Field Notes
U.S. Fish & Wildlife Service
Field Notes Entry   
Keeping Service Divers Safe
Midwest Region, November 15, 2011
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Region 3 Diver Andy Roberts with Multiple Air Delivery System.
Region 3 Diver Andy Roberts with Multiple Air Delivery System. - Photo Credit: Bryan Simmons
Region 3 Diver Bryan Simmons Beginning a River Dive.
Region 3 Diver Bryan Simmons Beginning a River Dive. - Photo Credit: Andy Roberts

When most of us think of SCUBA diving, crystal clear water over a coral reef or a large lake quickly comes to mind. Even though most U.S. Fish and Wildlife Service divers never get such an opportunity, we happily spend our time on the bottom of a murky, rushing river, looking for splendid occasions handling endangered species. In performing our work, our equipment needs to vary considerably from that of the standard recreational diver. Over the last year, we have developed a diving system that we now employ during our underwater research.

As Service divers in Missouri, our priorities are to monitor freshwater mussel populations. Our work locations vary from large regulated rivers; below hydroelectric and flood control facilities which are often plagued by unannounced high flows, poor visibility and underwater hazards; to small streams often burdened by poor water quality issues such as TMDL’s for metals or ammonia.

Surface-to-Diver “Hookah” diving has been and remains a common practice employed by both commercial mussel divers as well as the research community. Most Surface-to-Diver units have an oil-cooled, gas powered motor connected to an oil-less compressor (ensure the compressor is safe for breathing), which collects filtered atmospheric air via a long snorkel (to minimize CO from fuel combustion) and delivers it to the diver(s) via a hose and on-demand regulator. A main point here is that this type of system is of low pressure, usually not exceeding 80 bar as compared to standard SCUBA system usually in the range of 140 bar. I have personally used three different brands and know there are many more out there, including electric versions.

Two large benefits these units provide are: 1) a reduction of your underwater profile, 2) the increase of your underwater work time. These types of units are effectively unlimited air sources as long as the compressor motor maintains a sufficient fuel source. A typical fuel tank, if not refilled, can last nearly two hours, a very cheap cost when considering SCUBA tank refills, and the multiple complications involved with the transportation, delivery, storage and handling of numerous tanks to a remote river dive site.

The few down points would be: 1) that your remain tethered to the unit via a hose(s), 2) air supply hoses may become kinked, compromising your air delivery 3) multiple airlines can become crossed and tangled while buddy diving 4) the delay in set up/breakdown including the winding and unwinding of hoses 5) the need for a tender to feed lines if diving from a boat 6) and the background noise generated from the motor. In my opinion, these down points quickly fade, the very first time your dive is cut short, once you’ve become settled into work groove and spend what seems like most of your work time checking your air gauge to learn your scuba tank is empty AGAIN.

As an authorized diver within the USFWS, we are required to have numerous protocols employed to ensure our safety while performing our diving activities, as further described in 29 CFR 1910, Subpart T; 485 DM 27. Furthermore, because of our various diving situations and needs, while also effectively considering the seriousness of our safety, we strove to devise a back-up system that would provide a supplemental air source if the initial one failed. We also wanted to increase our options to maintain the independent use of the original equipment as well as limit the redundancy of having to break down air connectors, losing parts or the need to constantly have additional tools at hand to perform these tasks.

Our result, after one full season of trialing field work is one we’re very pleased with. We now feel very secure while diving, knowing we have a reliable easy-to-employ backup system at the turn of a knob. The story began shortly after we purchased the Surface-to-Diver system. We quickly noticed the regulator connector fittings to airline were of a well-machined swivel type. I contacted the manufacturer and found they develop various other fittings for other utilities. We then developed a schematic of our needs. We desired a multiple air source delivery system for both a low and high pressure combination.

To better describe this, we each have a standard Buoyancy Compensator Device (BCD) to ensure positive buoyancy in case an emergency accent is needed. This device is basically a vest with an air bladder that is connected to and also functions to hold our high pressure scuba tank and lines.

Attached to this vest, is the switch block. The switch block serves to separate two incoming air sources and only deliver one to the regulator/diver. In our case, the main source of air is the low pressure Surface-to-Diver compressor. In addition to this compressor, we also purchased an air reserve tank directly off the compressor to provide a limited amount of air reserve if the motor stops unexpectedly.

If this reserve air source becomes compromised, and if the diver hasn’t already surfaced, the diver can simply turn the switchblock knob to the second air source, in our case, the high pressure scuba tank for additional reserve air to return to the surface and exit point. In addition to the main regulator, we also have a secondary O2 high pressure regulator on the BCD that also remains directly connected to the scuba tank. This provides a redundant backup if the switchblock system fails. This also rids the contention of an additional Octopus regulator and hose failing from continual exposure to mud or gravel.

When we are working in streams with human health hazards because of water quality, we also employ an AGA (full-face) mask. This mask further minimizes skin exposure and has an additional option we desire - underwater communication to a buddy diver and/or boat operator, dive tender.

In addition to the switch block, all hoses, regulators and AGA masks are connected to each other via a lockable quick-disconnect fitting. This allows us to quickly change or remove regulators depending on the diving situation without the need or worry of additional tools in the field.

We feel, with this system we have become not only safer, but more effective to achieve our research goals, and hope is one that others could employ.

Contact Info: Bryan Simmons, 417-836-5302, Bryan_simmons@Fws.gov

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