Open Trench Failures Continue to Rise
Are Municipalities Neglecting Safer Trenchless Alternatives?
Construction worker Jose Gonzalez was killed while working
on a sewer project in Gilbert, Ariz., on June 21, 2001. The open trench he was
working in collapsed, burying him alive. Another co-worker was severely injured
in the accident. A similar death occurred in Scottsdale, Ariz., just weeks
Unfortunately, this scenario is not uncommon. Despite the
fact that hundreds of people are killed and severely injured in open-trenching
accidents throughout the United States every year, most municipalities continue
to award construction contracts to companies utilizing open-trench methods,
when safer trenchless technology is available to them.
The Occupational Safety and Health Administration (OSHA)
rates water, sewer and pipeline construction, essentially open-trench work, as
the fourth most deadly occupation in the United States for the period
1999–2000. This information is per the 2001 OSHA Industry Profile report
on occupational fatalities, injuries, safety violations and assessed penalties
for the prior 12-month period.
OSHA has been keenly aware of the high death rate associated
with open-trenching since 1973 and the difficulty gaining compliance from
trenching contractors to OSHA safety regulations. In a special report issued by
the Administration in 1985 specifically regarding open-trench safety violations
OSHA stated, “Trenching work creates hazards to workers that are
extremely dangerous. Although it would be expected that, after more than 12
years of enforcement activity, most employers would be adhering to shoring and
sloping requirements, experience has shown that such is not the case.
Compliance with OSHA construction standards applicable to such operations is
The OSHA report further states, “Because of the
continuing incidence of trench collapses and accompanying loss of life, the
agency has determined that an increased OSHA enforcement presence at worksites
where such operations are being conducted is warranted.”
Despite the increased OSHA emphasis on safety standards
enforcement in the mid-80s, open-trenching contractors continued to dominate
the construction industry in OSHA standards violations. In a 1995 OSHA report
listing the 100 most frequently cited OSHA construction safety violations,
open-trenching rated in the top five.
Since then, the situation has not improved. Following the
recent open-trenching death in Gilbert, Ariz., a senior OSHA spokesperson for
the state noted that open-trenching fatality incidents are rising. According to
the 2001 OSHA Industry report,
has the highest number of OSHA safety violations of all heavy construction
industries for the period 1999–2000,
highest number of safety violations in the utility, communications and power
line construction industries for this period, and
highest number of violations of all U.S. occupations for non-compliance to OSHA
safety training and education requirements.
Further, open-trenching leads all of the above categories in
dollar-volume of assessed penalties by OSHA.
OSHA statistics demonstrate that open-trenching is one of
the most hazardous and deadly occupations in the United States, largely because
of trenching contractor's non-compliance to OSHA safety standards. Another
factor is that the open-trenching process is inherently unstable. Excavated
soil stockpiled on the edge of a trench increases the pressure to trench walls.
Vibrations from nearby excavation equipment such as backhoes increase the
likelihood of a cave-in. Even trench wall sloping, shoring and worker shielding
offers only limited protection when collapsing soil can weigh more than a ton
per cubic yard. Most trenching deaths and serious injuries result from
cave-ins, toxic fumes, drowning, electrocution and explosions.
The question is why are not more municipalities turning to
trenching alternatives that avoid many of its inherent dangers? The
technologies exist, with a proven track record not only for safety, but also
for cost savings. Many of these technologies for trenchless construction have
already been adopted outside the U.S. In parts of the world such as Japan and
Germany, trenchless construction is utilized due to the heavy urbanization and
the impact open trenching causes.
Microtunneling and soil piercing pilot tubes are two
existing trenchless methods that are gathering support. A microtunneling
pipeline installation involves microtunneling excavation, a subterranean,
unmanned tunneling method that uses a laser-guided “mole” to lead
the way for sewer pipe installation through sections of soil spanning 300 to
500 ft. The only excavations on the surface of the ground are construction pits
located at either end of a pipeline section. The pipes are precisely pushed
through the soil from one pit to the other. In new sewer pipe systems, an auger
is used to perform the tunneling.
The process of installing a sewer using pilot tube
technology is similar to the microtunneling process, especially when clay pipe
is used. Since 1992, NO-DIG (a company specializing in trenchless technology)
has installed more than 220,000 linear feet of pipe using microtunneling
Today, more and more municipalities throughout the United
States are specifying that contractors use trenchless technologies that are
inherently safer and accrue substantially less liability. As an increasing
number of local governments are becoming self-insured, interest in using safer
methods is becoming more prevalent.
The Oregon Department of Transportation even has a
trenchless technology expert to help employees and contractors keep current
with new techniques that can eliminate the need to excavate. The department
saved a total of $1.5 million on six recent trenchless projects, according to
the Portland, Ore., Daily Journal of Commerce.
Yet, incidents such as the Gilbert cave-in remain a tragic reminder
that trenching is dangerous, despite all of OSHA’s efforts. While not a
panacea, trenchless technology has come of age and deserves a closer look by
both municipalities and the contractors they employ.