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2016SummerShotcreteEMag

Technical Tip is no need to monitor for crystalline silica or comply with the PEL. It is also noted that if combined tasks from Table 1 sum more than 4  hours, over-4-hour respiratory protection must be used. Active Monitoring: The second method applies to any tasks that are not listed in Table 1, and can be selected as an alternative by the Contractor for tasks in Table 1. Unfortunately, shotcrete is not covered in Table 1, so the assumption is this method will be the only option available to shotcrete contractors. This method requires monitoring for crystalline silica at prescribed times and with activities that represent the highest exposure conditions, if the amount of silica may be at or above the action level of 25 μg/m3. If above the action level, the contractor must: • Measure and record the amount of silica that workers are exposed to over an 8-hour TWA for all the tasks the employee may be reasonably exposed to. Exposure assessments must be repeated every 6 months or less if the exposure is above the action level but below PEL. If exposures are above the PEL, assessments must be made every 3 months or less; • Protect workers from exposure to crystalline silica above the PEL of 50 μg/m3 over an 8-hour TWA. If control of the PEL below the 50 μg/m3 is not feasible, supplemental respiratory equipment may be needed; • Use dust controls to protect from silica exposures above the PEL of 50 μg/m3; and • Provide proper respirators to workers when dust control measures are not adequate to limit exposures to the PEL. The monitoring option further requires employees to be notified in writing of the assessment results of the monitored levels of crystalline silica within 5 days. Also, if the PEL of 50 μg/m3 is exceeded, the employees must receive written notification of the corrective actions taken. Additionally, the employee (or their designated representative) must be allowed to observe the monitoring. The observer must also be provided clothing and equipment to protect them from exposure at no cost to the observer. Additional Requirements for BOTH Alternatives The construction employer must: • Produce and implement a written exposure control plan. The plan must identify tasks that produce exposure, and engineering and work practice methods used to protect workers. This may include restricting access to partic- Excerpt from Table 1: Specified Exposure Control Methods When Working with Materials Containing Crystalline Silica Equipment/task Engineering and work practice control methods Required respiratory protection and minimum assigned protection factor (APF) ≤ 4 hours per shift > 4 hours per shift (x) Jackhammers and handheld powered chipping tools Use tool with water delivery system that supplies a continuous stream or spray of water at the point of impact. • When used outdoors. None APF 10 • When used indoors or in an enclosed area. APF 10 APF 10 OR Use tool equipped with commercially available shroud and dust collection system. Operate and maintain tool in accordance with manufacturer’s instructions to minimize dust emissions. Dust collector must provide the air flow recommended by the tool manufacturer, or greater, and have a filter with 99% or greater efficiency and a filter-cleaning mechanism. • When used outdoors. None APF 10 • When used indoors or in an enclosed area. APF 10 APF 10 Shotcrete • Summer 2016 31


2016SummerShotcreteEMag
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