Replacing a cast iron sewer line to the septic tank.
We have a house that was built in the 70s and we bought it in 2004. Since this was our first house with a septic system, we didn't know all that we should have about such a system. I now realize that most of the cast iron waste pipe was replaced with (I think PVC) up to about 2 feet before the basement wall. Then the original cast iron pipe goes into the septic tank. The problem is that we are getting drips from the cast iron pipe that I assume contain waste material although there is no odor. There are what look like patches on the pipe-metal strip a couple of inches wide that wrap around the cast iron pipe and were tightened by screws.
Am I correct that the cast iron pipe is disintegrating? If so, what would be a ballpark cost to replace? We live in southeast Michigan.
Thank you.