Retaining walls basics - dig down vs build up
In thinking of my yard I was always thinking of building up and adding fill. Is there a major flaw in digging down instead? Put to pictures - is the blue triangle just as valid as the red triangle?
Obviously, drainage is a consideration (particularly in my case) - but this solution could save us a lot of money because for our usage (play area) building up needs a fence, but digging down might give us a defacto bench.
Is this a bad idea?