BY ERNIE PIERCE

“Finding new friends and gold on the Klamath River”

 

It was the end of a real good gold prospecting trip and a nice July morning when my family and I finished packing and headed East on Highway 96 away from Happy Camp. I was very pleased at the outcome of this trip I had dredged up over 35 pennyweight of gold. As we traveled home I thought “It sure would be nice if I could come back before the weather turned cold………”

Well, let me tell you about the power of positive thinking or making a wish come true. We arrived in Austin to find an unusual set of circumstances that allowed me to take the time off, put enough money in the bank for Mary to pay bills for September, and with the rest I started packing and thinking of Happy Camp….

August 26th rolled around and I was headed for California. Yes!! After a good trip I arrived in Happy Camp at 10:30 p.m. on the 28th (Monday).

Tuesday morning I gathered up supplies for my much modified 5-inch dredge, then went to Morgan Point to set up camp. Putting the dredge in the water and getting it set up was interesting, to say the least. I had extended the frame for more stability and added another motor, (an eight horsepower and a five) so it took some time to get things balanced and the sluice set.

The next two days I sampled and fine tuned the dredge so I was getting very good recovery and losing very little gold. I then had to change to another jet tube—I felt I was not getting the suction I should. The replacement jet tube had more power with only one motor (the 8hp B&S) than the first with both going! The dredge could really move some gravel after that. I found out quickly that I wasn’t getting much gold here so I decided to move to another claim.

I decided to go back to the claim I’d worked in July to try a little further downriver from the place I stopped working. Dave McCracken had told me back in July that I might drop back downriver from the pocket I was in and work the top couple of feet of gravel to see how much gold was in it. I didn’t have the time then but felt it was something that should be done. Now, Dave knows what he is doing in the gold dredging business and knows the rivers around the area, so he can be relied on to be correct if he suggests something you could do.

On the way to the claim I stopped at the Savage Rapids claim to help handle some maintenance a group of New 49er’s was taking care of. With the large group that was there it didn’t take very long to get the work done. While doing this I met a very nice fellow from Arizona, Philip, and we formed a partnership to work the claim on up the river.

I really love to camp out in the woods, out away from almost everyone, where you can listen to the insects, the birds and other wildlife. When Philip arrived we got his gear set up, then floated down through the claim to see where to put the dredge, using face masks and snorkles to watch the bottom. I noticed the inside bend of that part of the claim had a lot of large boulders, the current was much slower, and the spaces between were hard packed with gravel. The area looked like the typical gold trap to me! This definitely looked like the place to try a sample.

Going back to the truck we decided it was too late in the afternoon to set up the dredge but we made ready so we wouldn’t lose time in the morning.

Next morning we setup the dredge and got it ready to float downstream. Did I mention to take it through a nasty set of rapids? Well, we floated it near the bad part, then stopped to assess the situation. I showed Philip where I needed him to be to help catch me and the dredge after we came through the rapids. He agreed to do that with no reservations after I explained how I was going to guide it from behind all the way through them. He said he doubted my sanity but figured I knew what I was doing (little did he know).

After he was in position I eased the dredge out into the current (where it promptly turned and went the wrong direction around a large rock). This got interesting real fast when it went in between two large boulders, then got hung up on a third that was just underwater. Here I was, trying to hang on so I would not be swept away from the dredge and to get this thing off the rocks before it flipped over (you can think fast when you need to). In a few seconds I figured where to push or pull, then it was sliding on over that rock and a wild ride was beginning. Whoa, Nellie!!! I got through there and Philip pulled the dredge and me onto the gravel bar. Whew! This sure was a lot more fun and exciting than winching around and over this area.

I figured we’d have to make a few sample holes before finding the pay-streak, so the first place we tried was where the large boulders stopped and mostly smaller ones started. This, it turned out, was the right place the first time. After dredging for just over an hour we checked the sluice. Man, did our eyes bug out… Wow!! We had hit a good pay-streak on the first try. I could see gold all under the screen and in the mat. Oh boy! Screening this down quickly I could see we had a lot of gold so I set this aside to weigh separately. Later we found out it was about 2.5 pennyweight. A real good start. Feeling good, we went back in and dredged until the gas was gone. As we were dredging, we noticed flakes of gold as they were uncovered and went up the hose.

We developed a system of working. this area when we discovered that the gold was indeed in the top two or three feet of gravel. We’d go down till we hit a hard packed layer, work an area about ten feet wide from midstream at an angle up to the bank, then go back midstream and do it again, throwing the cobbles into the area we’d dredged.

I noticed the gold was still coming out of the gravel and off the hard-pack. It sure looked good underwater. When I saw it I showed Philip, and that got us encouraged and going again.

We had some very, very nice gold on this cleanup and added it to the rest. The next day we needed supplies, so into town we went to sell the gold. What we had for approximately seven hours of dredging was eighteen pennyweight of gold. (I measure dredging in hours underwater rather than days). Not bad at all.

