trench awareness

Trench Awareness

presented by the…presented by the…

Office of the State Fire Marshall of Office of the State Fire Marshall of IllinoisIllinois

Course Content

IntroductionIntroduction Trench Rescue HazardsTrench Rescue Hazards OSHA RegulationsOSHA Regulations Protective Systems Protective Systems Shoring System DesignShoring System Design Rescue ShoringRescue Shoring Trench Rescue OperationsTrench Rescue Operations

Introduction

OSFM technical rescue certificationsOSFM technical rescue certifications Definition of a trenchDefinition of a trench Trenching operations Trenching operations Trench accidents and statisticsTrench accidents and statistics

Introduction

OSFM technical rescue certificationsOSFM technical rescue certifications Definition of a trenchDefinition of a trench Trenching operationsTrenching operations Trench accidents and statisticsTrench accidents and statistics

OSFM Technical Rescue Specialist Certifications

Vertica l R escue II C onfined Space R escue(Equiva lency availab le)

Vertica l R escue I(Equivalency availab le)

Trench Rescue II

Trench R escue I(Equiva lency availab le)

C onfined-Space/Trench R escue Awareness

Introduction


Definition of a trench

OSHA defines a trench as an excavation which is deeper OSHA defines a trench as an excavation which is deeper and longer than it is wide and is less than 15 feet wide at and longer than it is wide and is less than 15 feet wide at the bottom.the bottom.

Introduction


Trenching operations

OSHA protection requirements are often ignoredOSHA protection requirements are often ignored Contractors are often family businesses Contractors are often family businesses


OSHA protection requirements are often ignoredOSHA protection requirements are often ignored Contractors are often family businessesContractors are often family businesses


OSHA protection requirements are often ignoredOSHA protection requirements are often ignored Ignorance/complacency of risksIgnorance/complacency of risks Economic factorsEconomic factors

Contractors are often family businessesContractors are often family businesses


OSHA protection requirements are often ignoredOSHA protection requirements are often ignored Ignorance/complacency of risksIgnorance/complacency of risks

• Inexperienced contractor Inexperienced contractor • Experienced contractor with no history of problemsExperienced contractor with no history of problems• Complaints of inconvenience from workersComplaints of inconvenience from workers

Economic factorsEconomic factors Contractors are often family businessesContractors are often family businesses




Economic factorsEconomic factors• Cost of equipmentCost of equipment• Labor cost to install equipmentLabor cost to install equipment• Elimination of protection equipment to be awarded low bidElimination of protection equipment to be awarded low bid

Contractors are often family businessesContractors are often family businesses




Economic factorsEconomic factors• Cost of equipmentCost of equipment• Labor cost to install equipmentLabor cost to install equipment• Elimination of protection equipment to be awarded low bidElimination of protection equipment to be awarded low bid

Contractors are often family businessesContractors are often family businesses Results in extremely emotional rescue scenesResults in extremely emotional rescue scenes

Introduction


Trench accidents and statistics

Trenching operations take place on a daily basis in Trenching operations take place on a daily basis in almost all jurisdictionsalmost all jurisdictions

Over 100 workers are killed annually in trench Over 100 workers are killed annually in trench accidentsaccidents

As much as 65% of those killed in trench As much as 65% of those killed in trench collapses are rescuerscollapses are rescuers

Introduction


Course Content


Trench Rescue Hazards Hazards are not obviousHazards are not obvious

Trenches don’t appear dangerousTrenches don’t appear dangerous Understanding the hazards requires trainingUnderstanding the hazards requires training By-standers, co-workers, and even fire officers will not By-standers, co-workers, and even fire officers will not

understand the inaction of trained rescuers until the understand the inaction of trained rescuers until the trench is properly protectedtrench is properly protected

Trench Rescue Hazards Hazards are not obviousHazards are not obvious Secondary collapseSecondary collapse

Depends upon the type of collapseDepends upon the type of collapse Responsible for most deaths in trench collapsesResponsible for most deaths in trench collapses Usually occurs just in time to trap a would-be rescuerUsually occurs just in time to trap a would-be rescuer

