The South Arkansas STEPS meeting on April 5 at Bonanza Creek in Magnolia featured a presentation on trenching and excavation from Brian Monistere, with Professional Safety Services, based in Mississippi.

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Trench Safety Course
Excavation Safety
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q The death rate for a trench
related incident is 2 1/2 times greater
than for any other construction related event!
q It is estimated that there are more than 10,000
entrapments each year. (About 10% of which
result in lost-time” injuries)
Hazards of Trenching

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Trench Deaths and Injuries
❑ Conservative estimates put the number
of deaths from cave-ins at near 100 per
year!
❑ Additionally, another 100 persons are
permanently disabled and cannot return
to work!
❑ Nearly 200 more are injured to the extent
that they cannot perform the same duties
and must be retrained!
4
Law of Effect
Current Behavior (CB) = Current Situation (CS)
+ Past Experience (PE)
CB = CS + PE
Unsafe = In Hurry + No prior
Trench Resources incidents

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Cave-in
The separation and movement of soil into
an excavation:
q Either by falling or sliding
q In sufficient quantities
that it could:
◆ Immobilize
◆ Entrap
◆ Injure
◆ Bury
How Quickly do Cave-ins Occur?
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Post- Fatality / Injury Inspection
After the fact inspections are the most difficult for a
contractor to defend against because:
A highly predictable, preventable event has occurred.
q PREDICTABLE: There are no permanently vertical
soil or rock walls found in nature!
q PREVENTABLE: There are MEANS (equipment) or
METHODS (work processes) available which will
prevent worker exposure.
CONCLUSION: Cave-ins are not accidents!
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4.5 Deep Trench
Would you
put shoring
in this
trench?

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Weights of Materials
§ Dry Sand=80-90 lbs.
§ Dry Clay=85-90 lbs.
§ Wet Clay=110-125 lbs.
§ Wet Mud, =120-125 lbs.
§ Limestone=160 lbs.
§ Granite=165 lbs.
Weights of Soils (Averages)
What Causes the Cave-In?

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Common Sense ?
This pipe repair in
Pittsburgh in the
winter of 1997 was
completed without
the benefit of any
shoring!

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Leadership Role
A safety Officer for
a major N.W. city
only needed to be
in the trench for a
few minutes!
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This backhoe operator is
having second thoughts
about the days events
which resulted in the
death of the company
owner!
North Carolina Tragedy

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Excavation Site Hazards
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Do Not Leave Protected Area

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Albuquerque New Mexico
An employee died
in this moist
sand trench!
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A Life Cut Short
Shoring had not
been installed
so that the job
could progress
faster!

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Improper Access-Egress
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Double Fatality

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The owner and his two
employees all claimed that
this excavation was sloped
and less than 5 in depth
when confronted by the
compliance officer.
Water Park Trench Collapse
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Water Park Trench Collapse!
Two men were
trapped in this
trench as co-
workers and
rescuers worked
frantically to
extricate them!

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Improper Loading
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Spoil
Pile
Utility
Pole
Structures
Equipment
Surface Encumbrances

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Assess The Hazard Potential
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Broken Water Line

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Proper Use Of A System ?
Tabulated Data

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Manufacturers Tabulated Data
Should Address Every Anticipated Hazard
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The Affected Zone

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Mobile Equipment At Excavations
USE:
Mechanical Signals
Hand Signals
Barricades
Stop logs
To prevent entry into the excavation
Rescue Planning
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End
General Requirements