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WHITE PAPER
THE DIRT ON SAFE DIGGING
Take Safety to
Mach 2 with an
Air-Powered
Excavation Tool
When it comes to underground utility lines, what you
can’t see can hurt you. The Common Ground Alliance,
an association that promotes efforts to reduce damage
to underground infrastructure, estimates that there are
more than 20 million miles of gas, electric, water, sewer
and telecommunication lines buried underground in the
United States. That’s the equivalent of more than one
football eld’s length of buried utilities for every man,
woman and child in the nation.
1
Digging without knowing the approximate location of
underground utilities can lead to injuries and fatalities,
property damage, service disruptions and costly repairs.
Consequently, utility companies and contractors go to
great lengths to ensure that their employees are taking
the necessary safety precautions when working around
underground utility infrastructure.
Still, incidents continue to occur. According to the
U.S. Department of Transportation, there were 1,815
pipeline incidents caused by excavation damage
between 1988 and 2014. These incidents resulted in
193 deaths, 757 injuries and nearly $545 million in
property damage.2
1 Common Ground Alliance, http://call811.com/before-you-dig/risk-reduction
2 Stacy Cummings, “Do You Know What’s Below? Call 811 Before You Dig!”,
U.S. Depar tment of Transportation “Fast Lane” blog, Aug. 6, 2015, https://www.
transportation.gov/fastlane/national-811-day-2015
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Among the incidents involving underground utility strikes
in recent years:
• OnJune7,2010,atruck-mountedpowerauger
struck and punctured a 36-inch-diameter natural gas
transmission line near Cleburne, Texas. The operator
was using the auger truck to dig holes for the
installation of new electric-service utility poles. The
natural gas ignited and killed the auger operator and
burned six workers. The total property damage and
cleanup costs were estimated to be over $1 million.3
• OnAugust20,2014,a38-year-oldworkerin
Edmonds, Wash., died when the jackhammer he was
using struck a 7,200-volt underground power line.
On the day of the incident, the worker and two other
employees were digging trenches and installing storm
drains on a hospital campus. According to a news
report, the incident temporarily cut power to the
hospital and to some residents in the surrounding
area. The Washington State Department of Labor
& Industries levied over $50,000 in nes to two
contractors for safety violations related to the fatal
accident.
4
• OnNovember20,2006,acableTVtechnicianon
a routine service call at a home in Huntington, Ind.,
inadvertently drove a grounding rod through a natural
gas pipeline. Gas began escaping from the pipeline,
and the technician notied the local gas company.
A responder from the gas company arrived quickly.
However, within minutes of his arrival, the house
exploded, killing the responder as well as a resident of
the home.5
Call Before You Dig
To prevent accidental utility-line
strikes, every state requires
professional excavators and
homeowners to call 811 at
least two days before digging.
The 811 operator will
connect the caller with his
or her state’s one-call center,
which will ask for information
about the location of the
intended dig and then contact
the companies that might
operate underground utilities in
that location. By law, the companies
must determine if their underground
utilities could be affected by the excavation,
and if so, they must mark the exact location of their
utilities with ags or paint.
The Department of Transportation and the Federal
Communications Commission launched 811 in 2007,
establishing a toll-free nationwide hotline that replaced a
patchwork of numbers that had been used to connect to
one-call centers for utility-locate requests. According to
the Common Ground Alliance, when excavators call 811
prior to digging, there’s a less than 1 percent chance of
striking a buried utility line.6
As part of its effort to promote the 811 hotline, the
Department of Transportation has created a video
that references the fatal 2006 accident in which a cable
TVtechnicianaccidentallypuncturedagaspipelinein
Huntington, Ind. The video notes that the cable technician
did not call 811 prior to digging, and the underground
utilities were not marked. The title of the video is: “A Call
to 811 Could Prevent a Call to 911.”
