Tech Talk

Tech Talk is a regular feature of Concrete Openings magazine, focusing on equipment, maintenance and technical issues of interest to concrete cutting, polishing and imaging contractors. Readers wishing to have a particular subject addressed can call or email CSDA with their suggestions at 727-577-5004 or editor@concreteopenings.com.

Vacuum Lifting a Viable Option to Help Protect Workers From Silica Dust By Paula Bell

Silica dust has been recognized for decades as an occupational health concern. In March 2016, OSHA announced a final rule pertaining to silica exposure regulations. Enforcement for employers covered by the construction standard began in September 2017.

Made up of microscopic particles typically at least 100 times smaller than ordinary sand, silica dust is commonly found in materials associated with constructionrelated activities. Industries that deal with roads, buildings, sidewalks or landscaping materials—which require tasks that involve sawing, drilling or breaking silica-containing substances—are particularly prone to creating large amounts of it.

OSHA’s final rule, which reduced the permissible exposure limit for crystalline silica to 50 micrograms per cubic meter of air (averaged over an eight-hour shift) requires employers to limit worker exposure via the use of engineering controls, work practices or respiratory protection.

With the identification of 18 common construction-related jobs, OSHA specifies exposure control methods to protect workers from crystalline silica in Table 1, focusing on equipment type and duration of the task at hand.

Types of engineering controls for silica include wet methods and local exhaust ventilation, as well as process isolation. Work practice controls involve performing a task in a manner that prevents or reduces the likelihood or levels of exposure by decreasing the quantity of airborne dust. Administrative controls revolve around limiting time spent working with or in close proximity to the material. In addition to instituting and executing a written, job-specific exposure control plan that includes a description of housekeeping measures, OSHA’s standard requires employers to train workers, limit access to high exposure areas and, in some cases, provide medical exams.

Numerous state agencies, universities and trade groups such as the Concrete Sawing and Drilling Association have also published articles in reference to the new rule, with information on topics such as dust control. OSHA, in an overview of the final rule, welcomes employers with “better ideas about how to provide protection” to incorporate alternate methods that “effectively reduce their workers’ exposure to silica dust.”

Multiple concrete contractors interviewed by Vacuworx stated vacuum lifting systems are a viable alternative to drills and jackhammers when lifting and handling concrete slabs. Here is a look at some innovative ways that companies are tackling the silica issue:

LIMITING THE NUMBER OF CUTS The use of walk-behind or handheld saws in enclosed areas is an example of one demolitionassociated situation where protective measures need to be taken. OSHA states such saws

should be equipped with an integrated water delivery system that continuously feeds water to the blade. In addition to this method, respiratory protection may be required – especially when cutting indoors, in enclosed areas or for an extended period of time.

In many cases, contractors commenting on their use of vacuum lifting equipment have reported the elimination of their need for dustgenerating tools. With fewer saw cuts required since the concrete to be handled in larger pieces, adding vacuum lifting to the mix can help limit the amount of silica dust that would otherwise be released in the air. In addition, slabs can be removed with greater efficiency, which reduces the amount of time that workers may be exposed to environments in which silica dust is present.

ELIMINATING THE NEED FOR HAMMERS AND DRILLS

According to the Centers for Disease Control and Prevention, jobs at risk for increased exposure to respirable crystalline silica include jackhammering, concrete drilling and sawing, demolition and mining, to name a few. In fact, researchers at the University of California found that silica dust generated by a pneumatic rock drill was at least 444 times greater than OSHA’s permissible exposure limit. Furthermore, drilling can expose workers

to hand vibration and noise at levels well above recommended limits.

Under OSHA’s standard, wet methods may be needed to keep dust from getting into the air when using rotary drills, jackhammers or chipping tools. In some instances, tools should be equipped with a proper shroud and dust collection system. The fact that pieces of concrete can be chipped away while moving or loading must also be taken into account.

Vacuum lifting can be used as an alternative to anchors, shackles or hammers as concrete may be cut into larger, more uniform pieces that can be lifted out without the drilling, prying or breaking associated with conventional methods of removal. “The problem with hammering concrete is it goes into a million pieces,” says Dave Weston with Blade Runners. “The jackhammer causes too much dust, not to mention labor. Now we can keep it in one piece.”

CUTTING DOWN ON CLEAN UP

Water systems may be needed to help control the amount of silica dust created on jobsites. OSHA stipulates that slurry produced by wet cutting must be cleaned up to prevent it from drying and releasing silica dust into the air. Wet slurry is generally cleaned up using shovels or HEPA-filtered vacuum systems.

An added benefit to contractors who embrace vacuum lifting equipment is tidier working environments that result in fewer housekeeping chores. “By sawing concrete into bigger pieces, we’re saving on diamond blades, water usage and especially manual labor,” says Dave Desserault with Interstate Sawing & Drilling. “There is less cutting involved, which means less slurry removal. It’s a lot quicker and a lot cleaner.”

It is estimated that 1 million construction workers are exposed to respirable crystalline silica dust, a material that can lead to severe diseases such as silicosis, lung cancer or chronic obstructive pulmonary disorder. All contractors engaging in activities that fall under OSHA’s silica rule are required to take measures to keep workers safe by reducing the quantity of hazardous dust they may inhale. Otherwise, they face the possibility of stiff penalties or costly fines for failing to comply.

Paula Bell is the Director of Marketing for CSDA member company Vacuworx. She serves on the CSDA Marketing, Manufacturer and Safety Committees.

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