Dipping the stone out requires owning your own truck and keeping the truck tied up the whole time vs hauling another load. I can dump the gravel in the gravel driveway and move it with the loader. There痴 no down time waiting on a truck and no need own a truck and still no mess. A construction backhoe is a completely adequate tool for digging a septic tank hole. A construction backhoe is a completely different class machine than a tractor backhoe. There痴 no shortage of people claiming a mini excavator out digs a backhoe. If the competition was fair they would. The excavator to actually do that is a rare breed. In my area you hardly ever see a mini excavator bigger than a 50 series mini. The 50 series is seriously lacking the brute force of a 310 full size hoe. If you want to buy a used mini bigger than a 50 it痴 going to cost a lot more because there aren稚 many out there. The smallest full size excavators require much bigger trucks to move.