Fast Water Dredging

By Dave McCracken

Something we have known for quite some time is that pay-streaks, often very rich pay-streaks, exist in the fast water.

At first, this may seem contra­dictory to our general understanding that high-grade gold deposits form in areas of the waterway where the water slows down. However, we must keep in mind that pay-streaks are created during major floods. During a major flood, a sudden drop in the bedrock can cause a very good gold trap, like the riffles in a sluice box, but on a very large scale.

If you turn on a garden hose at slow speed, the fast-water area is found directly where the water flows out of the hose. But when you turn the water-pressure up, momentum forces the water farther out. This condition also occurs within the river during a major flood. Areas where the water runs fast during low-water periods are likely to be drop-zones for gold during high water. The heavy momentum/velocity area will be forced farther downstream, leaving a drop-zone for gold just below the bedrock drop. This explains why you can often find pay-streaks under rapids when the river is flowing at low-water levels. It also explains why you seldom find pay-streaks within the first slow-water area below a set of rapids when the river is running at low levels.

Another reason why you are likely to find gold in fast water is because dredging fast water is more difficult. Therefore, others are less likely to have mined there before you – including the old-timers. For this reason, fast-water areas can often be virgin territory.

What exactly is “fast water?” This depends on each individual. It's primarily a matter of the diver's comfort level. To some people, if the water is moving at all, it’s too fast to dredge. Other dredgers are able to dredge in water moving so fast, that the air bubbles created by the turbulence eliminate all visibility. After diving in really turbulent water, a person’s equilibrium can become so disoriented that he/she can hardly stand up without weaving, as if intoxicated.

Several years ago, a friend and I were operating a five-inch dredge in some very fast, shallow water. Because of the extreme turbulence, one of us would work the nozzle, while the other would hold onto the dredge to keep it from flipping over. The water was so swift that my friend was swept out of the dredge hole time after time. Once, he was carried away so fast, he didn't have time to untangle himself from his air line before he reached the end of it. The air line was tangled around his neck! There he was, flopping around in the current, like a flag snapping in a stiff breeze, tethered by the air line around his neck and struggling, unsuccessfully, to regain his footing in three feet of water. After he got safely to the bank, we both laughed so hard that tears were streaming down our faces. That was emotional stress blowing off. Fifteen minutes later, I was the one bouncing in the current behind the dredge, facing backwards at the end of an air line caught between my legs. Needless to say, my friend thought this was pretty funny, too! Dredging in fast water can be fun and exciting (not to mention the gold you can find). But, you must be aware of, and prepared for, the dangers involved. If you get into a situation that is beyond your ability to handle, there is very little margin for error.

SAFETY

Notwithstanding all the excitement and gold, safety should always be the most important personal consideration. You are the one out there in the field with the responsibility for using good judgment about what you can safely do, without cutting your margin for error too close. The river does not have any sympathy for people who “get in over their heads.” I’ve known several dredgers who lost their lives by over-stepping their personal safety boundaries. It only takes a single mistake. The rest can happen very quickly. All the gold in the world is not worth dying over.

For the sake of safety, it makes good sense for you to not dredge in water that is faster than you are comfortable with. You will have to decide what that is. It is best to practice first in slower water, to gain experience and confidence.

One important thing you should remember about working underwater: Everything may be calm and under control right now; but five seconds later, you can find yourself in the most life-threatening emergency you have ever experienced! This is even true in slow water. But, fast water gives you less margin for safety if you make an error or something goes wrong. You should not dredge in fast water if you are unable to control the various problem-situations that could develop. You need to anticipate each problem that could possibly arise and work out your response, in advance.

Contrary to what many people believe, being swept down river by the current is not the major concern. This is a normal-happening in fast-water dredging. As long as you have your mask clear and your regulator in your mouth, being swept down river by the current is generally no big deal. That is, of course, unless you are dredging directly above a set of falls or extremely fast water.

In most cases, the “fast water” you are in is not a steady flow of current. It is usually turbulent, varying in direction and intensity. A swirl can hit you from the side and knock you off balance. Or, sometimes it can even hit you from underneath and lift you out of the dredge-hole and into the faster flow. If you get swept down river in fast water, you usually just need to grab hold of the river bottom and work your way over to the slower water, nearer the bank. This movement is best done by continuing to face upstream, into the current, while you point your head and upper body towards the river-bottom. That posture will drive you to the bottom where you can get a handhold on rocks or cobbles to anchor yourself down. Then, you can work your way upstream, through the more slack current near the bank, and back out to your worksite again. This is all pretty routine in fast-water dredging.

