Access: Infiltration through living soil

Hi,

we have been ordered by the water authority to have the driveway infiltrate through permeable pavement.
I have attached a cheap sketch.
Actually, we would have liked to pave the hatched area, but with the requirement (since it is a drinking water protection area) we are not allowed to do it that way.

Do you have any ideas? The only thing I thought of (and which the geologist from the water authority also considered good over the phone) is to design the driveway itself as permeable pavement and then lay some kind of grass grid (e.g. plastic) on top.

On the other hand, it will still settle, even if the manufacturer of the grid says that the load is distributed evenly.
According to the internet, we need 30 cm of soil for the permeable pavement before any substructure begins.

We also don’t want to get wet feet, but for a narrow footpath (say 60 cm wide) the 3 m driveway is almost too narrow already.
If we create the footpath and start the grass grids next to it, there is a very high probability that a car will drive exactly on this joint edge, so it will settle even more.

Do you have any good ideas what we could do?

Best regards!

that we have to infiltrate the access road through active ground.

The access road is supposed to infiltrate?? Or do you mean that the access road should be designed as "active," basically unsealed? So that it allows infiltration?! What does "active" mean to you? Have you asked? When I look it up, "active" refers to heavy use.

On the other hand, it will settle, though,

If you have a good construction, nothing needs to settle. Where should anything settle if the edges are properly set?

We don't want to get our feet wet either,

Why should you get your feet wet? There are surfaces, for example creeping thyme, gravel lawn, or grass pavers. You can also combine several things; it doesn't have to be all the same and static. Ikea also has the more modern grass pavers here in Hamburg; nothing settles there. And if the grass gets too long, you can mow. We ourselves have gravel, which is considered unsealed here. Whether gravel or grit counts as active surface, I don't know.

The infiltration from the roof etc. is to be done via a pipe infiltration trench. The wording of the water authority is:

"Rainwater from traffic areas (e.g. driveway) may only infiltrate through the biologically active soil zone." That means I am not allowed to simply lay a drainage / infiltration trench under a "simply paved" driveway, but the water coming from the driveway must somehow infiltrate through the biologically active soil zone. Since we have no space on the left and right, I think the only option is that the driveway itself must be the "biologically active soil zone." That is what the geologist also said.

I drew a second picture, the pipe infiltration trench (besides the fact that it is far away from the driveway) is also not approved by the water authority for infiltrating the water from the driveway.

"Rainwater from traffic areas (e.g., driveway) may only infiltrate through the active soil zone."

Oh, I see. That’s something different.
Rainwater must be drained on one’s own property. That would be the case in most situations.
I don’t know of any property where it is different or where one is allowed otherwise.
You can infiltrate through a soakaway, shaft, or basin. Whether the "active soil zone" only allows the basin, I don’t know.

If you are worried about rutting, you can have a base layer constructed. Geogrid and coarse gravel. 30-40 cm thick. On top of that the base layer made of frost protection material, e.g. 0-32 mm. Another 30-40 cm, compacted in layers. Above that the bedding layer about 5 cm made of gravel-split mix. At the very top then e.g. a grass grid system. It also works without a base layer if you don’t have mega clay soil in which nothing drains.

When we lay the footpath and start the grass grids next to it, there is a very high probability that the car will drive exactly on this joint edge, so it will rather settle.

You solve that as writes, with a correspondingly designed edging. And: grass pavers don’t make your feet wetter than paving stones. The "alive" part doesn’t have to grow tall.