The plumber broke up some of the slab, removed an old cast iron Y and put in a new elbow and closet flange. He left back filling and patching the slab to me (my choice). The edge of the hole is irregular and chiseled at an angle.
My question is what material do I back fill with? Sand, pea stones, cracked gravel? My first thought is tamped sand to support the new piping. How deep do I then want to pour concrete? 4 inches? 6 inches?
The hole is about 2' x 3'. The slab is below grade - there is just dirt below there. The house is 100 years old.