Hi all

I've just removed 4" thick gravel and a weed membrane. Most of the soil
underneath the membrane is fine, however there is a large patch where
underneath the membrane is another layer of gravel. This bottom layer of
gravel has been compressed into the soil underneath and is rock hard.

I am reluctant to remove this layer of compressed gravel unless I have no
option. The reason being is the physical quantity, It's one thing shifting
many tonnes of loose stuff, but I really could do without shifting another
good few tonnes of compacted almost cemented stuff.

So here's my plan. I am thinking of using my pickaxe to break the surface up
and then remove any of the bigger chunks. I could then lay between 4" and 6"
of soil on top of the surface, which will take the level to the top of the
retaining wall.

So the question is, will 4-6" of soil with a compacted base underneath be
enough to allow grass to grow from seed, or do I need to completely shift
this compacted base?

Thanks for any advice

Andy