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DIVING IN CONTAMINATED WATERS: TECHNIQUES
Diving in contaminated water is not much different from diving under ordinary conditions. The procedures and techniques used underwater are basically the same as those for any surface-supplied dive. The real differences in diving in contaminated water are the procedures and techniques that take place before and after the dive. Gear setup, dress-in procedures, and decontamination are quite different when diving in contaminated water compared with diving in less hostile environments.
Preparation for a contaminated water dive starts with the training. Even an experienced scuba diver requires training on the extra equipment needed for contaminated water diving. Thorough familiarity with dry-suit diving and surface-supplied diving techniques is necessary. The most difficult and important part of contaminated-water diving is dressing the diver quickly and efficiently so that he doesn’t overheat. Learning to operate the dive-control console that supplies the air to the diver also is essential.
Integrating the haz-mat team with the dive team is critical. The tender must be trained to use SCBAs and hazmat suits and must be prepared to tend the diver while he himself is totally encapsulated.
The dive team must be trained to use all this equipment and also must practice so that training is maintained and updated. It is unrealistic to expect the dive team to complete the initial training with a contaminated waterdiving system, put the gear aside, and be able to successfully complete a contaminated water-diving operation six or eight months later with no additional practice in the meantime. At a minimum, dive teams should train with the complete contaminated water-diving system with simulated decontamination once every three months. More frequent training is preferable.
SELECTING EQUIPMENT
The first step in planning a contaminated water dive is determining the equipment to be used. Generally, the dive should be made with the highest level of protection available—unless there is some good reason this is not possible. The justification for this is that many times more than the anticipated hazards are underwater. For example, while working in a biologically contaminated river, people upstream from your location can dump chemicals without giving notice.
When arriving at an incident—as with any haz-mat scenario—you must determine the center of the contaminated site. The locations of the hot zone, the adjacent contamination reduction zone, and the support zone greatly influence placement of the surface-support gear. The diver’s lifesupport equipment usually is placed as close to the contamination reduction corridor as possible. Ideally, the diver’s air manifold operator should be able to see the dive site and to have visual contact with the tender at the water’s edge. If this is not possible, at least there must be audio communications between both areas.
Under no circumstances should the diver’s topside air manifold operator be encapsulated. An encapsulated air manifold operator will be unable to communicate clearly with the diver without special communications equipment. In addition, the air manifold operator cannot leave the manifold unattended to change his own SCBA. Finally, if the manifold operator is in a location where there is a possibility of contacting contaminated material, contaminated air could be introduced into the diver’s breathing system. As with any hazardousmaterials incident, the dive station and incident command supervisor should be located upwind of any potential source of chemical fumes.
When setting up the equipment, thoughtful attention must be given to the routing of the diver’s umbilical. For example, the surface-supplied diver’s umbilical often may need to cross a street to reach a drainage canal or lake. While the street may be cordoned off to local traffic, the diver’s breathing air umbilical still must be protected from emergency vehicles that accidentally might run over the hose. If a truck runs over a diving hose, the hose could fail immediately. A truck parking on top of a diver’s hose could leave the diver w ith no air. Obviously, such situations must be avoided, as we are dealing with the diver’s lifeline.
The best protection for the dive hose is to route the traffic around it with traffic cones or crowd-control tape. If this is impossible, it may be necessary to build a simple protective shield to cover the hose—an example would be several nailed-together wooden two-by-four beams.
Also, all the equipment must be thoroughly inspected during setup. Although each piece of gear should have been tagged after its last cleaning and use, it all should be completely inspected again. Particular attention should be given to the seals on the suit, the valves, and the rubber parts on the helmet. Although a piece of gear may have been in good condition when it was put away, it still may have deteriorated in storage.
Divers should always personally test the nonreturn valve on any surface-supplied diving helmet to make sure it is operating properly. The diver should not be able to suck any air back through the valve. If a nonreturn valve fails, serious injury can occur. No diving should be done unless the nonreturn valve on the helmet is operating properly.
Special caution always must be exercised whenever hoses are connected to the diver’s air manifold. Two wrenches—a makeup wrench and a backup wrench —always should be used in such a situation. The only exception to this rule is when using a manifold with welded fittings.
Using only a single wrench may damage a fitting, loosen pipe tape that connects the fittings, or loosen the fittings in the manifold when disconnecting the hose. Any pipe tape that becomes loose inside the breathing system can clog the breathing line and shut off the air to the diver.
