I just ran across this today, which seems like an interesting way to decrease run-off. It also decreases the need for drainage systems, as the water filters through the Filtercrete into the soil below, rather than having to be handled by traditional drainage. This isn't my area of expertise, so I'd love to hear what you all think:
And here is their promo video that explains a bit more about how it works:
Note: I have no relationship to Filtercrete or Ozinga - just thought it was interesting and wanted to share.
