EXCAVATIONEXCAVATION

ExcavationExcavation activity involves use of manual

and mechanical means and interaction of both. Hence, safety aspect to plan involvement and inter action of the same:

Individual ExcavationDeep ExcavationExcavation of TrenchesCannal Excavation

Topic that will be dealt with

Hazards of ExcavationRemedial measuresInspectionsEmergency Response

Collapse of shoring

Falling loads

Excavation hazards

Slip & fall of workmen

Underground utilities

…..Excavation hazards

Vehicular traffic

Adjacent structures

…..Excavation hazards

Access / Egress

Mobile equipment.

…..Excavation hazards

Cave-in / Soil collapse

Improper shoring.

…..Excavation hazards

Excavation HazardsTo sum it up …….

• Cave -in / Soil Collapse•Utilities•Hazardous atmospheres•Adjacent structures•Falling loads•Access/Egress•Vehicle traffic•Mobile equipment

Before going down, check & sides are properly shored.

Inspect for proper shoring

Remedial measures

When working inside trench, location of safe exit to be ascertained.

If you notice any shift in position,stop and investigate.

…..Remedial measures

Use a proper means of access to cross a trench

Barricade the opening

…..Remedial measures

Proper shoring / Benching

During excavation ladder shallbe provided for access / egress.

…..Remedial measures

Use Gumboot while workinginside a trench

…..Remedial measures

Usage of stop blocks to prevent vehicle fall inside a trench

So what should be done prior to Excavation

Check for…..

Soil type & Ground condition

Ground / Surface Water / Water table

Under ground / Overhead utilities

Adjacent buildings

Dynamic (Traffic) load

Preventing Soil Collapse• Soil Classification determines construction

of protective system:

Sloping or benchingShoring

•Timber / Aluminum shoring•Sheet piling

Placing shield between the side of the excavation & the work area.Underpinning

Water Accumulation

• Ground water

• Surface water

• Water table

Soil classification

• Type A - Cohesive soils– Clay, Sandy clay, silty clay, clay loam

• Type B - Cohesionless soils– Silt, Sandy loam, silt loam

• Type C - Water is freely seeping– Gravel, sand,

Types of Soil

• Loose soil like black cotton and sandy soil

• Stiff soil like murrum

• Rock Excavation

ANGLE OF REPOSE

Minimum angle of inclination for free standing soil face for stability

Simple Sloping -Type A Soil

Unsupported Vertically-Sided Lower Portion <12 ft

Unsupported Vertically-Sided Lower Portion <8 ft

Simple Sloping -Type A Soil

Supported or Shielded Vertically-Sided Lower Portion

Simple Sloping

• Type A - 3/4:1 530

• Type B - 1:1 450

• Type C - 1½ :1 340

Greater than 20 feet deep shall be designed

by a registered professional engineer.

Benching

Preventing Soil Collapse

SLOPE / SHORING

Above 5 ft. depth.

1M3 SOIL WEIGHS APP. 1.3 MT

Timber Shoring Installations

Refer to Design Engr.

UtilitiesUnderground Above ground

PERMIT SYSTEM

Hazardous Atmospheres

• Oxygen• CO

• H2S

• Petroleum• Other toxics

Access / Egress

– Ladders - @ every

30mts.

– Ramps

– Stairs cut on earth

STACKING OF MATERIAL ETC.

Other parameters……..

BARRICATION FENCINGILLUMINATION

Mobile Equipment

Vehicle Traffic

»Traffic Control»Traffic Safety Vests

Adjacent Structures

• Ensure structure stability– Shoring– Bracing– Evaluation by

Professional

Excavation Inspections

• Daily Inspections by Competent Person – Start of shift, as needed, following

rainstorms or other hazard-increasing event

• Possible cave-ins• Protective system failure• Water accumulation• Hazardous atmospheres

Excavation Rescue

• Initial Size-up – Type of incident?

• Cave-in, flooding, medical, fire, spill

– Injuries?• Number and type

– Missing personnel?– Chemical (or sewage)

exposures?– Safety of excavation for

rescuers?

Excavation Rescue

• Notify:– Field personnel– SSC = Emergency Coordinator– Fire Department– Police Department– Emergency Medical Services

(EMS)/Hospital

Excavation Rescue

• Stabilize cave-in• Control flooding• Hazardous

Atmospheres?– Ventilate– SCBA– Safety harness and

line– Basket stretcher

Excavation Rescue

DON’T ROLL THE DICE!!!

Excavation Rescues

• The best rescue is the one you never have to make!– Practice proper procedures

• Make sure everything is safe before anybody goes in!

ACCIDENT SUMMARY

Accident Type : Cave-inWeather Conditions : Cloudy and DryType of Operation : ExcavationWas the worksite Inspected Regularly : YesTraining and Education Provided : NoAge & Sex : 32-MaleExperience at this Type of Work : 9 MonthsTime on Project : 2 Weeks

BRIEF DESCRIPTION OF ACCIDENTWorkmen were laying sewer pipe in a trench 15 feet deep. The sides of the trench, 4 feetwide at the bottom and 15 feet wide at the top, were not shored or protected. Soil in thelower portion of the trench was mostly sand and gravel and the upper portion was clay andloam. The trench was not protected from vibration caused by heavy vehicle traffic on the

road nearby. To leave the trench, employees had to exit by climbing over the backfill. Asthey attempted to leave the trench, there was a small cave-in covering one employee to hisankles. When the other employee went to his co-worker's aid another cave-in occurredcovering him to his waist. The first employee died of a rupture of the right ventricle of hisheart at the scene of the cave-in. The other employee suffered a hip injury.