ᐅ Filling due to Groundwater Issues...

Hello,

I hope this is the right subforum. A brief overview of the situation: My plot is on average 23 cm (9 inches) above the groundwater level. However, the surrounding ground rises, so the plot is basically a small hollow.
After the official survey, the construction company decided on a small embankment to create slightly higher elevation compared to the road (which is unpaved).
Just before the final specifications, I visited the site again—of course, it was snowy—but this clearly showed me how much the plot forms a dip. Now I would like a higher embankment.
However, the surveyor has already been there, and the building permit / planning permission has also been applied for but is not yet approved.

Is there a way to get a higher embankment without significant additional costs (the surveyor already cost me around 2000 euros)?

And if not, is 20 cm (8 inches) above groundwater level a cause for concern?

Thanks in advance for any replies.

Best regards,
MagNoona

Edit: I am building without a basement.

Hmm, no expert opinions on this yet?

What you’re describing sounds serious to me, it sets off alarm bells! I don’t want to cause panic, but 23 cm (9 inches) distance to the groundwater seems quite tight in my opinion. Water also rises capillarily through the soil, so the 23 cm (9 inches) of earth above probably isn't very dry either. Plus, the location in a low-lying area... after a few days of rain, everything could be underwater—water coming from above and below, so to speak. Especially if the neighbors around are directing their rainwater towards this low spot.

By the way, the groundwater level can rise quite quickly: shutdowns or reduced capacity of water treatment plants, pumped storage facilities in the catchment area, flooding of nearby bodies of water, etc. So 23 cm (9 inches) as a “buffer zone” is tight.

In my opinion, this situation requires special structural solutions. Even adding fill material might not be sufficient. What does the architect say about it?

Best regards

Hello,

thank you for your response. The depression will be filled with topsoil, and the elevation ensures proper drainage (the house will then be about 10cm (4 inches) higher than the street).
The foundation slab is a waterproof concrete slab. Both the architect and the earthworks contractor have no issues with this. I also just spoke again with the earthworks contractor, who wants to reassure me since I am building without a basement and there are already houses surrounding the site; I trust him, but still, somehow...

The building permit / planning permission application is still with the building authority. If I increase the fill by another 10cm (4 inches), will I have to pay the surveyor again? Can the building authority request an updated site plan?

Best regards
MagNoona

Hello, as far as I remember, the site plan included so-called "elevation points"

These were terrain heights that were marked and measured on site. The house was only labeled with the height information. I would be surprised if a completely new site plan is required. From my understanding, only the height of the house changes, or is the entire depression being filled in? In any case, I think the building authority should be informed because, among other things, the ridge height changes; it will naturally be higher due to the filling. Sometimes centimeters make a difference, especially when the municipality has so-called "design regulations."

By the way, a WU slab (waterproof concrete slab) is not completely watertight. In my opinion, when dealing with pressurized water, which based on your description may not be ruled out, a bit more work needs to be done.

Best regards

So the depression will then be filled with topsoil.

...you’re not serious, are you?

6Richtige schrieb:
So the depression will then be filled with topsoil

...you’re not serious, are you?

... if that’s really the case, the earthworks might end up being the most expensive part of the entire build ...