Overhead Sewer Question

[Jb9]

I am trying to render an overhead sewer design. I need to make a transition from 3" to 4" as I transition to the sewer lateral. I know I will need cleanouts as well. Do I have the basic concept of the overhead correct? I have a frost line of 36" so I assume I will exit below that line and then drop again to reach the sewer lateral. Is the long sweep 90 degree elbow what I will use for the drops?

Here are a couple renderings.

 

[Jb9]

Hello,

I have redrawn my design with cleanouts at the foundation to change from 3" to 4" as the building drain exits to become the building sewer.

Any thoughts?

 

[Sponsor]

 

[MKS]

Just some thoughts from a non plumber.
Not knowing the site limitations or topography this seems overly complicated, too many turns.
I would think you want to go out of the basement as directly as possible aimed at the sewer main line you are tapping into.
If you know the elevation of the main you are tapping into then you can work backward from there at a quarter inch per foot and have a better idea where the foundation penetration would be.

 

[Jb9]

Bump. I do think you may a good point MKS. My site is basically flat but I need to exit the building near my service cavity and pick up the drain from a small accessory dwelling unit adjacent to the house. I know I can't bring waste from a separate building into another building (nor would I want to). Those are some of the constraints I am facing. I will definitely have the proper grade. It does seem that folks work backward from the saddle at the sewer connection from my conversations with one of the public works guys.

 

[Jb9]

Here is a redraw. I would prefer to have the kitchen sink be the most upstream fixture but in this drawing, the kitchen sink is the most downstream fixture. Is this going to be a problem (sewer gas) with this design?