I have seen many city codes and standards say sanitary sewer laterals cannot connect to manholes. Sometimes it will state that you can get the city engineer's permission to do it. What is the reasoning behind not allowing this? I am doing a utility design for a cul-de-sac and it just seems to make sense to connect the service lateral at the end of the cul-de-sac to the manhole at the end of the cul-de-sac.