im planning on building a small extenstion over a sewer in my garden, iv already entered the building over a sewer agreement which i have not sent back as yet because the pipe had collapst as i was digging around it and dnt want the inspector around until iv sorted it,the pipe is around 6mtrs long and 9-10 diameter. iv now replaced the clay sewer pipe with the ribbed pipe is this the correct pipe or should it have been clay pipe put back there? im then hoping som1 will sign it off for me,ha.