Soil assessment before purchasing property - how to manage it in terms of time?

Are you absolutely sure about that? After all, the landfill is only approved for a specific disposal class, and that must be unequivocally certain.

I know we didn’t have that. And the BU all happened in Johannistal, that is our landfill.

Alright, maybe you were just lucky. Generally, the landfill only gets a concession for certain soils (e.g. LAGA Z0). If you then have, for example, Z1, you have to go to a different landfill. That it is still handled quite laxly in practice may be true, but then that is just luck and not law. ;) Otherwise, I'll soon go there with my dioxin soil and get rid of it right away. :)

If construction is already underway, just ask one of the builders. Otherwise, ask the civil engineers who are doing the road and infrastructure work there. Look into the justification for the development of the B plan, they are often available online and include trial drillings and drainage concepts. Is the issue of unexploded ordnance cleared?

Construction has not started yet. The plots in that area are being allocated for the first time. Infrastructure is already completed. The road has also already been paved. I can no longer ask anyone on site. Unexploded ordnance is also cleared or included by the municipality when purchasing. I will look into the development plan again to see if there is anything about that.

You must look not in the development plan but in the justification for the development plan. This is often not made public and is only released upon request.

If there was a field there, there is no moorland. There are no rocks in SH. If there was a field there, no poison is buried there. Therefore, the whole thing is 99.9999% suitable for proper construction.