Well, it rained yesterday and last night, WOW did it rain. And melted all the snow. Created a pond in the backyard, which flowed oh so gently along the foundation and to the corner of the house where I dug that trench and installed a nice 4" drainpipe. Which worked, as far as that goes.

Yes, folks, the flood this time was not from that corner backing up over the level of the foundation.

This time it came from the other corner, apparently where the slope of the ground along the other side of the house guides the water into the foundation. *sigh*

I don't think I can fix that part. We tried with landscaping, had them pile dirt, etc - and re-grade away from the house. Didn't work. Woke up at 1:30 to the dulcet tones of the water alarm (cheap little portable box, I keep the wires dangling into the floor register in the sunken den) which let me know that water was in the floor vents again. While it did not come up through the vents to flood the room, as I have seen before, there was definitely a watery presence - the floor was about 50% covered by water which came in at the concrete/wall junction. I think we may have a serious problem here.

I'm thinking we need to have the floor vents completely filled in, dig french drains along two sides of the house, and build a new vent system for the 1st floor. Ah well. Hopefully someone more of an expert can tell us more.