Hi all my first post
Want to connect new 100mm soil pope to main sewer. It need to run 14 meters across my drive way to my boundary where a approved contractor  will hook up to main sewer in  the road? The problem is that I have a river running under my drive and although I can archive a 1 in 40 drop I can only bury the pipe about 150mm deep as any deeper I'm in to the top of the arch of the bridge. I could raise the drive on top of the pipe by 150mm in concrete what is the minimum depth for soil pipe. Thought of using cast iron which I understand is much stronger but will it take a car lorry etc
Many thanks