Remove stones from the ground in the garden

Hello

We have a new building and are struggling with waterlogging in the garden.
We have a very clay and peat-heavy soil.

To combat the waterlogging, we want to drill drainage holes about 1.8 - 2.4m deep (deep enough to break through the clay layer)
(...)

Is it waterlogging? Or something else? High groundwater? Layer water?
The water standing underground doesn’t just stop at your property boundary.

If you now build an infiltration system there, in the worst case the water will just flow in from neighboring properties or from the entire catchment area. Then you have invested a lot of money and work and gained nothing. In the worst case, you try to drain tens of thousands of square meters through your few holes :D
Can the water infiltrate under the clay layer? How thick is the clay layer? What comes after?
Or is there possibly water or groundwater present? Then nothing infiltrates.

We have a similar problem here. From mid-November, the water stands up to 50cm below ground level until March. That’s just how it is; there’s nothing you can do.