Footings in disturbed soil

[Alan Gage]

As I'm planning my spring build I realized that my current house plan puts part of the footing over the old well pit, meaning that it will be sitting on disturbed soil. Thoughts on how serious this is? Is there a way to compact fill enough to keep it from settling?

The old well pit is about 5 feet wide, 6.5' deep, and 8 feet long. It has a cement floor and block walls. The foundation for the house will be slab on grade with frost protected footings 16-20" below grade (3-4' frost depth). The house will be a single story between 850-1000 sq. ft. The footing will cross the width of the old well pit (5').

I'm thinking that just knocking the concrete block into the hole and filling it would be very prone to settling.

Another option would be to remove the block but leave the cement floor of the well pit intact and run the footing down the 6+ feet in that area so it had a firm base. That would be a lot of cement and bracing though. Would I need to worry about poor drainage from the old concrete floor or would it not really matter at that depth (soil has great drainage - gravel)?

Last option I can think of would be to remove the block from the old well pit and fill the hole with something like crushed concrete and make sure it's well compacted. It seems to me this would be good enough since it would only be a 5' section of the footing.  Sound plausible or is it still likely to settle?

Moving the house location wouldn't be completely out of the question but it would sure throw some things off. Can't go farther to the front of the lot line because of setback limitations. Can't go further back because I'd have to go nearly 10' and that would start to squeeze the area for the septic. I could shift everything to one side so the old well pit would end up under the patio but then I wouldn't have enough setback from the adjacent property to add on in the future.

Who knew so much planning went into building a house!? 

Alan

[diyfrank]

Option 1 would be a poor choice.

Option 2&3 should both work fine. If you have a way to compact your fill, crush concrete is pretty good stuff.