Soil survey at the very beginning

Hello, I don't even know where the house will be situated on the plot (only approximately) and want cost clarity regarding the basement and excavation (Z0/Z1).

That's why I have requested several offers for soil surveys. Now I have 3 of them and cannot compare them at all. Each offer wants to do something different/offers different services. What makes sense now? I would like to know if my basement needs to be waterproof. And I would like to know if I have to take my excavation to the landfill. What else do you need in order to eliminate cost risks from the construction project? The concrete aggressiveness analysis is often also offered. Is that necessary? Will the survey then also be accepted by all earthworks contractors (landfills)? Is there an expiration date for the survey?

It is normal for there to be a building envelope on the land, meaning an area where the house will be located. A soil survey then consists of two boreholes about five meters deep within this envelope, preferably at two corners of the same. The bore core provides information about the soil condition. Is waterlogging to be expected? Does water drain well or poorly? Is a basement possible and if so, how? Is the load-bearing capacity good? Etc. This is what the civil engineer needs to create a proper foundation. Don’t buy gimmicks, but a soil survey that answers these questions. K.

I was advised to compare the total length and number of boreholes/probes for the performance comparison. For example, I had one offer with 1 percussion core drilling and 1 percussion probing, each 5 meters. Another offer included 2 percussion core probings and 2 heavy percussion probings, each 6 meters. Both were about the same price.
I distributed the boreholes/probes over the expected base area within the construction window. Even if a similar result comes out for all 4 boreholes/probes, it is still more representative than with 2 probes.

What also helped me was the experience of the neighbors. They had one done a year ago and already told us beforehand that after 3 meters, rock-like soil appears, and that’s exactly how it was in the end.

What you want are actually 2 different things:

1. A geotechnical survey, i.e. clarification of the soil structure, infiltration capacity, load-bearing capacity, etc. This allows you to estimate the costs for the basement and foundation. Conducted by drilling.

2. A soil analysis, i.e. an analysis of the soil composition, especially for contaminants, to classify the soil for the landfill. Conducted by soil sampling.

No. 1 costs about €1000, No. 2 about €500, regionally of course varying. At least here, the landfills only accept a soil analysis (No. 2) if it is no older than 6 months.

No. 1 costs about €1000, No. 2 about €500, regionally of course different. At least with us, landfills only accept a soil report (No. 2) if it is no older than 6 months.

Yes, that matches the values in the offer. That means whether Z0 or Z1, I only find out late, probably when the topsoil is removed, right? Strangely, they (the offers) always include that right away. I also once talked to a provider on the phone. He said they keep the soil samples and the chemical analysis can be done later. But that probably won't be accepted either, right? So someone has to come again and do No. 2.

As far as I remember, we are at €18 per cubic meter for Z0, €48 for Z1. That makes €10,000 for 300 cubic meters of excavation. What exactly do you look for when searching for a landfill that accepts excavation? Then I'll give them a call.

And could it be that the report (No. 2) is included with the earthworks contractor?

Oh yes, what about the analysis regarding concrete aggressiveness? Is that needed?

The storage was also offered to us, but we did not do it. It would work, the report is then redone upon request.

Searching by yourself is a tricky thing. Apart from needing the appropriate machines and transport options, in my experience they do not or rarely work with private individuals. Additionally, the landfill must not be far away, transport is expensive (time, tolls, ...). Try through civil engineers, landscaping gardeners, etc., some have good contacts there.

No one was interested in concrete aggressiveness with us. They wanted information on the foundation and, due to the basement, information on the infiltration capacity of the excavated material because of reuse.