On one dive we were dredging around a large rock (about 200 lbs) when we noticed that a lot of gold was in the area around it. We dredged a hole about three feet deep in front of the rock, spread it out some, then realized it was time to refuel the dredge. After taking care of that, back down we went to clean out that area. I forgot about the rock and was standing in the hole about thigh deep leaning on another large rock embedded in the side of this hole, dredging more of the hole out when I felt a grating vibration… I jumped straight up and pushed away from the suction hose which, thankfully stayed in the hole. As it was, the rock still hit my ankle very hard when it slid into the hole and into the other large rock. The suction hose kept them from pinning my foot in the hole. It took another three minutes to move the rock off the hose.

After the close call Philip signaled for us to go to the surface, but I wouldn’t go. What we did was stay down and keep working.

My ankle was hurting badly and I couldn’t put much pressure on it, but I kept right on going. I just placed my ankle against the rock where it hurt, then kept right on dredging until the pain quit. When the gas was getting low we went up for the day. Later at camp we looked at my ankle and it had a very dark bruise about the size of a half dollar, but I could walk very well on it.

A couple of days went by and the gold kept coming up real nice and stayed about the same amount or better so we kept going straight upstream. One day I tried to get a little further out in the middle of the river. This produced less gold so we continued to work the slope of the riverbed where the big rocks were.

Now on Saturday afternoons the New 49er’s put on a potluck dinner and all are invited. This is a real neat affair where everyone gets to sit around, eat, and tell their stories — you know, just really have a lot of fun. Philip and I really looked forward to Saturday night potlucks in Happy Camp even if we did have to drive thirty miles to get there.

Then one morning Philip bent over to tie his shoe laces and when he raised up he pulled his back out. For the next day or so he tried to recover, but when his back didn’t get better he decided to head back home. I enjoyed his company while he was there and missed him after he left.

I got my hands on a wetsuit heater that fits on the exhaust of a dredge engine and installed it. This heats water fed through a hose that fits inside the wetsuit. Oh, wow, it sure felt good to have warm water flowing while I was in that cold water every day. This sure helped to be able to stay in the water longer each day as I could barely stay in for one tank of gas before.

I now was working alone and had to really hustle to move a lot of gravel per day but I just did it and was soon to the point where I was moving an area about fifteen feet wide, about ten feet long, and two to three feet deep every four to five hours. That was moving a lot of material! This was also paying off very well. I was averaging half an ounce of gold every four or five working hours. For the next eight or ten days the area stayed productive and when I worked I found gold. The water was turning colder and I wouldn’t work every day. Two days later at the Saturday night pot luck dinner my nose started to bleed (I never get nosebleeds, ever). I realized I had a bad sinus infection. I took it easy Sunday, but on Monday I was still getting nose bleeds so I decided that it was time to head for Austin.

As this trip came to a close I started to look forward to next summer. I traded some of my gold for the pieces to put together a six -inch dredge. In a few hours I had most of what I needed, so I left Happy Camp with something to keep me busy over the winter.

I reflected that I had indeed had a good adventure. I met and got to know some very good, trustworthy people. I’d accomplished what I started out to do — find more gold and have a better time. The total gold for this trip came to just under five ounces. This was three times what I’d done on the last trip. Not bad at all. So, the target for next summer…..you guessed it, no less than three times what I recovered on this trip. Can I do it? You bet I can! I’ll see you on the Klamath.

 

 

By Dave McCracken

To succeed at gold dredging, you should be willing to take a rather athletic approach toward the work, especially during the sampling stages.

Dave Mack

Gold dredging consists mostly of physical activity. Heavy gear has to be carried around from place to place. Much of your time is spent wrestling with a suction hose, picking up and tossing cobbles as fast as you can, shoving against boulders, fighting to hold your position against the water’s current, packing 60-plus pounds of lead around your waste, swimming back and forth across the river, and pulling dredges around on ropes. There just never seems to be an end to the physical work! This is not bad. Unless you don’t like hard work.

If you have a distaste for hard, strenuous work, if you don’t enjoy it and are generally looking for ways to avoid it, you need to find some line of work other than gold dredging. To succeed at gold dredging, you should be willing to take a rather athletic approach toward work, especially during the sampling stages.

Some people are physically-inclined by nature, and they enjoy hard work. Other people are not so physically inclined, but they are willing to work hard and do whatever it takes to succeed. Such people can be very successful at gold dredging. But, no matter what your inclination, gold dredging requires hard work. There is no getting around it.

I have found, to be most effective, it is best to attack a gold-dredging operation with a rigid work schedule, just like any other job or business-activity. I personally prefer to “pour on the steam” for three straight days. Then, I take one day off from dredging to allow my body to recuperate. The work is physically exhausting on the body if you really pour out the energy. You need to find the appropriate rest-interval that works best for you. Otherwise, your body will get overworked and start breaking down. I use my day-off to perform gear maintenance and the many other miscellaneous chores that are needed to keep the operation running smoothly. I try to get some much-needed free time out of it, as well.

