15-20-050  Blasting operations.
   (a)   In blasting, it shall be unlawful to use a quantity of explosive exceeding in disruptive force the equivalent of one pound in weight of 40 percent dynamite for each two feet depth of hole that is above or less than ten feet below the curb; and the equivalent of one pound in weight of 60 percent dynamite, for each two feet depth of hole that is more than ten feet below the curb.
   (b)   Frozen or partly frozen explosives shall not be placed in drill holes. Frozen cartridges, if not capped, must be returned to the thawing apparatus to be thawed. The removal of a primer from a frozen cartridge is hereby prohibited.
   (c)   In tamping drill holes, wooden rammers only shall be employed. Tamping by strokes is forbidden, and only direct application of pressure permitted.
   (d)   Blasts, except as hereinafter provided, shall be fired by the application of some form of electrical current only. In blasting in stone quarries, it shall be permissible to fire blasts by the application of time fuses.
   (e)   In case of an explosion not carrying away the entire drill hole, but leaving the lower part intact, it is prohibited to begin drilling from the bottom of the old drill hole.
   (f)   In order to insure the safety of surrounding property and persons, no larger charge shall be used than is necessary to properly start the object it is intended to wreck or blast, and excavating contiguous to any structure shall be so carried on as not to cause damage to such structure. Weak walls or other supports of such structure must be shored up. The blasting of decomposed or soft rock is hereby prohibited.
   (g)   Before any blast shall be fired, except in tunnels, the rock to be blasted shall be covered on the top and sides with timber and covered with stout metal matting or some other equally serviceable material to prevent the debris from flying.
   (h)   When necessary, competent men carrying red flags shall be placed at a reasonable distance from the blasts on all sides to give warning at least three minutes in advance.
(Prior code §  125-5)