Where to connect new drain to existing stack

[RussellS]

Hi folks - Need some advice about how to connect a new drain to the existing stack in my crawl space.

I'm putting a bathroom into a detached garage, so the drain will run into the crawl space at one end of my house, then be pumped (using a liberty simplex sewage system) across the crawl space to the other end of the house to the existing stack, where drains from both a first floor bathroom and a second floor bathroom come in and flow to the septic.

Picture attached. The new drain would be coming directly from the direction where I took the picture. Where would you tie in and how? Thanks,

 

[Terry]

The 2" discharge from the pump does best if it goes to a 4" line. A 3" also works.
A wye or combo works best as it is pumped rather fast.

 

[Sponsor]

 

[RussellS]

The 2" discharge from the pump does best if it goes to a 4" line. A 3" also works.
A wye or combo works best as it is pumped rather fast.

Thanks Terry! Where would you connect it given the pic I uploaded? Into the 2nd floor vertical drain?

 

[Terry]

The second floor looks doable. Maybe replace the 90 with a combo?

 

[RussellS]

Thanks Terry - that's what i'm going to do.