DAM/General/TBT-DAM-004

Reservoir Safety

Dams, Reservoirs & Flood Defence › General › Reservoir Safety

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The Reservoirs Act 1975 applies to raised reservoirs holding more than 25,000 cubic metres of water above natural ground level.
Reservoir failure releases catastrophic volumes of water downstream, threatening communities, infrastructure, and lives.
Construction work on or near reservoirs must be coordinated with the reservoir owner and their supervising engineer.
Drowning risk is the primary hazard for all workers on reservoir structures, embankments, and adjacent areas.
Personal flotation devices must be worn by everyone working within two metres of the reservoir water surface.
Reservoir embankments must not be excavated, loaded, or altered without the supervising engineer's written approval.
Instrumentation including piezometers, settlement gauges, and seepage monitors must not be damaged during construction.
Vehicle movements on reservoir embankments must be controlled to prevent loading that exceeds the dam's design capacity.
Emergency drawdown procedures must be understood by all workers in case water levels rise to dangerous levels.
Spillway channels must remain clear and functional throughout all construction activities on the reservoir.

Catastrophic failure	A reservoir embankment failure releases thousands of tonnes of water into the valley below, destroying everything in its path.
Engineering sensitivity	Excavation, loading, or vibration on reservoir embankments changes the stress conditions the dam was designed for — engineer control is mandatory.
Drowning proximity	Reservoirs contain deep, cold water with steep sides — falling in without a PFD is often fatal due to cold water shock.

Don't

Coordinate all work with the reservoir owner and their supervising engineer.
Wear a PFD within two metres of the reservoir water surface at all times.
Obtain the supervising engineer's approval before any excavation on the embankment.
Protect reservoir instrumentation from damage during all construction activities.
Control vehicle movements on the embankment to prevent excessive loading.
Ensure rescue equipment is available at all waterside working locations.
Keep spillway channels clear and functional throughout the construction works.
Understand the emergency drawdown procedure before starting work on the reservoir.
Monitor weather forecasts for heavy rainfall that could raise water levels rapidly.
Brief all workers on the reservoir-specific hazards and emergency procedures.

DON'T carry out work on reservoir structures without the supervising engineer's approval.
DON'T work near reservoir water without wearing a personal flotation device.
DON'T excavate, load, or vibrate the embankment without the engineer's written consent.
DON'T damage piezometers, gauges, or monitoring instruments during construction work.
DON'T drive heavy vehicles on embankments without permission and load assessment.
DON'T work near deep water without rescue equipment available at the location.
DON'T block or obstruct spillway channels — they must remain operational at all times.
DON'T ignore rising water levels — follow the emergency drawdown procedure immediately.
DON'T remain on the embankment during severe weather without monitoring water levels.
DON'T treat reservoir work as routine — the consequences of failure are catastrophic.

See also: Dam and Reservoir Safety Awareness | Drowning Prevention and Water Safety

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