620.01 DEFINITIONS.

   (1)    "Blast area" shall have the following meaning:

      (a)    "Well holes" mean the area included within a distance equal to the greatest burden of any single hole contained in each blast, such distance to be measured in all directions;

      (b)    "Toe holes and block holes" mean the area included within a distance equal to the horizontal measurement of the combined area to be detonated, such distance to be measured in all directions, but not less than thirty-five feet.

   (2)    "Blaster" means a person in possession of a valid Municipal permit for blasting purposes.

   (3)    "Superintendent" (or equivalent) means the person designated by the contractor to be in charge of construction operations at a given location, in addition, included therein is such person so designated by any subcontractor.

   (4)    "Construction types" (excepting subaqueours and fill settlement) means:

      (a)    "Open pit" means the pit type of material removal operation in which the final subgrade is ten feet or more below the level of the surrounding area.

      (b)    "Side hill" means the type of rock cut with a wall on one side in which the subgrade is ten feet or more below the level of the surrounding area.

      (c)    "Through cut" means the type of material removal operation with a wall on both sides in which the subgrade is ten feet or more below the level of the surrounding area.

      (d)    "Trenching" means material removal where the depth is less than ten feet from the surrounding area to subgrade and including but not limited to pipe lines, foundations, pole lines and similar types of construction and demolition.

      (e)    "Tunnels and shafts" mean the type of construction operation in its normal connotation.

   (5)    "Contractor" means the person, firm or corporation when engaged in any construction operations involving the use of explosives for blasting purposes under prime contract with an owner.

   (6)    "Delay firing" means detonation by a special blasting cap or mechanical device in which the period between successive detonations initiated by such caps or device is of the order of thousandths of a second.

   (7)    "Line drilling" means the drilling on a line of vertical holes about four inches apart and to a depth of at least twelve inches below the depth of adjacent charged holes and between the holes to be charged with explosives and a line marking feature to be protected; such line drilling is intended to control the cleavage of the rock.

   (8)    "Primary blasting" means the extraction of a mineral volume from the original nature body or bed by the use of explosives in open pit, side hill, through cut, tunnel and shaft construction; primary blasting shall include toe and seam shooting.

      (a)    "Toe shooting" (snake-holing) means removing through the use of moderate quantities of explosives loaded in small diameter holes, ledge or high bottom that remains after a main primary shot.

      (b)    "Seam shooting" means removing loosened or overhanging material from the rock face by the use of explosives.

   (9)   "Secondary blasting" means the reduction of oversize material by the use of explosives to facilitate shovel operations; secondary blasting shall include mud capping, block-holing and trenching.

      (a)    "Mud capping" (adobe blasting, dobying) means the firing of a quantity of explosives on or against a rock, boulder or other object without confining the explosive in a bore hole.

      (b)    "Block-holing" means the fragmentation of boulders through the firing or a small quantity of explosives that has been loaded therein in a small diameter bore hole.

   (10)    "Sprung" means the enlargement of a bore hole with a moderate quantity of explosives in order that larger quantities of explosives may be inserted therein for the main primary blast.

   (11)    "Stemming" means suitable inert incombustible free flowing material of a relatively small size consistent with the size of the hole and used in confining explosives in a bore hole.

   (12)    "Displacement" means the amount of ground motion measured in fractions of an inch.

   (13)    "Velocity" means the rate at which the ground or earth particle vibrates measured in inches per second.

   (14)    "Acceleration" means a measure of the force exerted by the vibrating earth particle measured in g's. The acceleration of gravity (g-32.2 ft/sec 2).

   (15)    "Frequency" means the number of oscillations of the ground or earth particle that occur in one second, tabulated in cycles per second, c.p.s.

   (16)    "Energy ratio" means a measure of the kinetic energy of the vibrating earth particle. It is defined as follows:

   Energy Ratio - (a/f) 2      a - acceleration in ft. per second2 (note not in g's)

               f - frequency of vibration tabulated in cycles per second

   (17)    "Components of motion" means ground motion, measured in three mutually perpendicular components, namely:

      (a)    Longitudinal or radial motion;

      (b)    Transverse motion;

      (c)    Vertical motion.

   (18)    "Longitudinal or radial" means motion along a line joining the shot point and point of observation.

   (19)    "Transverse" means motion at right angles to the line joining shot point and point of observation.

   (20)    "Vertical" means motion up and down. (Ord. 1968-3. Passed 1-12-68.)  

   (21)    "Seismograph" means an instrument for measuring ground vibration and air blast levels. It may be a displacement type, a velocity type or an acceleration type instrument.

(Ord. 1999-31. Passed 10-12-99.)

   (22)    “Millisecond” means one/one thousandth of a second.

(Ord. 1968-3. Passed 1-12-68.)

   (23)    “Safe limit of vibration” means in any one of three mutually perpendicular planes of motion, i.e., vertical, longitudinal or transverse, ground vibration shall not exceed a peak particle velocity in the immediate vicinity of any structure. The safe limit of vibration index shall be that developed by the United States Bureau of Mines and published in its Report of Investigation 8507. (Ord. 1999-31. Passed 10-12-99.)

   (24)    "Explosive" means any chemical compound or mechanical mixture that is intended for the purpose of producing an explosion, that contains any oxidizing and combustible units or other ingredients in such proportions, quantities or packing that an ignition by fire, by friction, by concussion, by percussion or by detonator of any part of the compound or mixture may cause such a sudden generation of highly heated gases that the resultant gaseous pressures are capable of producing destructive effects on contiguous objects, or of destroying life or limb. Types of explosives are set forth in Section 620.08.

   (25)    "Charge weight, W" means weight in pounds, of an explosive charge.

   (26)    "Actual distance, D" means distance in feet from blast to the nearest structure.

    (27)    "Delay interval" means the time interval in milliseconds between successive detonations of explosive.

   (28)    "Scaled distance" means actual distance in feet divided by the square root of the maximum charge weight per delay for delay intervals eight milliseconds or greater.

               Actual distance in feet           D

      Scaled Distance =                  =        

                maximum charge per delay       W

(Ord. 1968-3. Passed 1-12-68; Ord. 1968-5. Passed 2-27-68.)