 

 

 

 

My approach is not the only way. I know successful gold dredgers who prefer to work fewer hours each day, or work at a less-intense level of physical activity; but they put in five or six straight days at a time. If we could add up the total units of energy expended on dredging, it would probably come out about the same, either way. It is just a matter of preference and what pace you are most comfortable with. The main point here is that no matter how you cut it, you’ve got to put in the dredging hours if you want to succeed at underwater mining.

When people ask me about gold dredging as a profession, I always answer as follows: “Given the knowledge of how to do it, and the willingness to apply the knowledge, gold dredging is an easy way to make a living, if you are willing to work hard at it.” And, this is the simple truth.

 

 

BY GENE MEDENWALD

 

 
Recently, after about a two-year absence from gold mining with a suction dredge, I returned to the activity.

I guess I am what is known as “middle-aged.” After the first day of dredging and diving (and not a long day), I found my body wracked with painful protests at what I had subjected it to; I mean aches and pains—everywhere. After the second day of dredging, my aches and pains had aches and pains. Just crawling into bed was agony. Getting out of bed the next morning was no easier.

On the third day, after I had run a tank of gas through the dredge, I found myself sitting on the bank of the river enjoying a coffee break; and the thought came in to my mind:

Why? Why are you doing this, Gene?

Well, I thought, I must like doing it. But then again came the question, why do you like it?

And then I remembered something I’d come across years ago in some obscure reading: Around the turn of the century, there were hundreds of signs posted throughout the Southwest which read: RIDE WITH PANCHO FOR GOLD AND GLORY! The small print on the signs supposedly told in glowing terms of Pancho Villa’s efforts toward furthering the Mexican Revolution and how he needed courageous and adventuresome young men. Some historians have called Pancho a plain and simple bandit and not a revolutionary at all—but that is beside from the point.

The point is, I think I’ve figured out why I do what some people call a totally insane activity: this business of gold mining by diving with a suction dredge…FOR THE GLORY OF IT! There is so little, too little, many say, opportunity for glory in the lives of contemporary Americans. Everything is organized, corporatized, burocratized.

How often have you been in a group of people where everyone does not know everyone else and the inevitable questions comes up, “What do you do?” The asker doesn’t want to know, really, what the person does. He or she wants to know, not what you do, but who you are. And how often when the response is, “I’m a mechanic-painter-doctor-lawyer or typical whatever category,” you hear the flat “Oh.” And there is a decidedly noticeable lapse in the conversation? Well, when the question is put to me and I respond, “I’m a gold miner,”there is no “Oh.” Instead, I must again respond to further questions and remarks like, “No kidding! Where do you do that?” and “Really! Can you actually make a living doing that?” and “Is there really still gold out there? I thought the old-timers got it all?” etc., etc., etc.

The nifty thing is, I think that most people like to put most people that they encounter into comfortable categories—and they don’t have a ready category for a “gold miner.” But what, really, do I mean by this idea called “glory?” Certainly, as regards cocktail party conversation, it is a quality of uniqueness. But it is much more than that. If I cannot define it accurately in so many given words, I can describe it by relating the first five minutes of a typical day of dredging for me.

It matters not if the weather is hot, cold, clear, rainy or even snowing. When I reach my dredge site, the first thing I do is slip out of my small backpack, pull out the thermos and pour myself just a small dash of coffee and pull out a cigarette and lighter from the waterproof pouch…light up, sit back with that dash of coffee and survey the scene before me.

The wildlife…the blue heron is working for his breakfast in the placid shallows as he is every morning. Some mornings, there is a black bear watching me from across the river, and he feels I don’t know he’s there, but I do, but don’t want to him know that I do (why disturb him?). The same silly mallard duck is foraging above the rapids (one day he’s going to begin his frenzied paddling toward the quiet water a tad too late!)…

The flora…two seasons now I’ve watched it turn from the lush green of summer to all of the brilliant yellow and reds and gold of fall to dreary winter drab…

I am here…it is wonderful…I am free…No one is telling me I have to be here, when I have to be here, what I have to be doing here, and how I have to be doing what I am doing here.

The gold I get here is important, very important. For, if I do not get it or enough of it, I cannot continue this life. But, for me, it is truly a secondary significance though a very important one.

And as I finish my coffee and cigarette, I reflect on yesterday’s activities. I got to my dredge site late yesterday. Only ran less than a tank of gasoline. I’d spent almost the entire day helping Larry move his dredge. But I’d volunteered to help him. Because two weeks after I’d arrived here, he helped me move my machine. And I owed him? Not really.

Glory and those who participate in it yield a kind of camaraderie that few humans alive ever have the good fortune to experience. It is not a question of owing. It is a goodwill, man to man, man to life.

And it is not all the proverbial bowl of cherries. The hardships are severe. It is a physically taxing activity to the extreme. Everything is against you. The rocks are sometimes so slippery with moss and slime, it can be dangerous attempting to walk upright. Add a 40 to 60-pound weight belt and it is, indeed, dangerous.

The river’s current is constantly, unremittingly, attempting to wash you downstream. Cobbles and boulders, which one must move constantly and as efficiently as possible, are unwieldy, slippery, cumbersome, heavy and tedious to exasperation. This, when things are going well. I’ve seen a series of exasperating breakdowns drive a grown dredger to tears, and been near the experience myself.

