# Chapter 15: Post-Blast Hazards and Requirements ## Learning Objectives - List the steps that must be taken after a blast before anyone can enter the blast site. - Describe how to protect workers from air contaminants. - Explain how to examine the blast site for undetonated explosives and other hazards. - Describe requirements for safely excavating blast rock. - Describe the post-blast hazards that can occur and measures used to control them. - Explain how hand scaling is carried out. - Describe how cleanup is conducted at the blast site. - Describe how to record and maintain pre- and post-blast loading details and results in a blasting log. - Describe the contents of dangerous incident reports and when they must be submitted to WorkSafeBC. --- ## Overview After a blast, the blaster of record must ensure that no one enters the blast site until all of the following occur: 1. The blaster has examined the blast site for misfires and other hazards. 2. The "all clear" has been sounded. 3. The blaster has given permission for work to proceed. The blaster must identify and control any hazards. The all-clear signal is not sounded until the site has been examined and found safe. The following precautions are required after a blast. --- ## Protect Workers from Air Contaminants Air contaminants (e.g., silica dust, fumes, and toxic gases) must be reduced to a safe level. As a general rule, no one should return to a blast site if air contaminants are visible. In surface blasting, air contaminants rapidly disperse into the atmosphere. In confined areas, such as underground, dust and fumes are a more serious problem. Atmospheric tests must be done following a blast. And the space should be ventilated before workers are permitted to enter. > **In the Regulation:** For information on identifying confined spaces in the workplace and preparing and implementing a confined space entry program, see Part 9 (Confined Spaces) and Part 22 (Underground Workings) of the Occupational Health and Safety Regulation. --- ## Examine the Blast Site The blaster must carefully examine the blast site for undetonated explosives and other hazards. The blaster must not leave the blast site before attending to any undetonated explosives or other hazards caused by the blast. Otherwise, serious injuries or damage may occur. The blaster should inspect for the following: - Loose material that could be released from above or from the face - Unstable trees - Hanging branches ### Excavating the Blast Rock (Muck Pile) Equipment operators who excavate blast rock must be trained and competent to recognize misfires. Whenever possible, blasters should supervise the initial excavation of the blast rock to ensure all the holes were initiated and the rock has broken to grade. Having eyes on the ground from outside the machine is always better than not. Operators must use caution when excavating blast rock. They should understand that a misfire may be handled only by, or under the direction of, a blaster. If a suspected misfire has occurred or explosives are seen in the muck pile, the operator should stop work immediately and notify the blaster of record to re-examine the area. --- ## Control Post-Blast Hazards All hazards must be identified and controlled before other work resumes on the blast site. The location of a misfire should be identified by a hole plug, flagging (coloured tape), spray paint, or other effective means. Control measures can include the following: - Roping off the area surrounding the hazard - Keeping metal tools and equipment away from misfires - Bracing or supporting loose material that may fall or move ### Remove or Manage Loose Material Any unstable material that could cause injury or property damage is commonly referred to as "loose material." Examples include the following: - Broken tree limbs - Overhanging rocks - Unstable boulders Loose material has caused fatalities, serious injuries, and incidents involving property damage. Loose material on a slope or face must be scaled (removed), trimmed, or otherwise stabilized. To remove loose material safely and effectively, use machinery such as front-end loaders or hydraulic excavators. This equipment reduces the risk of injury to workers. ### Carry Out Hand Scaling Where Appropriate In some cases, hand scaling may be appropriate. Hand scaling is done using a metal scaling bar. Determine the nature of the material by striking the surface with the end of the bar. A sharp (hard) sound indicates solid rock. A hollow (thud) sound indicates unstable or loose material. When hand scaling, do the following: - Wear a safety belt or harness attached to a securely anchored lifeline. - Wear protective footwear and a hard hat. - Use a scaling bar in good condition and of suitable length. - Begin scaling from a safe location and from the top down. - Stand on a solid surface and maintain your balance. - Watch for holes containing explosives. - Do not scale above any misfired holes or undetonated explosives. - Do not scale where anyone may be endangered by falling rock. After the blaster has examined the site and deemed it clear of all hazards, sound the five-second all-clear signal. > **In the Regulation:** For more information on scaling operations, see