Installing retaining wall for pool. Sump pump drain line in area
Well, without much finding of information on this, and trying to do this project alongside a full time job, and rain delays, I moved on and did what made sense. 

I just left a space where the pipe was with a couple of inches on each side to reduce side pressure, and hand tamped the base around the pipe. The hardest part was getting both sides of base rock level with each other, but got it done.

I just made sure to start the blocks at the pipe to get the right gap. 

After leaving the space and filling the gap with crushed stone, and because the bottom layer is mostly burried anyway, the gap isnt noticeable, and the wall seems pretty stable. 

Again, this is just a small gravity wall.