Managing your money in this business is incredibly tricky. One day you may be rich with gold. Pounds of it. Then you may go for 60-days or more without finding more than a few pennyweights. Meanwhile, you have daily operating expenses, daily living expenses, breakdowns which can be costly, the constant risk of uninsurable theft of some or all of your equipment or machinery, and the constant worry of having to set enough aside for the constant and rapid depreciation of your gear and equipment. There have been times when I’ve felt guilt for going into a restaurant to share a cup of coffee with a friend; or buying a pack of cigarettes instead of rolling my own, which is much cheaper.

There is no wonder nearly all miners are single. What lady would want to participate in a venture of such uncertainty? And yet…

Yet, when you see two miners together who have spent the last three or four days in a row underwater to the point where they are obviously taking well-earned days off because of sheer bodily exhaustion, what are they avidly speaking of and gesticulating about? Dredging!

In a very real sense, this dredging activity is almost a kind of madness. And, yes, I am proud of myself for doing what I am doing and for the fact that I am doing it. I bow to no man. In the words of William Hailey:

“I am the master of my fate; I am the captain of my soul.”

And yet, the dredging-miners for whom I have the most admiration are those who are not only successful and making a living or a very good living at it, but who are doing so with the companionship of a lady-friend.

Being a man, it is of course impossible for me to view things from the point of a woman. Yet, knowing this is not the kind of vocation the typical man embraces, I am doubly sure it is not viewed positively by many of the female gender. The evidence supports me! I have not seen so many lonely single men engaged in one activity since my woeful experience with the military. Yet, contrary to my military experience, I have never met so many dedicated, intelligent, physically virile men of all ages gathered together in one spot in my life.

Glorious men!

If I were a lonesome single lady, an absolute sure-bet for sophisticated companionship would be to drive along a gold-veering river, keeping my eyes out for a machine floating on yellow pontoons. For, underwater, not far away, is one hell of a man — a bit grubby in appearance, perhaps, but only temporarily. One friendly, feminine grin will most assuredly send him immediately to the nearest tonsorial parlor with the day’s take in hand…

But, alas, whimsy is not reality. My coffee cup is empty and my cigarette is smoked down to the filter. It is time to crank up the engines and don the weight belt and the rest of my gear and begin another day of diving for Gold and Glory.

More Stories by this author:

 

 

BY ULF DANNENBERG

 

The memory is still very clear. When I was a kid about 9 years old, we played Cowboys and Indians in the ruins of bombed-out Hamburg in postwar Germany. We kids consumed the mandatory literature about Billy the Kid, the Lone Ranger, and the exploring of America’s Wild West. Sometimes we read with a flashlight under the bedspread, reading until deep into the night.

These stories had such an impact on me that my fantasies about America nearly became an obsession. The dream that formed in my mind at that time came true in 1965.

My first time in America and I was hooked. I spent the second half of the 60’s in Hollywood, California, became part of the Hippie crowd with all its good and bad things. While I survived all of that in pretty good shape, I was hopelessly spoiled. Unable to go back to the 9-to-5 routine in Germany, I became a world traveler with odd job opportunities that lay left and right along my way of life.

Mining for gold was one of the more adventurous tasks I took on in ’81. The last frontier–Alaska was calling me from afar. My old VW camper was shipped from Germany to Houston, Texas; and after four weeks, I picked it up and was on my way. I made a stop in Phoenix, Arizona and bought a 2″ dredge, together with all the other mining paraphernalia that was needed

The distance between Los Angeles and Fairbanks on a small scale map doesn’t look very far–but drive it and you’ll be surprised. It took me about a week to get there. Fantastic landscape and thrilling wildlife throughout the trip. Breathtaking, awesome, unbelievable, hard to put into words!!

My first mining experience was a bad one. Everywhere I went along the rivers and creeks, I saw huge signs with KEEP OUT, ACTIVE MINING CLAIM. After two days of looking, I ended up along the old Steese Highway some 30 miles out of Fairbanks, working the tailings of one of the old bucket-line dredges they used in the past. The outside temperature was 75 degrees by the end of June; but when I put my hands into the water -brrr – I pulled them out and checked for frostbite. The water temperature was barely above the freezing point, and it took all the fun out of the gold mining.

Disappointed, I left Alaska and went south. A short stop over in Auburn, California along the North Fork of the American River looked much more promising. I recovered two ounces of gold in six weeks – not bad for a beginner with my little dredge.

When I went back to Germany (I had run out of cash), I decided to become a belt-maker. For the next five years, I worked in Spain on the lovely island of Ibiza, making and selling my designer-belts with great success. In 1987, I tired and retired. I had enough funds to be on the road again for the rest of my life and could do whatever I wanted.

Shortly after my retirement, in Germany, I saw a TV special about the New 49’ers Gold Prospecting Association in Happy Camp, California. The impression I got was sound and solid. I was off to California in a jiffy and arrived in Happy Camp in July of 1989. I joined the New 49’ers and scouted out the miles and miles of claims along the Klamath River.

