Flow Fill is poured as a virtual liquid. The material will be self leveling. Here is a video produced by a concrete block company which shows flowfill being poured in a trench to be used as a base for a concrete block wall. You can see it is self leveling. You can see it is extremely fast and easy compared to placing base rock in the trench and then compacting and leveling the base rock over a 40 or 50 foot long trench.