Bored Pier & Caisson Construction SWMS

Bored pier and caisson construction is the drilling, reinforcing and concreting of cast-in-place deep foundations. It is high risk construction work under the WHS Regulation because it creates open shafts deeper than 1.5 m, may require confined-space entry to the shaft, involves lifting operations and reinforcement cages at height above 2 m, and is dominated by the movement of heavy powered mobile plant — piling rigs and cranes (s291), so a SWMS is mandatory (s299). Two hazards define the work. The first is platform and rig stability: piling rigs impose very high track pressures (150-250 kPa), and a bearing failure, a punch-through, or a platform softened after rain can tip the rig. The second is the open shaft: an uncovered hole is a fatality trap, especially at overnight and shift changeover, for both people and plant tracking into it. Where a worker enters the shaft it is a confined space with oxygen deficiency at depth, H2S from organic strata and CO from exhaust drift. Add cage buckling or drops on the lift, auger spin-off strike, and rig-mast powerline contact (masts 15-25 m). The SWMS controls the certified working platform, the open/covered-hole regime, confined-space entry, lifting and powerline clearance. It supports the AS 2159 pile design and does not replace the engineer's certification. It is supplied in eight jurisdiction editions, each citing its own Act, Regulation and regulator.

Hazards identified

8 hazards covered, sorted by priority.

Control measures

Hierarchy-of-controls order: elimination → substitution → isolation → engineering → administrative → PPE.

1. 1Elimination — Use driven or screw piles, or design out entry, so open wet shafts and confined-space entry are avoided where the ground allows
2. 2Substitution — Substitute temporary casing and remote cleaning for personnel entry, and mechanical hole covers for open holes
3. 3Engineering — Working platform designed and engineer-certified for the rig load cases, with punch-through risks bridged and edges set back
4. 4Engineering — Every shaft covered with a rated cover or hard-barricaded the moment the rig moves off, tracked in an open/covered-hole register
5. 5Engineering — Powerline exclusion zones and a tiger-tail/spotter regime for the rig mast, and certified lifting gear for the cage
6. 6Administrative — Platform certificate before mobilisation, daily inspection and mandatory post-rain re-certification
7. 7Administrative — Confined space entry permit with atmospheric testing, ventilation and rescue where entry is unavoidable
8. 8Administrative — Lift study and exclusion zone for cage lifts, with no personnel under a suspended load
9. 9PPE — Type 1 hard hat and Type R day/night high-visibility around the rig and lifts, plus fall protection at open edges
10. 10PPE — Air-supplied or appropriate RPE and a retrieval harness for any shaft entry

Applicable Codes of Practice

High-Risk Construction Work triggered

Worked example

At 6:30 am a piling crew from Deepcore Foundations mobilises a bored-pier rig. The supervisor will not let it track on until the working-platform certificate is confirmed and, because it rained overnight, the platform is re-certified as required. As each pier is drilled, the auger spin-off zone is kept clear and spoil directed away from the crew. The moment the rig moves to the next hole, the completed shaft is covered with a rated cover and logged in the open-hole register — the rule is no open hole is ever left uncovered, because changeover is when people fall in. The nearby distribution line is treated with an exclusion zone and a spotter watching the 20 m mast. The reinforcement cage is lifted on certified gear with the exclusion zone clear and no one beneath it. Design avoids shaft entry, but where a base has to be cleaned the shaft is treated as a confined space with atmosphere testing, ventilation, a permit and a retrieval system. The piers are concreted by tremie with every hold point signed, and at shift end every shaft is proven covered before the crew leaves.

Related legislation

• WHS Act 2011 (model)
• WHS Regulation 2025
• Excavation Work Code of Practice
• AS 2159 Piling — Design and installation

Frequently asked questions