thanks for reply. I am a complete novice when it comes to laying drains and totally lost when one is dealing with rockbreakers. Unfortunately I am no longer the strapping lad I once was, sport and age has taken its toll, hence no good with a crowbar. I am after a bit of knowledge so I dont get outlandish qoutes/reasons thrown at me. Your answer is fine and adds to the amount of knowledge I am gaining. Pipes to septic tank at the moment are above ground and the explanation given was " to avoid a deep dig because of possible rock" . I went back and found another manhole that has a drain running below the one that is raised! It is about a foot below surface.I was afraid the rock was impenetrable and I want to add an extension etc. The raised drain looks very unsightly.
Drain does not cross road so 300mm will be fine. I am assuming that wheover I get to do the work will know what to use as backfill or I will have found out by the time any work gets done. 6-8 weeks to get plans drawn, 2 -3 weeks to do plans, 3 months for planning permission!! cant get a quote until I have plans and so on it goes. I might as well get a degree in house construction etc while I am waiting. Should be ready in time for next world cup.
Thanks again for replying.
ebmitie