Originally Posted by korda
We spec Tremco stuff down here. Drainage board and waterproofing. No idea if they have something that works for you but might be worth looking.
I don’t know if you gain anything from the upper drain tile, wouldn’t the water just “fall out” of it and down into the lower one?
If the lower one can't keep up, my upper one flows. Also serves as a back up if silt builds up in the lower.