(a) Seismograph measurements may be used to increase the charge weight per delay period, provided that the velocity limit of two inches per second of any of the three mutually perpendicular components of ground motion is not exceeded.
(b) Seismograph measurements must be used in each individual blasting operation in which the standard table of distance is not being complied with. Notwithstanding the foregoing, a modified table for blasting operations may be established for use at a particular site, provided that the velocity limit of two inches per second of any of the three mutually perpendicular components of ground motion is not exceeded. Blasting operations without instrumentation will be considered as being within the limits set forth in this subsection if, at a specified location on at least five blasts, instrumentation has shown that the maximum peak particle velocity of any of the three mutually perpendicular components of ground motion at the specified location is 50 percent or less than the limit set forth in this subsection, provided that on all future blasts the scaled distance is equal to or greater than the scaled distance for the instrumented blast.
(c) In estimating the maximum peak particle velocity at a particular position, the following formula shall be used:
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