ENE/Wind/TBT-ENE-009

Wind Turbine Foundation Construction

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Presenter		Project
Location		Date

Wind turbine foundations are massive reinforced concrete structures resisting enormous overturning forces.
Typical onshore foundations are 15 to 25 metres in diameter and 2 to 4 metres deep.
The concrete pour for a single foundation can exceed 500 cubic metres requiring continuous placement.
Holding down bolt cages or anchor ring assemblies must be positioned to very tight tolerances.
The remote, exposed locations of wind farm sites create logistical, weather, and welfare challenges.
Excavations for foundations are deep and wide, requiring full support and safe access controls.
Continuous pours may require night working with associated fatigue and lighting risks.
Haul roads across agricultural land deteriorate rapidly in wet weather creating vehicle hazards.
CDM 2015, LOLER 1998, and excavation safety regulations all apply to foundation construction.
Quality control is critical; foundation defects cannot be repaired once the turbine is erected.

Massive pour risk	Continuous pours over 12-24 hours create fatigue, plant congestion, and concrete placement hazards.
Remote location	Wind farm sites are remote and exposed, with long emergency response times and limited welfare.
Tolerance critical	Bolt cage errors of just millimetres prevent the tower fitting, requiring foundation reconstruction.

Don't

Support or batter excavation sides before anyone enters the foundation dig.
Position bolt cages using surveyed templates to achieve specified tolerances.
Plan continuous pours with shift cover, fatigue management, and adequate lighting.
Maintain haul roads in safe condition for heavy concrete delivery vehicles.
Provide adequate welfare facilities close to the foundation work area.
Brief the pour team on sequence, shift handover, and emergency procedures.
Monitor weather forecasts and protect fresh concrete from rain and frost.
Use a lift plan for placing rebar cages and bolt assemblies.
Record bolt cage positions, concrete test results, and pour times for handover.
Ensure safe access and egress from the excavation throughout all operations.

DON'T enter deep foundation excavations without adequate side support in place.
DON'T allow bolt cage positions to deviate from the specified tolerances.
DON'T continue a continuous pour without managing driver and operative fatigue.
DON'T allow delivery vehicles on haul roads that are rutted or waterlogged.
DON'T pour concrete in severe weather without protection for fresh concrete.
DON'T lift rebar cages or bolt assemblies without an approved lift plan.
DON'T skip concrete cube testing during the pour; it cannot be repeated later.
DON'T leave the pour unattended during shift handovers on continuous placements.
DON'T assume the remote location means normal safety standards can be relaxed.
DON'T work at night on the foundation without adequate artificial lighting.

See also: Wind Turbine Construction Safety | Concrete Pour Safety

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