THE RISK OF SILICA EXPOSURE TO OIL & GAS WORKERS DURING HYDRAULIC FRACTURING ACTIVITIES
We wrote last week about the potential exposure to harmful radioactive chemicals during oil & gas exploration and production activities. Radioactivity exposures are just one of the many liabilities facing the insureds, with traffic fatalities, well blowouts and pollution liabilities being at the top of the list. One very significant liability could also arise from worker exposure to silica and diesel particulates. This blog addresses the crystalline silica issue.
In 2012, the National Institute for Occupational Safety and Health (NIOSH) released field study findings concerning worker overexposure to airborne silica during hydraulic fracturing operations. Air samples were collected at 11 North American hydraulic fracturing sites with the following results of 116 samples collected:
• 47% showed silica exposures greater than the calculated OSHA PEL;
• 79% showed silica exposures greater than the NIOSH REL of 0.05 milligrams per cubic meter (mg/m3);
• 9% of all samples showed silica exposures 10 or more times the PEL, with one sample more than 25 times the PEL;
• 31% of all samples showed silica exposures 10 or more times the REL, with one sample more than 100 times the REL.
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HYDRAULIC FRACTURING AND DUST GENERATION
Hydraulic fracturing has been used for hydrocarbon recovery for decades, but has become widespread in North America due to higher natural gas and oil prices, a modern process known as high volume horizontal slickwater fracking, as well as other technologies that provide more efficient access to oil and gas deposits. High volumes (up to 5 million gallons of water/sand per well) of water and silica sand are injected under very high pressures (the pressures can exceed 10,000 psi, depending on the depth of the fracturing and the type of formation) via drilled wellbores into shale formations, causing new rock fractures and/or enhancing existing fractures that allow natural gas and oil that was trapped in discontinuous rock voids to be released and collected. Thousands of tons of crystalline silica are use in the process.
Crystalline silica, A.K.A frac sand, is used as part of the mix that is injected into wells for hydrocarbon recovery. As low as 6 percent and as high as 15 percent sand as part of the 4-5 million gallons of fracking fluid can be used at a single well location. This means that between 1,200 tons and 3,000 tons of frac sand will be injected into the subsurface. Frac sand acts as a proppant, or means of holding open (i.e., “propping up”) fractured rock to allow the oil and natural gas to enter the production well for extraction. Thousands of pounds of sand are transported by truck loads to well sites. Based on the volume of frac sand that must be used at each well location, as low as 120 trucks and as high as 300 sand trucks could be used at a site, or more. The sand is then emptied into a pile, then conveyed and blended with fracking fluids before the high pressure injection; all of these processes can expose well site workers to respirable silica dust. At some sites, where wind was blowing, we measured respirable silica sand at locations well beyond the 5 acre well pad. Therefore, the NIOSH field study confirmed other health professionals’ measurements and observations during fracking activities.
The primary dust generation points during the hydraulic fracturing activities include:
• Sand placed in the blender hopper;
• Transfer belt under the sand movers;
• Releases from top hatches, sand movers;
• Site traffic;
• Sand blowing from sand piles;
• Release from T-belt operations;
• Release from Dragon’s Tail’;
• Dust released from fill ports on the sand movers
THE PROBLEM WITH SILICA AT HYDRAULIC FRACTURING SITES
The big issue facing the oil & gas producers at these fracking or fracing sites is the type of frac sand required for this process. The oil & gas producers require a very specific sand proppant during fracturing operations to ensure that the shale fractures remain open after the fracing fluid flows out of the formation. To be able to meet the compressive strength requirements, the frac sand must be made almost of 100 percent of crystalline silica sand. A review of the MSDS sheets of the frac sands used in the various fracing jobs will reveal that the crystalline silica present in the frac sand can be as high as 95 percent or more. See for example the MSDS sheet from Mississippi Sand, LLC, showing a greater than 95 percent composition of silica. The Halliburton frac sand MSDS sheet shows the crystalline sand composition varying between 60 and 100 percent.
Close view of the proppant sand used at hydraulic fracturing sites. It is almost 100 percent crystalline silica.
Since the OSHA PEL-TWA (the permissible exposure to dust over a worker’s shift) depends on the amount of silica present in the dust, it can be easily seen that the hydraulic fracturing industry is facing a very significant, perhaps insurmountable problem regarding the worker exposures to crystalline silica. For example, assuming a 95 percent crystalline silica content in the frac sand, the respirable dust level should be about 0.1 mg/m3. This is an extremely low dust level that is impossible to meet. All the frac sand applications we have inspected at these sites evidence 10 to 100 times higher levels than the 0.1 mg/m3 OSHA PEL-TWA.
Importantly, the Halliburton MSDS sheet for frac sand states that the frac sand may become airborne without a cloud and provides the following caution:
This product contains quartz, cristobalite, and/or tridymite which may become airborne without a visible cloud. Avoid breathing dust. Avoid creating dusty conditions. Use only with adequate ventilation to keep exposures below recommended exposure limits. Wear a NIOSH certified, European Standard EN 149, or equivalent respirator when using this product.
Source: Halliburton MSDS sheet for Frac Sand.
