I have a leaning retaining wall that I've had a few local companies take a look at. They all recommend either plate style earth anchors or helical tiebacks. Looks like having four of these installed will be between 6 and 8 grand. This seems like something I could easily do myself if I had the right materials. Does anyone know where/if you can buy plate syle earth anchors. And what do you think about just using a long threaded rod with steel plates on each end (one in center of yard, the other on inside of the wall). There is detailed info online of what most companies use for rod length and torque values. The rods could be driven through holes in the wall and through the dirt with an air hammer.
Long rods with plates or concrete should do the job. You could also look at screw in anchors used for utility poles. Screw them in sideways and fasten to long rods. Or just dig and bury them and fasten to long rods.