I can't get under the sidewalk and out the curb without leaving a low spot in the pipe. The opening would be prone to plugging from debris, some of which could be pushed up against the back flow valve and hold it closed.
Install it at the curb.
That way if it is blocked for any reason, you can clear it from the end.
The top of the sidewalk is slightly lower than the curb so you have to start at least two inches down.
Not much room to work with.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind. - Stu Harmon
