Tips and cautions for when you find yourself working / diving in an overhead environment
The email was simple enough: “Dear ERDI, our Public Safety Dive team has members who received their training from several different training agencies, not just ERDI, and as team leader, my job is to standardize training and to develop SOP/SOGs for the tasks we are called on to do in our community.”
So far, so good, and the fix is a simple one. It is common for a PSD Team Leader to be faced with this sort of situation, and the instructors and instructor-trainers at ERDI have helped plenty of dive teams on both accounts in the past. They have the experience and resources to share with team leaders.
The documents that earn the biggest thanks are the ones outlining how to approach dives in “difficult” environments. Defining these procedures is particularly important in a situation where divers have received PSD instruction through different channels, and more specifically when PSD team members have only sport diver training.
The immediate challenge – and huge red flag – was contained in the message’s second part which explained that during a recent “town-hall-type meeting” among the team there was disagreement in what constitutes an Overhead Environment and how to dive one.
“We did not find much common ground on this topic, not even what special regard an overhead environment demands.”
Once again, this is a common problem when team divers have very diverse experience and opinions informed by different training standards.
The first step in getting situations like this sorted is to define definitively an overhead environment.
In the ERDI manual, an overhead is defined as any environment from which there is no clear and direct access to the surface and fresh air. A public safety diver can be faced with many types of overhead, and these include: inside pipes and sewers, under piers and docks, inside submerged vehicles, in storage vessels, working in sunken buildings, inside and beneath ship’s hulls, working in tangled debris such as fallen trees and tree limbs, in mine shafts, in caverns and caves. ALL of these require special training, special equipment, and special techniques.
Let’s look briefly at a list of the major hazards that a diver may face when working in an overhead environment.
Entanglement: This is a real danger in many of the types of overhead environments that a PSD may be called on to enter. This danger can be compounded by restricted space, which means help from a support diver would be difficult and/or slow to arrive.
Entrapment: Submerged vehicles and storage vessels are notorious for trapping divers. A misplaced hand, fin or a bump against a “wall” dislodges a piece of wood or metal and starts a “landslide” of debris falling on the diver.
Zero visibility: PSD are used to working in poor visibility, but many overhead environments seem to collect silt and mud which virtually guarantees bad or zero visibility within seconds of entry.
Poor or Zero ambient light: Divers have to bring their own illumination.
Disorientation: Even the “simplest” overhead environments can become a confusing mess to an unprepared diver when visibility disappears and debris has been dislodged.
Depth: Narcosis is influenced by many things and the phrase “deep dive” takes on a whole new meaning and shallower lineal depth for a PSD under stress.
Gas Volume: All environments demand very conservative management procedures, but overheads require more detailed gas management plans because a “simple in and out” can easily become a long and drawn out operation.
The silver bullet solution for each of the hazards listed above boil down to four short words: “Training, equipment, practice, procedures.” ERDI has specialized programs that will prepare a PSD for the rigors they will find when asked to work in an overhead environment. These programs drill divers in the tricks/strategies that make working in an overhead possible. They will be coached on the specialized equipment they must carry, which includes lights (primary and backups), cutting devices (several, and carried in easy-to-reach locations on harness, body and pockets), redundant gas source (even on surface supplied), and a harness and line.
Most of all, this sort of training will coach PSD teams in all aspects of risk management that will help to keep them safe and give them the highest chance of success.
Chances are that your PSD Team has been or will soon have an overhead environment mission to complete. Please consider contacting your local ERDI PSD professional for help making sure the job runs as smoothly as possible and ALL your team members are protected by the right information and training.
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