3 National Transportation Safety Board, pipeline accident brief, http://www.ntsb.
gov/investigations/AccidentReports/Reports/PAB1302.pdf
4 Washington State Department of Labor & Industr ies, http://www.lni.wa.gov/
safety/research/face/les/711362015laborerelectrocuted.pdf
5 Cynthia Quarterman, “An Easy Call to 811 Could Prevent a Call to 911,” U.S.
Department of Transportation “Fast Lane” blog, https://www.transportation.gov/
fastlane/easy-call-8-1-1-can-prevent-call-9-1-1
“If the ‘Call Before You Dig’ service had been used, my
dad would still be here today,” says Brandon Dalr ymple,
whose father, Alan, died in the 2006 explosion. “I have no
doubt about that.”
6 Common Ground Alliance, 2014 DIRT Report
7 U.S. Depar tment of Transportation, Pipeline and Hazardous Materials Safety
Administration, “Safe Digging Testimonial: A Call to 811 Could Prevent a Call to
911,”April21,2014,https://www.youtube.com/watch?v=_VaT0g-76bI#t=21
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Calling 811 Is Just the Start
While calling 811 is a critical rst step in any excavation
project, it’s just one element of a safe digging plan. OSHA
requires employers to protect their workers from injur y
on any job site, and the agency notes that excavation is
one of the most hazardous construction operations.8
In OSHA’s “Trenching and Excavation Safety” guide
issued in 2015, the agency notes that excavators can
“proceed with caution” if the affected utility companies
cannot respond within the time period required by state
or local law or cannot establish the exact location of
the underground installations. Proceeding with caution
includes “using detection equipment or other acceptable
means to locate utility installations,” the guide explains.
“Determine the exact location of underground
installations by safe and acceptable means when
excavation operations approach the approximate
location of the installations,” the OSHA guide says.9
A safe approach to excavating near underground utility
lines should include the use of digging equipment
that minimizes the risk of puncturing or damaging
underground pipes and cables, and minimizes the risk of
creating a spark in the presence of combustible gas. Also,
digging tools should feature insulated components to
protect workers from electric shock.
Chicopee, Mass.-based Guardair Corporation developed
the Utility AirSpade 4000 excavation tool with those
concerns in mind. Designed to safely uncover buried
utilities, the air-powered tool features an insulated
berglass barrel rated up to 300 kilovolts to provide
protection against electric shock, and a non-sparking
brass nozzle to eliminate sparking.
Rick Sweet, AirSpade Product Specialist, notes that
the Utility AirSpade 4000 is based on technology that
the military developed to uncover landmines and
unexploded ordnance – tasks that require the utmost
care and precision. Powered by a por table tow-behind
air compressor, the Utility AirSpade 4000 converts the
8 OSHA “Trenching and Excavation” Web page, https://www.osha.gov/SLTC/
trenchingexcavation/
9 OSHA, “Trenching and Excavation Safety” guide, 2015, https://www.osha.gov/
Publications/osha2226.pdf
THE HIDDEN COSTS – AND HAZARDS –
OF HOMEMADE EXCAVATION TOOLS
Employers in every industry
are under pressure to control
their operating costs. Utility
companies and contractors
are no exception. With air
compressors so common on job
sites, some work crews take it
upon themselves to fashion their
own air-powered excavation tool
out of spare parts – in hopes
of nding a cheaper alternative
to safe, commercially available
excavation products such as the
Utility AirSpade 4000.
People say, ‘All it’s doing is
blowing air so I’ll make one
of my own for $50,’” explains
Rick Sweet, AirSpade Product
Specialist. “So they’ll take a piece
of pipe, put a ball valve on it,
attach it to an air compressor
and blow air.”
While it might be cheaper to
make a tool from spare parts
and materials, there are hidden
costs and hazards that should be
considered.
For example, a homemade
tool with a pipe nipple or
crimped orice functioning as
the nozzle disperses air in an
unfocused manner – making
it far less efcient and precise
than a commercially available
tool. Typically, air exiting from
a homemade nozzle diffuses
outward three to four times
wider than the air jet coming
from the Utility AirSpade’s
nozzle.
