study regrding trenching methods and rules which we need to know

methadologies

1. Excavation for Excavation for
ConstructionConstruction

2. Industries engaged in Industries engaged in
excavationexcavation

General contractorsGeneral contractors

Highway and Highway and
street construction street construction
contractorscontractors

Bridge and tunnel Bridge and tunnel
contractorscontractors
1a

3. Industries engaged in Industries engaged in
excavationexcavation

Water, sewer, pipeline Water, sewer, pipeline
contractorscontractors

Communication and Communication and
power line power line
contractorscontractors

Concrete worker Concrete worker
and well drilling and well drilling
contractorscontractors
1b

4. Hazards of excavation Hazards of excavation
workwork

Cave-insCave-ins

Underground Underground
utilitiesutilities

Materials/Materials/
equipment falling into equipment falling into
excavation sitesexcavation sites
2a

5. Hazards of excavation Hazards of excavation
workwork

Struck-by accidentsStruck-by accidents

AsphyxiationAsphyxiation

ExplosionsExplosions

FallsFalls
2b

6. Hazards of excavation Hazards of excavation
workwork

ElectrocutionsElectrocutions

DrowningDrowning
2c

7. Safety considerationsSafety considerations

Excavation is one of the most Excavation is one of the most
hazardous types of work in the hazardous types of work in the
construction industryconstruction industry

Accidents result Accidents result
from inadequate from inadequate
planningplanning

Build safety into Build safety into
pre-bid planningpre-bid planning
3a

8. Safety considerationsSafety considerations

Plan safety into the job. Plan safety into the job.
Consider:Consider:
•TrafficTraffic
•Nearness of structures Nearness of structures
and their and their
conditionsconditions
•SoilSoil
3b

9. Safety considerationsSafety considerations

Plan safety into the job. Plan safety into the job.
Consider:Consider:
•Surface and ground waterSurface and ground water
•Water tableWater table
•Overhead/Overhead/
underground underground
utilitiesutilities
•WeatherWeather
3c

10. Jobsite safety and Jobsite safety and
health programshealth programs

Establish and maintain a safety and Establish and maintain a safety and
health program for the worksitehealth program for the worksite

Provide adequate systematic Provide adequate systematic
policies, procedures, practicespolicies, procedures, practices

Recognize job-related safety/health Recognize job-related safety/health
hazardshazards
4a

11. Jobsite safety and Jobsite safety and
health programshealth programs

Safety and health programs should Safety and health programs should
reflect the unique characteristics of reflect the unique characteristics of
the jobsitethe jobsite

Proper implementation depends on Proper implementation depends on
cooperation among:cooperation among:
•supervisorssupervisors
•employee groupsemployee groups
•individual employeesindividual employees
4b

12. Jobsite safety and Jobsite safety and
health programshealth programs

Supervisors must understand Supervisors must understand
his/her degree of his/her degree of
responsibility/authorityresponsibility/authority

Get unions involvedGet unions involved
4c

13. Locating utilitiesLocating utilities

Employers must determine the Employers must determine the
estimated locations of utility estimated locations of utility
installationsinstallations

Contact utility Contact utility
companies before companies before
starting excavationstarting excavation

Utility owners must attempt to Utility owners must attempt to
find exact location of utilitiesfind exact location of utilities
5a

14. Locating utilitiesLocating utilities

Proceed with caution if the Proceed with caution if the
exact location of utilities cannot exact location of utilities cannot
be foundbe found

Use safe and Use safe and
acceptable means to acceptable means to
locate exact locations of locate exact locations of
installationsinstallations
5b

15. Safety starts at the Safety starts at the
surfacesurface

Surface encumbrances that create Surface encumbrances that create
hazards must be removed/supportedhazards must be removed/supported

Wear warning vests when near Wear warning vests when near
traffictraffic

Employees must be trained to Employees must be trained to
operate heavy equipmentoperate heavy equipment
6a

