I recently removed a large concrete patio and plan to replace it with a ground-level deck. The septic line that services the house runs under this area, and I've decided to replace it because it is 35 year old cast iron, it has a leak inside of the foundation wall with several roots in the pipe at that location, it isn't very deep (30" at most), and is convenient to do at this time.
The line leaves the house at two points and combines near the septic tank. Currently, the only cleanouts are in the basement, which would make a big mess if they ever had to be used.
I propose to replace the cast iron with SCH40 PVC. All joints will be solvent weld except for those denoted by the blue line, which will be sheilded connectors. I will dig around the cast iron pipe, but not under it, to retain the proper pitch and bedding. I want to back fill the pipe with sand, followed by some class-2 fill , then native rocky-gravel fill on top of that.
I plan on adding cleanouts at the locations denoted by the red circles.
Does this sound like a good plan? I checked Wisconsin code, which indicates that septic lines don't need frost protection within 30 feet of the foundation.
Thanks in advance.