Every step of your construction project requires attention to detail, this includes backfilling and compacting. Whenever backfilling, adequate compaction is essential. The keys to gaining compaction are: Water, Incremental lifts of fill dirt, and the proper Compaction Machine.
Water, you’ll likely need plenty of it whenever moving dirt, and especially when backfilling. If you are backfilling around pipes, then you’ll need to “jet” in sand. Using a high pressure hose, spray the sand with enough water so that it actually flows under the pipe. Let this mud “set up” to a super hard layer. *All pipes need to be completely surrounded with sand to avoid any damage from rocks*
Next, you can start adding your lifts of dirt. Generally, your lifts should be done in 10-12 inch increments. The compactor you choose will depend on the amount of backfilling you have to do and the space your doing it in. The most popular compaction machine is the “Rammer” or “Jumping Jack.” This machine does an excellent job compacting the soil. Again you’ll need to continue adding water to fill dirt, you’ll know if you’ve got too much water as the soil will not compact hard, but will "pump" under the machine. This can be fixed very easily by digging up the mud and mixing in some drier material.
Before using a rammer compactor over top of pipes you’ll need a good amount of fill so that you don’t damage the pipe. Be sure to compact along the sides of the pipe in normal lifts, but get 18”-24” inches of sand/fill covering the pipe before running the machine directly on top of it.
By using plenty of water, small lifts, and 2 to 3 passes per lift with the rammer, you can have confidence that your backfill will be solid and ready for testing, or your next phase.