Mook Johnson wrote:

There are other homes in my neighborhood with a similar
opening in the curb (actually 3 - 4" wide) with a PVC drain pipe
installed for this very purpose so I assume its OK of me to do as
well.

If you check with the city you might find it isn't okay but people are doing
it anyway because of drainage issues and either they haven't been noticed or
no city employee has bothered to report it. Even if it's legal you probably
need a permit to go under a city sidewalk or through a curb.