Our sump pump is connected to our sewer line. There is a 2-3" diameter pipe that exits the setup up along the wall, above the foundation level, makes a 45' angle and goes up through the subfloor above joists. I do not see it exiting the house anywhere. What is this? What's it purpose? I have a pic but don't see how to attached it...

Without seeing it then its just a guess. But it is either a vent of some kind or most likely a drain pipe. It may be installed below the floor of a tub if its made of fiberglass and is for a time when a leak may occur so you dont flood your house.

Hi JennieandNate

There are usually two pipes associated with a sewage ejector system...

One pipe connects into the main drain and the other pipe is a dedicated pump vent. If this vent does not penetrate the roof by itself then it connects into the vent system upstairs in the attic so there should be nothing to worry about!

Mark