Total s Golden rules

Transcription

1 Total s Golden rules

2 Golden rule No. 9: Excavation works

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4 Excavation works The many risks we regularly face in our activities include those related to excavation works. It s wrong to think that only people working on construction or laying pipelines encounter these risks. In fact, excavation often takes place on our sites, e.g. in the following instances: Lower levels of construction (of a building for example) Installation of equipment (such as a pit for a buried tank) A buried or semi-buried structure: settling pit storm water or wastewater basin Laying an underground pipe or electrical cable Work on a buried pipe or cable.

5 Excavation works Which operators encounter the risks directly? Personnel who work at the bottom of excavations are potentially the most exposed: Welders / pipefitters Radiography operators Electricians Inspection technicians Civil engineering technicians Site supervisors Drivers of motorized machinery However, if a trench or excavation is not properly marked, anyone could be involved in an accident. And lastly, in the most serious accidents, the people who are killed or injured are those who happen to be in the immediate environment.

6 Excavation works As we saw in the previous slide, many different trades are concerned. Accidents related to excavation works may be infrequent but they always have the potential to be very serious. Because of the many different trades and operators involved and the potential severity of the accidents, it is important to take another look at the basic safety rules for excavation works.

7 Types of accidents related to excavation works Drawing on your own knowledge of accidents / near-misses on or outside your site, or simply by imagining an excavation works scenario, list the possible hazards and classify them according to their potential severity level. Hazards Potential severity Who is affected? Frequency (1 = infrequent, 3 = frequent)

8 Types of accidents related to excavation works The risks are different depending on whether works take place in the public domain or on our sites and whether they are done by Total or our contractors. Nevertheless, the most frequent accidents are Contact with an underground structure (pipe or electrical cable) Collapse of the excavation wall, resulting in people being buried Objects falling on personnel working in the excavation Worker(s) being struck by the bucket of a loader Vehicles or personnel falling into the excavation Ground slumping, causing the machine to tip over Release of toxic or flammable pollutants Bodily injury following a fire or explosion.

9 Prevention (1/6) Do not perform excavation work without a valid work permit comprising a map of all underground utilities The most serious excavation-related accidents arise when pipes carrying flammable products (gas or liquid) that are either entirely unsuspected or not expected at that particular point/depth are torn out or damaged. It is therefore paramount that no work should begin until a work permit has been approved by all the entities concerned, and until the accuracy of the plans stating whether or not underground structures are present has been established beyond doubt. This means that plans must be up to date and include a clear indication of the layout and depth of any structures. If there is any doubt, the excavation works will be performed using nonaggressive methods such as: Manual digging with spades Removal of the earth by vacuum suction technique. /

10 Prevention (2/6) Do not perform excavation work without a valid work permit comprising a map of all underground utilities Even if the consequences are usually less serious, pulling out a buried medium or high voltage electrical cable can result in tragedy for the excavator operator or anyone else in the immediate area. Electrical cables must be considered as important as pipes. Have you seen buried structures marked on plans in your unit(s) before? Such as? How are they marked? /

11 Prevention (3/6) Take precautions to prevent ground movements Ground movements can result in workers being buried in an excavation and killed. They happen for various reasons, often in combination: Natural causes nature of the ground earth pressure water infiltration gully erosion due to rainfall seismic micro-tremors Human intervention pressure exerted on the ground trench walls sloping too steeply vibrations generated by machinery /

12 Prevention (4/6) Take precautions to prevent ground movements We can ensure that the ground remains stable during the works by observing some basic rules: Determine the earth bank angles beforehand according to the nature of the ground and local seismic conditions Optimize the distribution of the downward forces of machinery maneuvering near the trench Respect the minimum distance of 1 m between machinery and the edge of the excavation Shield trenches if they are over 1.3 m deep and their width is less than 2/3 of their depth. In your opinion: good practice or dangerous practice? /

13 Prevention (5/6) Where necessary, take appropriate precautions for work in confined spaces In some cases, excavations should be considered confined spaces, and the appropriate precautions must be taken to ensure the health and safety of the people working. When the excavation is over 1.3 m deep, such precautions may be justified in a number of cases: Work on ground that has been polluted by toxic or harmful products (hydrocarbons, mercury, etc.) Work on a gas or hydrocarbon pipe that may be leaking Release of toxic gases (such as H 2 S, CO 2 ) by decomposing organic matter The rules for working in confined spaces must therefore be respected (presence of a safety attendant, atmosphere testing, wearing of PPE, and so on) /

14 Prevention (6/6) Stay alert while working to safeguard against unexpected hazards What are the hazards involved in the following situations? Why? Who is most exposed? What safety measure(s) should be taken? A surface level electrical line or a pipe rack A pole in the ground near the excavation A building in the vicinity of the excavation Ground water table A traffic route close to the excavation Can you think of any more? /

15 Excavation works (1/2) One might assume that accidents involving burial of workers are rare. The following is an account of three such incidents that happened in France within two months in (Accidents outside the Total group) April 2011*: Shortly before 13:00 the fire brigade were called out to rescue an employee buried in the trench he was working in. 38 firemen were sent out to try and evacuate the victim from where he lay under several meters of earth. Despite the action of the emergency team, the doctor was unable to resuscitate the man. It took several hours to clear away the earth in order to remove the victim from the area. (*) accident described in the local media; a brief extract is shown in the testimonials video for Golden rule no. 9

16 Excavation works (2/2) March 2011: Two workers were buried in a trench they were digging on a site when one of the walls of the 3-meter-deep hole gave way. A third worker immediately alerted the GREP (Deep Search and Exploration Group) of the Paris Fire Brigade who arrived on the scene. The firemen were able to get one of the men out alive, a 37-year-old who was then taken to the nearest hospital. However, the second man, aged 50, died before he could be retrieved. The employees were digging a trench for a water discharge pipe. The trench was not supported with struts. March 2011: A man, aged 45, died while working in a trench 4 meters deep on a sanitation site. The trench collapsed, trapping him beneath the rubble. When the fire brigade arrived on the scene, the operation to free the victim was already under way. In spite of their swift emergency action, they were unable to revive him. The trench where the accident occurred Sapeurs-pompiers SDIS 35