C A S E Y I N D U S T R I A L
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E X C AVAT I O N & T R E N C H I N G
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C A S E Y I N D U S T R I A L
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W H AT I S E X C AVAT I O N & T R E N C H I N G ?
Excavation: OSHA defines as “any man-made cut,
cavity, trench, or depression in an earth surface
formed by earth removal.”
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According to this definition, all trenches are
excavations , but not all excavations are trenches.
The specific safety requirements for trenches
depend on the depth of the trench.
Trenching: is a type of narrow excavation in which
the depth is typically greater than the width which
does not exceed 15 ft.
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TRENCHES
Trenches 5 feet to 19 feet: OSHA explains that
any trench other than those made of stable rock
exceeding 5 feet in depth must have a protective
system in place. The protective system must be
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implemented by a competent person
Trenches 20 feet and deeper: A registered
professional engineer must implement a
protective system for any trench exceeding 20
feet in depth as required by OSHA
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CASEY POLICY ON TRENCHING
General
General Requirements
Requirements
1. BeforeIngress
beginning
andanegress
excavation
means or "entry"
trench,andutility
"exit,"
companies,
respectively.
the In
senior
trenching
company
and representative
excavation operations,
and/or owner
they shall
be contacted
referand
to the
advised
provision
of theofproposed
safe meanswork.forThis
employees
is necessary
to enter
to ordetermine
exit an excavation
the locations
or trench.
of underground
installations (sewer,
1. Trenches
telephone,
4 ft orcable,
morewater,
in depth
fuel,
shall beelectric,
provided and
withgasalines).
means of egress.
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2. Any overhead 2. Spacing
hazards present
betweenshallladders
be assessed
or other and
meansdealt
of with
egressat shall
this time.
be such a worker will not have to
3. All opentravel
trenches/excavations
more than 25 ft. laterally
shall be tobarricaded
the nearestor otherwise
means protected
of egress.when actual work is not being done.
4. All trenches/excavations
3. Ladders shall
shall
bebesecured
inspected
and atextend
the end
a minimum
of each shift
of 36 to in
assure
(0.9 m)
open-trench
above thehazards
landing.have been addressed.
5. Employees shall
4. Metal
not ladders
enter theshall
working
not bearea
used.
of trenching equipment operations without first notifying the operator.
Operators for trenching operations shall cease operation for as long as any employee is required to be within reach of
the equipment.
6. Bridges or walkways used for crossing trenches/excavations shall be properly designed and maintained.
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H A Z A R D S I N E X C AVAT I O N / T R E N C H I N G
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Trenching and excavation work presents serious
hazards to all workers involved. Cave-ins pose the
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greatest risk and are more likely than some other
excavation-related incidents to result in worker
fatalities. One cubic yard of soil can weigh as much as
a car
Other potential hazards associated with trenching
work include falling loads, hazardous atmospheres,
and hazards from mobile equipment
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H A Z A R D S I N E X C AVAT I O N / T R E N C H I N G
SOIL CLASSIFICATIONS:
Stable Rock - A stable rock formation is Type B Soil - Commonly including angular gravel, silt, and
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normally a solid mineral or material that can be sandy loam, type B soil is somewhat cohesive but has a lower
excavated with side walls that are vertical.
compressive strength than a Type A. As the case with Type A
Additionally, soil that is rock will remain intact
and not fall apart when exposed to the weather soil, any previously disturbed Type B soil drops a category to
Type C because of the changes in soil characteristics
Type A Soil - The next most stable type of soil, Type C Soil - Often referred to as “plain” or “farmers” dirt,
Type A, is normally defined as a clay or sandy Type C usually has some combination of loose gravel, sand, or
clay soil. It is stable and holds up well when
loam; sometimes with water leaching from it. Type C soil can
exposed to the elements. Type A soil is
cohesive in nature but does not contain any be cohesive but breaks down easily when exposed to the
fissures. Lastly, Type A soil cannot be subjected weather. This is the most dangerous type of soil for trenching
to vibration from heavy traffic, or have been operations because it is the weakest and requires that the most
previously disturbed or dug stringent protective measures.
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SOIL TESTING
During earthwork and/or trenching operations, both a
visual test and a manual test must be performed by a
competent person, unless the visual test determines
that soil is Type C
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There are five accepted manual tests that are used
in excavations. The first three tests do not use any
instruments, only your hands. The last two
generate actual measured readings
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SOIL TESTING
Plasticity Test – A moist soil sample is taken from the area being
excavated, and molded/formed into a ball. The ball is then rolled
between your hands until it becomes the shape of a dirt “snake”,
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about 1/8” wide. A two (2) inch sample of the “snake” is broken-
off and held by one end. If the soil holds together, the soil is
considered cohesive
Dry Strength Test - A soil sample is taken and attempted to be
crushed in one’s hands. If the soil crumbles on its own, the soil
is granular. If the soil sticks together in smaller, stiff clumps, it
is most likely comprised of clay. If the dry soil breaks into
clumps, and there is no evidence of fissures, the soil may be
considered to be un-fissured soil
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SOIL TESTING
Pocket
Thumb Penetrometer
Penetration TestTest – In– the
Thisindustry,
instrument
this test
test is
is anot
simple
viewed
method
as the most
usedaccurate
to measure method the compression
of testing thestrength
soil, butofit exposed
is accepted,
trench
nonetheless.
soil. TheAn penetrometer
area of undisturbed has a rod
soilthat
is located,
when pressed
and theinto
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the
competent
wall of person
a trenchattempts
generates to apress
reading.
his extended
The measurements
thumb into the
generated
soil. If it isindicate
very difficult
the compressive
to penetratestrength
the soil,and
thetype
soil of
would
the be
soil:
considered Type A. If the thumb penetrates no further than the
Type
lengthA:of1.50
a fingernail,
tsf or greater
it is probably Type B. If the thumb
Type
penetrates
B: 1.50 easily
- 0.50
intotsfthe soil, then the soil is Type C
Type C: 0.50 tsf or less tsf - tons per square foot
Hand-Operated Shear vane - A shear vane is another
direct reading instrument to determine the unconfined
compression strength of soils. This instrument is pressed
into the vane of a soil and rotated. The soil strength can
then be read directly on the wheel of the device
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SOIL TESTING
Once the competent person has properly analyzed the soil and a
determination as to what the soil type is, then the best method to protect the
workers from an excavation collapse can be determined
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S A F E P R A C T I C E S F O R E X C AVAT I O N
( S U M M A RY )
1. Inspect trenches daily before work begins. Don’t go near an unprotected trench.
2. Check weather conditions before work, be mindful of rain and storms.
3. Keep heavy equipment away from trench edges.
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4. Be mindful of the location of utilities underground.
5. Always wear proper protective equipment.
6. Don’t work beneath raised loads.
7. Conduct atmosphere tests. If low oxygen and toxic gases were detected, workers must not
enter the trench.
8. Protective systems like benching, sloping, shoring and shielding must be created.
9. Planning and implementation of safety measures must be done by a competent person.
10. Use a checklist to perform regular self inspections – download free excavation safety
checklists here.
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E X C AVAT I O N & T R E N C H I N G
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QUESTIONS ???
