Quality of Building Ground / Soil - Assessment

Hello everyone,
we are interested in a building plot in a development area.
There is a brief description of the "building ground investigation" in the development plan, which makes me somewhat suspicious.

Does anyone here know a bit about the subject of soil/soil quality, so that I can get a very first indication of whether this area is "quite okay," or if I should already prepare for extreme additional costs due to poor building ground?
I am fully aware that an individual soil report is naturally necessary for this. But maybe I can already get some initial indications – thanks!!!

Here is the description from the development plan:

The building ground consists in the upper layers of highly clayey silt and clay soils, which transition downward into stony weathering soils of the Keuper formation. In the eastern area, obstacles caused by beginning rock soils of the Keuper have also been identified. The topsoil thickness is about 0.40m. These soils were found between 1.0m and 3.0m below the surface and form a moderate and settlement-prone subsoil. From northeast to southwest, the clay soils become increasingly thicker. The stone content in the soils increases downward (stony weathering loams of the Keuper). Slight layering within the soils was occasionally observed, indicating the beginning rock soils in the subsoil.
Overall, only moderate bearing capacities are to be expected on the street planum with strongly frost-sensitive soils. Soil replacement measures are required.

The last paragraph in particular makes me wary. Is something like this normal, or should one already expect "problematic ground" here?
Also, cellars are not possible on all plots. In some cases, the top layer is too thin to allow for sufficient excavation for a cellar.

I would be very happy to hear your opinions!!
Thank you very much,
Robin

If the description applies to a larger development area, it does not necessarily have to be the same for all plots. However, one should expect that soil replacement is required and accordingly plan money for it.

It says right here:

From northeast to southwest, the clay soils become increasingly thick

Soil replacement measures are necessary.

Of course, this applies to the entire construction area.

Frost sensitivity is not an issue; every house must have a frost-free foundation.

If I understand and interpret this correctly, there is only one problem: the soil is difficult to compact and could settle. Therefore, I think that in the ground investigation reports for the builders without a cellar request, a pile foundation will partly be recommended. Alternatively, build with a cellar at living space height; then you excavate the "critical" 3m mentioned in the report anyway, and the foundation should no longer be an issue.

Thank you in advance.

What would a pile foundation mean?
I want to estimate whether to expect moderate additional costs (maybe up to 10k) or significantly more (maybe up to 30-50k) compared to a "standard soil."
Sure, you can't say that in general, but maybe someone has had similar conditions before.
Thank you

No one can tell you, but just from how many times I have read the word "Fels" alone, the excavation and disposal will not be anywhere near a moderate €10k. Everything else will then come on top.