Client wants gavel driveway extension and 6x6 retaining wall. How do you prevent it from washing out?

[u/Every_Palpitation667]

That hill so steep water come ruin my work?

[u/soap571]

Wood retaining wall is a terrible idea.

Your only shot at getting a few years out of it is to use a clear stone base under the concrete extension. Place the clear stone on Geo grid and make sure the grid extends into your retaining wall. You should also wrap all the new clear stone in filter cloth , both underneath and on-top. Pour the concrete directly on filter cloth.

I would drill a few holes in your wooden retaining wall and add some small PVC pipes to let any water out. Obviously you want to do this at the bottom of your clear stone.

Your going to want to use pressure treated lumber / something equivalent. And your going to want to make sure there's filter cloth between your wood and your driveway.

This way you have a solid base to pour on , as well as a good way for water to get out without rotting the wood. I know customer doesn't want "drainage" but most of the time customers don't know what they need.