P-trap under grade beam for outdoor drainage

[D Rose]

I am installing a drainage system in an atrium that has one exterior wall. That wall has the same type of grade beam as the other 3 walls. The grade beam is 10 inches thick. I have measured the various elevations between the atrium and the existing positive drainage in the yard that I will tie into. I think the best way to get the pipe from the atrium to the outside yard area drainage system is to go under the grade beam.

My plan would be to build my own P-trap configuration under the grade beam from PVC fittings and pipe. For this discussion, I am calling the elevation of the pipe inside the atrium at the beginning of the P-trap to be at zero level (before it goes down). How much lower does the elevation of the pipe outside the atrium at the end of the P-trap (after it comes up) need to be for the P-trap to work properly and the drainage to work? Thanks.

 

[Markts30]

Drainage

Will this system be connected to an existing sewer system?
I am asking, basically, is if this is going to be for floor drains like in washrooms etc. or will it be for "area drains" as in outdoor areas for disposing of rainwater and the like...
For area drains, if not tied into a sewage system, a P-trap should not be required...
For floor drains, you would require a P-trap for each drain as well as a vent...
The drainage pipes should be sloped 1/4" / ft. of travel.

 

[Sponsor]

 

[D Rose]

Thanks for the reply. The drain will connect to area drain lines in the yard. It will not connect to the sewer system. I know that I don't "need" a P-trap as in a sewer connection since I won't be dealing with any sewer gas. The reason I was going to use the P-trap configuration was because the drain line in the yard is higher than the bottom of the grade beam that the pipe will go under. I need to have the pipe go under the grade beam then come back up to the level of the pipe in the yard.

Please excuse me if you have already answered my question but I would like to ask it again. When I run the pipe, I am calling the elevation of the pipe inside the atrium at the beginning of the P-trap to be at zero level (before it goes down). How much lower does the elevation of the pipe outside the atrium at the end of the P-trap (after it comes up) need to be for the P-trap to work properly and the drainage to work? Thanks.