PRECAUTIONS MUST BE TAKEN TO ENSURE EARTH WALLS IN
EXCAVATIONS DON'T COLLAPSE: SAFETY OFFICIALS
Most excavators know that the walls of holes dug in
the ground will collapse if the proper precautions are
not taken, but provincial government officials point
out that problems still occur frequently enough that
fire departments across Manitoba have specially
trained personnel to rescue people when excavations
give way.
Workplace Safety and Health officials suggest that
a majority of commercial excavators have experience in
trench shoring, have some training in safe excavating
and know the unpredictability of what appears to be a
stable wall of earth. However, officials stress that
farmers and others who choose to do the work
themselves should not attempt the task without the
critical understanding of the hazards associated with
the job.
The consequences of an excavation collapse are
often tragic, said Dr. Ted Redekop, chief occupational
medical officer for the Workplace Safety and Health
Division. "Even being partially covered by a collapse
of earth may be life threatening. The pressure of the
earth on the body will divert blood from the covered
area, overloading the lungs and heart. The release of
the pressure when the victim is freed may result in
shock from the blood rushing to body parts that were
previously drained."
The experts agree that the rules regarding
prevention of personal injuries and damage to
equipment are quite straightforward. However, the
following general considerations must be adjusted to
suit local conditions which may vary depending on
rain, soil type and other nearby activities.
* Never enter any excavation deeper than 1.5 metres
(4.5 feet) unless
it is shored with materials capable of supporting
the thousands of tonnes of force on the wall face.
* If shoring is not possible, vee out the trench or
excavation at
approximately 45 degrees so that no point at the
bottom of the excavation has a vertical wall greater
than 1.5 metres.
* Most importantly, remember additional weight near
the edge of a
un-shored excavation (even a person standing on the
edge) increases the load on the wall of the excavation
and greatly increases the potential for the wall to
collapse. The earth that is removed from the
excavation must not be piled closer than one metre
(three feet) to the nearest cut face of the
excavation.
The Workplace Safety and Health Division has a
guidance document of accepted procedures for preparing
an excavation for workers to enter safely. It was
developed by experts in the excavation industry and
based on experience and science. Copies of the
guidelines can be obtained by contacting the division
at 200 - 401 York Ave., Winnipeg, MB R3C 0P8, by
telephoning 204-945-2315 (toll free at 1-800-282-8069,
ext. 3446), or by visiting the Web site at:
<http://www.gov.mb.ca/labour/safety/pdf/excavaguide.pdf >.
Contact: Glen Blahey, 204-945-2315
This is the ninth in a series of news releases on
agricultural safety and health produced by the
provincial farm safety co-ordinator who administers a
program that assists Manitoba's agricultural community
in the development of safer practices to achieve
greater sustainability.
