Chapter 12: Securing the Area Surrounding a Blast

Learning Objectives

• Explain what the most critical period in a blasting operation is, and why.
• Describe the authority and responsibilities of the blaster of record for blasting operations.
• List the qualifications, training, supervision, and responsibilities of assistants to a blaster.
• Describe the blast site and the danger area.
• Discuss specific actions the blaster of record must take to clear and control the danger area.
• Describe blaster responsibilities for guarding the danger area.
• Describe guard qualifications and duties for guarding the danger area.
• Describe standard blasting signals, including how and when they are used.
• Explain the safety protocols required to ensure safety of aircraft.

Overview

The most critical period in a blasting operation is the time of the blast. At that time there is the greatest potential for damage and serious injury.

To prevent incidents resulting from the detonation of explosives, the area surrounding a blast must be under the control of the blaster of record. The blaster of record is responsible for the safety of persons who could be affected. In addition, the area must be guarded to prevent entry during the time of the blast.

The blaster of record has the sole authority to limit people, equipment, and materials on the blast site at any given time. People, equipment, and vehicles not required during loading of explosives should be removed from the blast site.

About the Blaster of Record and the Assistants

The Blaster of Record and Their Authority

To avoid conflict when more than one certified blaster is involved in a blasting operation, the employer must designate one blaster as the "blaster of record." The blaster of record is responsible for conducting or directing the use of explosives on the blast site. They also must have authority to safely conduct and direct activities on the blast site. The employer and supervisors must support the blaster in exercising this authority.

The employer and supervisors should not interfere with the blaster of record during a blasting operation. However, the employer must ensure that all activities are planned and conducted in a manner consistent with the Occupational Health and Safety Regulation and recognized safe blasting practices. If an employer has evidence that the blaster of record has failed to comply with the Regulation or safe blasting practices, the employer should immediately investigate the incident and may suspend the blaster from performing their duties.

In the Regulation: Section 21.5 of the Regulation sets out the blaster of record's authority to blast and the requirements for assistants.

Verifying the Blaster of Record's Certification

The blaster of record must have a valid blaster's certificate issued by WorkSafeBC. The certificate specifies the type of blasting the blaster of record is qualified to conduct or direct. The employer should verify details of the blaster's certification, including the following:

• Name and address
• Certificate number
• Certification codes
• All conditions and/or restrictions
• The expiry date

Most employers retain a copy of the blaster's certificate. The original must be kept by the blaster of record. Whenever the blaster of record conducts or directs a blasting operation, the certificate must be readily available at the worksite. The blaster must show the certificate to a WorkSafeBC officer upon request.

Qualifications, Training, Supervision, and Responsibilities of Assistants

Only competent persons are permitted to assist a blaster, and then only if they have demonstrated a knowledge of safe work procedures.

The blaster is responsible for the assistants and any work they perform. When an assistant is unfamiliar with a task, the blaster is expected to provide training and exercise continuous visual supervision.

An assistant must not conduct tasks in a blasting operation unless the blaster directing the work is physically present on the blast site. Whenever the blaster leaves the blast site, the assistants must guard the explosives and wait until the blaster returns before continuing the operation.

Defining the Blast Site and the Danger Area

Blast Site

Under the Occupational Health and Safety Regulation, the blast site is the area that extends 15 m (50 ft.) in all directions from:

• Loaded holes
• Explosives stored outside of a magazine
• A known or suspected misfire

Danger Area

The blast may create hazards beyond the blast site. This larger zone is called the danger area. This is the distance in which people, equipment, or property could suffer injury or damage from the effects of the blast. These effects include the following:

• Air blast (concussion)
• Flying material (e.g., fly rock)
• Ground vibration
• A mud or snow slide
• Fire
• Fumes and dust

The danger area exists at the time of a blast or misfire. Its size is determined by the blaster based on the following:

• The amount of explosives used
• The blasting technique and the type of material blasted
• The potential for geological or environmental instability

Clearing and Controlling the Area

The blaster of record is responsible for ensuring that all tasks in the blast site are coordinated so that they may be performed safely.

During priming, placing, and connecting charges, only the blaster and the blaster's assistant(s) should remain in the area. No other person is allowed entry unless the blaster gives permission and maintains control over that person's activities.