16. Safety starts at the Safety starts at the
surfacesurface

Stay away from loads being Stay away from loads being
handled by lifting/digging handled by lifting/digging
equipmentequipment

Stay away from vehicles being Stay away from vehicles being
loaded/unloadedloaded/unloaded
6b

17. Safety starts at the Safety starts at the
surfacesurface

Use barricades, hand or Use barricades, hand or
mechanical signals, stop logs to mechanical signals, stop logs to
keep operators safekeep operators safe
6c

18. Safety starts at the Safety starts at the
surfacesurface

Warn mobile equipment Warn mobile equipment
operators about the edge of the operators about the edge of the
excavation siteexcavation site

Keep the grade away from the Keep the grade away from the
excavation siteexcavation site
6d

19. Safety starts at the Safety starts at the
surfacesurface

Take care when walking near Take care when walking near
excavation sitesexcavation sites

Barricade or cover Barricade or cover
wells, pits, shaftswells, pits, shafts

Use appropriate Use appropriate
PPEPPE
6e

20. Protecting utilitiesProtecting utilities

Exact locations of utilities must Exact locations of utilities must
be determinedbe determined

Utilities must Utilities must
be exposed be exposed
before diggingbefore digging
7a

21. Protecting utilitiesProtecting utilities

Excavation sites must be Excavation sites must be
protected, supported to protected, supported to
safeguard safeguard
employeesemployees

Approach Approach
utility lines as utility lines as
if they are if they are
land minesland mines
7b

22. Employee access/egress Employee access/egress
from excavationsfrom excavations

Ramps must be designed by a Ramps must be designed by a
competent personcompetent person

Ramps must be structurally sound Ramps must be structurally sound
and not create a tripping hazardand not create a tripping hazard

Use surface treatments on ramps Use surface treatments on ramps
to prevent slippingto prevent slipping
8a

23. Employee access/egress Employee access/egress
from excavationsfrom excavations

Trenches 4 or more feet deep Trenches 4 or more feet deep
need a safe means of egressneed a safe means of egress
•StairwayStairway
•LadderLadder
•RampsRamps

Means of egress must be fixed Means of egress must be fixed
and secureand secure
8b

24. Employee access/egress Employee access/egress
from excavationsfrom excavations

Means of egress must be within Means of egress must be within
25 feet of workers25 feet of workers

Ladders must extend a minimum Ladders must extend a minimum
of 36 inches above the landingof 36 inches above the landing

Use metal ladders with caution Use metal ladders with caution
around utilitiesaround utilities
8c

25. Hazardous atmospheresHazardous atmospheres

ExplosiveExplosive

FlammableFlammable

PoisonousPoisonous

CorrosiveCorrosive
9a

26. Hazardous atmospheresHazardous atmospheres

OxidizingOxidizing

IrritatingIrritating

Oxygen Oxygen
deficientdeficient

ToxicToxic
9b

27. Hazardous atmospheresHazardous atmospheres

Operations inside an excavation Operations inside an excavation
can introduce a hazardous can introduce a hazardous
atmosphereatmosphere

Test the air of excavation sites Test the air of excavation sites
more than 4 feet deep before more than 4 feet deep before
enteringentering
9c

28. Hazardous atmospheresHazardous atmospheres

Take extra precautions when the Take extra precautions when the
atmosphere has:atmosphere has:
•less than 19.5 percent, or more than less than 19.5 percent, or more than
23.5 percent oxygen23.5 percent oxygen
•a combustible gas concentration greater a combustible gas concentration greater
than 20 percent of the lower flammable than 20 percent of the lower flammable
limitlimit
•concentrations of hazardous substances concentrations of hazardous substances
that exceed threshold limit valuesthat exceed threshold limit values
9d

29. Hazardous atmospheresHazardous atmospheres

Conduct all operations within Conduct all operations within
OSHA requirementsOSHA requirements

