Site is all sand. However as per another thread I will import clay, probably Soil Solver Clay Plus at 10kg p m2. So the top section behind the wall @ 70m2 will end up with 70x10 =700kg of clay imported there but only in the top 100-200mm of soil prior to lawn.
I would have been able to say i have zero issues with clay heave or expansion/contraction but maybe introducing this clay to help with my soil will cause this a little? The wall is double maxi brick with concrete infill also with starter bars so pretty strong.
The wall builder said because its sand dont bother with drainage, the water will simply just run straight down. I will apply Black bitumen sealer to the wall but that is more to stop the texture coat of render not being pushed off due to water coming through.
I think whilst i have the chance I should put some drainage in. ie. Socked and slotted 100mm Agi pipe, encased in either 10 or 20mm bluemetal and the lot wrapped in geofabric.
Q Should I wrap the entire blue metal lot in fabric? bottom sides and top?
Q The wall is only about 550mm high, how far up it should I go, i assume i need at least 200mm for top soil for the lawn, also i dont want to loose my expensive ammendemnts through the fabric.
the water has to go somewhere, the diagram shows how I have two 100mm wide sleeves through my foundations but then i also have this oversize soakwell with a spare outlet.
Q Should i direct the water out to the other side of the wall or into this 1200x1200 soakwell that currently only has one downpipe going into it?