That's heart breaking! It was such a beautiful setup too!
I just read this thread, for the first time, from start to finish. I was going to say how jealous I was, until I got to the last few photos. Now I can only offer my sympathy. Is there any way to make that basement iron-clad flood-proof? Looks like the sump pump arrangement can't cope with major flooding. If not, as you already mentioned, it might be best not to tempt mother nature by re-building the HT in that location. Is there a suitable room available above ground level?
As for the house,: Sweet Mother Of God! I don't think my house cost as much as that model of yours...