After the DWV lines are tested it is time to start covering them up. This doesn't seem like a big deal on the surface, however all lines need to be kept in the proper position so things like the toilets or bathtubs do not end up being located in the middle of the floor becaue their hook-ups are in the wrong position. Ha! Also the ground needs to be compacted so it doesn't settle after the concrete slab is poured. The tamper I used to compact the ground was a homemade tamp. It weighs about 40 lbs. and runs out of gas very quickly. The power source (me) is getting old and worn out. Ha! The trench with the DWV lines is filled and compacted in steps. About 2"-3" of dirt was placed in the ditch and then tamped down by about 1/2". This is a slow and tiring process, but you really need to see how big my delts, biceps, etc. have gotten. Ha!