I am removing a 4 inch waste pipe that is hanging from the joists in the basement. This same waste pipe will be placed outside in the ground.

I will also be installing a sump pump discharge pipe. Sump pump discharge pipe will be sharing the same trench that the 4 inch waste pipe is going to reside in.

Question: how do I place the sump pump discharge pipe in the waste pipe trench? Especially since the waste pipe is lower in the ground (waste pipe will be connected to city sewer). Sump pump discharge pipe is going out to the storm drain at street. Storm drain is 26 1/2 inches below grade from the grate to the bottom.

I will definitely ask building inspector about the exact placement of these two pipes. However, I wanted to ask the plumbing professionals first.

Waste pipe would lay in bottom of the trench - then cover waste pipe with sand and dirt, then place sump pump discharge pipe above waste pipe in the same trench, then bury and close the trench?

Do the Plumbers out there think that the sand and dirt placed on top of the waste pipe will possibly settle causing sump pump discharge pipe to lose its pitch?

Check with the inspector first. Some of the inspectors that my previous employer dealt with required 6 inches of pea gravel under and on the sides filled to the half way point on the pipe prior to inspection, then topped with another 6 inch minimum.

Yes that much is understood. Sand below and sand on top of the waste pipe. Placement of pipes and settlement of the dirt are concerns