ᐅ The neighbor’s rainwater drainage is flowing onto our property.

Our neighbor (a large residential construction company) is currently digging the pit for stormwater infiltration just behind the wall. The roof area is about 500 m² (5,380 sq ft). We believe the location is completely unsuitable and worry that not all the water will be absorbed, causing runoff onto our property.
The flaws we have noticed so far:
- Infiltration is only possible on two sides (both adjacent to boundary walls)
- The size is far too small
- There are holes in the concrete wall that can only be barely patched
- The backfilled soil does not absorb water as well as natural soil, which increases the risk of overflow.

Unfortunately, it is impossible to communicate with the workers (foreign construction crew). They seem unconcerned and have already damaged our property several times.

Who can we contact for an inspection in this situation, and what do you think about this setup?

A civil engineer friend told us that no setbacks from the property boundary are required regarding infiltration systems.

Tx-25 schrieb:

Who can you contact here for an inspection, and what do you think about the implementation?

You should contact the building authority. They must have approved the drainage plan.

An infiltration system is designed based on the permeability coefficient (soil type), the connected surface area, and the rainfall amount for your region. Only infiltration through the base area (not the sides) is taken into account.
The volume of the system therefore acts as storage for extreme rain events. Usually, if the parameters are tight, an emergency overflow to the sewer is installed.

Tx-25 schrieb:

- Perimeter way too small

From your experience, how large should it be?

Clearance distances only need to be maintained for buildings with basements (and from the groundwater).
I do not initially see your mentioned concerns as valid.

Regards