Safe Quarry - Health and Safety Authority

PART 5
EXPLOSIVES
The shotfirer will be in charge of the physical
loading of the blast and must ensure that all
shotfiring operations are carried out in accordance
with the shotfiring rules and prepared blast specification
for each blast. Any deviation or alteration of
the blast specification during the loading of the
blast must be approved by the explosives supervisor
before the shot is fired.The physical integrity of
the blast is the responsibility of the shotfirer.
Connections must be checked immediately before a
blast to ensure the integrity of the system and to
minimise the risk of a misfire. Where in-hole initiation
is used, i.e.with the detonator placed inside the
hole, two detonators are recommended for each
deck or column of explosives to minimise the possibility
of a misfire occurring. This is because faulty
detonators cannot be easily identified or recovered.
Before a shot is fired, a shotfirer must –
(a) check the shotfiring system or circuit to ensure
that it has been connected correctly;
(b) where electrical detonators are used, ensure
that they have been correctly connected to the
shotfiring system or circuit and that the
shotfiring system or circuit is tested with an
instrument suitable for the purpose;
(c) where appropriate, ensure that the electrical
integrity of the shotfiring system or circuit is
such as to make a misfire unlikely;
(d) ensure that an adequate danger zone is
established, cleared and sentries appointed to
prevent inadvertent access; and
(e) ensure that the shot is fired from a safe place.
The danger zone should be as large as reasonably
possible and should ensure that materials from the
blast are not projected beyond it.
Figure 37: Drilled Face
After the shot is fired, the shotfirer must –
ensure nobody enters the danger zone until
the all clear signal is given,
inspect the blast to ensure that all holes have
fired and that no misfires have occurred,
ensure that the quarry face and sides are in a
safe condition
establish that material did not project beyond
the danger zone
If during the course of an inspection of the blasted
area, or at some later date, it is discovered that
materials were projected beyond the defined danger
zone for that blast and that persons,either employed
at the quarry or other persons who may be affected,
were placed at risk of injury then the details must be
recorded on the blasting records. As soon as is
reasonably practicable the explosives supervisor
must investigate the cause of such projection of fly
rock and ensure that all measures are taken to
prevent re-occurrence at subsequent blasts.
47. MISFIRES
(Regulation 50)
50. In the event of a misfire, the operator, in
consultation with the quarry manager (if not the
same person), shall ensure, so far as is reasonably
practicable, that -
(a) no person, other than himself or herself, the
explosives supervisor, the shotfirer, any
trainee shotfirer or any other person authorised
by him or her, enters the danger area -
(i) where the shot was fired by means of safety
fuse, until a period of 30 minutes has
elapsed since the misfire, or
(ii) where the shot was fired by other means,
until a period of 5 minutes has elapsed since
the misfire and any shotfiring apparatus has
been disconnected from the shot,
(b) appropriate steps are taken to determine
the cause of the misfire and to deal with it,
and
(c) a suitable record is kept of the misfire and
any action taken.
SAFE QUARRY GUIDELINES TO THE SAFETY, HEALTH AND WELFARE AT WORK (QUARRIES) REGULATIONS 2008 67