Regularly conduct atmospheric Regularly conduct atmospheric
testing if atmospheric hazards testing if atmospheric hazards
are presentare present
9e

30. Hazardous atmospheresHazardous atmospheres

Wear respiratory equipment Wear respiratory equipment
when requiredwhen required

Know the hazards of confined Know the hazards of confined
spacesspaces
9f

31. Emergency equipmentEmergency equipment

Emergency rescue equipment is Emergency rescue equipment is
required when there is a risk for required when there is a risk for
hazardous atmosphereshazardous atmospheres

Emergency rescue equipment Emergency rescue equipment
must be attended when in usemust be attended when in use
10a

32. Emergency equipmentEmergency equipment

Respirators must be suitable for Respirators must be suitable for
the type of exposurethe type of exposure

Independent lifelines must be Independent lifelines must be
provided when appropriateprovided when appropriate
10b

33. Water accumulation Water accumulation
hazardshazards

Employees are prohibited from Employees are prohibited from
entering excavation sites with entering excavation sites with
accumulated water unless accumulated water unless
adequate protection has been adequate protection has been
providedprovided
11a

34. Water accumulation Water accumulation
hazardshazards

Methods for controlling standing Methods for controlling standing
water include:water include:
•special support/shield systemsspecial support/shield systems
•water removal equipmentwater removal equipment
•safety harnesses and lifelinessafety harnesses and lifelines
11b

35. Water accumulation Water accumulation
hazardshazards

Workers should be prepared to Workers should be prepared to
leave excavation sites if control leave excavation sites if control
measures begin to failmeasures begin to fail

Use diversion ditches or dikes Use diversion ditches or dikes
to prevent surface water from to prevent surface water from
entering excavation sitesentering excavation sites
11c

36. Water accumulation Water accumulation
hazardshazards

Competent person inspects Competent person inspects
excavation sites subject to excavation sites subject to
water runoffwater runoff
11d

37. Protect structures next to Protect structures next to
excavation sitesexcavation sites

Use support systems to keep Use support systems to keep
nearby buildings, walls stablenearby buildings, walls stable
•ShoringShoring
•BracingBracing
•UnderpinningUnderpinning
12a

38. Protect structures next to Protect structures next to
excavation sitesexcavation sites

Excavation below the base of a Excavation below the base of a
footing or retaining wall is footing or retaining wall is
prohibited unless a support system prohibited unless a support system
is providedis provided

Excavations under Excavations under
sidewalks/pavements are prohibited sidewalks/pavements are prohibited
unless a support system is usedunless a support system is used
12b

39. Protect structures next to Protect structures next to
excavation sitesexcavation sites

Workers must be prepared to Workers must be prepared to
leave excavation sites if leave excavation sites if
support systems begin to failsupport systems begin to fail
12c

40. Loose rock and soil as Loose rock and soil as
hazardshazards

Prevent loose rock/soil from Prevent loose rock/soil from
falling onto employees in falling onto employees in
excavation sitesexcavation sites

Use barricades to Use barricades to
contain materialcontain material
13a

41. Loose rock and soil as Loose rock and soil as
hazardshazards

Keep surface materials at least Keep surface materials at least
2 feet from the edge of 2 feet from the edge of
excavation sitesexcavation sites

Keep employees Keep employees
off of sloped off of sloped
surfaces at levels surfaces at levels
above other above other
employeesemployees
13b

42. Protective systemsProtective systems

Excavations where employees Excavations where employees
are exposed to cave-ins must be are exposed to cave-ins must be
protected by:protected by:
•sloping or benchingsloping or benching
•support systemssupport systems
•shield systemsshield systems
•other protective other protective
systemssystems
14a

43. Protective systemsProtective systems

Protective systems are not Protective systems are not
needed if the excavation is:needed if the excavation is:
•made in stable rockmade in stable rock
•less than 5 feet deepless than 5 feet deep

