Lock down status has reinvigorated the garden pump track plans. I’m going to have to get some dirt in, so I may as well think about it and try to get the best sort of dirt for building rollers and berms.
Default will be top soil I guess. But should I be thinking about something else? Perhaps just mix in some builders sand to bind the clay element of topsoil?
I’ll dig up the grass and pack that into the bases of bigger dirt piles to make the brought in dirt go further.

Excellent thread. I was thinking similar.
But….

some builders sand to bind the clay

I don’t think sand binds anything unless you chuck some cement on there too…

Could be wrong though.

I think hoggin a soil/clay mix is supposed to be pretty good, they use it for paths in parks etc.

Avoid sand, does the opposite of bind IME.
Nice dark topsoil would work well.
Build a bit, compress it, build more, compress

Glad I checked then. Topsoil will be easy to get hold of in nice big wagon loads.

A bit of sub soil would be good. More clay

The soil that’s there already, your borrow pit for each feature is the down for said feature. Then feature only needs to be half height it was.

Imagine half your pump track is below ground level, you’ll get the idea. Only issue is drainage, would be fine where I live, very sandy soils.

if not using type1 hardcore you need what i call golden sand. its red incolour as it has a bit of soil/clay in.DONT use cement

The soil that’s there already, your borrow pit for each feature is the down for said feature.

Yeah, I’m keen not to go down far, it’ll be too wet in the winter. I’d rather bring in more dirt.

DONT use cement

Deffo!