Standard procedure in blasting is to drill a hole and then fill it mostly full of explosives. The purpose of stemming is to keep the force in the hole or directed horizontally. If the force is directed vertically or up out of the hole, flyrock results. Usually flyrock comes from inadequate stemming. These are nets made out of chains that a company can drag over the blast site to prevent the possibility of flyrock.
Some companies make mats by connecting old tires into a mat and dragging that over the blast.
It would probably only occur on a coal mine if there had been some highly publicized incidents and the company felt it had to respond. Highway construction companies working in populated areas are more likely to use them . Current Law There are two sources of law on blasting, common law and regulatory law. At common law , blasting is considered an ultrahazardous activity. As such, there was no need to show negligence.