Types of collapses

Slough-in Sidewall-in

Shear-in Spoil-in

How rescuers become victims

Trench Rescue Hazards Hazards are not obviousHazards are not obvious Secondary collapseSecondary collapse The weight of dirtThe weight of dirt

90-145 lbs. per cubic foot90-145 lbs. per cubic foot Averages 100 lbs. per cubic footAverages 100 lbs. per cubic foot Average collapse is 1.5 cubic yards (about 4000 lbs.)Average collapse is 1.5 cubic yards (about 4000 lbs.) A victim under 2 feet of soil will be under about 3000 A victim under 2 feet of soil will be under about 3000

lbs. of soil, approximately 1000 lbs. of which will be on lbs. of soil, approximately 1000 lbs. of which will be on his chesthis chest

Trench Rescue Hazards Hazards are not obviousHazards are not obvious Secondary collapseSecondary collapse The weight of dirtThe weight of dirt The speed that dirt can moveThe speed that dirt can move

Trenches will often collapse within 1/10th of a secondTrenches will often collapse within 1/10th of a second There is often little or no warning of collapseThere is often little or no warning of collapse

Spalling of soil or widening fissures are signs of Spalling of soil or widening fissures are signs of eminent collapseeminent collapse

Escape is unlikely during a collapseEscape is unlikely during a collapse Victims are often “frozen” in place Victims are often “frozen” in place

Trench Rescue Hazards Hazards are not obviousHazards are not obvious Secondary collapseSecondary collapse The weight of dirtThe weight of dirt The speed that dirt can moveThe speed that dirt can move Rescues are usually long-term operationsRescues are usually long-term operations

Trench rescues will often require in excess of 4-6 hoursTrench rescues will often require in excess of 4-6 hours The trench will become more unstable with timeThe trench will become more unstable with time

Trench Rescue Hazards Hazards are not obviousHazards are not obvious Secondary collapseSecondary collapse The weight of dirtThe weight of dirt The speed that dirt can moveThe speed that dirt can move Rescues are usually long-term operationsRescues are usually long-term operations Backhoes are not safe for victim rescueBackhoes are not safe for victim rescue

The operator is likely to inflict serious or fatal injury to The operator is likely to inflict serious or fatal injury to the victimthe victim

The weight and vibration from the backhoe is likely to The weight and vibration from the backhoe is likely to accelerate the occurrence of a fatal secondary collapseaccelerate the occurrence of a fatal secondary collapse

Backhoes are an acceptable device for recovery Backhoes are an acceptable device for recovery operationsoperations


Trenches exceed OSHA limitsTrenches exceed OSHA limits Backhoes are not safe for victim rescueBackhoes are not safe for victim rescue

OSHA provides guidelines for trenches up to 15 feet OSHA provides guidelines for trenches up to 15 feet wide and 20 feet deep. Custom engineering is required wide and 20 feet deep. Custom engineering is required beyond those limitsbeyond those limits

A contractor who did not provide proper protection for A contractor who did not provide proper protection for his employees is likely to not understand the limitshis employees is likely to not understand the limits



Buried utilitiesBuried utilities Many more injuries and deaths in trenches are caused Many more injuries and deaths in trenches are caused

by contact with buried utilities than are from collapse by contact with buried utilities than are from collapse Rescuers are not immune to this dangerRescuers are not immune to this danger



Buried utilitiesBuried utilities Impact or entrapment from falling objectsImpact or entrapment from falling objects

This is the leading cause of death and injury in trenchesThis is the leading cause of death and injury in trenches Rescuers must control this hazard prior to entryRescuers must control this hazard prior to entry



Buried utilitiesBuried utilities Impact or entrapment from falling objectsImpact or entrapment from falling objects Uncollapsed unprotected trenches still dangerousUncollapsed unprotected trenches still dangerous

Rescuers must be wary of apparently simple rescues Rescuers must be wary of apparently simple rescues from uncollapsed trenchesfrom uncollapsed trenches



