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Safety Around Hydroelectric Facilities

At Newfoundland and Labrador Hydro, safety is our number one priority and we are committed to keeping our employees and the public safe.

NL Hydro and Nalcor operate and manage over 200 dams, spillways, powerhouses and other hydraulic structures on reservoirs throughout Newfoundland and Labrador. These areas and structures pose inherent safety hazards, which may not always be obvious to those nearby. To help protect the public, we assess these hazards and risks and install control measures, such as fencing, signage, alarms and waterway booms and buoys to reduce risks. We base these measures on the Canadian Dam Association (CDA) Guidelines for Public Safety Around Dams as well as our own guidelines for the assessment of risks and implementation of controls. As dam owners, we have a responsibility to ensure appropriate measures are taken to protect public safety, and to raise awareness of the dangers and the risks associated with recreational activities near these structures.

Our hydraulic plants generate the electricity that Newfoundlanders and Labradorians use every minute of every day, by utilizing the flow of water. In order to do so, the flow and levels of water must be regulated. So, the water in the rivers and reservoirs around our dams and generation plants can rise and fall rapidly, and sometimes without warning.

What are dams and hydraulic structures…and what hazards do they present?

Dams
A dam is an engineered structure designed to hold water for our hydroelectric reservoirs. Most of our dams are embankment types (meaning they are constructed of earth fill and rock fill materials). Others are made of concrete or timber cribs.

Dams and reservoirs present several safety hazards. These include:
• Submerged objects – Objects just under the surface can pose a risk to boaters.
• Changing water levels –Water levels in the reservoir (as well as downstream of spillways and hydro plants) may change during the normal operation of our hydro facilities. In winter, these changes can cause an unstable ice cover.
• Steep slopes – Some dams have steep slopes that pose a risk of roll-over if they are accessed by a vehicle, ATV or snowmobile.
• Heights – Some dams have vertical faces that present a risk of falling.
• Low head dams – These dams are smaller structures with water flowing over them. They are particularly hazardous because they are often difficult to see, and strong currents near the structure can pull boats or swimmers into a circular flow that is almost impossible to escape. Click here for more information.

Hydraulic Structures
Hydraulic structures are used to control the flow of water. At Hydro, these include spillways, flow control structures and intakes.

Spillways are either gated or overflow structures that release water from the reservoir when levels are higher than needed. Typically, our spillways consist of vertical lift gates that are remotely opened, closed and adjusted. Some spillways are overflow type, which means water will flow over them in an uncontrolled manner when levels rise.

Flow control structures also have vertical gates and are used to control the flow of water from one part of the reservoir to another. They operate very similar to gated spillways except the gates are usually submerged on both sides.

An intake is where the reservoir water begins its final journey to the hydro plant for electricity generation.

Some of the hazards present at hydraulic structures include:

High velocity flows – Water in front of hydraulic structures is often very fast-moving and strong currents can pose dangers.
Sudden changes in water levels – As gates are opened to release water, the area downstream of a hydraulic structure can suddenly turn from a trickle to a torrent, posing a risk to anyone on the river or onshore of being stranded or swept downstream.
Falling from heights – The embankments near hydraulic structures are often vertical and present a risk of fall from height. Additionally, some overflow spillways have an “infinity edge”; it is often difficult to see the edge of the structure. There is a risk that someone on the reservoir could fall over this unseen edge.
Electrical and mechanical equipment – Hydraulic structures are operated by a series of high voltage equipment and moving parts, which can present serious safety risks to anyone near them.

Did you know? Large dams may command more respect from the public than smaller structures do. But, low head and small diversion dams can be dangerous too because many of the hazards are not readily apparent. 

How we assess risks
Hydro conducts public safety risk assessments at each of its facilities, using methodology outlined by the CDA and our own guidelines. Assessment of risk requires identification of danger and warning zones, determination of hazards and public activity in these zones, and a rating of the consequence of encountering the hazard. Once risks are defined, Hydro determines appropriate control measures in order to reduce those risks.

Common control measures
Typical control measures at our hydroelectric sites include:

  • fencing and vehicle barriers to prevent access to dangerous areas,
  • signage to warn of the hazard and consequence,
  • alarms that sound when spillway gates are opening or closing,
  • camera monitoring, and
  • safety booms and buoys in waterways to prevent watercraft from coming too close.

Hydro has operating procedures that require us to check certain areas before operating equipment. In addition to control measures, we promote public awareness and education by issuing public advisories (e.g. spilling water at certain locations).

What’s that siren for? In some locations, such as our Bishop’s Falls generating station, alarms are sounded whenever the spillway gates are opened or closed. It warns people nearby (especially those on the water or on shore either downstream or upstream of the dam) that water levels and flow will change. Without an alert, a sudden and unexpected increase in the water level and speed could potentially put someone on or near the river at risk. The alarm sounds for a longer period when the gate is being opened, and there is a relatively shorter sound when it is closing.

What you can do to stay safe
It is important to stay away from dams and hydraulic structures. Be aware of the risks that these structures pose; the potential consequences are often severe. Pay attention to our control measures, which are there to keep you safe. 

  • Listen for sirens warning that water levels are suddenly changing.
  • Stay outside of public safety booms and buoys.
  • Stay clear of generating facilities including dams, powerhouses, power lines and all electrical equipment.
  • Always supervise children and help them to learn how to keep safe.
  • Obey all warning signs and keep out of fenced, gated, and restricted areas.
  • Stay on designated trails and within observation areas. They’re clearly marked.
  • Stay well back from the edge of a waterway where footing may be slippery or the bank unstable.

During the winter, keep off the ice. It’s not safe to ice fish, skate, ski, snowmobile, or walk on the ice. The ice around these facilities is unstable because currents and water levels are always changing.

Whether you’re on the water or on shore, make sure you stay safe by respecting warning signs and other safety features at these sites and by following some simple safety rules.

 

More information:

 

If you have any questions about public safety at our facilities, please contact us.