That is a problem I am having with my system now that Im hooking up. From the pipe coming out of the shop to the pipe going into the tank I have 6 1/4" fall in 68ft. I shot it with the laser transit and measured it. I talked to a plumber yesterday and he said that all I will have basically is 1/8" fall in 10 ft. It should be 1/4" fall in 10ft for best drainage but I just could not achieve that without the pipe being exposed to the surface of the ground close to coming out of the shop. He told me to pull a string along the longest ditch line (see picture above) and set the pipe to the string. When I did that it got the pipe nice and straight and has that little fall I need all the way. I really don't believe I will have in problems now but before I pulled the string it was like a roller coaster with high and low spots.
