We had a new bathroom fitted a few years ago and the sewage went straight across the driveway, across where 3 cars park it’s probably less that 400mm at it’s most shallow and I think the pipe has sunk/ bowed under the weight. It is impossible to get any deeper as there was already an existing manhole this went into. Does anyone have any idea how we can reinforce the driveway where the cars park to stop this happening again after it gets repaired or is it just too shallow?