The wrong driveway material?

[Mr Punter]

If you are on clay soil you would need to excavate a vast amount and backfill with the granular permeable base material.  You may need to go down half a metre from the finish level.

 

I have laid permeable paving on a fairly thin bed of granite chippings on chalk subgrade and it drains very well.

[Alan Ambrose]

I’m going to respectively disagree - as I said our type 3 drive is working well. You can get a SUDs calc done, receive the volume you need to store, and then calc the volume of driveway that represents, bearing in mind the ‘void ratio’ or some such i.e. proportion of your drive that can be water. I’ve a calc like that here somewhere. Helpful if it can drain somewhere by gravity.