Because of my busted eardrum, deep diving was out of the question. I could only operate a gold dredge in shallow water, hoping to find bedrock in no more depth than five feet. For the rest of the summer, I was finding enough gold to show the folks back home.

I especially like the fringe benefits of mining, like the unspoiled nature, the abundance of wildlife, and the friendly, helpful people. That was something I had never experienced before. Socializing at the Saturday potlucks with raffles, stories and games, made my stay a happy one.

I have returned to Happy Camp multiple times in the preceding years. I can think of no other place where there is more active small-scale mining going on, and so many other people who have similar interests.
The very valuable training and assistance I received from the New 49’ers was thorough and founded on many years of experience. All I can say is – thank you – you’ve been a great help – and I’ll be back!

 

Let me end with a little poem that just crossed my mind:

The summer is gone,
Now is September,
And the end of your vacation is near.
You had a good time,
And you’ll remember –
Back home – frustrations you fear.
Then think of the Klamath,
Its gold and its fame,
Make plans for the upcoming year.
And maybe – who knows –
I’ll be seeing you again,
‘Cause part of my heart is left here.

 

It is getting pretty close to dredging time, and if you are anything like me and the many other dredgers I know, you are probably just itching to get started.

My partners and I, from past experience, now spend the necessary time and energy, before the dredging season starts, in getting all of our equipment repaired-to avoid the otherwise often confrontations with Murphy’s Law.

Some of the standard things we go through are as follows:

Engine and Pump: We always replace the spark plug, motor oil, points and condenser and air filter at the beginning of every season. We also pull the pump impeller to make sure it is not worn or damaged, and to make sure nothing is lodged in it. And we check the pump seal and replace it if it looks the least bit worn.

Air Compressor System: All of the compressors I have seen on gold dredges have reed valves. These are stainless steel plates which allow air to only flow one way through a chamber. These reed valves ought to be cleaned, polished and straightened at the beginning of every season. Some compressors have rubber diaphragms and some have piston rings. These ought to be checked and replaced if necessary. Rebuild kits are generally available for each type of compressor-usually from your local prospecting equipment dealer.

We always open up our regulators and blow them out with compressed air. You will want to check to make sure there are no holes in the rubber diaphragm, and make sure the rubber exhaust seal is working properly. If you have problems with water getting inside your regulator, it is almost always because of a worn out rubber exhaust valve. These are easy to obtain and replace.

It is especially important to open up and clean any check (one-way flow) valves in the air system. We also always soak our air lines in a very mild bleach-water solution before starting a season. We let the airline sink in a tub of the solution to allow the bleach to kill off any fungus which has grown inside the airline. This is to avoid potential respiratory problems from the fungus. The line needs to be thoroughly rinsed with fresh water afterwards.

We check all of our airlines and fittings to make sure everything is working properly-no leaks, and no weak connections!

We thoroughly clean out our air reserve tank to make sure there is no rust, fungus or other substances which could potentially cause problems.

Dredge (Structural): And, of course, we go over the sluice boxes, dredge frame and jets to make sure there are no holes, cracks or other structural problems. And if we find problems, we fix them on the spot. No need to wait until it becomes a more serious problem during the season.

We hit all of the steel with a wire brush and follow up with a fresh paint-job every spring. It’s nice to start the season off looking good!

We go through all of our rope and make sure all of the weak points are cut out and spliced back together, and all of the ends are spliced or melted so there are no frayed ends.

Diving Gear: We go through all of our diving gear, replacing anything that is worn out, patching holes in suits, etc. No need to be any colder than necessary during the early spring!

While fixing up the dredging equipment is not as good as using it, I personally gain a great deal of satisfaction getting it all prepared for the season. And, it’s always a good feeling when I do get out on the river when I have it all together the way it should be. And when “Mr. Murphy” comes knocking at my door, at least I know it wasn’t because I failed to plan ahead.

 

By Dave McCracken

It is common to find rich gold deposits in shallow streambed material out under the fast water where nobody has ever ventured before!

Dave Mack

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 in 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 — meaning places where the original streambed material remains in place from thousands of years of natural geologic activity.

  

What exactly is “fast water?” This depends upon each individual person’s viewpoint. It is primarily a matter of the diver’s comfort level. To some people, if the water is moving at all, it is already 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 around, 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. There is very little margin for error if you get into a situation that is beyond your ability to manage. We all have our limits!

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. Even I have come close to drowning on more than one occasion! 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 anything 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 to the stream bank. This movement is normally 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 nearly always 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 stream bank, and back out to your work-site again. This is all pretty routine in fast-water dredging.

Getting a hole started is one of the most difficult challenges in fast-water dredging. Once you even get just a small hole started into the surface of the streambed, the suction nozzle in the hole can serve as an anchor to help hold you there against the current. There will also be several cobbles behind you to use as footholds, which also make it easier to hold a position there. After the hole has been expanded to the point where you can get at least part of 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 is not a single 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 your safety margin 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 is already too late to make such plans the moment 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 have worked with several guys 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. These limits can actually change from day-to-day, depending upon what other things are happening in our lives. 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 is not the type of panic that I am 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 is 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. Such emergencies can happen in a split second, any time you are in a dredging environment.

