I am building a playground area, and as part of having the ground level, I ended up building a retaining wall, and I have a question about drainage. Some data on the project:
- The wall will be retaining 12 inches of soil in a sloped area.
- The lateral sides of the area, start at 12 inches, and slowly gets reduced until it meets the leveled ground (as you can see in the picture, 12 inches, 10 inches, 8 inches...)
- I am planning to build the wall with landscape timber.
- The wall will be acting as part of the border of a playground. It will be a rectangle of landscape timber.
- The playground area will be filled with cedar wood chips.
- The playground area is leveled. That's why I did the retaining wall to start with. So, the playground area doesn't have a slope (we are installing a swing playset).
- I live in Seattle. Not a lot of storms, but constant rain.
I have a couple of questions:
- Is it recommended to add any type of drainage behind the wall given the height/context of the project? And if so, what type? Gravel, Gravel+Pipe? If I do piping, where should the pipe output go to? At the end of the slope I have my neighbors fence.
- Should the drainage also be added on the lateral sides of the playground?
- Would it be enough with just covering the soil with some landscape fabric, put the timbers on top, and then just covering with the cedar wood chips?
Here is a picture showing a part of the area. The other lateral side looks just like the one shown on the picture.