Ground Works
Deep Excavation & Temporary Works
The parent work package for deep excavation: geotechnical and groundwater investigation, temporary-works design and independent check, excavation sequencing, stability, access and emergency controls.
v2.1Updated 9 Aug 2026ADOSH-SF v4.1 (February 2026)Learning Objectives
- Explain why sheet piling and dewatering are scope elements of a deep-excavation work package, not stand-alone activities.
- Describe the temporary-works design, independent check and Temporary Works Coordinator (TWC) roles.
- Set out a safe excavation and support installation sequence.
- Identify inspection triggers: after rain, vibration, surcharge change or ground-condition change.
- Plan access, egress, edge protection and emergency rescue for a deep excavation.
Training Video
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1. Why a Work Package, Not a Task
ADOSH-SF CoP 29.0 (Excavation Work) links excavation, support systems, dewatering, service protection and stability control as one controlled activity. Splitting them into unrelated tasks loses the interfaces where most incidents occur — for example a dewatering shutdown that destabilises a sheet-piled wall.
2. Investigation & Design
Geotechnical and groundwater investigation (boreholes, SPT, permeability, water-table levels) precedes design. Temporary works — sheet piles, walings, struts, tie rods, anchors, capping beams, battering profiles — require a designed solution with an independent design check appropriate to the risk category, held by the Temporary Works Coordinator.
3. Pre-Construction Controls
Adjacent-property and buried-utility survey with NOCs, survey and set-out, construction sequence drawing, MSRA/RAMS, permit and inspection plan, competency records for the TWC, excavation supervisor, banksman and plant operators.
4. Excavation Sequencing
Bulk excavation, trenching, benching or battering must follow the designed sequence, with support installed progressively as depth increases. Never over-dig below the designed level of the next support frame. Spoil, plant and material loads must be kept outside the designed surcharge zone.
5. Access, Egress & Edge Protection
Secured ladders within 7.5 m of every worker, extending 1 m above the edge; ramps designed for plant; hard barriers or edge protection to all open edges; lighting for night work; separated pedestrian and plant routes.
6. Inspection & Change Control
Daily competent-person inspection before shift start and after rain, vibration (piling or traffic), loading change or any collapse. Any alteration to the designed support requires TWC approval — no strut, waling or prop is removed on site judgement.
7. Emergency Arrangements
Rescue plan for collapse, flooding and casualty retrieval from depth; rescue equipment and trained team; muster and access route kept clear for emergency vehicles; escalation to the client, consultant and authority where third-party property is affected.
Knowledge Assessment
1. Sheet piling and dewatering are best managed as:
2. Which ADOSH-SF Code of Practice covers excavation work?
3. Temporary works design for a deep excavation requires:
4. Support systems should be installed:
5. Spoil and plant must be kept:
6. Removal of a strut or waling requires:
7. Inspection triggers include:
8. A ladder in a deep excavation must extend above the edge by:
9. A dewatering shutdown during deep excavation can:
10. Geotechnical and groundwater investigation should occur:
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