Backfilling due to groundwater

Hello,

I hope I am in the right subforum here. A brief overview of the situation: My plot of land is on average 23 cm above the groundwater level. However, the ground around it rises, so the plot basically forms a small valley. After the official survey, the construction company decided on a small embankment to create some elevation compared to the street (which is unpaved). Just before the final specification, I visited the site again—of course, there was snow—but this made it clear to me how much the plot forms a hollow. Now I would like a higher embankment. However, the surveyor has already been there and the building application has already been submitted. It has not yet been approved, though.

Is there a way to get a higher embankment without major financial expense (the surveyor cost me about €2,000) nonetheless?

And if not, is 20 cm groundwater level somehow problematic?

Thank you in advance for any answers.

Best regards MagNoona

Edit: I am building without a basement.

Hmm, no expert opinion on this yet?

What you’re writing sounds bad to me, alarm bells are ringing! I don’t want to cause panic, but 23 cm distance to the groundwater is in my opinion rather tight. The water also rises capillarily in the soil, so the 23 cm of earth above probably won’t be particularly dry. Plus the location in the hollow ... after a few days of rain everything would likely be underwater, water from above and from below so to speak. Especially if the neighbors around direct their rainwater towards the hollow.

By the way, the groundwater level can rise pretty quickly: shutdown or reduced output of waterworks, pumped storage plants in the catchment area, flooding of nearby waters, etc. Those 23 cm “buffer zone” are tight.

In my opinion the situation requires special constructive solutions. Even with an embankment that probably wouldn’t be fully sufficient. What does the architect say about it?

Regards

Hello,

thank you very much for the reply. So the depression will then be filled with topsoil and thanks to the embankment drainage is ensured (the house will then be about 10cm higher than the street).
The slab is a WU concrete slab. The architect and the earthworker have no problem with it, I just spoke again with the earthworker who wants to ease my concerns since I am building without a basement and there are already houses all around; I trust him, but still, somehow...

So the building application is still at the building authority. If I increase the embankment by another 10 cm, do I then also have to pay the surveyor again? So can they request a site plan again at the building authority?

Best regards
MagNoona

Hello, as far as I remember, there were so-called "high points" on the site plan

These were terrain elevations that were marked and measured on the ground. The house was only labeled with the height information. I would be surprised if a completely new site plan were required. From my understanding, only the height of the house changes, or is the entire depression being filled? In any case, I believe the building authority should be informed because, among other things, the ridge height changes; it will of course also be higher due to the filling. Sometimes centimeters decide, especially if there are so-called "design statutes" of the municipality.

By the way, a reinforced concrete slab is not watertight. In my opinion, with pressing water, which according to your description is probably not to be ruled out, a bit more has to be done.

Regards

So the depression will then be filled with topsoil

...you’re not serious right now, are you?

So the pit will then be filled with topsoil

... you’re not serious, are you?

... if that’s really true, then the earthworks might be the most expensive part of the entire construction ...