I also am laying ABS drain lines in concrete footings (12"x12") in northern CA. From my new toilet, 3" line will run to my existing septic tank @ approx 1/4"/ft. I don't have the option to go below the footing for any of my Bathroom fixtures, (sink, shower or toilet) as I would be unable to maintain the 1/4" drop. Will concrete have any affect on the ABS pipe or should I encase the lines with some other material protecting them?

Thanks in advance,

Stan

Would 1/8th. To the foot be more acceptable? Is this a poured footer or cement blocks on top of a poured footer that you have to go through? If it's a poured footer then, in my area, we install a chase consisting of a larger diameter PVC pipe and if it's cement block we simply knock out a hole.
Milo's a plumber in your code and could probably answer much better then I. What say you Milo. Regards, Tom

As Tom said, sleeve it. Just put in a piece of 6" pvc where the drain will go through the footing. then poor around the sleeve(6" pipe) then run your sewer pipe through the sleeve.

Thanks to you both. I will add a piece of PVC (sleeve) each place it goes through the footing. This is a new concrete pour so I shouldn't have a problem.

Thanks again,

Stan