Can I vent a high efficiency furnace pipes next to sump pump pvc dischage?

Your question is very difficult to answer without knowing your local ordinances as well as what state you are in. In my home this would be illegal, in the town a mere 8 miles from here it would be fine but has to be inspected before use. And yet another scenario my brother's house (in another state)was set-up very similar to your description, his neighbor reported it and a costly remodel was in order. I'd recommend checking your local ordinances but most likely it is not ok.

I would think if you called the inspector you would receive the correct answer for the area of the country you live in, not all of the states are exactly the same.