International Marine Contractors Association publishes guidance on protecting divers during underwater excavations

Photo: International Marine Contractors Association
Photo: International Marine Contractors Association

A newly published document from the International Marine Contractors Association (IMCA) aims to raise awareness of the hazards associated with subsea excavation works and, in particular, the significant risks to divers who engage in such work.

Guidance on Underwater Excavation Works Involving Divers IMCA D 074 was drafted after many incidents of divers have been trapped, injured, or killed either by direct contact with excavation equipment or by collapses while working inside various types of excavations below seabed level have occurred over the years, said IMCA Technical Adviser Bill Chilton.

In addition to raising awareness of the hazards, the aims of IMCA D 074 are to:

  • Emphasise in particular the risk of serious harm to divers arising from underwater trench wall collapses or from the sudden unexpected backfilling of excavations
  • Provide industry with information and guidance that may help diving contractors and others control or mitigate the risks associated with underwater excavation works involving divers
  • Describe the types of equipment commonly used on diving projects involving subsea excavation works

IMCA D 074 also includes a section on the background to the new guidance, lays out its aims and application, and provides an overview. A section on "Risk Assessment" follows with bullet points highlighting "Factors to Consider" and "Causes of Previous Incidents".

Attention then turns to "Working in Pre-Existing Sites". This section clearly highlights that divers should not be permitted to enter pre-existing subsea excavations that have not been properly assessed for safe diver access.

Proposed diver entries to pre-existing underwater excavation must always be carefully planned and properly risk assessed in line with the guidance contained in IMCA D 074.

The final detailed section is the "Plant and Equipment Overview" featuring airlifts, diver/ROV operated suction dredges, water jets, and a summary of airlifts and dredges operational safety.

References to relevant IMCA and external documents complete the contents.

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