(i) When there is danger of drilling into a charged or
misfired hole.
(ii) Until all remaining butts of old holes are examined
for unexploded charges.
(b) Unexploded charges must be refired before work
proceeds.
(2) Distance limits during drilling. Blasters cannot
load or use explosives closer than:
(a) The length of the steel being used for drilling
OR
(b) Within fifty feet of drilling operations, whichever
is greater.
(3) Prior to loading drill holes.
(a) Holes must be checked prior to loading to determine
depth and conditions.
(b) Drill holes that have contained explosives or
blasting agents cannot be deepened.
(c) Drill holes must be large enough to allow
unobstructed or free insertion of explosive cartridges.
(4) Enlarging or springing a drill hole.
(a) A drill hole cannot be sprung when it is near a
loaded hole.
(b) A minimum of two hours must pass after a charge has
exploded in a drill hole that was enlarged or "sprung," before
loading another charge of explosives into the hole.
Note:
You do not have to wait two hours if the sprung hole is thoroughly wet down with water before it is loaded.
(c) Flashlight batteries cannot be used as a power source
for springing holes.