Precautions must be taken to prevent unintended electric
detonator discharge from extraneous electricity and radio frequency (RF)
transmitters. The following are sources of common hazards for extraneous
electricity and RF transmissions:
(1)
Extraneous electricity. Common hazardous sources of extraneous
electricity include:
(a) Adjacent power
lines;
(b) Dust storms;
(c) Lightning storms.
(2)
RF transmission sources.
Common hazardous sources of RF transmissions include:
(a)
Mobile transmitters:
(i)
Citizen band (CB);
(ii)
Side band radio;
(iii)
VHF (FM) radio;
(iv)
UHF cellular telephones;
(v)
Radar.
(b)
Fixed
location transmitters:
(i) Base
stations for CB;
(ii) Side band or
FM radio communications;
(iii) UHF
cellular telephone transmitters and service extension repeater
systems;
(iv) AM and FM
(commercial) radio broadcast transmitters;
(v)
TV broadcast transmitters and repeater system
transmitters;
(vi) Surface scan
and radio navigation beacons.
(c)
Low flying aircraft (in particular military
aircraft) create the most common serious RF exposures. These highly
unpredictable mobile transmitters are very powerful and transmit on a broad
spectrum of frequencies, which include, but are not limited to:
(i) Radar;
(ii) Laser;
(iii) All common communications bands.
Note:
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The two most dangerous examples are:
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- Low flying automatic terrain following guidance
systems
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- Airplanes which are equipped to jam all common
radar and communications frequencies for a distance of several miles around the
airborne transmitters.
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(3)
Transportation.
Transportation of explosives must meet these requirements:
(a)
Public highways. The
Washington utilities and transportation commission (UTC) and Washington state
department of transportation (WSDOT) require compliance with ANSI D6.1-1988,
Uniform Traffic Control Devices;
(b)
Private roads. You do not have to comply with ANSI
on private roads under department jurisdiction if required warning signs are
properly placed when electric detonators are present.
(4)
Site survey. The blaster in
charge must conduct or assign a designated appointee to conduct an accurate
survey of the entire blast area, to determine:
(a)
The clearance points where roads or right of ways enter and exit
the required clearance zone;
(b)
If the one thousand-foot clearance zone needs adjusting to maintain the
permissible clearance zone at all times, if the blast area moves as the job
progresses.
(5)
Clearance zones.
Required clearance zones for: |
Number of feet |
Construction operations |
1000 feet |
Demolition operations |
1000 feet |
General industry operations, not subject
to construction requirements |
350 feet |
(6)
RF-transmitter warning signs.
RF-TRANSMITTER WARNING SIGNS
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image
(a) RF-transmitter
warning-sign specifications.
Signs must:
(i)
Be a specific size. See the signs above for sign dimensions;
(ii) Have a "construction" orange
background;
(iii) Have black
letters and borders;
(iv) Use all
upper case letters that are at least the size shown above.
Note:
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Larger signs may be required where the highway
speed limit is more than fifty-five miles per hour.
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(b)
Posting warning signs must:
(i)
Be adequately placed to warn:
(A)
All transmitter users against the use of:
(I) Radio frequency transmitters;
(II) CBs;
(III) Mobile phones;
(IV) Two-way radios.
(B) All users of routes into the electric
detonator clearance zone.
(ii)
Be prominently displayed when an electric detonator initiation
system is being used during blasting operations and when the electric
detonators have been removed from the original U.S. DOT approved shipping
container;
(iii) Be posted at the
beginning of the blast zone minimum clearance point saying:
"TURN OFF CB, MOBILE PHONE, 2-WAY RADIO"
(c)
Blast zone signs.
(i) The "BLAST ZONE 1,000 FEET" sign must be
posted one thousand feet before the "TURN OFF CB, MOBILE PHONE, 2-WAY RADIO"
sign;
(ii) The one thousand-foot
separation distance limit may be reduced (not less than three hundred feet) in
very slow vehicle travel zones (such as off-road construction right of ways,
rock pits, or quarries).
(d)
An "END BLAST ZONE" sign must be posted outside the blasting zone
clearance limits.
(e) Signs must
be covered or removed when blasting operations are not being conducted.
(7)
Voltage
identification. Electrical transmission and distribution line voltage
must be accurately identified.
(8)
System clearance identification. The required clearance for each
system must be accurately identified.
(9)
RF transmitters. Mobile RF transmitters must be
deenergized or disconnected when they are less than one hundred feet from
electric detonators that are not fully contained in their original U.S. DOT
shipping containers.
Note:
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Fixed location RF transmitters represent a higher
level of hazard to both storage and blasting operations involving electric
detonators because the transmitters are more powerful and transmit dangerous
levels of RF exposure over much greater distances.
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(10)
Prevention of radio frequency hazards:
(a)
Electric detonators in storage or at blasting operations must
meet the appropriate distance table requirements published in the IME
Publication Number 20, 1988, "Safety Guide for the Prevention of Radio
Frequency Hazards in the Use of Commercial Electric Detonators (Blasting
Caps)."
(b) If it is
necessary to conduct blasting operations inside the required separation
distances specified in the IME Pamphlet Number 20, 1988:
(i) Storage and use of electric detonators
is prohibited on the site;
(ii)
Only detonating cord, safety fuse, shock tube, or other approved nonelectric
systems can be used.