TAKING EXTRA PRECAUTIONS

Other types of underwater vulnerabilities are especially present during fast-water dredging activity. Some of this vulnerability is because it is sometimes necessary to weigh yourself down more-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 it is impossible to 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 cannot 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!

 

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 has been designed 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 are in the water (which can be a particular problem when you are 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 usually within a foot or so of 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 need to move 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 or some other anchor point further upstream. 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! If you kink the hose in the middle, you will have to replace the hose!

We have also worked out a way to extend the suction hose, swing it out on a pendulum line, and anchor it in place using a spare weight belt.  This method nearly eliminates all of the hose drag for the person managing the nozzle.

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 by tying the nozzle to a large rock in the bottom of the dredge hole. It is not any fun to start a production-dive by having to work against the current to get your suction hose back up into your dredge hole, because the fast water blew it out after your previous dive. But, of course, all fast-water dredgers get many chances to experience this. It is a normal part of the routine!

One important safety point: When using ropes underwater, it is a bad idea to use any more than is absolutely necessary. A lose rope is poison to divers underwater, especially in swift water! 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. Not fun!

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 or sampling, 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 single breath of air. I always try this once, quickly, when my own air is suddenly cut off. If that does not 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.

These days, you can buy a heavier-type of “safety” airline that will prevent kinking in all but the swiftest 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 solely upon 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 standard practice, all dredgers should always untangle your air lines each time you return to the surface for any reason. I personally never end a dive without first freeing my airline completely, so it will be ready for the next 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 against the current 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 cannot 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, it is wise to 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!

Here is some really good advice: Do not tie yourself into a dredge hole in fast water to keep from being swept down river. It is 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 (with no loose rope flapping in your face). Then hold onto the nozzle to keep yourself steady and in place, while you get the hole started. Get rid of the rope as soon as you have a 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, it is very unwise to solve your fast-water buoyancy/stability problem by adding a bunch of additional weight belts. Take it from me; it is hard enough to get one belt off in a hurry, without compounding the emergency with three of them! Sometimes, you cannot manage the needed extra weight without 2 weight belts, but you must understand that a second belt substantially reduces safety margin in an emergency. Additional belts tend to shift around so that the quick releases are in different places, often behind you where it is more difficult to release them during an emergency. 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, it is wise to 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 was not going to work, they were in too much trouble (panic) to get their own belts off!

This does not 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 is not 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 on 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. There is not much you can do about that. So with two belts, you should be prepared to find the top buckle behind your body!

You may also find that it is better to first remove your work glove before trying to release your buckle in an emergency. When I get in trouble, the first thing I do is get rid of the glove on my right hand!

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 allows the shoulder harness to come loose on one side 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.

All this advice is coming from a guy that has devoted a large part of my life living on the edge. You can sit there in the comfort of your computer reading this stuff and feel quite certain that you can manage any or all of these things if they should come to pass when you are out dredging. But when the severe emergency happens, you are not the same person. You are a maniac!

You should 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. Otherwise, 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 is not 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 without distraction 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 upon the individual. An experienced dredger might be much safer in a typhoon of fast, turbulent water, than an inexperienced person 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 manage, with safety.

 

 

BY ROBERT MILES

“Whenever I need some money, I tell my wife Karolyn that I’m going down to the bank to get some…the river bank that is. And so far, my belief that the gold is there, combined with hard work and good fortune, has never let me down.” … Jim Britton

 

Jim Britton’s the kind of man who will tell you right off that he’s doing exactly what he’s always dreamed of doing — that’s mining for gold. And even if he’s not pulling gold at the level he’d really like to at a particular point in time, he’s quick to say, “I’d rather be here beside the river enjoying the looking and anticipating the discovery than living in the city and breathing all that pollution and just working at some regular job.

“I was introduced to the Gold Bug at a very early age,” he says with a warm smile that turns quickly into a grin and makes one think that he may be about to spin a yarn. “Probably when I was six or seven years old. Back then, all us kids would watch adventure movies. I was hooked on the ones that had anything to do with gold. Then as I grew up I started reading about the old 49ers, and I just couldn’t seem to find out enough about where they mined and the methods they would use. Still it wasn’t till a few years later when I was out on my own with a shovel and a pan that I really got the ‘gold bite’. It was near a little town called Quartsville, just outside of Sweet Home, Oregon, where I actually found my first gold — about 1/2 pennyweight, and I’ve never been the same since.

“I’ve always believed you’ve got to do your homework, and that includes a lot of research. And in those days I had just began to discover all about underwater dredging, and I figured that since panning for gold was giving me such a kick, I would pull more gold and have a lot more fun if I had a dredge. So I went out and bought myself a two-inch suction dredge, and within no time at all I was pulling two to three pennyweight a day and just having a great time.

