Excavating strip foundation on poor soil

Hello everyone,
I am the new guy. My name is Tobias, I am 30 years old and professionally an electronics technician.
That’s a bit about me.

Now for the first question.
As it turned out, the soil on the property is quite bad, i.e. groundwater at about 1m depth and firm soil only at 2.2m.

The architect said that it would be best to put a strip foundation under all load-bearing walls. So at those spots, dig down to 2m and fill with concrete and steel.

Now I have a few questions about that.
1. Has anyone already had experience with such poor soil and possibly with a high groundwater level and could give me tips?

2. Does the rest of the soil inside the strip foundation still need to be excavated down to 2m and filled with gravel? Or would, for example, 0.5-1m be enough here?

3. Is it possible to roughly calculate the cost per m^3 for such a job?

Thanks for your help.

Soil replacement is expensive.

What does the soil report say about the foundation recommendation?

One would first have to define what firm ground from 2 m actually means and what is above that. The geotechnical engineer or the structural engineer, in cooperation with the [BGG], then gives a foundation recommendation and not the architect.

It is advisable to set the house slightly above ground level by 30-50cm and to have 30-40 cm of washed gravel under the base slab. Talk to the person who did the [Bodengutachten], they should know what is necessary. The advice from architects is always a tricky matter.

So the soil survey is from the street that lies directly in front of the property. Boreholes were made throughout the entire new development area, but not directly on the properties. However, this can be roughly inferred because the soil is everywhere sh...
About the soil:
0.3 topsoil
0.8 fine sandy, clayey, very moist
1.0 clay, strongly fine sandy
2.2 clay, organic, silty
Groundwater 1.0m

I have not yet purchased the property, so there is no soil survey from the property itself or a calculation from a structural engineer.

Orgasmic .. And what is underneath there? Or does the drilling profile end there?