I had a leak on my cast iron drain line under the basement concrete slab. I opened up the concrete and replaced an entire section of about 15' of the drain line with 2" ABS pipe. So the hard part is done. I'm about to fill in the trench (12" wide) and patch the concrete. However, my question is, what material should I use to backfill under the concrete patch? The old pipe was in the dirt. I have read conflicting information about using dirt, gravel or sand. Any suggestions would be appreciated.

You might consider using the smaller concrete rubble that you took out.

around here they don't want any sharp stones in the fill around plastic pipe. fine sand for 6 inches in all directions of the pipe is what we must use..

Clean fill dirt here.

Thanks for the replies! However, three replies with three different suggestions... I kind of like the idea of sand, as it would probably be friendliest to the ABS pipe, but I have read elsewhere, that under concrete, it tends to settle more leading to easier concrete cracking. Any thoughts about this? Do you still compact the sand, if so keep it damp while compacting?



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I would compact it as you fill it, 6" between compacting sessions. Make sure you don't lift the pipe by forcing sand under it. Take your time and keep your level handy and check it as you go. After you have covered the pipe, continue adding damp sand and compacting consistently until you reach the desired level for the pour. Start at the ends of the ditch and work towards the middle to prevent raising the pipe. Moist sand just washes dust and smaller particles to the bottom of the ditch and is recommended. I don't remember how wide a Jumping Jack Compactor is but hopefully it will fit into your ditch. Good luck.