“That was really just the beginning,” recalled Jim, “because within a short time I had run into another guy who let me spend some time on his five-inch dredge. After a half an hour of pulling gold with it, I just couldn’t go back to working with my little two-inch. That’s when I had to get my entire family gold bitten,” he reflected. “My dad and mom had always been really supportive of the things I tried to do, but this time they just couldn’t believe that you could really just go out and find gold. Like most people, they figured all the gold was already found. However, within a short time I had them out there with me on the river bank, and by just getting them exposed to the gold I was bringing up with my two-inch, they were gold bitten real hard. Then within a short time, the entire family, including my older brother, was mining with our new five-inch, and we were pulling more gold than any of us had ever seen at one time.”

Like most successful gold miners, Jim Britton has tried working at a number of different jobs, but he says he just can’t get the river and the gold out of his mind. “It’s the thing I love to do,” he reports, “and besides, where could I ever get a job that pays as well as gold mining and has as much job security? There’s been gold miners since the dawn of recorded time, and there probably always will be. Some days I’ll make as much as $800 or even more, and I’ll do it in four hours. Of course, you gotta do your homework, and you gotta pay your dues.”

Jim’s formula for success still begins with a gold pan. “Before I put my dredge into a spot, I’ll pan up and down the bank, usually on both sides of the river looking for the point where the river’s deposited the most color during high water. I’ll have picked a particular stretch to check out, either because my knowledge and experience of how the gold is carried and pay-streaks are formed tells me that here should be good, or because someone else had been working there and either couldn’t locate the pay-streak, or had wandered off the mark and had decided to move on to a different area. By using my gold pan, I can usually get a good idea of where the river is ‘willing to payoff’ or at least where the pay dirt has hit the bank, and there’s where I’ll put my dredge in. I’ll first punch my hole and pay very close attention to the different pay layers. A lot of times I’ll find that the gold is lying four to five feet above the bedrock, and if I’d continue on down I’d just be wasting a lot of time and energy. Other times the bedrock’s where it’s gonna be, so I just have to keep on punching down till I hit bottom, and then I’ll begin a cut straight across the river channel.”

Jim has worked a lot of different areas of the Pacific Northwest, basically following up the different strikes of the old 49ers. He says he’s hit most of the hot spots in eastern and southern Oregon as well as spots in Idaho and California. Right now he’s mining the Klamath River in northern California, using a customized six-inch with a Keene power train and sluice box that is mounted on an R & R Mining frame and float bag kit.

“When I first saw the Klamath it looked mighty big, but within three days from the time I launched my 5-inch, I was into the gold and had enough money to cover my expenses and meet the bills for the next couple of months. I’ve dived this river for two years on a commercial basis, even in the winter when the dredge was white with a layer of ground frost, and the water temperature was probably 45°. Last summer in just three weeks I pulled one and a half pounds of gold in an area we call Glory Hole.”

Jim is also quick to point out that while mining is right for him, it may not be right for everyone. A person’s got to work really hard and be mentally and financially able to stand the dry spells. “I’ve been able to make it work because I’ve got the full support of my wife Karolyn and our two daughters. Karolyn, who lives and works in Vancouver, Washington, makes the long trip up to the Klamath every two weeks, spending the weekend helping to tend the dredge, enjoying the beauty of the great outdoors, and picking nuggets out of the sluice box. My folks have also been behind us a hundred percent, spending ,time at the river as well.”

Everett Gene Britton, Jim’s father, who helped finance that first 5-inch dredge, remained an avid gold miner until his death early this spring, stating in no uncertain terms that some of his very best days were spent panning gold and tending dredge.

In the local area surrounding the Klamath, Jim Britton is known as a man who will lend a helping hand. The kind of person who will take time out of his own diving schedule to get a neophyte gold miner off to a little better start. And he’s an advocate of “miners helping miners” and the necessity of miners working and standing together to protect their rights as granted under the 1872 Mining Law.

“My life is gold,” he reports. “In fact whenever I’m back home and someone comes to visit, my wife will tell them not to mention gold, or I’ll never stop talking about it. I’ve even tried to stay away from the river and the dredge, but it’s in my blood, and I get withdrawal pains whenever I’m away from it. My life is like living an adventure, and if someone would offer me a job at say a $100,000 a year, I would just have to pass it up, because finding gold is what I love and it’s what I’m good at.”

 
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By Dave McCracken

“A Preliminary Evaluation”

Dave Mack

Note: This is the non-proprietary portion of an initial report from a preliminary evaluation of a potential suction dredging project in Northern Sumatra (Indonesia). The opportunity to do something with this prospect still exists. The evaluation was done in April of 2005. The gold values have been modified to reflect gold prices in mid 2010.


This project is located on the island of Sumatra in Indonesia, directly to the west of Singapore. I arrived there by flying to Singapore, and then by taking a 1-hour boat-ride to Batam Island (Indonesia). From there, I caught a flight to Padang. Padang is the capital of Western Sumatra. At the time, this was a better connection than trying to fly directly to Padang from Singapore.

