Soil design parameters for residential above ground planter retaining wall

[shacked]

I have a small project, residential site walls to include planter walls that will be retaining 3ft max above grade. I'm curious as to what active soil pressure I should be using to design these planters with.
If I assume code minimum values then my active design pressure would be 60pcf. The planter is 6ft square and 3ft above the adjacent grade. I can't imagine that in such a small confined area that the active soil pressure would develop to 60pcf.

Any input would be appreciated.

 

[EireChch]

Do you really need to do a design if its 3ft high? I would image a standard block wall would be fine.

 

[BridgeSmith]

Whether it will develop that pressure will depend on the soil and the restraint. If the planter is restrained, you may have at-rest pressure. 60 pcf doesn't seems overly high. That said, EireChch is correct that walls of that height are often done with standard retaining wall blocks without any design, as long as the retained soil is not clay.

 

[shacked]

Thanks guys. Yes, I know that at these retaining heights that a standard cmu wall will be fine, but the city is requiring a design.