ᐅ What does this soil report from the neighboring property tell me?

Hello everyone,

I am in the process of purchasing a building plot in Baden-Württemberg. It is located at approximately 326m (1070 feet) above sea level, while the neighboring property is 1m (3 feet) lower, at about 325m (1066 feet) above sea level. I plan to build with a basement. I received a soil report from the neighbor (borehole about 25m (82 feet) further south), which looks as follows...

What does this report mean for me????

0–0.05m (0–2 inches): clay, slightly gravelly, brown
-0.6m (-2 feet): silty clay, slightly sandy, yellow-brown, with many iron-manganese concretions
-0.8m (-2.6 feet): clayey silt, slightly sandy, brown, stiff
-2.15m (-7 feet): silty clay to weakly silty, stiff. Yellow-brown down to 1.5m (5 feet), below that yellow-brown to gray-blue marbled
-2.3m (-7.5 feet): gray-blue clay, stiff to soft, with bleached root residues
-3.15m (-10 feet): weathered to heavily weathered claystone, yellow-brown to light gray and blue-gray marbled, upper claystone texture barely visible, increasing disintegration to claystone fragments downward

Groundwater encountered from 3.2m (10.5 feet) depth

Thanks,
TuGi

Tugi2o schrieb:

What does the report mean for me????

That you should commission one yourself for your property!

Otherwise, your neighbor’s geotechnical report should normally include a foundation recommendation.
Or is it a general report for the building area?

Yes... exactly... it is a general report for the building area!
I will definitely have one done before the purchase.

But maybe someone can already tell me in advance what to expect... for example, a waterproof concrete shell (white tank) etc. Then it will probably be expensive for me... the building plot is already expensive enough...

No one here will be able to tell you what conditions are like on "your" plot of land.

Invest about EUR 800.00 and have a site survey or soil report prepared for "your" property.

That way, you will be on the safe side.

Our building plot has been in the family for 65 years and had a single-family house with a basement on it for 64 of those years. The basement was a standard masonry basement and always remained dry.

Nevertheless, we had a soil survey done and learned that about 20 cm (8 inches) below the existing foundation there is a water-bearing layer. Because our new basement will be 30 cm (12 inches) deeper in the ground overall, we now need a waterproof concrete shell (a "white tank").

Tugi2o schrieb:

Groundwater encountered from 3.2 m (10.5 ft)

If groundwater appears already at 3.2 m (10.5 ft), a waterproof concrete shell (commonly called a “white tank”) will very likely be necessary – keyword: 100-year flood high level – which will probably be around 2 m (6.5 ft) and thus within your excavation depth.
This would also raise the question for me: groundwater heat pump, since the groundwater is so close to the surface.
At first glance, this sounds like additional foundation costs might be expected due to insufficient soil bearing capacity – that’s why (as my predecessors already mentioned):
Have a site-specific soil report carried out.

How did the neighbor build the foundation? Soil replacement? Reinforced slab? They would also need to be below the expected highest groundwater level (zeHGW) and therefore require a waterproof concrete structure (white tank).