The blaster must ensure that the danger area is clear of people and is kept clear during the blasting period.

Pre-Firing Requirements

The blaster must ensure that no charge is fired unless the following apply:

• All persons are at a safe distance from the blast or are in a shelter sufficient to protect them from injury.
• All property, including machinery and equipment, is located at a safe distance from the blast. (This does not apply to implosions.)
• Sufficient audible warning signals are given to all persons in or near an area where the blast may create a hazard.

Note: If there is any sign of thunder or lightning storm activity, all blasting activity must be suspended. In addition, the danger area must be cleared and guarded if explosives are present at the blast site.

Guarding the Danger Area

The blaster is responsible for posting guards to prevent entry to the danger area. Whistles, signs, or other signals cannot substitute for guards. The guards must be posted in safe locations, usually outside the danger area.

When blasting near a highway or populated area, it may be difficult to control public access. Traffic control personnel may be needed to block off streets or stop traffic.

Blasters should be in constant communication with guards posted at the perimeter of the danger area.

Guard Qualifications and Duties

Only competent persons should be assigned to guard a danger area. They must be mature individuals capable of performing guard duties.

The blaster is responsible for instructing all guards on their duties and responsibilities, including the following:

• Knowing the location of the guard post
• Understanding how and when to use warning devices and signals
• Preventing persons from entering the danger area
• Watching for flying material
• Preventing re-entry to the danger area until the all-clear signal is given or the guard is personally relieved by the blaster

Guarding Charges

Charges must be guarded at all times, at every point of the loading and blasting process. The blaster should ensure that explosives are attended by a competent person, except when they are stored in a locked magazine.

The competent person must:

• Protect the charges from damage or accidental detonation.
• Prevent deliberate tampering with or theft of any part of a charge.

When Overnight Guarding Is Required

Typically, a member of the blasting crew will guard charges until they are detonated. If the charges cannot be detonated during normal working hours, a designated person must be posted overnight.

The designated person should be provided with suitable equipment, including lights and signs. If equipped with a radio, the designated person must maintain a safe distance from any electric detonators.

Blasting Signals

Once charges are connected to one another or to a means of firing, blasters and employers must ensure that firing takes place as soon as it is safe to do so.

Every person in the area surrounding a blast should understand the blasting signals. These signals warn that a blast is about to be fired.

Standard Blasting Signal Sequence

1. Before the blast - Sound 12 short whistle signals at one-second intervals.
2. After the last warning signal - Wait two minutes before initiating the blast.
3. Following the blast - Examine the area. If the area is found to be safe, sound one whistle for at least five seconds. This whistle indicates permission to return to the blast site.

Blaster Requirements

Before any charge is fired, the blaster must do the following:

• Post blasting-signal signs where they can be easily seen at each blasting operation.
• Ensure that workers have been instructed in what the blasting signals mean and what to do when they hear the signals.

Signal Devices

Devices for sounding blasting signals must be both of the following:

• Distinct from other signal devices in the danger area
• Audible throughout the danger area

A compressed-air horn, or a horn device attached to a compressor or air hose, is commonly used. A standard car or truck horn is not distinct. For this reason, it is unacceptable as a blasting-signal device.

Notice to Airmen (NOTAM)

If the blast could pose a hazard to aircraft, special precautions must be taken. A Notice to Airmen (NOTAM) warning of the blasting operation should be issued to pilots.

When a NOTAM Is Required

A NOTAM will be required if the blast site is within 5 nautical miles of a location from which flight operations take place. To request a NOTAM, contact NAV Canada at least 24 hours before the scheduled time of blasting.

Communication with Aircraft

Do not assume the NOTAM has been received and understood by all pilots in the area. If blasters detect an aircraft in the immediate vicinity of a blast, they should contact the aircraft by radio on the 123.2 MHz frequency and identify the aircraft by type and colour. (For example, "Red and white helicopter, you are over an active blast site. Clear the area immediately.")

Requesting a NOTAM

To request a NOTAM for blasting operations, visit NAV Canada's Data Submission webpage. In the NOTAM Request Forms section, download the Airspace NOTAM request form, and then complete and submit it to NAV Canada. For more information on NOTAM requests and blasting, see section 5.5.5 of the Canadian NOTAM Operating Procedures (CNOP).