Containment Dike Grading 1

[Althalus]

I have a set of plans from a previous engineer. It is a containment dike for a large oil tank.

I noticed that the inside was graded ad 2:1 (which I am used to. But the outside was graded at 3:1. Is there a reason for this?

 

[redtide]

3:1 is much easier to maintain like mowing etc...