excavation & trench safety - pncwa.memberclicks.net file• soils are classified by osha into...

EXCAVATION & TRENCH SAFETY

BY John T. Shawcroft

TRENCH COLLAPSE HAZARDS

• Four types to be aware of:– 1. Spoil Pile Slide– 2. Shear Wall Collapse– 3. Belly Slough– 4. Lip Slide

Spoil Pile Slide 8 ft. trench

Belly Slough 8 ft. trench

Shear Wall Collapse 8 ft. trench

Lip Slide 8 ft. trench

RESCUES

• Facts and figures

Trench Rescue

Trench Rescue in Progress

Classification of Soil Types

• Soils are classified by OSHA into three types:

» 1. Group A - clay, hardpan, and caliche » 2. Group B – loam, sandy loam, silt, silty loam &

angular gravel» 3. Group C – sand and other “running” types of

soil

• Soils can and do shift from one type to another as the environment acts upon it.

Access Ladder with Shoring

Ladder in Trench

What’s Wrong?

Inspection

• Daily inspection of excavation and adjacent areas by a competent person prior to start of work each shift and as needed throughout the shift.

• Inspections must be made after each rain storm or other hazard-increasing event.

OSHA QUICK CARD

Type A Soil

Soil Type B

Type C Soils

Simple Bench for Type A Soils

Adjustable Shielding Strut

Access Ladder with Shoring

Credits• National Institute for Occupational Safety &

Health Spokane Research Laboratory – Trench Safety Awareness

• Excavation/ Trenching Safety – Veolia Water EHS&S

• 29 CFR 1926.652 Safety Rules• Texas Trial Lawyer: Trench Collapse Accidents

& Excavation Cave-in Injuries & DeathsWillis Law Firm1221 McKinney; Suite 3333Houston, TX