Question 4 of 7: Hazardous-Material Controls and Confined Spaces

Question 4: Hazardous-Material Controls and Confined Spaces (20 marks: 7/7/6)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

(i) Controls for Hazardous-Material Exposure

• Elimination/substitution; engineering (enclosure/isolation, local exhaust and dilution ventilation, wet methods); administrative (procedures, limited exposure time, hygiene, labelling/SDS, training); PPE (respirators, gloves, suits, eye protection). Backed by monitoring, medical surveillance and emergency provisions.

(ii) Characteristics and Examples of Confined Spaces

• Characteristics: large enough to enter and work; limited/restricted entry-exit; not designed for continuous occupancy; may accumulate a hazardous atmosphere.
• Examples: tanks, vessels, boilers, silos, hoppers, sewers, pipelines, tunnels, pits, manholes, ductwork.

(iii) Main Hazards of Confined Spaces

• Atmospheric — oxygen deficiency/enrichment, toxic gases, flammable atmospheres.
• Engulfment (liquids/free-flowing solids); entrapment (converging walls).
• Physical/mechanical — moving parts, electrical, heat, noise, falls.
• Difficult rescue — restricted access; many fatalities are unprotected rescuers—hence permits, testing, ventilation, isolation, attendant and rescue plan are essential.