Conversely, the Utility AirSpade’s
patented, supersonic nozzle
turns compressed air into a
laser-like jet moving at Mach
2 – delivering signicantly more
kinetic energy and more focused
momentum. This tight blast of
air dislodges soil particles in a
fraction of a second, enabling
operators to do more work
in less time compared to a
homemade tool.
In addition to being inefcient
at digging, a homemade tool
lacks critical safety features such
as a dead-man trigger.
“If you drop the Utility AirSpade,
the dead-man trigger will release
and the air will stop owing,”
Sweet explains. “If you drop a
homemade tool, air will continue
to ow through it. Now you
have a safety hazard, because
you have a steel pipe whipping
around and blowing air.”
And unlike the Utility AirSpade
– which features a non-sparking
nozzle and connectors along with
an insulated, berglass barrel– a
homemade tool fashioned out of
a steel pipe or other metal parts
can create a risk of explosions
or electric shock when working
around buried gas or electric
installations.
While it might be tempting
to try to build a homemade
tool as a cheaper alternative
to commercially available
equipment, the risks outweigh
the temporary cost savings.
“If you hit a utility line, the
human and nancial costs can
be enormous,” Sweet says.
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power of compressed air into a laser-like jet moving at
nearly twice the speed of sound. By aiming the nozzle
at the surface to be excavated, and actuating the trigger,
the operator unleashes a tightly focused, supersonic air
jet that penetrates tiny voids in the soil and dislodges
particles in a fraction of a second.
“Air exiting the tool at Mach 2 has to go somewhere,”
Sweet explains. “So it goes into anything that has holes in
it. Soil – even clay – is porous. The Utility AirSpade forces
air into those pores and fractures the soil.”
Unlike the sharp edges of shovels, picks, blades and
buckets, the focused air jet from the Utility AirSpade
4000 is harmless to non-porous items such as
buried pipes, tree roots and underground utility lines.
Consequently, the tool is a safe alternative for a number
of excavation tasks, including utility locating, keyholing,
potholing, valve-box cleaning and cable trenching.
Protecting Workers and Infrastructure
For AGI Construction, a Smitheld, R.I.-based
underground-utility contractor, the possibility of an
explosion is a daily concern. AGI, which installs pipeline
for many of the major gas providers in the New England
region, is well-aware that digging around gas lines can
be dangerous for its crews, nearby residents and the
environment. The company makes safety a top priority
and a requirement on every job site.
In the past, AGI workers used shovels to locate and verify
the presence of buried utility lines – a process known as
“potholing.” After a crew accidentally damaged a buried
utility line (because the company received inaccurate
information about the location of the underground
infrastructure), AGI began looking for a safer and more
effective way to dig verication holes.
Soon after the incident, AGI equipped each of its work
crewswithaUtilityAirSpade4000.JamieCarpenter,
Director of Safety for AGI Construction, notes that
the AirSpade has become “a favorite tool among all
the crews,” as workers no longer have to worry about
damaging sensitive underground utility lines. And
because digging with the Utility AirSpade 4000 is two to
three times faster than shoveling, crews appreciate the
efciency gains as well.
“In the past, we did all our verication-hole digging
by hand, which was tough on our crew members,”
Carpenter says. “Not only does the AirSpade make for a
safer environment on the job, but it also makes life easier
for our crew members.”
Keeping Strains and Sprains at Bay
Explosions and electrocutions caused by accidental
utility-line strikes aren’t the only safety concerns for
excavators working around buried utility installations.
Because of the physical and repetitive nature of
excavation tasks, workers can be susceptible to
musculoskeletal disorders, which the Department of
Labor denes as injuries or disorders of the muscles,
nerves, tendons, joints, cartilage and spinal discs. In 2014,
musculoskeletal disorders accounted for 32 percent of all
job-related injuries and illnesses that required days away
from work in the United States, according to the most
recent data from the U.S. Bureau of Labor Statistics.
