What the wall is actually holding
A retaining wall carries the weight of the soil behind it plus whatever water is moving through that soil. On a dry day the load is manageable. During spring runoff or after a heavy irrigation cycle, saturated ground can double the pressure on the back of the wall.
So the first thing we look at is the slope above it, where water enters the hill, and what is sitting on the ground up top. A wall under a driveway is a different structure than a wall behind a flower bed.