A diver and a standby diver normally are used for a contaminated waterdiving operation so that the standby diver can assist the diver should it become necessary. The diver and the standby diver when dressing must have a chair or other comfortable place to sit. They will be wearing a lot of equipment, and a sturdy bench, chair, or stool is a necessity. In addition, if the weather is warm, some type of shade and cooling must be provided. Overheating is a major problem in contaminated water diving, as it is in all haz-mat operations.
A ladder or some other means of exiting the water must be provided if the diving is from a boat. The ladder must be much stronger than an ordinary sport diving ladder. It must be able to carry the weight of two hilly equipped divers, or an approximate load of600 to 700 pounds. In a worstcase situation, the standby diver must be able to earn,’ an unconscious diver up the ladder.
The diver’s tender, who must be posted right at the water’s edge, also must be totally encapsulated and ensured an adequate air supply and cooling. The tender must not leave the diver’s hose unattended at any time.
If diving operations are conducted from a boat—whether the diver is using scuba with a communications tether or surface-supplied equipment—a minimum two-point anchoring system must be used. One anchor should be off the bow and the second anchor off the stern. Without a twopoint mooring, the boat would swing with the wind or current, and the diver could be dragged away from the dive site. More than one diver has been killed in this type of accident. It is much safer to use a three-point mooring system, with one anchor at the bow and one anchor at each corner of the boat’s stern.
Live boating operations, during which the vessel is not anchored but follows the diver, are not recommended. Live boating is very dangerous and should be practiced only by the most experienced divers, tenders, and boat skippers. Many divers have been killed when their umbilical became entangled in a ship’s propeller during live boating operations.
THE DIVE TEAM
Dive team organization must be completely discussed prior to every dive so that each person understands his responsibilities. The dive team should be composed of a diving supervisor, the diver’s air manifold operator, the diver’s tender, the diver, the standby diver’s tender, and the standby diver. Additional team members will be needed to help ensure a continuous air supply and to assist during the washdown of the diver and the tender. Obviously, contaminated water divers require a great deal of logistical support.
The diving supervisor should be the most senior member of the dive team by virtue of diving experience. Diving supervisors are responsible for overall coordination of the diving operation, interfacing with other agencies, and the welfare of the diver. They must have a thorough knowledge of the diving equipment and its capabilities, the environment, the hazardous materials, decompression, and diving physiology. Diving supervisors must operate as the diver’s advocate, always keeping the diver’s best interests in mind.
The diver’s air manifold operator must be thoroughly familiar with the operation of the diver’s manifold and other life-support equipment. The manifold operator need not be a diver but still must have the same knowledge as the diver regarding diving physiology and techniques. Divers’ air manifold operators must be able to rapidly and accurately calculate decompression-dive and no-decompression-dive profiles. Experienced manifold operators can listen to the diver over the communications system and instantly assess the diver’s mental status and physiological work load—the relationship should be that close.
Divers ultimately must understand that they are responsible for making the decision of whether it is safe to dive. They never must be forced to dive when they feel conditions are unsafe. Underwater, the diver must follow the directions of the air manifold operator and diving supervisor explicitly. If the diver is given the order to come up, he must respond, even if there is only a little more work to be done.
Tenders must be as familiar with all aspects of the diving equipment as divers. The tender is responsible for dressing the diver and attending to his needs at all times while the diver is dressed in gear. When the diver is fully encapsulated, his vision and mobility are severely restricted, and the tender carefully must guide the diver to and from the water. Tenders must be protected from overheating, too.
Standby divers must be prepared to assist the diver in the water at a moment’s notice. Some dive teams assume that the standby diver need not be experienced, since it is unlikely that he ever will be required to dive in an emergency situation. In reality, the standby diver should be one of the most experienced divers on the team, since he may be required to save the life of the diver in the water. The standby diver’s tender also must be an extremely competent team member. If the standby diver is needed, the standby tender must be capable of dressing him very quickly.
THE OPERATION
At the dive site, the diving supervisor and divers must evaluate all conditions affecting the dive. Important aspects to consider include the depth, physical underwater hazards (aside from the contaminant), topside weather conditions, underwater visibility’, currents, and the location of the nearest recompression chamber.
If the decision is not to dive, a remotely operated vehicle (ROV) might be used. Many commercial diving companies having ROVs that can be used for this type of work, and some dive teams are using this equipment already. Even if an ROV is destroyed during the course of a contaminated water dive, it is worth much less than a diver’s life. Consider using an ROV if the hazard level is unsafe for manned diving.
