Table 3-30
                             Peak Particle Velocity for Blasting Events

                                                                        Ground
Surface
                                      Normal Charge                    Peak
Particle Velocity
           Blasting Event            Per Delay (lbs.)            0.5 Miles
Distant (in/sec)

           Main Shaft Sinking                 32                        
  0.002
           Mine Level Drifting                51                        
  0.003
           95m Stope Blasting                660                        
  0.02
           140m Stope Blasting             2,930                        
  0.07
           29Gm Stope Blasting             2,930                        
  0.06

Peak particle velocity was the primary factor utilized in evaluating off
site impacts. Various
explosive charge weights and distances from the blast were used to develop
charts depicting the
estimated peak particle velocity expected during shaft sinking and production
blasting.

For comparison purposes, the 0.01 to 0.1 inches per second range for the
limit of human response is
roughly equivalent to the vibrations one would feel in a house located about
one city block from a
fast freight railroad. Several of the planned explosive charges yield peak
particle velocities values of
0.01 to 0.1 inches per second at distances of one-half to one mile. For example,
a typical residence
will vibrate locally (one room) under the impact of heavy walking, at levels
from 0.2 inches per
second or less. This form and level of vibration is common to humans in the
area. Higher peak
particle velocities are predicted at less than one-half mile for some of
the heavier charges. Exxon
does not intend to exceed 2.0 inches per second peak particle velocity for
nearby structures (e.g., 650
feet from the blast site). There is the possibility, however, due to orientation
of the orebody that
private structures may be as close to the blast site as the Exxon structure
being monitored. Thus,
there are potential situations where the non-Exxon-owned structures may receive
seismic vibrations
that are in the unpleasant category, or possibly in the category where cracks
in plaster walls may
occur. A summary of Bureau of Mines data on the possible damage for various
vibration levels is
included in Table 3-31.

                                             Table 3-31
                               Human Responses to Seismic Vibrations

Psank PnrtirlalValnroifvr  W-I'ln n



JUi V 1IUU1LY  I1UIIIWI
r second      Response                   Comments

            Below human detection
            Barely detectable
            Detectable                  People should be advised of blasting
            Definitely detectable
            Disturbing                  Rigidly mounted mercury switches
may trip out
            Unpleasant
            Very unpleasant          Safe blasting criterion for residential
structures
                                         Minor cracking of plaster
             Intolerable                 Minor falling of plaster, heavy
cracking of plaster

cimate nature of the available prediction techniques provide a range over
which potential
ing would develop, especially when the long-term effects of fatigue enter
the picture.
given some consideration to the use of smaller explosive charges.

Structures - Damaging vibrations would not be produced on-site because of
designed
monitoring of blast impacts at various charge levels. A safe level of blasting
vibrations is
er second for modem homes with gypsum board interiors and 0.5 inch per second
for






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