Need an existing irrigation system repaired and modified for a large restaurant

Hello, we are looking to push back a wall to a raised garden. This would include knocking down the current wall (10m long and 80cm tall) and removing about 3 grab loads of soil/bricks. Also to dig out and remove about 28 sq m of flagstones. Once this is done, we will be able to see what the next step in the process is, which will probably mean a new wall and wide stairs plus tiling. But we...