Buried utilitiesBuried utilities Impact or entrapment from falling objectsImpact or entrapment from falling objects Uncollapsed unprotected trenches still dangerousUncollapsed unprotected trenches still dangerous Inadequate equipment for shoringInadequate equipment for shoring

Untrained rescuers may be lulled into false security by Untrained rescuers may be lulled into false security by using inadequate shoring materials such as backboardsusing inadequate shoring materials such as backboards

Shoring systems require extremely strong materialsShoring systems require extremely strong materials



Buried utilitiesBuried utilities Impact or entrapment from falling objectsImpact or entrapment from falling objects Uncollapsed unprotected trenches still dangerousUncollapsed unprotected trenches still dangerous Inadequate equipment for shoringInadequate equipment for shoring Possible legal liabilities for fire officersPossible legal liabilities for fire officers

Fire officers may face both criminal and civil charges Fire officers may face both criminal and civil charges for injuries to their personnel resulting from ignoring for injuries to their personnel resulting from ignoring OSHA regulationsOSHA regulations

Trench Rescue Hazards Hazards are not obviousHazards are not obvious Secondary collapseSecondary collapse The weight of dirtThe weight of dirt The speed that dirt can moveThe speed that dirt can move Rescues are usually long-term operationsRescues are usually long-term operations Backhoes are not safe for victim rescueBackhoes are not safe for victim rescue Trenches exceed OSHA limitsTrenches exceed OSHA limits Buried utilitiesBuried utilities Impact or entrapment from falling equipmentImpact or entrapment from falling equipment Uncollapsed unprotected trenches still dangerousUncollapsed unprotected trenches still dangerous Inadequate equipment for shoringInadequate equipment for shoring Possible legal liabilities for fire officers Possible legal liabilities for fire officers

Course Content


Course Content

IntroductionIntroduction Trench Rescue HazardsTrench Rescue Hazards OSHA RegulationsOSHA Regulations Protective SystemsProtective Systems Shoring System DesignShoring System Design Rescue ShoringRescue Shoring Trench Rescue OperationsTrench Rescue Operations

OSHA Regulations Applicable regulationsApplicable regulations

29 CFR 1926 Subpart P (Excavations)29 CFR 1926 Subpart P (Excavations) Applies to public sector and to Federal employeesApplies to public sector and to Federal employees

Illinois has adopted 1926 by reference in the Illinois Illinois has adopted 1926 by reference in the Illinois Register Part 350 Section 350.280Register Part 350 Section 350.280 Applies to municipal, fire district, and State Applies to municipal, fire district, and State

employeesemployees

OSHA Regulations Applicable regulationsApplicable regulations Methods of providing worker protectionMethods of providing worker protection

SlopingSloping ShoringShoring ShieldingShielding

Methods of providing worker protection

Sloping

Shoring

Shielding


Soil classificationsSoil classifications Stable rockStable rock Class-AClass-A

Cohesive soils Cohesive soils Clumps which are difficult to break apartClumps which are difficult to break apart

Class-BClass-B Some cohesivenessSome cohesiveness Clumps which are easily broken or moldedClumps which are easily broken or molded

Class-CClass-C Loose soilsLoose soils Wet soilsWet soils

Methods of providing worker protectionMethods of providing worker protection


Soil classification testsSoil classification tests OSHA requires at least one visual & one manual testOSHA requires at least one visual & one manual test

Visual testsVisual tests• Observe spoil pile and its clumping behaviorObserve spoil pile and its clumping behavior• Observe sides and lip of trench for layers and tension cracksObserve sides and lip of trench for layers and tension cracks• Watch for seeping waterWatch for seeping water• Determine likelihood of previously disturbed soilDetermine likelihood of previously disturbed soil

Manual testsManual tests• Thumb penetration testThumb penetration test• Pocket penetrometerPocket penetrometer• ShearvaneShearvane

Methods of providing worker protectionMethods of providing worker protection Soil classificationsSoil classifications