Once the zone-management system is in place and the hazards have been identified, it is time to start dressing the diver. While each diver should establish weighting requirements during training, it is critical to ensure that each diver is using the correct amount of weight. Most new dry-suit divers tend to use too much weight. This is a big mistake.
A diver who is too heavy will have a difficult time controlling his buoyancy. Proper weighting for a dry-suit diver constitutes the diver’s wearing the minimum amount of weight possible to complete a precautionary decompression stop at the end of the dive at a depth of 10 feet. A scubaequipped diver must be able to do this when there is no more than 500 psi of air remaining in his tank. Underwater, dry-suit divers should add only the minimum volume of air possible to their dry suits.
During the dress-in for a contaminated water dive, the diver always should allow the tender to adjust the neck seal and other pieces of equipment as much as possible. There are two principal reasons for this. First, the tender can see things that may be wrong with the equipment that the diver may not be able to determine by feel alone. Second, the tender is less likely to tear or damage a neck seal or other piece of equipment than a diver working by himself.
Scuba divers using a full face mask must be capable of donning and removing the mask by themselves. Surface-supplied divers wearing diving helmets will be unable to mate the helmet to the dry suit by themselves. Tenders who assist in mating the helmet to the suit must take care not to injure the diver’s neck. The weight of the helmet itself, combined with careless handling by the tenders, can produce serious injury and discomfort.
While many search and rescue divers use dry gloves for ice diving, using dry gloves in contaminated water requires extra care. Dry gloves never should be equalized, either with surgical tubing or open-cell foam, with the pressure inside the suit. Leaking gloves compromise the entire dry-suit system.
Clamps or waterproof tape should be used on the outside of the gloves to help hold them in place, although even these additional closures do not guarantee that the gloves will stay on. Caution should be used to avoid damaging the connection between the gloves and the suit whenever the diver works around wreckage or other debris. If latex dry gloves are worn, the diver may need to wear additional disposable work gloves over them to protect the dry gloves from puncture.
After the diver is dressed in but before he enters the water, the diver’s diving system must be tested for leaks. The best way to accomplish this is to submerge the diver in a vat of clear, clean water. Carefully observe the system for leaks. If a test tank is not available, then the diver’s suit should be sprayed with a solution of soapy water.
The diver should take a down line with him when entering the water. The down line is used to establish a direct link to the work site so that other divers may proceed directly to work without wasting time. The down line also permits the topside crew to send tools and other equipment directly to the diver. Down lines typically are made of stout nylon, usually ‘/2-inch thick or greater. The last 10 feet of the line usually is a thinner, weaker line such as ¼-inch manila so that the line may be broken if necessary without losing the nylon. The manila is tied to the nylon for easy replacement. The down line must be compatible with the contaminant, and contaminated down lines usually must be replaced. A shackle on the bottom end of the line fastens the line to the work site. The shackle should be turned so that the line will not rub on the pin and unfasten it.
The diver must inform topside of his movements at all times. For example, the diver must let the dive control system operator know when he is leaving the surface so that his bottom time may be accurately recorded. Since divers should know how to dive with a minimum of hose slack, tenders must learn to provide the diver with hose only when he asks for it. In addition, the diver must learn to remember to tell topside when the tender should take up his slack.
If the dive is made with scuba, or if it is a surface-supplied diving operation using cylinders of compressed air, the rule of thirds must be observed: One-third of the air is used to swim to the dive site and work, onethird is used to complete the precautionary decompression stop and return to the surface, and one-third is reserved for emergencies. For a surface-supplied dive, the amount of air available should be three times the amount you anticipate needing for the dive. Most divers consume more air when they are diving on a hose or using communications than when using ordinary scuba.
During a contaminated-water dive, the diver constantly must be alert to feelings of wetness inside his suit or unusual smells inside the diving helmet. If a leak in the diving system is even suspected, the diver must exit the water immediately and proceed to decontamination.
While the diver is underwater, the tender periodically should “fish” the diver. To “fish” the diver, the tender gently takes up on the diver’s hose until he can just feel the diver and then slacks it off just a few feet. This helps the tender ensure that there is no excess hose in the water to foul on submerged objects.
Upon reaching the bottom, the diver must inform topside that he is “on the bottom.” At this time the manifold control operator should take a good reading on the diver’s depth.
