The city required our contractor to dig around the entire new foundation, water proof it and put in a french drain. Luckily we knew this from the beginning, or it would have been a pretty expensive shock.
Even though we abandoned the idea of sistering the foundation after the collapse, there are two parts of the house where we still have some of the original foundation. Here, they have to dig under the old foundation and support it with posts so that they can get to the new foundation to waterproof it.
And if that isn't crazy enough, he still has to figure out how he's going to dig under the front steps and under the old chimney in order to waterproof the foundation in those areas. Fun!