Rainwater infiltration and heavy rain

Hello everyone, many of us build with rainwater infiltration, we also have a [Rigole]. This was calculated based on maximum rainfall. What came down last night in the west of the country, no [Rigole] can absorb. Does anyone have an idea what happens when it is full? Does it become dangerous, or does water just overflow from the gutters?

Yes, the water runs out of the gutters after a short time given the current amounts. Regardless of the [Rigole].

When the [Rigole] is full, water is already at least ankle-high on the property and then it continues to rise because the ground cannot absorb it.

The infiltration trench simply overflows, if it is enclosed with edge stones, the overflow direction can be influenced by omitting one edge stone (not towards the house, but towards the street or paths). Gutters can overflow during heavy rain and hail, in which case the drainage should also be away from the house.

We have an underground infiltration trench, it has no overflow (where to, into the sewer is not allowed). Only roof drainage is discharged. The water would probably come first from the upstream inspection chamber. The water on the property runs off. In all directions away from the house (the house is 50cm higher than the street).

We had an underground infiltration trench covered with grass, when it was theoretically full every 100 years (after 4 months it was the first time) a 50cm fountain stood in the garden due to the pressure from the downpipes and flooded everything.
Clear the path of the water to the street

We had an underground soakaway covered with grass, when it was theoretically full every 100 years (the first time was after 4 months), there was a 50cm fountain in the garden due to the pressure from the downpipes and it flooded everything.

What volume did your soakaway have? The bad feeling is that you never know how full the thing is. Mathematically, it should be empty again after 24 hours without rain, but who really knows. It can store 45 liters/sqm if nothing seeps away. But then it overflows. Thinking of Hagen yesterday, where it was 150l, then good night.