I just started a job on a lot with bad dirt we scraped the grass off and started digging a footer for a house dug down about 2 ft or so and still in that gummy dirt that's wet hadn't ran into this in a while . If I dig down how much compacted fill does it take to build a pad over it (depth)
I'd just keep digging until you hit a solid base. Once you hit that, you're going to have to throw some clean rock or compacted lime in and bring it back up to desired grade or pour a taller wall with a little wider spread footing.
Im pretty sure you need a geo survey done because the amount of good clean fill will vary with the size of the home zoning etc.... ussually before we build the pads for home we have these guys come out run a test see how the soil conditions are under neath and then the engineer/architect will draw up plan with the specs for the pad with everything. But if I am working way south in florida we dont to do the test because we have limestone about 4" under the top soil
I agree with Monster on the geo survey.. Better safe than sorry.
I told the contractor we had to dig out the whole area where the house is going and truck compact able or get geo tec guy out to tell us what to do my biggest concern is the deeper I dig the wetter it gets and here the codes will not allow you to fill with gravel
The last pad I did where the water table was high we had the same problem no gravel I had to dig out the pad and drain the water out with pumps and haul in fill and compact while pumping out the water
That was what I told the contractor digging it down and at least a 2 ft min. Pad build from good compact able fill to bridge over the wet area
Dig a test hole to see how deep the bad soils are
I ussually try to have everything I do on a set of plans to release my self of any liability which is why I said the geo survey either way that proposed home will have a set of engineered drawings and if they do the survey and draw up a set up plan you all are going by the plans not going by what you say even if it is exactly how you would of done it
Just got off the phone with contractor were gonna hold up on that project til the geo tec draws up a plan
We run into this a lot. Usually if the ground is bad but not horrible we will over excavate 3-4 feet down and 5 feet outside the footer. Sometimes we lay down geofabric then compact up to final grade. If ground is to unstable for this method we drill and pour concrete piers. This is always done with the enginieers recommendation and monitored from start to finish.