Blasting operations shall be conducted so that ground vibrations and airblast do not exceed the limits recommended by the United States Department of the Interior, Bureau of Mines, as measured at the nearest protected structure. A protected structure is herein defined as any structure or building not owned or leased by the mine, quarry, construction or demolition contractor conducting the blasting, except high-tension lines, supporting towers and appurtenances. The following standards shall apply:
(a) The maximum ground vibrations at the nearest protected structure shall not exceed the variable particle velocity versus frequency limits described in Appendix B of US Bureau of Mines Report of Investigations 8507, published in 1980. A graphical representation of these limits is included as Figure 1 of this Section.
(b) The maximum airblast at the nearest protected structure shall not exceed 133 decibels for any recording system having a linear response range of 2-250 hertz. Other airblast recording equipment and limits may be acceptable provided they conform to the recommendations described in US Bureau of Mines Report of Investigations 8485, published in 1980.
(c) The maximum particle velocity on the ground surface above any buried storage tank or utility, including sewer, water and low-pressure gas lines, and electrical and fiber optic communications cables, shall not exceed 4.0 inches per second, as measured in any of the three mutually-perpendicular planes of motion: vertical, longitudinal or transverse.
(d) Allowable limits for ground vibration and airblast contained in this section shall be considered not to produce structural damage in any structure.
(e) No blasting shall be permitted unless the City Seismologist or authorized representative is present.
(f) All ground vibration and airblast waveforms, graphs and supporting data, whether obtained directly by the Seismologist, and shall be filed in the permanent records of the City. All data shall be kept for a minimum of three years.
(g) When the characteristics or environment of any specific blasting event have been determined to be extraordinarily hazardous by the Seismologist and Mayor, additional safety precautions may be lawfully required. The permittee shall be advised of the nature of such extraordinary hazard, and instructed as to what specific additional safety precautions are required.
FIGURE 1
(Ord. 207-1999. Passed 1-25-00.)