We are putting in a bathroom in the basement and they have to dig under the foundation wall to connect the basement plumbing to the sewer line.
Luckily, our sewer pipe is 9 feet down at the curb, so we can use gravity to do the deed and save on a sump pump.
Our poor contractor, though, had to move steel and the sand and gravel he'd put down for the basement floor. Sigh. Some things are just destined to be done twice.