How is the weight of my debris determined?

The truck drives onto a scale at the disposal facility where an initial weight is recorded (gross weight).  The truck then empties the contents of the dumpster.  Next, the truck drives onto a second scale that records the weight of the truck and the empty dumpster (tare weight).  The difference between the first and second weights (gross – tare) is the weight of the debris in the dumpster.  The scales are regulated by state bureaus of weights and measures.