The latest revision of DMAC 12 – Safe Diving Distance from Seismic Surveying Operations – has been published by the independent Diving Medical Advisory Committee (DMAC) and can be freely downloaded from dmac-diving.org/guidance.
DMAC 12 has been updated to take into account recent incidents which demonstrate that significant adverse effects may be experienced by divers at distances of up to 27km (16.8 miles) from the seismic source, which is a considerably greater distance than was previously recognised. In view of these reports, DMAC 12 Rev. 2 recommends that:
- Where diving and seismic activity are scheduled to occur within a distance of 45km (28 miles), it would be good practice for all parties to be made aware of the planned activity where practicable. This should include clients/operators, diving and seismic contractors.
- Where diving and seismic activity will occur within a distance of 30km (18.6 miles) a joint risk assessment should be conducted, between the clients/operators involved and the seismic and diving contractors in advance of any simultaneous operations. The risk assessment should consider ramp-up trials as well as other risk control measures e.g. reduction in source sizes, changes to firing intervals, timeshare/prioritisation etc.
Importantly, DMAC 12 Rev. 2 includes a mechanism for submitting a short online Report of Simultaneous Seismic and Diving Operations as they occur in the field. This could provide the industry with much-needed data on the issue of determining safe diving distance from seismic survey operations. DMAC will periodically review the data gathered from such reports, and we look forward to receiving them. The form will appear at www.dmac-diving.org/data shortly, with a non-interactive PDF currently available for manual submission.