Over sverall hundred ingame years, mega dumpers are not fully loaded up to 180 when they are loaded by a mega excavator digging 3 or more resources at once. In this specific case: waste, limestone, slag ยด(and rock). Mega dumpers get loaded circa half at best, then driving to the sorter.
This does not happen at the same digging site with less than 3 resources, e.g. only limestone or limestone+waste.