Employers are free to choose Employers are free to choose
the most practical design the most practical design
approach for a particular approach for a particular
circumstancecircumstance
14b

44. Protective systemsProtective systems

Designing a protective system is Designing a protective system is
complexcomplex

Protective systems must be able Protective systems must be able
to resist all loadsto resist all loads

A competent person must examine A competent person must examine
protective systems’ materialsprotective systems’ materials
14c

45. Soil typesSoil types

Classify the soil type:Classify the soil type:
•Stable rockStable rock
•Type AType A
•Type BType B
•Type CType C
15a

46. Sloping and benchingSloping and benching

Slope the excavation’s sides to a Slope the excavation’s sides to a
safe anglesafe angle

Slope angle not be steeper than 1 Slope angle not be steeper than 1
1/2 horizontal to 1 or less vertical is 1/2 horizontal to 1 or less vertical is
safesafe

Soil classification may not be Soil classification may not be
needed if sloped to this angleneeded if sloped to this angle
16a

47. Sloping and benchingSloping and benching

Other slopes may be used for Other slopes may be used for
other soil typesother soil types

Benching systems excavate the Benching systems excavate the
sides of an excavation to form a sides of an excavation to form a
series of horizontal levels or series of horizontal levels or
stepssteps
16b

48. Sloping and benchingSloping and benching

Benching systems have vertical Benching systems have vertical
or near-vertical surfaces or near-vertical surfaces
between levelsbetween levels
16c

49. Support, shield, and Support, shield, and
protective systemsprotective systems

Shoring systems support the Shoring systems support the
sides of the excavation with:sides of the excavation with:
•timbertimber
•aluminumaluminum
•hydraulic, hydraulic,
pneumatic, or pneumatic, or
mechanical mechanical
systemssystems
17a

50. Support, shield, and Support, shield, and
protective systemsprotective systems

Shoring systems are made up of Shoring systems are made up of
cross braces, wales, and cross braces, wales, and
uprightsuprights

Selection and Selection and
design involves design involves
using tabulated using tabulated
datadata
17b

51. Precautions when Precautions when
protective systems are protective systems are
being installedbeing installed

Securely connect members of Securely connect members of
support systemssupport systems

Safely install support systemsSafely install support systems

Never overload members of Never overload members of
support systemssupport systems
18a

52. 
Install other structural members Install other structural members
to carry loads when temporary to carry loads when temporary
removal of members is necessaryremoval of members is necessary

The installation of support The installation of support
systems must be closely systems must be closely
coordinated with the excavation coordinated with the excavation
processprocess
18b
Precautions when Precautions when
protective systems are protective systems are
being installedbeing installed

53. Daily inspectionsDaily inspections

Inspect excavations for Inspect excavations for
possible:possible:
•cave-inscave-ins
•failure of protective systemsfailure of protective systems
•hazardous atmosphereshazardous atmospheres
•other hazardous conditionsother hazardous conditions
19a

54. Trench failureTrench failure

Recognize hazardous conditionsRecognize hazardous conditions

Sudden changes can mean Sudden changes can mean
disasterdisaster
20a

55. Trench failureTrench failure

Things that can cause Things that can cause
immediate change include:immediate change include:
•bulldozers coming too close to the bulldozers coming too close to the
trenchtrench
•a sudden downpoura sudden downpour
•striking an underground utility linestriking an underground utility line
20b

56. Trench failureTrench failure

Tension cracks can cause Tension cracks can cause
sliding, sluffing, or topplingsliding, sluffing, or toppling

Unsupported excavation can Unsupported excavation can
cause bulging in the vertical cause bulging in the vertical
faceface
20c

57. Trench failureTrench failure

Downward pressure can cause Downward pressure can cause
bottom heaving or squeezingbottom heaving or squeezing

Upward water flow can cause Upward water flow can cause
boiling in the bottom of the boiling in the bottom of the
excavationexcavation
20d