Advance payments for a possible future construction site

I am 28. Professionally, I have just started a job where I am confident that I can work in this field until retirement (not have to) and should also not have any major problems changing positions.

That is an age at which all development directions are still open: you can be overtaken in seven years - think of Schober from the Sparkassen commercial - but also be doing something completely different in twelve years (really much more different than what the Monty Pythons call "completely different").

Basically, the municipality had already made an inquiry a few years ago to purchase this meadow and develop it into a small residential area with 9 units, which my grandparents (owners at the time) refused.

Oh dear. We have already had cases here where the municipality has "remembered" such a refusal very thoroughly.

Yes, with bad luck you are not allowed to build anything there :(
So the first stop is now the city, everything else makes no sense.

Oh dear. We've already had cases here where the community has very thoroughly "remembered" such a rejection.

I do not assume that. At least I hope not. Since my sister's request was not met with resistance but rather with support. And my sister's request was about 2 years ago, while the community's request dates back over a decade.

We also had a soil survey and an elevation survey carried out in advance for our property.

The soil survey was conducted according to the building requirements (house without a basement) and the boreholes were carried out accordingly.

We had the elevation survey done, then later had the property cleared so that it would be ready for the start of construction and so that the summer felling ban would not thwart our plans.

Accordingly, the data in the elevation survey were no longer accurate when we signed our construction contract. Therefore, our general contractor wanted a current survey and we had to have a new one carried out…

if you want precise basics to play around with house planning on (extreme?) sloping terrain:

Get a cadastral map extract in advance. Mark a grid of your choice on it (5x5m?) and transfer this grid onto the property with stakes. How to get stakes in a row was already known by the ancient Egyptians when they staked out the pyramids. Google helps if necessary ;)

Borrow a construction laser with accessories. Take a good friend and a weekend free.

Drive in the stakes and take the height of each point relative to a fixed point with the construction laser (alternatively a theodolite, but I think that is harder for a layman to learn than the simple operation of a construction laser) (nearest manhole cover in the middle of the street in the development direction)

Now you can digitize the whole thing or buy Styrofoam boxes to model the property at a scale of 1:X, mark the measured height on each corner, then cut off the excess. Assemble - done.

O.K, maybe more than a weekend after all :rolleyes:

Ouch.
If you’re not up for a weekend with stakes, then you go online for 10 minutes.
In NRW you can overlay free elevation maps on Tim Online. Here is a random example somewhere in NRW:

Each color represents an elevation difference of 1m.