Getting a hole started is one of the most difficult aspects of fast-water dredging. Once the suction nozzle gets a hole started (the suction nozzle in the hole can serve as an anchor to help hold you there against the current), and there are several cobbles behind you to use as footholds, it does get easier to hold a position there. After the hole has been expanded to the point where you can get your body inside, you will find significant relief from the effects of the current's flow. But, it can sometimes be a real challenge until you do get to that point! At times, you may find it necessary to start your hole in slower water, then gradually work your way out into the faster current.

One of the main concerns when dredging in fast water is having your mask and/or your regulator swept or knocked off your face. This situation is one that can cause a person to panic, especially when both mask (vision) and regulator (air) are lost at the same time.

PANIC

There isn't a person among us who won’t panic, given the right (wrong) situation. People who say they will never panic under any circumstances are just not facing reality and, obviously, have never come close to drowning. I believe it is better to understand and acknowledge your limitations before you get into trouble. The closer you cut it on safety issues, the more aware of your limitations you should be. And, the more important it is to plan in advance how you will react to certain types of emergencies. It’s too late to make such plans after something bad happens!

For me, it takes a lot of personal discipline to stay under control when an unexpected rush of turbulent water jerks my mask off and drags me, blindly and chaotically, down river. This has happened to me on several occasions. I know that under those circumstances, it would not take much more confusion (e.g., air line getting snagged, my body being banged against something, losing my balance, getting a breath full of water from my regulator, etc…) for me to totally lose control and freak out (panic).

I’ve worked with some who have a higher tolerance from panic in the water than I do. And, I know others who feel panicky as soon as they put their heads underwater, even under perfectly-controlled conditions. We are all different, and we each have our own particular point at which we will panic in different circumstances. Everyone has a limit. It is better that we not delude ourselves about this. If you allow yourself to get overly confident, and continually put yourself into situations that can take you beyond your limit, sooner or later you will almost-certainly find yourself tested in a life or death situation.

Panic is a survival-mechanism that takes over when your mind is convinced that your life is in grave danger. At this point, your animal instincts take charge and deprive your intellect of the ability to reason things out. Panic tells you that there is no time left, that you are literally fighting for life just before unconsciousness. The situation demands that you spend your last/maximum physical effort to remove yourself from the danger that is about to mortally injure you or cause you to lose your life. Panic is a horrible, terrifying, and, sometimes, embarrassing experience that happens when your normal, rational self loses control, and the animal-part of you takes over.

There are milder versions of panic. Someone might “panic” and do something silly or foolish in a business or a personal setting. That’s not the type of panic I’m talking about here. I’m talking about the raw physical panic that grips you at the moment you realize you may be at the point of losing your life.

There's always a chance of getting into serious trouble any time you are working under the water. Trouble underwater is serious because humans cannot breathe water. There is no margin. You are either breathing air or you are not. It is an immediate emergency when there is no air. And, such emergencies can happen in a split second, any time you are in a dredging environment.

TAKING EXTRA PRECAUTIONS

Underwater vulnerabilities are especially present during dredging activity. Some of this vulnerability is because it is necessary to weigh yourself down heavily with lead weights to stay on the river bottom. Extra weight is needed to give you the necessary stability and leverage to control the suction hose and nozzle and to move rocks and obstacles out of your way. The demands of dredging activity require divers to be so heavily weighted down, that you cannot possibly swim at the surface without first discarding the weights that hold you to the bottom.

One of the most serious dangers to a dredger is the possibility of being pinned to the bottom by a heavy rock or boulder. All of the oversized rocks that can’t be sucked through the dredge nozzle must be moved out of the hole by hand or with the use of winching equipment. When undercutting the streambed, or taking apart the dredge hole, there is the possibility of larger rocks rolling in on top of you. This possibility increases when you are working in turbulent, fast water. The erratic changes in the pressure that the water exerts on the exposed streambed material, inside and around the dredge-hole, can cause boulders to loosen up and roll into the hole. These same boulders, if located in a streambed where the water is running more slowly, might not loosen up the same way, if at all. For this reason, a fast-water dredger must take extra precautions to remove all larger-sized rocks when they are exposed. One of our mottos is: "You have to get the boulders before they have a chance to get you!"

