"Grandpa" wrote in message
Call them and ask them what the pipe is
for and why it is there, and what your options are. I've seen
something like this in the back yards of a housing tract that we did
some work in. They were connected to the sewer system, but I didn't
find anyone who knew about them.

One thought just came to mind here. It may be that high because it will not
vent if snow covered. Not knowing where the OP lives I can't say if that
would be the case. If up north where it is common to have a few feet of
snow on the ground it may be raised to compensate.