Suitable material to backfill incoming main cable?

[Mr Sparkle]

What are suitable/ recommended materials to backfill trench to cover main incoming electrical cable?

The MDPE and Gas pipe are in close proximity too

I have some of the following materials spare

- Soil (but it gas tiny rocks in there)

- Sand (building/ plastering sand which has been mixed together)

When backfilling does one need to do any additional steps like compacting at certain stages?

 

[Taylortwocities]

I'd cover with a layer of the sand then top layer of soil.
But the cables are designed to be buried straight into the ground without any additional protection, so no need to be super careful about this,