I have seen a lot of great DIY carpenter bee traps that fill up with bees. I have friends that say the traps keep them out of the house.
https://www.pinterest.com/explore/carpenter-bee-trap/
In Georgia a wall retaining over 48" grade requires an engineers stamp.
You might consider terracing and have two or more lower retaining walls. Be aware of hydrostatic pressure and provide adequate w ... read more