GUARDING SEWER ACCESS HOLES Produced by: Industrial Health and Safety Program, Ministry of Labour, Alert I13/0695 ISSN 1195-5228 HAZARD SUMMARY: After an explosion at a Scarborough chemical factory, sewer access covers in the area were removed so that solvents that had drained into the sewers could be monitored and allowed to escape into the open air. A member of the clean-up crew instructed a police officer to move his cruiser over an open sewer access hold to guard against anyone falling in. To do so would have endangered the police officer and nearby workers since the running motor or the heat of a catalytic converted could have ignited flammable gases escaping from the sewer system. REQUIRED PRECAUTIONS: - Always assume that contaminants in the sewer system whose vapours will escape through sewer access holes are flammable. - During chemical spills, vehicles shall not be used as barriers near or over open surface sewer access holes since they could ignite a fire or explosion. - When open sewer access holes are to be guarded, they should be guarded either by someone assigned to the task and wearing suitable respiratory equipment or by portable barricades that cannot be a source of ignition. The plastic barrier tape used to mark off crime scenes could be used for this purpose. REFERENCE: Dangerous Goods Initial Emergency Response Guide 1992, CANUTEC, Transport Canada [ISBN 0-660-14385-2]. For assistance in an emergency involving dangerous goods, call the CANUTEC 24-hour number (613) 996-6666 collect. Their general information number is (613) 992-4624. For more information, call your nearest Ministry of Labour office.