In total it cost me about $350 for the materials. A big thanks for my dad for helping me out with some of the tricky parts.
This was the old wall. The wall wasn't straight and the posts were only in 150-200mm in the ground, retaining about 700mm, the pressure from the soil behind would have pulled it over. Also there was an ag-pipe behind the wall but it was just surrounded by soil. The pipe would have clogged by the soil after the first rain fall and never worked again.
These shots show me digging it all out and digging the wall back to give me room. Took me a few hours to do this.
These shots show some of the work a fair bit down the track. I dug the retaining wall posts down 700-900mm based on the string line of the top of the fence. My posts were a lot deeper. I used about 2-3 bags of concrete per hole. The fence posts are extended at 3m, they also went just as deep.
These photos show the ditch I dug from the retaining wall to my sewrage pipe. I'll be tapping into it with some 90mm pipe, there about $12 for a 6m length. This really helps with the water problems. You should run the ag-pipe to a pipe in your yard to carry the water away. I know it seems your doing it for them but trust me your not. If I can take most of the water away then I save it soaking my backyard. Make sure you put one of these in. I dug the ditch about 200-300mm deep.