Super thanks, we will definitely bring this up at our next appointment.
If you actually buy that thing, get everything in writing. Ideally, the pipeline should be described somewhat more precisely in the purchase contracts.
Then also ask for further information about the pipeline. What purpose, year of construction, when decommissioned, and which material (steel, ductile iron, concrete, GRP, asbestos cement...). If applicable, the pipeline is also filled with flow mortar, which would of course be the best case for you.
Conversely: The material is dilapidated, collapses at some point, and settlements occur.
There shouldn’t be too much additional cost from that, right?
Well, excavating half a meter for the foundation slab certainly costs significantly less than a pipe trench about 1.5 to 2 meters deep. If it goes wrong, you need shoring, construction water management, you first have to locate the pipeline, and you must properly dispose of the removed pipe sections (that’s why the material is important, asbestos cement). That can add up.
What exactly is meant by "properly sealing"?
I would say here: Seal tightly so that neither soil nor water (longitudinal drainage) can penetrate.