Excavate your trench to specified depth and slope for the sides. Spread bedding material to an even width on the bottom, sloping the length for drainage. Compact as required for concrete pipe. Check the slope of the pipe bed as each section of pipe is laid, and adjust as necessary.
Place backfill around the pipe carefully, in 6-inch layers, to the top of the pipe. Don't allow rocks 3 inches and larger to touch the pipe. Compact each layer thoroughly with the compactor, for the full length of the layer.
Place backfill on top of the pipe in 12-inch layers, compacting each layer. Backfill to the top of the trench.
Add soil to a depth of at least 2 feet -- including the depth of the backfill -- to cover the pipe for the width of the trench. Maintain the cover during construction activities that follow.