I hope someone can help answer my question, thanks in advance. My question is whether is is ok to tee into a sewer cleanout to add a new sewer drain line.

We are installing a backyard BBQ sink, and the best place for me to connect my new 4" ABS line to the existing sewer is at the cleanout next to the sidewalk in the front yard. This is the only accessible point of the sewer without cutting into my concrete driveway.

My sewer main at this point is approx 5 feet under current ground level. But, since my yard has a good slope from back to front, I only need to be at 18 inches below ground at this point in my new sewer grade.

I will check with my city building dept, but for now, is there any reason that prevents me from teeing into the vertical cleanout pipe at the level that works best for me? I don't want to excavate down 5 feet if I don't have to.