When working in fast water, all of your normal safety precautions, preventative maintenance measures, and common sense instincts must be scrupulously observed. Fast water may be thought of as a liquid flow of energy that is constantly challenging you and your equipment. Murphy's Law ("anything that can go wrong, will go wrong") is always at work in fast water. It is hard enough to deal with the things that you cannot anticipate will happen. You will have enough of these as it is. But, if you neglect to take action with respect to those things that you can reasonably expect to go wrong, you will almost certainly fail in your efforts to dredge in fast water. If it is wrong, fix it now, before it gets worse!
Preparation of Equipment

OPERATIONAL CONSIDERATIONS

My dredging partners and I have found that it is physically possible to dredge in water that is too fast for the safety of our dredge -- even the kind of dredge that is best suited for fast water. Therefore, the need to operate in an environment that is safe for your dredge is one of the major limiting factors in fast-water dredging.

Most fast-water dredgers add more flotation to their dredge platforms to give more stability. This can be done in different ways, including additional pontoons, inflated tire inner tubes, PVC pipe material, Styrofoam, etc.

One of the main considerations when adding more flotation to a dredge is to avoid increasing the drag against the current. Additional drag causes problems in two ways:

1) The fast-water current puts more strain on your dredge, frame, and tie-off lines.

2) More importantly, the surface-tension caused by all that additional water dragging around the dredge makes it difficult to work near the dredge when you’re in the water (which can be a particular problem when you’re trying to knock out plug-ups from the suction hose near the dredge).

Another goal when adding flotation is to keep the floats as narrow as possible. A wide set of floats is more likely to be tossed or dragged around by the turbulent flow of fast water.

Generally, when working in fast water, I try to find a location for the dredge where the water is a bit slower, just next to the fast water where I plan to work. This way, I can enter the river in slower water and work my way out underneath the faster water, adding suction hose as necessary.

Otherwise, if we position the dredge directly in the fast water, it will become necessary for the divers to contend with fast water when entering the water from the dredge. This can be done; but it makes the operation more difficult – especially, when the dredgers need to climb back onto the dredge.

Also, the buildup of cobbles and tailings near the dredge can add to the surface-tension and create an even faster current flow under and around the dredge.

When you are set up with the dredge positioned off to the side in some pocket of slower water, your suction hose will be running perpendicular, at least to some degree, to the flow of the fast water. That much hose exposed broadside to the current creates enormous drag, which can cause the suction hose to kink at the point where it attaches to your power jet. Hose-kinks will cause continuous plug-up problems, so they must be avoided. Therefore, you may find it necessary to disconnect the suction hose and cut off the section that has been kinked. However, you cannot shorten your suction hose very much before you lose the amount of operational flexibility you need for freedom of movement while dredging.

Suction-hose kinks can usually be avoided by setting up a special harness to support the hose in fast water. This is often done by rigging one or two extra ropes down from your main tie-off line. The ropes are fastened to the suction hose at points which will allow the hose to be flexed back by the current, but not to the critical kinking point. You must allow the hose to flex back. It is the bend in the suction hose which allows you the movement to expand the size of your dredge hole.

It is best, when rigging a fast-water harness, to rig it in conjunction with your main dredge tie-off line. This way, the entire dredge and suction-hose harness will move together, as a unit, when you take the equipment forward as your dredge-hole progresses.

Suction hose support booms are standard equipment on the commercial  Pro-Mack dredges.

Larger and commercial dredges may be equipped with booms, which can be extended out in front and used to secure a suction-hose safety harness. In this manner, when the dredge moves forward, the suction-hose safety harness moves with it, as in the situation above.

Another concern in fast-water dredging is to keep your suction nozzle and hose from being swept out of your dredge hole. Sometimes, the current will put so much drag on the suction hose that it takes all of your strength and energy to get any nozzle-work done at all! In such a case, you can relieve the main strain of the drag by tying a section of the suction hose to a large rock at the rear of the dredge hole. When doing this, always leave enough slack in the hose to allow you to move the suction nozzle forward as your dredge-hole progresses. Also, be sure to remember to untie the suction hose from the river-bottom before you move the dredge. Otherwise, you can damage the hose by causing kinks in the middle!

