crashz
Elite Member
I wasn’t there when they did it but how are you going to get 45 yards of dirt or sand through a fairly small hole in the top? Writing the check for runny concrete sounds like a cheaper option than trying to deal with that. The runny concrete got the job done fast and with minimal manual labor. They also want the tank ridged so it can’t collapse when something drives over it. It would be hard to ever get dirt packed in tight even if you did spread it by hand.
Right, the "runny concrete" is a Controlled Density Fill or Flow Fill. Once cured, it is an excavatable material that provides structural integrity as equivalent to stiff compacted earth fill. As Moss mentioned, the tanker was located in a an alley with heavy truck traffic. The soil there was supporting that traffic as well as the buildings to each side (assuming that the alley had larger buildings nearby). To ensure that there would be no structural damage to the surrounding buildings, the landowner needed to backfill the tanker in a manner that would not cause any voids in the soil. Filling with CDF is much cheaper than removing the tanker. Pulling it would likely require significant effort and engineered shoring.