Excavation activities in the company start to increase as the weather warms up. An important hazard we have to identify during excavations is how to minimize the exposure to crystalline silica. Silica is a common mineral found throughout the world and is especially found in soil. OSHA published a Table 1 reference guide that shows 18 common tasks throughout the construction industry. The guide identifies each task, what the engineering controls are, and if respiratory protection will be required when performing the work. One of the tasks that are identified is using heavy equipment & utility vehicles for grading & excavations. Two engineering controls were identified for this task which consists of wet methods and operator isolation.
Wet methods are used during excavations to control the dust suppressants from the soil. Water trucks equipped with hoses or nozzles is a common wet method that can be used to spray throughout the job site to control the dust. When you are using water, be sure to use enough to control the dust. However, don’t use too much water as it creates muddy areas and additional hazards. This would apply to both the excavation and the spoil pile that is being created during the work activity.
Operators must rely on working in an enclosed cab so they can be protected from silica:
• Windows and doors must be closed, along with heat and air conditioning in the cab.
• Check the seals around the doors and windows to prevent any silica dust from entering the cab.
This practice is only required when there is no water source or when the operator is the only worker performing the work activity. If ONE of the engineering controls are met, then no respiratory protection is required. However, using engineering controls can bring additional hazards or challenges that we have to identify. For example, we would need to reassess the sloping/benching to prevent any cave-ins, and ensure the operator working from an enclosed cab can hear the spotter.