When you take a lunch-break or knock off for the day, you can anchor your hose and nozzle by either piling rocks on the suction nozzle or tying the nozzle to a large rock in the bottom of the dredge hole. It's no fun to start a production-dive by having to work against the current to get your suction hose back into your dredge hole, because the fast water blew it out after your last dive. But, of course, all fast-water dredgers get many chances to experience this. It’s a normal part of the routine!

One safety point: When using ropes underwater, it is a bad idea to use any more than is absolutely necessary. Always cut off any excess rope or pile rocks on top to hold it down. If there is a length of loose rope flopping around in the current, something (like your air line) always seems to get tangled in it. Loose rope under water is dangerous!

Your air line can be another source of problems when dredging in fast water. Always be sure to get all the loops out of your air line before starting your dive. Otherwise, the current can pull these loops into kinks, which can immediately cut off your air supply.

When you turn around in your dredge hole to roll boulders, toss cobbles, or do any of the many other things associated with production dredging, get into the habit of exactly reversing your turn when you face forward again (turning back counterclockwise is “cancelled out” by turning forward clockwise). This practice will help prevent you from putting lots of loops in your air line during the course of the dive. Each loop is a potential kink that can cut off your air supply in fast water. Each loop also increases the amount of drag being brought to bear on your air line in fast water.

If you should get a kink in your air line that cuts off your air supply, you can usually get some immediate relief by pulling your air line in toward your body and letting it go. When you let it go, the pressure is temporarily removed from the kink, and you can usually
get a breath of air. I always try this once, quickly, when my own air is suddenly cut off. If that doesn’t give me immediate relief, I crawl right over to the surface so I can properly correct the problem.

If you are experiencing any difficulty with a kinking air line, your best course of action is to immediately remove every single loop in the line. Getting rid of the loops will require you to rotate yourself in circles, going in the appropriate direction, until the air line is straight again.

Several years ago, I was dredging in fast water with a guy who had to repeatedly dive out of our dredge hole because of a kinking air line. After about the fifth time, I suggested that he take the time to straighten out his air line to fix this problem. This remedy only worked for a short time, because he had developed the habit of turning around and around in the dredge hole as he was moving rocks, which just created more and more loops in his line. Fifteen minutes later, he was diving right back out of the dredge hole again.

Today, you can buy a heavier-type of "safety" airline that will prevent kinking in all but the fastest of fast water. I recommend this heavier air line to anyone who plans to dredge in swift current.

By the way, your air line is also your direct connection to the dredge and to safety. When you connect your air line to the dredge, even in slow water, it should be wrapped around the dredge frame several times before being attached to the air fitting on the dredge. Most air fittings are made of brass. If you should need to use your air line to pull yourself to the dredge in an emergency, it is better that you not have to depend on the strength of a brass fitting!

Nearly all experienced dredgers are aware of the fact that their air lines are an extension of themselves while under water. Especially in fast water, it is very important that you not allow your air line to tangle around parts of the dredge, underwater obstacles, and/or the air lines of other divers in the dredge hole. If you cross over the top of another diver's air line, keep that in mind, so you will be sure to cross back over it again when you return. Each time you go to the surface, to remove a plug-up or for whatever reason, take a moment to untangle your line from anything it may have wrapped around. As a practice, all dredgers should always untangle their air lines each time they return to the surface after a dive.

One of the persistent problems of dredging in fast water is the heavy drag on your air line. This can normally be solved by pulling some slack-line into the dredge hole and anchoring it with a single cobble placed on top. This will allow some slack air line between you and the cobble. You want to be sure that your cobble-anchor is not so large that you can’t quickly free your air line in an emergency. Also, when you leave the dredge hole, don't forget to first disconnect your air line from your anchor.

Full face masks are generally not well suited for diving in swift water. Since they are larger, with substantially more surface area, they are more likely to get accidentally dislodged from your face. This can happen when the mask is bumped on another diver, or an obstacle, or when turbulent water catches it, especially from the side. To further complicate matters, when a full face mask fills with water, the regulator usually does as well. Having to clear the water out of your mask and regulator at the same time can be more difficult and contribute to a panic situation. I personally find that I am more prone to feeling panicky when something goes wrong inside of a full face mask. If your reactions are similar to mine, you may want to avoid using a full face mask in fast water.

DO'S AND DON'TS!

