During our 2014 seminar in Peace River, Alberta we had several vacuum tankers to use during the program. Occasionally, we encounter folks who don't use a vacuum tanker to its full ability - that was NOT the case in Peace River. But...we were able to grab a couple of good comparison photos showing a vacuum tanker being unloaded by gravity and being unloaded under pressure. If you run a vacuum tanker it is important to "blow" that water off at the dump site. Otherwise you have a 6-inch round (in most cases) gravity dump that is not very efficient when compared to the bigger 10-inch gravity dumps on some tankers. Too many times (again, not the case in Alberta) we have seen operators hesitant to take the vacuum tanker to its maximum potential.