Before I invested a lot of money in my lower level with all its new plumbing, I wanted to make sure that the waste line was reliably connected to the municipal sewer. I had replaced some of the sewer main the previous winter and was pretty sure that there was a lot more bad terracotta pipe between the house and the main sewer line. Sure enough, I had the plumber snake the video camera down the line and he declared that the terracotta was basically gone (100+ years old) and that my sewer line was really just a tunnel through the dirt.
Replacing a sewer main is not that big a deal normally. It involves a backhoe, two guys, two days, and a check for $10-15 thousand. You have to reseed your lawn too. Except nothing is normal about my house. Turns out that my sewer main runs 200+ feet down the block under my neighbors sidewalk to the sewer line on the next street down the hill. The plumber said that replacing it would be $20-25k for his part, plus $15k or so to replace the half block of sidewalk and curb that would have to be removed.
To make matters worse, my neighbor was an elderly woman in her 80s who would get upset when the leaves from my trees would fall on her lawn. She was not going to be wild about the renovation I would have to do to her yard.
So, I did what any good DIYer does, I went to Google to see if there were alternatives. There are several. The one I liked the best involved stringing a 1 inch diameter steel cable through the sewer line and then pulling a bullet-shaped head through the line, behind which is pulled a 4 inch diameter Polyethylene pipe. By this process, the entire line is replaced without disrupting the surface of the street/sidewalk.
My plumber arranged for Larry the Pipeshark to come do it. It cost less than half of the conventional approach, and involved a lot less anxiety for my neighbor.