29.I Post-Blast Procedures.
29.I.01 Immediately after blast has been fired, the firing line must be disconnected from the blasting machine or power source. Power switches must be locked open. Atmospheres in confined areas must be tested and/or ventilated after blast.
Blasting at I-90.
29.I.02 An inspection must be made by the blaster to determine that all charges have been exploded. All wires must be traced and search made for unexploded cartridges.
29.I.03 Other persons must not be allowed to return to the area of the blast until an "all clear" signal is given.
29.I.04 Loose pieces of rock and other debris must be scaled down from the sides of the face of excavation and the area made safe before proceeding with the work.
29.I.05 Misfires.
- Misfires must be handled under the direction of the blaster. The blaster must determine the safest method for handling the hazards of misfires (some misfires may require consultation with the supplier or manufacturer of the explosive material).
- When a misfire is declared, the blaster must wait 1 hour before inspecting the site and provide proper safeguards for excluding all employees, except those necessary to do the work, from the danger zone.
- Other work must not be done except that necessary to remove the hazard of the misfire. Only those employees necessary to do the work shall remain in the danger zone.
- Drilling, digging, or picking must not be permitted until all misfire holes have been detonated or the blaster has approved that work can proceed.
- Based on contractor experience, a secondary/dual initiation system to prevent misfires should be considered.
Knowledge Check Choose the best answer for the question.
29-13. When a misfire is declared, the blaster must wait _____ before inspecting the site.
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