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Safe Practices for Diving in Hazardous Environments

Diving in Hazardous Environments: Fixed Cathode Protection of Jetties.

Cathode Protection (CP) systems are installed underwater to protect structures from corrosion by means of electrically supplied anodes. The protective effect takes some hours or days to establish and they are rarely switched off unless special circumstances require. Impressed current CP systems present a hazard to divers not only because they represent a non-isolated circuit but also because they are normally incidental to the tasks being carried out.


Precautions to be taken:

  1. Impressed current systems must be closed down, tagged out and confirmed as such by the dive supervisor before divers may work on such systems.
  2. Divers working in the vicinity of active systems (1-5 m) must wear a full dry suit/unsuits, hood and gloves.
  3. The risk presented by active CP systems must be emphasized to the diver by the diving team leader/supervisor and the position of all elements discussed in the pre-dive briefing.
  4. Where divers are required to work within one meter of an active system, where visibility is poor or where there is a risk of approaching or touching an anode, the system is to be closed down. Only in ideal conditions of visibility and tidal stream should a system remain active. Under these conditions the diver should remain at a minimum of one meter distance from the anode.

Diving in Hazardous Environments: Diving Near Culverts and Other Inlets.

Before commencing diving operations in the vicinity of docks, locks and basins, the diving team leader/supervisor is to take the following precautions:

  1. Ascertain the position of culverts and inlets, which could endanger the divers in the event of penstocks or sluice valves being operated.
  2. Ensure that the authorities in charge of persons in a position to operate penstocks or sluice valves; the operation of which would constitute a risk to divers, are fully informed of the area and time of any diving operations.
  3. Ensure that warning signals visible to both those ashore and afloat are prominently displayed.
  4. Local safety orders for the specific areas must be adhered to and included within the risk assessment.

These precautions must never be overlooked even in areas thought normally to be perfectly safe.

Diving in Underground Drainage Installations.

There are occasions when search operations have to be carried out in Underground Drainage Installations, they include searches for bombs or IEDs, searches for bodies, and reconnaissance of flooded cavities. If the search involves diving, all normal diving regulations apply and in addition the diver is to wear a breathing apparatus delivering a constant pressure to a full-face mask with oral-nasal delivery, a dry suit, and gloves.


Other control measures are as follows:

  1. The drainage system must be fully vented and tested for dangerous gas before entry by personnel.
  2. Storm water drains must not be entered during, or until 24 hours has elapsed after, heavy rainfall.
  3. Naked lights and non-waterproof torches must not be used in or near the entry to a drainage system.

Note!: All members of the team, both divers and support party, must be fully briefed on the symptoms of illnesses, which may be caused by working in polluted water

Enclosed/Confined Space Regulations.

Diving Team Leader/supervisors should take care to ensure that when planning to enter confined or enclosed spaces that they are diving. Reference should be made to the definition of a dive. Specific risks for diving in confined spaces are:

(1) Entrapment. (2) Solid materials that can flow. (3) Pockets of gas that can be toxic or explosive. (4) Chemical or biological contamination. (5) Overhead hazards.

confined-space-regulations diving skeleton
confined-space-regulations diving skeleton


In conclusion, implementing proper safety protocols is vital for diving operations in various hazardous environments. Whether it involves fixed cathode protection systems, diving near culverts and inlets, underground drainage installations, or enclosed/confined spaces, adherence to precautions and regulations ensures diver safety. By prioritizing risk assessment and effective control measures, accidents can be minimized, and successful operations can be carried out.

By promoting communication, emphasizing risks, and following established procedures, diver safety can be enhanced in these challenging underwater environments.

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