9 Common Excavation Hazards and their Preventive Measures

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Excavation is one of the preliminary processes for any construction project. The hazards and risks associated with it include the collapse of the earth, injuries to workers due to the failure of the trench, machines falling into improperly excavated areas, etc. These mishaps could prove to be dangerous and life-threatening.

This article discusses the 9 most common excavation hazards and their preventive measures. 

1. Location of Machinery and Tools

1. Excavating machinery consisting of both light and heavy types shall be kept back from the excavation site at a safe distance.
2. Heavy equipment, such as road trucks and excavating machinery, shall be kept away from the excavated sites at a distance of not less than 6 m.
3. Care shall be taken to keep excavating materials and tools far away from the edge of the trench to prevent such items from being inadvertently knocked into the trench.

2. Excavated Materials

1. Excavated materials must be kept away from the edges of the trench to provide a clear berm of safe width.
2. In places where this is not feasible, sloping, benching, or shoring of the trenches shall be done to carry the additional load due to the overburden of materials.

3. Other Surcharges

1. The proximity of buildings, crushed rocks, piles of lumber, large trees, sand, and other construction materials may impose additional load on the side of the trench to cause sliding, etc.
2. In these conditions, additional protective works (sloping, benching, and shoring) shall be provided to support the sides of the trench.

4. Type of Strata

1. Adequate precautions shall be taken to protect the workmen during excavation, depending upon the type of strata encountered during excavation (like quicksand, loose boulder, and loose fills).
2. The effect of moisture content and climatic variations on the materials under excavation shall be constantly watched, and precautions must be taken immediately to prevent accidents at the worksite.

5. Overhang and Slopes

1. During any excavation, sufficient slopes shall be provided by providing steps or gradual slopes to ensure the safety of men and machines working in the area.
2. Blasting for the building's foundation is prohibited unless special permission is obtained from the authority.
3. Where blasting is required, prior inspection for the stability of slopes shall be carried out by the competent authority. 
4. After blasting is carried out, overhangs or loose boulders shall be cleared by expert workers before continuing the excavation by normal working parties. 
5. Mining or burrowing or gophering shall not be allowed.
6. In any trench where such methods are undertaken, the cavities left shall be abolished by cutting back the bare slope before removing any further material from the section of the trench.

6. Health Hazards

1. Where fumes or gases are likely to suffuse in trenches, sufficient mechanical ventilation shall be provided to protect the health and safety of personnel.
2. The personnel working in such unhealthy conditions and locations shall be provided with respiratory protective equipment.
3. The local health authority's preventive measures shall be given due heed before the commencement of the work.

7. Safety of Materials

Materials required for excavation, like planks for gangways, ropes, and walkways, ladders, etc., shall be inspected to ensure that no accident shall occur due to their failure.

8. Fencing and Warning Signals

1. During the excavation process, for the safety of the public and the workmen, fencing shall be erected to prevent the movement of humans and animals at the worksite. 
2. A sufficient number of notice boards and danger sign lights shall be provided in the area to prevent the public from inadvertently falling into the excavation pit.
3. When excavations are carried out on roads, diversion of the roads shall be provided with adequate light indicators and notice boards and lights indicating the diversion well ahead.
4. Where necessary, security guards are deployed as additional preventive measures to prevent accidents, especially during hours of darkness.

9. Effect of Freezing and Thawing

1. Due to the expansion of water when freezing, rock fragments, boulders, etc., loosen.
2. Therefore, the sidewalls of the excavation shall be constantly kept under inspection for signs of cracks due to thawing.

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