Excavation

1. Excavation Hazards & Controls

2. Hazards

3. Collapse of sides • Type of soil structure is an important factor • What might appear to be a safe soil structure can change dramatically with changes in the weather

4. Hazards - Physical • Materials falling onto people working in the excavation • People & vehicles falling into excavation • People being struck by plant • Undermining nearby structures • Contact with underground services • Access to excavation

5. Hazards - Chemical • Fumes from vehicles/plant (C02) • Methane/other gases • Contaminated land/previous use?

6. Hazards - Biological • Leptospirosis • Previous use e.g. hospitals • Drains/sewers • Rubbish and waste

7. Control Measures Tied ladder provides safe access and egress Guard rails to prevent falls Poling boards extend above edge to act as toeboards Exposed services are supported Supported by timbering and props

8. Collapse of Sides • Batter sides and ends • Support with timber, sheeting or proprietary support systems • Use 1.2m as a guide for support, but assess conditions at all times • Even work in shallow trenches can be dangerous, especially if bending or kneeling

9. Materials Falling into Excavations • Do not store spoil or other materials close to excavation – they could fall in or cause sides to collapse • Provide guard rails and toe boards where necessary • Wear hard hat in excavations

10. People & Vehicles Falling into Excavations • Provide guard rails & toe boards (2m) • Use stop blocks to prevent vehicles over-running • Keep vehicles away from excavations wherever necessary

11. People Being Struck by Plant • Keep workers separate from moving plant where possible • Plant operators should be trained and competent • High visibility PPE

12. Undermining Nearby Structures • Make sure excavations do not affect footings of scaffolds or foundations of nearby structures • Provide temporary support for structure if necessary • Surveys of foundations and advice of a structural engineer may be necessary

13. Avoiding Underground Services • Look around for obvious signs of underground services e.g. drains, patching of surface etc. • Use cable locators to trace any services. Mark the ground accordingly • Use service plan • Dig trial holes by hand • Hand dig if in doubt (particularly for plastic cables which cannot be detected) • Have emergency procedures/contact in place

14. Safe Access & Egress • Create steps in excavation • Provide good ladder access or other safe ways of getting in and out of the excavation

15. Fumes • Do not site petrol or diesel engined equipment such as generators or compressors in, or near the edge of, an excavation unless fumes can be ducted away or area can be ventilated

16. Protecting the Public • Barrier off all excavations in public places to prevent falls • NRSWA • Where people may get onto the site out of hours, backfill or cover excavations to reduce risks

17. Supervision • A competent person must supervise the installation, alteration or removal of excavation support • People working in excavations should be given clear instructions on how to work safely

18. Inspections • Competent person must inspect: • At start of shift; • After any event likely to have affected strength or stability of excavation; and • After any accidental fall of rock, earth and other material. • A written report should be made after most inspections • Stop work if inspection shows excavation to be unsafe