what I mean.

And yes, that's the short story.