This failed portion of retaining wall has many things wrong with it.

First: no stone backfill and no drain behind it at all. The soil was super wet all the way to the base. Should always backfill a retaining wall with angular stone (not round)

Second: the grass/topsoil had settled so far below the top courses that the wall acted as a water dam and funneled all the surface water to one low spot.

Third: the wall seams to have been built on fill material. Should never build a wall on disturbed material. There was a giant sink hole under the bottom course that was just a giant air pocket that needed to be filled. (See shovel in hole)

Fourth: the base material (footing area) was very thin in width. So once erosion started, the base material just washed away from under the blocks and the wall slid forward off the footing area.

Let’s try to repair this section of wall. I used a caterpillar 302.5 mini excavator, a tracked self loading stone buggy, laser transit, and basic hand tools.