Hi I used a jack hammer to open the 4" concrete slab and made a trench for
the plumber to come to redo the underground pipe fittings.

Once they are done I need to pour the concrete slab back.

Question I have is...

(1) As I broke off the old concrete slab, there were a lot of the large
chunks of concrete I have as debris. Should I use those to fill in the
trench up to the 4" mark below grade, or should I use sand and pack them
tight?

(2) There were wire mesh inside the concrete slab that I broke up. The
trench is about 8" to 12" wide about 10 feet long. Is there anything I need
to do as far as the wire mesh? Should I cut another wire mesh of that size
and put it in? The way many of them broke off I am not sure I can tie back
to the old ones.

(3) Underneath the concrete slab is a sheet of plastic, is that a moisture
barrier or some insect barrier? Now that it's broken what can I do to have
the same effect?

Thanks,

MC