sections 20.96 to 20.101 of the Occupational Health and Safety Regulation. --- ## Clean Up The blaster should ensure that empty explosives containers are removed from the blast site. They must be handled with care to prevent undue impact or exposure to excessive heat or flame. Boxes, cartons, and liners that have contained explosives must be collected and destroyed safely or as recommended by the manufacturer. Never allow any explosives packaging materials to be burned in a confined space or a non-ventilated area. Check that detonators, explosives, and other hazardous substances are separated from other waste material. These items must be destroyed in the manner recommended by the manufacturers. Never abandon any explosives. Unused explosives and detonators that were on the blast site must be returned to a day box or magazine. The employer should ensure that a blaster inspects unused explosives and detonators. The goal is to determine if they can be stored safely before they are returned to a magazine. --- ## Maintain a Blasting Log Under the Regulation, the blaster of record must record and maintain pre- and post-blast loading details and results in a blasting log. Blasting logs must be maintained at the worksite. They must be available for inspection by WorkSafeBC officers, workers, and worker representatives. The employer must ensure blasting logs are kept for at least five years after the blasting operation ends. And they should be kept indefinitely. ### Pre-Blast Loading Details The blaster must include the following pre-blast loading details in the blasting log: - Time, date, and location of the blast - Names of the blaster of record and all other persons handling explosives - Type and weight of explosives used - Number of detonators used - Type of initiating device used ### Post-Blast Remarks The blaster must also include a post-blast remarks section. This section is used to record detailed results of the blast and the results of the post-blast examination. ### Additional Recommended Information The blaster should also include the following information in the blasting log: - Distance from the nearest potentially occupied building or significant structure - Number of holes - Hole diameter - Hole depth - Burden - Spacing - Overburden - Total quantity of explosives - Type and length of stemming - Material blasted - Number of delays used - The period numbers of the detonators used in the blast - Electrical resistance (in ohms) in an electric blasting circuit - Seismograph reading (for close proximity blasting) - Number of blasting mats and precautions taken to contain flying material ### Blast Site Sketch The second part of a blasting log should include a sketch of the blast site that shows the following: - Details of the loading pattern and tie-in for the blast - The direction to north - Timing and delays - Point of initiation - Nearest structures > **Resources:** Blasting log templates are available on worksafebc.com. They cover the following types of blasting: Urban and construction, Forestry, and Avalanche control. Look for the "Blasting log templates" section on the Blaster certification webpage. --- ## Submit Dangerous Incident Reports When Required The Regulation requires employers to report to WorkSafeBC in the following cases: - A blasting accident occurs that causes personal injury. - Any other dangerous incident occurs involving explosives, whether or not there is personal injury. In such cases, the employer must do both of the following: - Report the incident immediately to WorkSafeBC. - Forward a written report of the incident to WorkSafeBC without undue delay. ### Written Report Contents The written report of the incident must contain the following: - The date, time, and location of the incident - The names and certificate numbers of all blasters involved - The names and occupations of any persons injured - The types of explosives, including detonators, and initiating device used - The instrument used to test the electric blasting circuit - A factual account of events including the blaster's log records - The names of all employers responsible for workers present at the worksite when the incident occurred - The actions taken by each employer ### Definitions of Reporting Terms **Dangerous incidents** include the following: - Incidents involving explosives, whether or not they cause personal injury - Problems with particular products (for example, repeated or suspicious misfires or premature detonations) **"Immediately"** means the reporting should occur as part of the employer's response at the time of the incident. To report a dangerous incident, call WorkSafeBC's Prevention Information Line at 604.276.3100 (Lower Mainland) or 1.888.621.7233 (toll-free). For more information, see the Reporting serious injuries and fatalities webpage on worksafebc.com. **"Without undue delay"** means that the written report must be submitted within 48 hours of the incident unless the particular circumstances of the operation prevent this. The report should be submitted to the nearest WorkSafeBC office, which will forward a copy to Certification Services. > **Note:** For more information, see "Reporting incidents and injuries to WorkSafeBC" in Chapter 1.