The photo of this failed SPL wall is pretty remarkable. It was discussed in a thread I came accross on EngTips.com. The originator of the thread (kleo) says he was involved from the contractor side on this project in a mountainous rainforest region near Cuba. He also says the wall was designed by “FHWA”, don’t know if that means US FHWA or what. But if so, I have no idea where this project would be located. The wall was designed for a 15-ft high cantilever with around 20-ft embedded with the last 7-ft being into bedrock. Check out the thread to kick in your hypothesis for kleo.