I'm laying a new gravel driveway. I've dug down and filled with Type 1 to the recommended depth, and as per best practice started with a separation membrane underneath the Type 1 to prevent mixing with the soil. I've then compacted the Type 1 in layers.
For the most part the Type 1 has bound together to form a nice hard surface and I finished off with a bag of 0-6mm Grano Dust for the odd area where the Type 1 appeared to contain fewer 'fines'.
I'm ready to spread a 5cm depth of Gravel on top, but I'm worried about the gravel mixing with the Type 1 / Grano Dust over time - I know the separation membrane should be below the Type 1 as I have done, but would there be any actual downside to another separation membrane between the Type 1 and the Gravel?