Tethered divers always must avoid going under any line or other object on the bottom that would prevent them from making a direct ascent to the surface. Penetrating a wreck is safer with surface-supplied equipment than with scuba, but it still is a hazardous dive and should be attempted only by the most experienced divers.
Surface-supplied divers should check the status of their bail-out bottles frequently during the dive. It is easy to accidentally hit the valve on an obstruction and breathe through the emergency supply without knowing it. The valve and the submersible pressure gauge attached to the regulator must be checked frequently during the dive.
When it’s time to return to the surface, the diver must ascend on the down line. If he spirals around the line as he comes up, he will not be able to get out of the water. If the down line was in the diver’s right hand when he went down, it should be in his left hand when he comes back up. Ascending on the down line also helps to control buoyancy.
In an out-of-air situation, a lull face mask or helmet should never be removed. Aside from the danger of exposing himself to contaminants, the diver will not be able to see underwater. In the surface-applied mode, the diver should be able to switch to his bail-out with no interruption of breathing air supply. Training for other emergencies, such as entanglement and regulator failure, should be a regular part of the dive team’s program.
DECONTAMINATION
Decontamination should start as the diver exits the water. When the diver first mounts the ladder to exit the water, the tenders hose the diver off as part of the gross decontamination process.
During the gross decontamination process, the diver still is wearing all his equipment. Considering the weight of most diving helmets and the other equipment the diver is wearing, it is very important for the tenders to move quickly. The diver is apt to be extremely fatigued after a hard dive, and the heat buildup inside the dry suit can be extreme during decontamination. A diver passing out during decontamination poses a serious emergency for the dive team.
One of the areas of special concern during the decontamination procedure is the point at which the diving helmet mates to the dry suit. In most diving systems, this area traps contaminants. Extra care must be taken to ensure that all traces of contaminants have been removed from the suit’s collar when the helmet is pulled away. Any contaminants remaining in this area will roll down inside the collar toward the diver’s neck. This area must be scrubbed and rinsed with large amounts of water.
Decon solutions should be specific to the hazard encountered. For biological contamination, commonly used solutions include Betadine® and tincture green soap. For chemical solutions, the appropriate neutralizing agents must be used. When the chemicals present are very toxic or hazardous or where decontamination procedures are complex, the equipment usually is containerized for safe handling and transport.
Large amounts of water must be used during the decontamination process, and all that water must be captured. Recovery drums must be available to transport the spent decon fluids.
As the diver removes each piece of equipment, it should be placed in a marked container or bag. A tag listing the date, the exposure time, the contaminants, the level of decontamination achieved, and the piece of gear inside should be attached to the container. Equipment that has been damaged or cannot be effectively decontaminated may need to be destroyed. Dive teams should remember to budget for the replacement of one-third of their equipment on an annual basis. The offenders who caused the contamination should be charged for the gear that must be replaced.
Dry’ suits, helmets, and related items must be cleaned as soon as possible after the dive. A suit dampened by the diver’s sweat will grow mold inside if it is not properly cleaned and dried. This final cleaning takes place during definitive decontamination.
Definitive decontamination for the diver includes a minimum five-minute shower after removal of all dry-suit undergarments and bathing suit. The diver then towels himself dry, disposes of the towel, and enters a second shower. A trailerable decontamination facility is the best location for these showers.
Definitive decontamination of diving equipment usually takes place back at the firehouse or another dedicated facility. At a minimum, the valves in diving helmets and dry suits must be completely disassembled and checked for any sign of damage. If the contaminants encountered during the dive are beyond the scope of the dive team, the manufacturer of the equipment should be contacted for further instructions. Gear should never be returned to a manufacturer without first contacting the company.
To perform proper maintenance on surface-supplied diving equipment and dry suits, each dive team should send at least two members to receive factory training in maintenance and repair. Most manufacturers are eager to provide this training.
All equipment used in contaminated water diving operations should have a use log and a maintenance log to record the information on the gear’s history. At the completion of maintenance, each piece of gear should be tagged and dated to indicate that it is ready for the next operation. Any piece of equipment not operational should have a red tag clearly affixed to it indicating the problems with the gear.
Diving in contaminated w’ater is one of the most dangerous and complex types of diving performed by fire serv ice personnel. Although someday there may be less polluted water than there is today, divers always will have to contend with contaminated water diving incidents as long as there are accidents.
