How To Perform A Safe Excavation
Almost three years ago, I was told of an incident that happened here in Nigeria at my current work location, Nigerdock PLC Snake Island. My colleague who was telling me of the story said, there was an excavation operation going on, and as usual they could not finish that day, so they closed for the day and everybody went home to have a good night rest. During the night it rained heavily and everyone slept well.The next morning, everybody trooped in for the day’s work, from the changing room, an operative went straight to the excavation site without obtaining instruction from his supervisor.
He got there and together with other operatives like him, they commenced work. Unknown to them, the rain that poured the previous day had really weakened the sides and edges of the excavation. Not long after, while they were still working inside the trench, the walls of the trench caved in.Most of the operatives were lucky and hurriedly climbed out of the trench unhurt, but there was this certain operative who was not as lucky as the others, the collapse wall of the trench had trapped from his waste downwards and he couldn't pull himself out. He shouted for help and help was which was not forth coming, his colleagues were afraid to go back into the trench because they were afraid that the remaining walls of the excavation could collapse.
Emergency alarm was raised, some people gathered the confidence to go in and rescue the helpless operative, he was brought out and rushed to the clinic, after serious medical treatment and tests, it was discovered by the medical team that his left legs has been seriously damaged. The medical team tried all they could do and had to immediately refer him to a specialist hospital for further and special medical attention.
The operative in question survived but I heard he would not be able to use his legs perfectly for ever again.
Safety steps to put in place for an Excavation work
1. Planning. You need to plan your excavation work, remember the purpose of the excavation operation is not just to successfully finish the exaction work, but to successfully finish it safely, workers and people should not get hurt as a result of your work operations, so when planning for how to perform your excavation , let safety be one of the most important criteria for selecting your work method.
2. Check for underground services
Technology has made things easier for us; we now have underground service scanners with high accuracy detection using ultrasonic methods, some scanners even have the ability to tell you which kind of underground service is present below and at the particular depth from the top of the surface at which they are located. These equipment are not that expensive and should be owned by anybody that wants to perform an excavation operation.
Some of the underground service you could come across includes
Underground Electrical services. This is a major hazard associated with excavation works, this is so because while excavating, if electrical cables are stricken, it will not only cause damage to the service, it could also lead to fatality. Either it’s a life electrical cable or it is dead one, the risk associated with underground electrical service is very high and we need to ensure that our proposed excavation site is adequately scanned for underground services
Underground Mechanical Services. Underground services such as waste water piping, solid waste piping, clean water piping etc. are all categorized as mechanical services, most of the time these mechanical services are buried under the ground and are not visible from the surface.
Although underground mechanical services may not have the risk of fatality directly attached to it, it could still cause major health and safety issues like environmental spillages, flooding, biological hazards etc. we must make sure that we scan our proposed excavation site before the digging of trenches can commence.
Underground Gas services. Underground gas services are as dangerous as underground electrical services if not more, in some cities and area; they have underground channels of gas service from a distribution point to usage point. As we all know these gases can be volatile, flammable, toxic and deadly. If gas pipes are mistakenly punctured during excavation works, it could be a major disaster. It is on this note that it is important that we perform underground service scan test before commencing any excavation work.
3. Excavations must be battered. The sides of your excavation must be battered, this simply means, you should shore your excavation to avoid the walls caving in just like the scenario in the scenario discussed above. Immediately your excavation is exceeding more than 1m in depth make sure you batter all the sides of your trenches to avoid them from caving in.
4. Provide Proper access and egress: proper access and egress must be provided for operatives that will be carrying out the excavation work. If you are using a ladder, make sure wide surface area base plate are used with the ladder to avoid the ladders from sinking when it is under load
5. Keep the spoils far away from the edge of the excavation. The soil that has been dug out should be moved away from the edges of the excavation, if this is left at the side of the excavation, it serves as load on the edges, and may cause the sides and walls of the excavation to cave in. Bests practice stipulates that you should keep your spoils at a minimum of 1.5meters away from the edge of the excavation
6. Make use of stop Blocks. Make sure stop blocks
are used to stop vehicles and equipment from falling into or coming close to
the excavated are.
7. Wear your PPEs. Personal protective equipment such as safety helmet (hard hat), safety boot, safety glasses, high visibility vest (reflective jacket) should be worn by all operatives at all time while working.
8. Never throw your tools. Never ever throw tools from or into the excavation. Ensure that tools are lowered into the excavation using a tool bucket or passed from hand to hand until it gets to the person who needs. Never throw any tools or material from above into the trench.
9. Excavations should be inspected by a competent person at the start of work every day or when it is suspected to have been affected like an environmental factor like rain
10. Don’t ever attempt to jump across any excavation no matter how slim it is. At the point of trying to jump from one side to the other , the edges may give way and you will end up inside the trench
11. Make sure you barricade any open excavation during and after the close of work for the day. This is very important to keep unauthorized persons or members of the public away from the area.
Finally, ensure you take additional safety precautions and steps if necessary to ensure the operation is executed safely.
Remember, no work is completed until it has been safely completed.