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.
To read
more, please use this link:
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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