MAR/Specific/TBT-MAR-015

Intertidal Zone Working Safety

Marine & Coastal Works › Specific › Intertidal Zone Working Safety

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The intertidal zone is the area between high and low tide marks where construction work is affected by tidal cycles.
Work windows in the intertidal zone are limited to periods when the tide has receded sufficiently for safe access.
Incoming tides can cut off escape routes rapidly, trapping workers between the sea and cliffs or structures.
Mud, sand, and silt exposed at low tide create soft ground hazards where workers and plant can become stuck.
Marine debris, sharp shells, and slippery seaweed create laceration, puncture, and slip hazards underfoot.
Cold water immersion from unexpected wave surges or rapid tidal rises causes cold water shock and drowning.
Tidal predictions must be checked before every shift and a clear withdrawal time agreed with the whole team.
CDM 2015 requires a specific risk assessment for all construction work carried out in the intertidal zone.
Communication between the work team and a tide watcher or shore-based lookout is essential throughout.
Rescue plans must account for the fact that emergency services may not be able to reach the intertidal area quickly.

Prevent drowning	Incoming tides trap workers against structures and in soft ground — tidal planning and withdrawal times save lives.
Soft ground entrapment	Workers and plant sink into exposed mud and sand, becoming stuck as the tide returns around them.
Limited rescue access	Emergency services cannot easily reach the intertidal zone — on-site rescue capability is essential.

Don't

Check tidal predictions and agree a safe withdrawal time before every intertidal work shift
Appoint a tide watcher to monitor conditions and alert the team to withdraw on time
Wear PFDs and carry throw lines when working in the intertidal zone at all times
Test ground conditions before driving plant onto exposed mud or sand at low tide
Maintain a clear escape route from the work area to high ground throughout the shift
Brief all workers on the tidal cycle, withdrawal time, and emergency escape routes daily
Wear boots with good ankle support and non-slip soles for walking on seaweed and rocks
Carry a charged radio or phone for emergency communication from the intertidal area
Plan work activities to be completed well before the agreed withdrawal time
Ensure an on-site rescue capability is available as emergency services may be delayed

DON'T enter the intertidal zone without checking tidal predictions and setting a withdrawal time
DON'T continue working past the agreed withdrawal time under any circumstances
DON'T drive plant onto soft mud or sand without confirming the ground can support it
DON'T work in the intertidal zone without a PFD and rescue equipment available
DON'T rely on mobile phone signal in remote coastal areas — carry a marine VHF radio
DON'T assume the tide comes in slowly — some areas flood within minutes at spring tides
DON'T walk on seaweed-covered rocks without extreme care — they are highly slippery
DON'T leave tools or materials in the intertidal zone where the tide will carry them away
DON'T work alone in the intertidal zone — always maintain a buddy and shore lookout
DON'T ignore wave surge warnings — unexpected waves can sweep workers off their feet

See also: Tidal Working Procedures | Cold Water Shock Awareness

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