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Excavation for Excavation for ConstructionConstruction
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
Industries engaged in Industries engaged in excavationexcavation
Water, sewer, pipeline contractorsWater, sewer, pipeline contractors
Communication and Communication and power line power line contractorscontractors
Concrete worker Concrete worker and well drilling and well drilling contractorscontractors
1b
Hazards of excavation Hazards of excavation workwork
Cave-insCave-ins
Underground Underground utilitiesutilities
Materials/Materials/equipment falling into excavation equipment falling into excavation sitessites
2a
Hazards of excavation Hazards of excavation workwork
Struck-by accidentsStruck-by accidents
AsphyxiationAsphyxiation
ExplosionsExplosions
FallsFalls
2b
Hazards of excavation Hazards of excavation workwork
ElectrocutionsElectrocutions
DrowningDrowning
2c
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
Safety considerationsSafety considerations
Plan safety into the job. Consider:Plan safety into the job. Consider:• TrafficTraffic• Nearness of structures Nearness of structures
and their and their conditionsconditions
• SoilSoil
3b
Safety considerationsSafety considerations
Plan safety into the job. Consider:Plan safety into the job. Consider:• Surface and ground waterSurface and ground water• Water tableWater table• Overhead/Overhead/
underground underground utilitiesutilities
• WeatherWeather
3c
Jobsite safety and health Jobsite safety and health programsprograms
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
Jobsite safety and health Jobsite safety and health programsprograms
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
Jobsite safety and health Jobsite safety and health programsprograms
Supervisors must understand Supervisors must understand his/her degree of his/her degree of responsibility/authorityresponsibility/authority
Get unions involvedGet unions involved
4c
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 find Utility owners must attempt to find exact location of utilitiesexact location of utilities
5a
Locating utilitiesLocating utilities
Proceed with caution if the exact Proceed with caution if the exact location of utilities cannot be foundlocation of utilities cannot be found
Use safe and Use safe and acceptable means to acceptable means to locate exact locations of locate exact locations of installationsinstallations
5b
Safety starts at the Safety starts at the surfacesurface
Surface encumbrances that create Surface encumbrances that create hazards must be hazards must be removed/supportedremoved/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
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
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
Safety starts at the Safety starts at the surfacesurface
Warn mobile equipment operators Warn mobile equipment operators about the edge of the excavation about the edge of the excavation sitesite
Keep the grade away from the Keep the grade away from the excavation siteexcavation site
6d
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
Protecting utilitiesProtecting utilities
Exact locations of utilities must be Exact locations of utilities must be determineddetermined
Utilities must Utilities must be exposed be exposed before diggingbefore digging
7a
Protecting utilitiesProtecting utilities
Excavation sites must be Excavation sites must be protected, supported to safeguard protected, supported to safeguard employeesemployees
Approach Approach utility lines as utility lines as if they are if they are land minesland mines
7b
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
Employee access/egress Employee access/egress from excavationsfrom excavations
Trenches 4 or more feet deep need Trenches 4 or more feet deep need a safe means of egressa safe means of egress• StairwayStairway• LadderLadder• RampsRamps
Means of egress must be fixed and Means of egress must be fixed and securesecure
8b
Employee access/egress Employee access/egress from excavationsfrom excavations
Means of egress must be within 25 Means of egress must be within 25 feet of workersfeet 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
Hazardous atmospheresHazardous atmospheres
ExplosiveExplosive
FlammableFlammable
PoisonousPoisonous
CorrosiveCorrosive
9a
Hazardous atmospheresHazardous atmospheres
OxidizingOxidizing
IrritatingIrritating
Oxygen Oxygen deficientdeficient
ToxicToxic
9b
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
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 a combustible gas concentration
greater than 20 percent of the lower greater than 20 percent of the lower flammable limitflammable limit
• concentrations of hazardous substances concentrations of hazardous substances that exceed threshold limit valuesthat exceed threshold limit values
9d
Hazardous atmospheresHazardous atmospheres
Conduct all operations within OSHA Conduct all operations within OSHA requirementsrequirements
Regularly conduct atmospheric Regularly conduct atmospheric testing if atmospheric hazards are testing if atmospheric hazards are presentpresent
9e
Hazardous atmospheresHazardous atmospheres
Wear respiratory equipment when Wear respiratory equipment when requiredrequired
Know the hazards of confined Know the hazards of confined spacesspaces
