Raising ground levels within the RPA

[Gary Prentice]

I'm currently writing some method statements for a development site (one of those things that you do to tick the boxes for the planning department that then gets totally ignored once site activities start). 

 

Due to some changes in levels across the site it's looking likely that some within some RPAs some modifications will be necessary. Basically they might need to raise ground levels along the length of the garden (trees are at the bottom boundary), sloping up from the dwelling towards the trees at the higher levels. It's nothing significant that would require load-spreading or under-soil aeration - just a matter of inches.

 

I can't find anything very specific to describe a soil type that wouldn't negatively impact on the trees. I've read a lot of Standards and other literature regarding back-fill for trenches within the RPA but they're a bit vague - soils that'll allow air and moisture to pass through and won't impede new root growth and that's about it.

 

Can anyone point me towards anything that I can specify so that the builders don't just use whatevers to hand to sort out levels?

 

Thanks in anticipation. 

[Toad]

Have you looked at what is specified by the manufacturers of cellweb or similar?

[Gary Prentice]

11 minutes ago, Toad said:

Have you looked at what is specified by the manufacturers of cellweb or similar?

No, it's not applicable to the application.

 

I'm after some sort of specification along the lines of that for backfill in trenches - a soil type that isn't detrimental to the tree by reducing moisture percolation and gaseous exchange. 

 

The more I'm reading the more I'm seeing that everything is vague; "an inert material mixed with the soil gently tamped down" 

 

All I'm after is some sort of specification of soil that can be used to raise levels by a few inches without being detrimental but there doesn't appear to be much out there. Reluctantly I might have to result to specifying using the existing topsoil (from the site strip) mixed with a ratio of sharp sand to ensure permeability.