I appreciate everyones help but I am still missing something. I set up to view only "North Hills" subdivision under that layers properties.
I then did a select by attribute, selecting only 6" pipe. See image 1.jpg (only 6" pipe selected)
then I did a select by location, using the selection set of sewer lines, intersecting with the subdivision layer. See image 2.jpg.
See Image 3.jpg as the result. 8" pipe is then selected along w/ 6"