Suppose they are perimeter drains. And suppose they did go to the sewer.
In the process of installing new line, you'll likely need to have the line
surrounded with stone. Well, if I were doing it, I'd probably go ahead with
the installation project, and do all the things that needed to be done. As
well as putting a bag and some dirt over the ends
so they wouldn't even be apparent when the pipe was being inspected and
smoketested, if it is.
Then, before things started being filled back up with gravel and dirt, I'd
uncover them and let their drainage be by way of the gravel surrounding the
pipe.
I suspect that they could well be perimeter drain, and if it is, you've got
a path already to the street. Matter of fact, there are some folks that have
connected a 2" line to their perimeter drain pipes and ran it further below
grade to the street as they were putting in their gravel after inspection.
Would certainly never show if they ran a camera up your line. And after all,
you wouldn't be connecting to the sewer.
See how a smoke test gets done. I watched as someone smoketested an unknown
pipe, and smoke came up alongside a corner of his house, and from a spot in
the garden where there was an erosion path. The unknown pipe was a perimeter
drain pipe, one of two.

wrote in message
oups.com...
Thanks everyone for the replies. We have done some more checking and
verified the two unknown pipes are NOT wastewater from other
properties. We have also verified the downspouts go to the street
gutter now (but probably did feed into these two pipes originally). My
question now is, do you think it's likely that a perimieter drain
system (under the foundation) may still feed into these pipes? A
contractor we asked told us this is quite possible in a home 50 years
old.

We cannot just connect these pipes back up to the side sewer, as the
City will not allow it, knowing the pipes are not wastewater. Even
though the downspouts no longer feed into these pipes, if they are
collecting stormwater then the discharge ends have to be connected to
something, otherwise water will collect around the foundation.