Im new to the realm of landscape installation so I have been reading all posts lately to in an attempt to absorb some information. I keep reading about two things which have been keeping me confused. Every time a subject on a wall comes up, the use of geogrid comes into question. I am not quite sure what is it, so I was hoping someone would clear that up for me. Also, the phrase "that wall needs to be engineered". My best assumption was that an architect needs to test it out in CAD, but thats only a guess. So I was hoping someone could clear these two things up.