Soil classification testsSoil classification tests Adjustments to soil classificationAdjustments to soil classification

Wet soils are Wet soils are alwaysalways Class-C Class-C


Dangers of wet soils

Standing water undermines trench walls

Dangers of wet soils

Seeping water causes the soil to shift

Water table



Wet soils are Wet soils are alwaysalways Class-C Class-C




Wet soils are Wet soils are alwaysalways Class-C Class-C Soil classification must be lowered if:Soil classification must be lowered if:

Layered soils slope toward the trenchLayered soils slope toward the trench


Sloped, layered soils

Trench must be classified to the worst soil layer

If layers slope toward the trench, class must also be dropped

Top soil

Sand

Clay




Layered soils slope toward the trenchLayered soils slope toward the trench





Layered soils slope toward the trenchLayered soils slope toward the trench Fissures are presentFissures are present


Fissured soils

Soil classification must be lowered one level

Top view Side view



Soil has been previously disturbed Soil has been previously disturbed Soil is subject to vibrationSoil is subject to vibration

Trench collapse rescues must be no better than Class-BTrench collapse rescues must be no better than Class-B Many rescue teams will operate as if all areMany rescue teams will operate as if all are Class-CClass-C





Soil classification testsSoil classification tests Adjustments to soil classificationAdjustments to soil classification Other factors which will effect trench stabilityOther factors which will effect trench stability

Exposure to elementsExposure to elements Long term trench is open >24 hoursLong term trench is open >24 hours

Superimposed loadsSuperimposed loads


Superimposed loads

OSHA requires all superimposed loads to be no closer than 2 feet from trench

Superimposed loads

Spoil piles are exceptionally dangerous superimposed loads

Superimposed loads

OSHA requires the spoil pile to be at least 2’ from trenchWhenever possible, move the spoil pile further back to increase

work area, expose fissures, and reduce possible impact from spoil weight

2’


Soil classification testsSoil classification tests Adjustments to soil classificationAdjustments to soil classification Other factors which will effect trench stabilityOther factors which will effect trench stability

Underground utilitiesUnderground utilities May require shoring of their ownMay require shoring of their own

Surface encumbrancesSurface encumbrances Will require a registered professional engineerWill require a registered professional engineer

Water removalWater removal Standing water must be removedStanding water must be removed


Exposure to elementsExposure to elements Long term trench is open >24 hoursLong term trench is open >24 hours

Superimposed loadsSuperimposed loads


Soil classification testsSoil classification tests Adjustments to soil classificationAdjustments to soil classification Other factors which will effect trench stabilityOther factors which will effect trench stability Additional regulations for worker safetyAdditional regulations for worker safety

Escape routesEscape routes No more than 25 ft. travel distanceNo more than 25 ft. travel distance If using a ladder, it must extend a few feet above the If using a ladder, it must extend a few feet above the

trench and be securedtrench and be secured Air quality monitoringAir quality monitoring Personal protective equipmentPersonal protective equipment

Helmet, boots, reflective vests, eye protection...Helmet, boots, reflective vests, eye protection... Impact protectionImpact protection

Stop logs, warning devices, spottersStop logs, warning devices, spotters


Course Content


Protective systems SlopingSloping

Must slope to the angle of reposeMust slope to the angle of repose Angle depends on the soil classificationAngle depends on the soil classification

Sloping a trench

Slope angle is determined by soil classification

4’

8’ 8’ 8’

8’ 12’

Class-A Class-B Class-C


Must slope to the angle of reposeMust slope to the angle of repose Angle depends on the soil classificationAngle depends on the soil classification May incorporate steps or benchesMay incorporate steps or benches May be used in combination with shielding or shoringMay be used in combination with shielding or shoring

Sloping a trench

Benching a trench Using sloping with shielding/shoring


Must slope to the angle of reposeMust slope to the angle of repose Angle depends on the soil classificationAngle depends on the soil classification May incorporate steps or benchesMay incorporate steps or benches May be used in combination with shielding or shoringMay be used in combination with shielding or shoring Impractical in the Midwest due to width of openingImpractical in the Midwest due to width of opening

