I have a concrete pad next to a soil portion of the yard. I'd like to make the soil level with the pad (and will be adding sod later), but to do so, I need some sort of retaining wall. There is wood below the fence creating a sloped retaining wall, but to raise the dirt, I'll need to go above the current wall onto the fence.
My current thought is I have two options
1) Build a second, more shallow retaining wall against the fence to retain the new soil.
If I do this, do I need any space between the old retaining wall the new one? If so how much? Will filling with gravel be sufficient?
2) Add new pressure treated 2x6s to the base of the existing fence (on top of the panels).
This seems like much less work, but will I have any issues with this? Drainage seems to be working fine and the wood is holding up well on the current fence.
In the picture below, the bottom vertical piece of wood is 'submerged' under gravel and the entire yard drains towards that point and I've yet to have issues. . The bottom of the fence is badly rotted in the corner, I just couldn't see it under the gravel, so something else clearly needs to be done there.
For reference, the soil on the left most part is ~8in" below the concrete and above that there is about a 6" lip