Trenching or excavating near waterways

The damp areas around waterways, including sediments of Lake Alexandrina, may produce hazardous chemicals, including methane gas. 

Toxic gases may be released when sediments are disturbed.

Substantial volumes of asphyxiating gases may be released into the immediate surroundings during earth works in and around damp areas and sediments and these gases are often heavier than air and can accumulate to potentially harmful levels in freshly disturbed areas.

Precautions when trenching or excavating

If you are planning to conduct earth work in damp areas around waterways you should take the following precautions:

  • Never excavate alone.
  • Always make sure you have reliable means of communication in case of emergency.
  • Look out for the early signs of poisoning. Signs of poisoning include:
    • headache
    • rapid breathing
    • fatigue
    • reduced coordination
    • nausea
    • dizziness
    • drowsiness
    • disorientation
    • confusion.
  • Evacuate the affected area.
  • If asphyxiating gases are inhaled, leave the site immediately, move to an area with fresh air and seek medical advice. Call 000 or 112 from mobiles if required.

For more information

For more information on trenching or excavating near waterways, contact SA Health Public Health Scientific Services or Safework SA