Sloping a trench

23’

10’ 10’3’

10’

Sloping is often impractical

Protective systems SlopingSloping ShieldingShielding

Strong metal boxes which can hold back the force of Strong metal boxes which can hold back the force of moving soilmoving soil

Typically assembled at the work site and maneuvered Typically assembled at the work site and maneuvered into position with a backhoeinto position with a backhoe

Shielding

Typical trench shield


Strong metal boxes which can hold back the force of Strong metal boxes which can hold back the force of moving soilmoving soil

Typically assembled at the work site and maneuvered Typically assembled at the work site and maneuvered into position with a backhoeinto position with a backhoe

Boxes must be designed for the trench dimensions and Boxes must be designed for the trench dimensions and the type of soil they are to be used inthe type of soil they are to be used in

Worker must stay within the box to be protected Worker must stay within the box to be protected Box must be positioned correctly:Box must be positioned correctly:

Must extend a few inches above the trench lipMust extend a few inches above the trench lip Must be no further than 2 ft. off bottomMust be no further than 2 ft. off bottom

Shielding

Proper positioning of a trench box

2’ max.

Shielding

Dangers of improper placement of a trench box


ShoringShoring A support system which is only strong enough to stop A support system which is only strong enough to stop

dirt from starting to movedirt from starting to move Works by exerting pressure and resistance into the Works by exerting pressure and resistance into the

trench walls creating arches of protectiontrench walls creating arches of protection

Shoring

Shoring works by creating arches of protection




trench walls creating arches of protectiontrench walls creating arches of protection Shoring system componentsShoring system components

Simple shoring systemSimple shoring system Shoring system with walesShoring system with wales Sheeting systemsSheeting systems

Shoring

Simple shoring system

Upright

Crossbrace

Shoring

Shoring system with wales

Allows for additional uprights or sheeting as required

Upright

CrossbraceWale

Shoring

Close sheeting

Shoring

Tight sheeting

Shoring

Plywood sheeting

Not considered structural unless it is specified as part of an engineered systemOSHA requires 1 1/8” soft plywood or 3/4” 14-ply finland form






Types of shoring systemsTypes of shoring systems TimberTimber ScrewjackScrewjack PneumaticPneumatic HydraulicHydraulic

Shoring•OSHA has charts for construction

•Requires numerous large timbers

•Wood must be Douglas Fir or mixed oak

•Difficult to find and store

•Must be custom cut at scene

•Requires installer to enter trench

•Pressurized with wooden wedges

Timber shoring

Shoring

Timbers required for 12’ length of 4’ wide, 10’ deep trench in Class-B soil

4” x 6” x 14’ uprights

8” x 8” x 14’ walers

6” x 6” x 4’ crossbraces

2” x 2” blocks

2” x 4” wedges

Shoring•Difficult to find engineering tables

•Are often equipped with inadequate pipe

•Must be custom cut at scene


•Pressurized by screwing jack out

•Must have feet installed

•Must not expose more than 1/2 of the screw

Screwjack shoring

Shoring•Most popular rescue strut

•Requires purchase of multiple lengths for rescue


•Pressurized by air pressure, then locked into place

•Requires timber components for uprights and walers

•Manufacturer has engineering data to help eliminate timber requirements

•Airshore & Paratech manufacturers

Pneumatic shoring

Shoring•OSHA has design charts

•Requires purchase of multiple lengths for rescue

•Bulky to store

•Pressurized by hydraulic hand pump

•Only system which does not require the installer to enter the trench

•Difficult to use on uneven walls

•Allows greater depths without walers

Hydraulic shoring






Types of shoring systemsTypes of shoring systems TimberTimber ScrewjackScrewjack PneumaticPneumatic HydraulicHydraulic

Course Content


trench awareness

Documents

history of problemscomplaints

low bidcontractors

trench awarenesspresented

feet wide