I ran a sanitary sewer line about 16″ away(parallel) to an interior garage wall footing for a run of about 8′-0″ before exiting the house.  I was trying to avoid a huge tree and root system in the front yard.  We had exhaused all the options.   The lateral was hand dug and is about 5″ deep and it just passes under the front wall footing (perpendicular) when it exits the house.  The plumber says it is not to code, but it is done all the time.  I also spoke to an engineer who also happens to be a builder and he said it is fine.  What do you think?  The pipe is 4″ PVC, and the soil is midwest, black dirt and clay.  The footing is on virgin soil and we are not under it, but rather just beside it (16″ away).