In any kind of a dredging operation, fast or slow water, do become familiar with your surroundings as your first priority. Before you begin work, make sure you know the easiest and most direct route to crawl over to the surface in the case of an emergency. Don’t wait until an emergency happens before you think about this. By then, it is too late!

Don’t tie yourself into a dredge hole in fast water to keep from being swept down river. It’s bad enough having a heavy load of lead attached to your body! If you have to tie something, tie the suction nozzle from a point further up river. Then hold onto the nozzle to keep yourself steady and in place, while you get the hole started.

Generally, the most effective way to maintain your position in fast water is to streamline your body properly, with your head and chest close to the river-bottom and your rear-end slightly elevated. This posture allows the water-flow to push you down, toward the bottom, so you can get a better footing. Begin creating your dredge hole as soon as you can. The hole will help anchor you in place. The larger you dredge the hole, the easier it gets.

Some dredgers try to solve their stability problem by putting a lot more lead on their weight belts. Sometimes in turbulent water, more lead can be a help. But, be extra careful when walking out of the water on the slippery bottom, so you don't overload your ankles and knees and injure yourself.

Most importantly, don’t solve your fast-water buoyancy/stability problem by adding a bunch of additional weight belts. It’s hard enough to get one belt off in a hurry, without compounding the emergency with three of them! Sometimes, you cannot do it without 2 weight belts, but you must understand that a second belt reduces safety margin in an emergency. Additional belts tend to shift around so that the quick releases are in different places. Difficulty in finding them in an emergency can contribute to a panic situation and put your life at risk.

Whatever else you do, early in your dredging career, do discipline yourself to never try and swim for the surface in an emergency, while wearing your heavy weight belt. It just doesn't work! In a panic situation, your body will want to go immediately for the surface instead of removing the weight belt. I have personally saved two people from drowning who were trying to ”swim for it” with their weight belts on. By the time they realized swimming wasn't going to work, they were in too much trouble (panic) to get their own belts off!

This doesn’t mean you can't get a good footing on the bottom and jump up to the surface for one quick breath of air. You can do that in an emergency, as long as the water isn't too deep or fast. But, if you cannot crawl over to the surface quickly, your first priority should always be to get the lead weights off as soon as possible.

Keep in mind that you usually cannot see the quick-release buckle on your weight belt while underwater. This is because your face mask blocks your vision at that angle. So, it is important to practice locating the quick-release buckle by feeling for it.
It is also very important to keep your belt from shifting around, so that the buckle always remains directly in the front of your body. One of the problems we already noted when wearing more than one belt, is that the top one tends to shift around.

You may also find that it is better to first remove your work glove before trying to release your buckle in an emergency.

These are all things you must be able to do quickly and instinctively before venturing into fast water. A wise skydiver would never jump out of an airplane without first receiving enough practice and instruction in how to find his rip cord. Similarly, a dredger’s life should be just as well protected by having a confident ability to release your weight belt quickly in an emergency.

Some of the weight belts on the market also include a suspender harness. The only ones I recommend are the ones that have a quick-release, D-ring on one of the suspenders that permits the shoulder harness to come loose when you release a single waist belt buckle. Otherwise, in an emergency, you may find it too difficult to get out of the suspenders, even if the waist belt is released.

Do, always, keep an eye on your diving buddy while dredging in fast water. When we dive with multiple dredgers on an operation, it is standard policy for us all to keep track of each other. If one person needs to leave the dredge-hole or go to the surface for some reason, he always lets someone know he is leaving. Therefore, when a diver suddenly disappears, we immediately go looking for him. A person in serious trouble underwater only has about 30 seconds to get it together. This isn't much time. What good is diving with someone else, for the sake of safely, if you are not paying attention to what is happening with him/her, especially in fast water where there is so very little margin for error? A tender, or anyone else resting at the water’s surface, should be paying close attention when there are dredgers down working in fast water.

If all of this has frightened you, that’s good! That means I have accomplished my goal of alerting you to the dangers inherent in fast-water dredging. Being alert to, and fearful of, those dangers is the starting-point for making your own preparations and contingency plans for dealing with them – before you start working in fast water.

What is fast water? It depends on the individual. An experienced diver might be much safer in a storm of fast, turbulent water, than an inexperienced one would be in slow, shallow water near the bank. The key for each person is to begin learning in a safe and comfortable environment, gain valuable experience over time, and never attempt to do anything that you cannot easily handle, with safety.

Hard Work

Application is the Key to Success

Never Give Up!