Holes shall be stemmed with earth or sand. Rock chips, gravel or similar materials shall not be used for tamping the bore holes. No holes shall be loaded except those to be fired at the next round of blasting. After charging, all remaining explosives shall be immediately returned to the magazine. Drilling shall not be started until all remaining butts of old holes are examined with a wooden stick for unexploded charges, and if any are found, they shall be refired before work proceeds. (Ord. 65-105. Passed 6-1-65.)