Excavation work also can lead to sprains, strains and
tears – the most common type of job-related injury
10 U.S. Bureau of Labor Statistics, “Nonfatal Occupational Injuries and Illnesses
Requiring Days Away from Work, 2014,” http://www.bls.gov/news.release/pdf/
osh2.pdf
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requiring days away from work across all industries
in 2014. According to the Bureau of Labor Statistics,
workers who suffered sprains, strains or tears required a
median of 10 days away from work in 2014.
To minimize operator discomfor t and fatigue, the Utility
AirSpade was designed with a lightweight, ergonomic
handle featuring a full-size grip opening to accommodate
protective gloves. The Utility AirSpade 4000 also has a
retractable stabilizer bar, enabling the user to operate the
tool with two hands, if desired.
“We developed the Utility AirSpade 4000 in conjunction
with utility companies and contractors so we could
11 U.S. Bureau of Labor Statistics, “Nonfatal Occupational Injuries and Illnesses
Requiring Days Away from Work, 2014,” http://www.bls.gov/news.release/pdf/
osh2.pdf
DANGER
BELOW
SAFE PRACTICES FOR EXCAVATION AND TRENCHING AROUND UTILITIES
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OSHA 1926 Subpart P spells out the safety requirements for excavation
and trenching operations. These include measures to protect workers from
cave-ins, falls, hazardous atmospheres and underground utility-line strikes.
OSHA’s 2015 “Trenching and Excavation Safety” guide
highlights key elements of the standard, and recommends
that employers emphasize the following safe work practices
to minimize the risk of injuries at excavation sites:
•Know where underground utilities are located before digging.
•Keep excavated soil (spoils) and other materials
at least 2 feet from trench edges.
•Keep heavy equipment away from trench edges.
•Identify any equipment or activities that could affect trench stability.
•Test for atmospheric hazards such as low oxygen, hazardous fumes
and toxic gases when workers are more than 4 feet deep.
•Inspect trenches at the start of each shift.
•Inspect trenches following a rainstorm or other water intrusion.
•Inspect trenches after any occurrence that could
have changed conditions in the trench.
•Do not work under suspended or raised loads and materials.
•Ensure that personnel wear high-visibility or other
suitable clothing when exposed to vehicular trafc.
address their specic needs and concerns,” Sweet
explains. “The non-sparking and insulated components
address their concerns about utility-line strikes, and the
ergonomic design makes it physically easier and safer
for the operator to use, with the goal of minimizing
musculoskeletal injuries.”
Because AGI crew members now use the Utility
AirSpade 4000 – instead of a shovel – to uncover buried
utility lines, Carpenter has seen fewer back sprains and
strains, among other injuries.
“Using shovels to de-compact soil, gravel, rocks and
roots put strain on employees’ backs,” Carpenter says.
“Switching to the Utility AirSpade 4000 has denitely
been a factor in reducing our injuries.”
In addition, Guardair Corporation urges utility companies and contractors to
follow these safety practices when operating the Utility AirSpade 4000:
•Wear appropriate personal protective equipment. This includes cut- and punctureresistant gloves, approved safety glasses with side shields and/or face protection, and
approved earplugs or earmuffs. Eye protection should comply with ANSI Z87.1-1989.
Ear protection should provide a noise-reduction rating of at least 20 decibels.
•Wear approved, electrically insulated footwear and gloves
if working near underground utility lines.
•Wear approved respiratory protection when working in extremely dusty conditions.
•Ensure that all personnel near the area being excavated are aware that the
tool is being used and that they wear appropriate PPE as indicated.
•Protect surfaces that could be chipped or damaged by dislodged
soil or rock particles adjacent to the excavation work area by
using suitable drop cloths, screens or other means.
•Check the tool for loose or damaged parts prior to use.
Tighten, repair and/or replace as necessary.
•Inspect hoses for leakage, kinking, abrasion, corrosion or any other signs of
wear or damage. Immediately replace worn or damaged hose assemblies.
•Check that the air compressor is delivering the specied pressure to operate the tool.
•When using the 45-degree adapter anticipate that the nozzle will
produce a force opposite in direction to the exiting compressed
air. Grip the barrel tightly and brace accordingly.
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