There's a plastic pipe with a vent cover in my back yard that runs to a green cap in the middle of the yard. What is this for? I don't have a septic tank.
Update: this picture shows the entire length of the pipe that I'm aware of. The green cap from my second picture wasn't visible from this angle so I marked it with the piece of cardboard.
Update 2:
Based on everybody's comments, I felt comfortable digging it up. Here's the entire thing:
Thanks for all the help everyone! Your comments/answers let me dig up this unused nuisance I've had to mow and trim around for far too long.
Best Answer
Looks like a rain gutter or sump pump outlet. Place a noisy device directed into it and walk around and listen.
You could probably bury the white pipe and just leave the grille exposed, flush with the lawn.