ᐅ Soil investigation: relatively deep soil replacement required

Hello everyone,

My wife and I have been allocated a plot in a new development area through a lottery system, and we are now considering whether to purchase it. While reviewing the geotechnical report (see attached images), we get the impression that the soil conditions are rather poor, and we are leaning towards not taking the plot. According to the report, the load-bearing terrace sediments are only found at a depth of 4.30 m (14.1 ft), which would require soil replacement. The RKS 24 referred to in the report is located very close to our plot.

I would be interested in your assessments of this report, especially regarding the additional costs for foundation work compared to a “problem-free” soil. We plan to build with a basement.

Thank you very much and best regards

Organic soils up to 4.3 m (14 ft) are unusual to my knowledge.
What was found there? What do the other boreholes indicate?

The expert also recommends using a load-bearing slab for economic reasons.

Since you are building with a basement, I don’t see a major issue for you.
The soil will have to be removed anyway, followed by some gravel backfilling and then the slab.

Thank you for your response! The area has been used for agricultural purposes until now. I am not sure where the 4.30m (14 feet) of organic soil comes from; perhaps a tributary of the Rhine once flowed along there. We will reconsider the purchase of the plot.

Hello,
if you are building with a basement, you will have to excavate at least 3.3–3.6 m deep (11–12 feet) anyway. Of course, that extra meter will cost more, but if everything else is in order, I wouldn’t let that discourage you.

Best regards,

Andreas