OK folks I searched and searched for this answer, but everything I found focuses more on the plumbing itself rather than the last step - covering it all up.

I am remodeling a house built in 1923. It had a concrete slabbed basement, but was just one big room. Since then I've added a den, laundry room and new bathroom. The bathroom is complete with shower, toilet and sink and its all connected to the main sewer lines now. What's left is a new bathroom with a cement floor that has an open trench in it with all my new plumbing pipes. Now I have a very simple question... how do I cover it all up and replace the cement that I cut out to lay down the new plumbing?

What I'm basically looking for are the "ingredients" and steps to properly cover over the plumbing so that I don't have to worry about settling, etc once the cement floor goes back down. Any tips on the proper way to lay cement and smooth it out with the old cement would be ideal as well.

Thank you!:)

Well, it's kind of difficult for me to tell you how to proceed.

For lack of a better word, the plumbing work in the ditch is what I and other Plumbers would call an Abortion.

All but two of the fittings I see in the ditch (The closet flange and the closet 90) are the wrong fittings to use in a horizontal manner.

And I'm having a hard time understanding how you made the connection to the white pipe, the photo isn't exactly clear, although it looks like you glued the hub of the ABS San-Tee into the 4" PVC pipe.

I agree with growler, the tee should be a t y combination, basically a one piece fitting that looks like a wye and 1/8 bend glued together. The closet flange is premature. The elbow rising to the toilet should be a 4" x 3" elbow with a 4" riser cut off 1/4" below floor level and a 4" x 3" closet flange glued in. cut it off at that level so when you skree the concrete the floor will be level. As for the fitting glued inside the 4" pipe, a 3" pvc coupling will do the same thing, and many 3" fittings are of the same outside diameter. it just works out that you actually can glue many 3" fittings inside a 4" pvc pipe.
using tees instead of combinations will work but not well. it also is going to give you problems if you ever put a sewer cable down there.
as for covering, you should have had a surface that was compacted and had a downward grade on the 3" pipe of at least 1/8" per foot and 1/4" per foot for the 2" pipe. This would keep the pipe from settling. Then simply backfill with loose dirt, no rocks or gravel touching pipe and walk it down on the sides of the pipe until it is 'bedded in', then backfill the trench leaving 3.5 inches for concrete. Make sure the dirt is well compacted. Box out for tub or shower drains to be installed later. Mix the concrete wet enough for slow dry so you have time to work with it.you can rent an electric mixer. Talk to concrete people to learn how to skree concrete and how to 'finish' it

Hey guys thanks for the information. Yes the picture is not that great. The t-connections that you mention are actually y connections, but they are not as prominent as typical y's. The turn in these are angled and are not 90 degree. Also there is significant slant to those pipes in the floor, well beyond what code requires. Even the glued 3" into the 4" pvc is misleading. It's the proper connect but it's the glue itself (dark color) that makes it look like one pipe is just shoved into the next. It's actually a coupler within the pipe and dark glue applied around it.

But just to be sure, I've asked a certified plumber friend of mine to drop by today and assess before I move forward.

Thanks for the information on how to backfill though. That is the issue that I needed to understand. With the help of my plumber friend, I'll get this resolved and can move on it this weekend!

Actually, they look like sanitary tees, which is what we were addressing

actually, they look like sanitary tees, which is what we were addressing

Oh I gotcha. Well my plumber friend is going to do a bit if work on it tomorrow to resolve any issues that he has with it. Thanks everyone!

Ya want to cover that up?? Comon growler! Abortion? Well, perhaps a botched miscarriage.

"The t-connections that you mention are actually y connections, but they are not as prominent as typical y's."

I don't know, I seem to be looking at sanitary tees laid over on their side andb?what are those itty-bitty drain pipe doing under the slah
" there is significant slant to those pipes in the floor, well beyond what code requires."
In drainage more fall is not necessary better. Too little slope and there's not enough force to carry the solids and too much slope and the water will run so fast the solids will drop and build up to a clog.

All in all I think your plumber has his work cut out for him when he sees this configuration. Good luck and let us see the changes he makes. Regards Tom

Speedball, I think we need to call you hardball. You sure play rough [chuckles] anyway, I think we did our best and hopefully we will not have to run a sewer machine there.