WorkCover NSW: RISKS OF DROWNING AROUND DRAINAGE PIPES SAFETY ALERT

Source: WorkCover NSW

A worker recently drowned after becoming trapped at the inlet of a 300 mm water drainage pipe. The purpose of the pipe was to remove water from an open water retention area. 

During a storm the inlet pipe became blocked with debris. A worker was sucked in feet first while unblocking the inlet and became trapped at the waist.The area flooded, drowning the trapped worker. 

Due to the strong suction forces the trapped worker was unable to be released at the time of the incident.

CONTRIBUTING FACTORS

A pipe inlet similar to the one involved in the incident.

There was no barrier in place at the time to prevent a person from being sucked in and trapped at the drain pipe inlet.

Other contributing factors include:

• workers were unaware of the strong suction forces created in the pipe
• the design of the drain allowed a suction force sufficient to trap a person
• there was no signage to warn workers not to work at, or  near the unguarded drain pipe inlet during a storm or flooding event.

ACTION REQUIRED

Systems of work should be reviewed when water or other fluids flow into a pipe inlet and there is the potential to trap and drown a person.

Action is warranted where all of the following are present:

• possibility for a person to be trapped against or in a pipe inlet and cannot easily release themselves from the suction forces. Suction forces can be due to:
  • gravity - eg stormwater or flow from a tank
  • plant - eg a pump
• the size of the inlet is sufficient to trap and hold a body part - eg hand, foot, leg, arm, torso, head
• the inlet can flood to a depth sufficient  to cause drowning - eg open area during a storm  or where the inlet is normally flooded - eg a process tank, pool, dam, river or pit

 Where an entrapment and drowning hazard exists:

• provide a barrier such as a grate, guarding or fencing to prevent people accessing, being trapped or held against a pipe inlet or being pulled into or through pipework
• where a barrier is used it should be designed by a competent person so a person can release themselves if held against the barrier by suction forces
• where it is not reasonably practicable to provide a barrier, alternative systems  of work should be considered  - eg a system that relieves the entrapping suction or shuts down the pump when a blockage is detected
• provide relevant instruction, information, training and supervision on safe access and dangers associated with drains or pipe inlets

• provide local signage warning of entrapment and drowning  hazards
• consider placing bollards (posts) in an arc upstream of the pipe inlet so that the inlet can be identified when flooded.

FURTHER INFORMATION

Call us on 13 10 50 or visit  workcover.nsw.gov.au where you will find the  How to manage work health and safety risks code of practice.