There's nothing quite like an earth moving machine to find a pipe - especially when you don't want it to...
It seems to me that the bigger machine you use, the easier it is to stuff something up, badly. Not that I stuffed anything up too badly, but it's real easy to. We dug through the original sewer line (just nicking it) when we were excavating for the cellar. I assumed that the toilet line would run to the sewer line along the laneway, the closest connection point, but I was wrong. I contacted the water authority and got a copy of the original sewer plan. I really should have done that before we began digging.
On reflection I think that we should have repaired, cleaned, extended and connected into the exisiting line - as I want to try and use all greywater and compost all manure on site. This would make the sewer line obsolete. However, having the new sewer line in place gives more options with less maintenance - at a greater cost.