Silica Exposure & Silicosis Risk to Workers
Workers who are exposed to high levels of respirable crystalline silica may be at risk for silicosis, an occupational lung disease. Symptoms may take years to develop and include inflamed lungs, severe shortness of breath, cough, fever, and weight loss. Scarring lesions reduce the lung’s oxygen intake ability, and can result in susceptibility to tuberculosis, chronic bronchitis and even death in acute cases. Silicosis has no cure. A silicosis damaged section of a lung is shown below and is compared to a healthy lung.
Based on their field studies, NIOSH, together with OSHA, the U.S. Department of Labor's Occupational Safety and Health Administration, have issued an alert regarding fracking sand.
Regulatory Action and Oil & Gas Operator Recommendations
NIOSH reported their findings to hydraulic fracturing operators, along with recommendations as to site evaluation and control of crystalline silica exposure. Those measures included effective respiratory protection program, dust reduction through capping unused sand mover fill ports and nozzles, reduce the drop height between the sand transfer belt and T-belts and blender hoppers close the thief hatches, substitution of silica sand with ceramic, fresh water application around well sites and limiting time spent by workers in dusty areas. Other recommended practices include enclosure of dust release areas and use of installed dust collection and ventilation systems.
If silica dust exposure levels have been determined to be a workplace hazard at a given site, OSHA 29 CFR 1910.134 Respiratory Protection Standard requires that employers provide correct, NIOSH-approved respirators as well as respirator fit testing, training and medical evaluations. Basic respirator guidelines include use of an N95 NIOSH-certified respirator for crystalline silica airborne exposures at concentrations less than or equal to 0.5 milligrams per cubic meter of air (mg/m3). Silica levels exceeding 0.5 mg/m3 require use of a full-face piece respirator that provides protection for up to 2.5 milligrams per cubic meter of air (mg/m3).
For additional protection and comfort, a PAPR equipped with high-efficiency filters and tightfitting face piece may also be used within concentrations of up to 2.5 mg/m3. When working within environments with concentrations of up to 25 mg/m3, a supplied-air respirator in pressure-demand or positive-pressure mode may be used.
OSHA's Proposed Crystalline Silica Rule: Construction
OSHA is proposing two standards to protect workers from exposure to respirable crystalline silica-one for construction, and the other for general industry and maritime-in order to allow employers to tailor solutions to the conditions in their workplaces. The final silica standard is expected in 2016, after the recent hearings on the proposed rule are reviewed by OSHA.
About 1.85 million workers are currently exposed to respirable crystalline silica in construction workplaces. Over 640,000 of these workers are estimated to be exposed to silica levels that exceed OSHA's proposed permissible exposure limit (PEL).
These exposures occur during common construction operations such as: Using masonry saws; using hand-operated grinders; tuckpointing; using jackhammers; using rotary hammers or drills; operating vehicle-mounted drilling rigs; milling; rock crushing; drywall finishing using silica-containing material; and use of heavy equipment during earthmoving. As was stated above, the NIOSH field investigation revealed some critical exposure issues facing the fracking industry. The proposed rule is expected to save nearly 700 lives and prevent 1,600 new cases of silicosis per year once the full effects of the rule are realized. Of these, over 560 lives would be saved and about 1,080 cases of silicosis would be prevented among construction workers.
Major Provisions of the Proposed Construction Standard
The proposed standard for construction includes provisions for employers to:
• Measure the amount of silica that workers are exposed to if it may be at or above an action level of 25 μg/m3(micrograms of silica per cubic meter of air), averaged over an 8-hour day;
• Protect workers from respirable crystalline silica exposures above the PEL of 50 μg/m3, averaged over an 8-hour day;
• Limit workers' access to areas where they could be exposed above the PEL;
• Use dust controls to protect workers from silica exposures above the PEL;
• Provide respirators to workers when dust controls cannot limit exposures to the PEL;
• Offer medical exams-including chest X-rays and lung function tests-every three years for workers exposed above the PEL for 30 or more days per year;
• Train workers on work operations that result in silica exposure and ways to limit exposure; and
• Keep records of workers' silica exposure and medical exams.
As of today’s blog, the oil & gas producers are vehemently lobbying to exempt them from these new rules or not to issue any more rules. Dust control, especially at the low levels of exposure recommended by OSHA is challenging and complex. Workers Compensation insurers be aware.
Allen Schultz, a retired foundry worker and United Steelworkers union member from Waukesha, Wis., says he saw employers try to bypass even the 40-year-old standards. “One time the company hired an outside company of furnace repair experts to teach our workers how to do a better job of removal and rebuild. They had their people in white plastic airtight suits, gloves and booties with forced, filtered clean air into their helmets,” Schultz said in written testimony.
“They built an airtight overpressure clear plastic room where they would put their outfits on and off. They were working next to our workers who were white with dust everywhere from the jackhammers and the tamping machinery and, maybe, a damp sweaty respirator hanging around their necks. They weren't hired back again. I don't think the company liked our guys seeing all the safety precautions their people had to take.”
And the lack of control took its toll, Schultz said. “It became apparent that many of our senior guys were suffering breathing problems. Many were dying around the time of their 25 years either just before or after they retired,” Schultz testified during the hearings on the proposed OSHA rule.
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