9f
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
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
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
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
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 to Use diversion ditches or dikes to prevent surface water from prevent surface water from entering excavation sitesentering excavation sites
11c
Water accumulation Water accumulation hazardshazards
Competent person inspects Competent person inspects excavation sites subject to water excavation sites subject to water runoffrunoff
11d
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
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 prohibited footing or retaining wall is prohibited unless a support system is providedunless a support system is 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
Protect structures next to Protect structures next to excavation sitesexcavation sites
Workers must be prepared to leave Workers must be prepared to leave excavation sites if support systems excavation sites if support systems begin to failbegin to fail
12c
Loose rock and soil as Loose rock and soil as hazardshazards
Prevent loose rock/soil from falling Prevent loose rock/soil from falling onto employees in excavation sitesonto employees in excavation sites
Use barricades to Use barricades to contain materialcontain material
13a
Loose rock and soil as Loose rock and soil as hazardshazards
Keep surface materials at least 2 Keep surface materials at least 2 feet from the edge of excavation feet from the edge of excavation sitessites
Keep employees Keep employees off of sloped off of sloped surfaces at levels surfaces at levels above other above other employeesemployees
13b
Protective systemsProtective systems
Excavations where employees are Excavations where employees are exposed to cave-ins must be 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
Protective systemsProtective systems
Protective systems are not needed Protective systems are not needed if the excavation is: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 the Employers are free to choose the most practical design most practical design approach for a particular approach for a particular circumstancecircumstance
14b
Protective systemsProtective systems
Designing a protective system is Designing a protective system is complexcomplex
Protective systems must be able to Protective systems must be able to resist all loadsresist all loads
A competent person must examine A competent person must examine protective systems’ materialsprotective systems’ materials
14c
Soil typesSoil types
Classify the soil type:Classify the soil type:• Stable rockStable rock• Type AType A• Type BType B• Type CType C
15a
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
Sloping and benchingSloping and benching
Other slopes may be used for other Other slopes may be used for other soil typessoil 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 stepsseries of horizontal levels or steps
16b
Sloping and benchingSloping and benching
Benching systems have vertical or Benching systems have vertical or near-vertical surfaces between near-vertical surfaces between levelslevels
16c
Support, shield, and Support, shield, and protective systemsprotective systems
Shoring systems support the sides Shoring systems support the sides of the excavation with:of the excavation with:• timbertimber• aluminumaluminum• hydraulic, hydraulic,
pneumatic, or pneumatic, or mechanical mechanical systemssystems
17a
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 uprightscross braces, wales, and uprights
Selection and Selection and design involves design involves using tabulated using tabulated datadata
17b
Precautions when protective Precautions when protective systems are being installedsystems are being 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
Install other structural members to Install other structural members to carry loads when temporary carry loads when temporary removal of members is necessaryremoval of members is necessary
The installation of support systems The installation of support systems must be closely coordinated with must be closely coordinated with the excavation processthe excavation process
18b
Precautions when protective Precautions when protective systems are being installedsystems are being installed
Daily inspectionsDaily inspections
Inspect excavations for possible:Inspect excavations for possible:• cave-inscave-ins• failure of protective systemsfailure of protective systems• hazardous atmosphereshazardous atmospheres• other hazardous conditionsother hazardous conditions
19a
Trench failureTrench failure
Recognize hazardous conditionsRecognize hazardous conditions
Sudden changes can mean Sudden changes can mean disasterdisaster
20a
Trench failureTrench failure
Things that can cause immediate Things that can cause immediate change include: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
Trench failureTrench failure
Tension cracks can cause sliding, Tension cracks can cause sliding, sluffing, or topplingsluffing, or toppling
Unsupported excavation can cause Unsupported excavation can cause bulging in the vertical facebulging in the vertical face
20c
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