A representative from the company that hired me was waiting at the airport in Padang. We then drove 2 hours north to a place called Bukittinggi where they have a home and office. The company manager was already up at the base camp. They had arranged for a driver to bring me up there on the following day.

Bukittinggi is a lot like the towns we have in the West. In fact, as shown in the following video segment, if it were not for the different language on the signs, this city could easily be mistaken for almost any town in America.

The roads and other infrastructure in western Sumatra are pretty darn good. The people seem nice. Things are relatively inexpensive. English is not spoken very much, but the people are forgiving and do their best to help figure things out.

The location of this project was situated about a third of the way north to Medan (from Padang). Medan is the capital of northern Sumatra. It is the second-largest city in Indonesia.

There is a good road that leads to the project-area and follows alongside the river. So accessibility to the river is generally very good.The following video sequence was taken as we were driving north to the project site. You will notice that they drive on the left side of the road in Sumatra:

The river is about the same size as the Klamath River in northern California, but will reduce in size as the dry season progresses. The river is flowing with clear water. Although, visibility can be lost during the afternoons if local miners are sluicing upstream (more on this follows).

During my visit, the river was ideal to sample using a 5-inch dredge. Productiondredging or volume sampling could easily be accomplished using 8-inch dredges or larger.

There are regular access-points to the river from the road along the river. And there are small villages along the road where local miners and other laborers or helpers and various services and supplies are available at relative low cost. Power and land-line telephone appear to be present along the entire road.

As the speedometer was not working on the vehicle that we were using, I did not get an exact mileage-count on the amount of river that is available to this project. But it is safe to say that there is at least a 20-mile stretch of readily-accessible gold-bearing river where local small-scale miners are actively recovering gold.

Our client has hired a local administrator from the main town along the river. The local administrator has arranged permission to temporarily set up a base camp in a vacant house which is owned by the government. The house and property are ideal for a base until other arrangements can be made. There is a small store and restaurant on the property. There is some storage. The house has several comfortable bedrooms, electric power, bathrooms and a dining room. The local cook does a good job. It is a comfortable setting. The base camp contains all of the basic structure needed to support a gold dredging project.

  

Local communities are generally Muslim. Friendly. I did not detect a single bad feeling from anyone during the entire time that I was on the river. There was actually a lot of friendly interest, because white folks are not often seen in these parts.Here is a video sequence I captured in a nearby, larger-sized community:

  

It will be important to be mindful of possible cultural differences, though. Any westerners brought in to assist with this project will need to be careful to not disrupt local tranquility. Hiring a good, local administrator will be important so that we can facilitate communication in a positive way. Interpreters will be important in key places where local labor is being directed or managed by outsiders.

Our client has done a great job putting the basic support structure in place.

My client is a mining engineer from Europe who settled in Sumatra and has devoted the past 20+ years locating and developing mineral opportunities there. We have worked together on several projects in the past, two which were located in Borneo (Indonesia), another in Cambodia.. He has been involved with numerous different types of projects which I will not go into here. He is very experienced at working in Sumatra. He understands the culture(s) and he speaks the languages.

One interesting thing at the moment is that my client has also recently located an important iron-ore discovery in the same area. He is in the process of quantifying the deposit with a company of consulting-geologists that are based out of Jakarta. I was fortunate to meet the Director of this consulting-group during my visit. They are doing exactly what we have in mind: They are mapping and certifying reserves of proven mineral deposits in a manner that the final documentation can be placed on a bankable balance sheet.

While pursuing the iron-ore program, my client observed that the locals along the river were actively sluicing for gold. So he asked me to come over for a look. This was my first trip to this particular area of Sumatra.

Local Mining Activity

I observed three different methods of active gold mining occurring along the river:

 
1. Panning gravels from the gravel bars alongside the river.

2. High-banking the river gravels from the gravel bars in and alongside the river (description follows).

3. Panning river gravels that are being extracted from the bottom of the active river by divers (referred to in this report as “dive-miners”).

I could also see the telltale signs of past high-banking activity in placer diggings alongside the river not far downstream of the main town. My client’s local administrator told me that he believes the richest area along the river is upstream of the main town. That portion of the river extends away from the main road. I did not get a look at it on this first visit. He says that gold nuggets as big as several kilograms in size have been found up there. But, because local miners have no means to deal with the larger boulders, they mostly do their mining further downriver where we saw them operating.

I observed a of dozen or so active panning operations along the edges of the river where locals are panning surface gravels.

  

I also observed around a dozen active high-banking projects. Most of these projects are being accomplished with the use of two motorized pumps. One pump is used to suck ground-water out of active excavations, lowering water levels so that workers can excavate bottom gravels. The other pump is used to create suction through a 4-inch PVC (plastic) suction pipe. Material is washed down to the intake-pipe at the bottom of the excavation, sucked up and directed through a primitive (very) sluice box that rests on stilts out of the water. These pumps allow gravel-material up to (approximately) 3-inches in size to be passed through the pump.

Local miners are building wing dams, which allow them access to gravel out in the active waterway.

Local miners are actively wing-damming (building a barrier to direct the water around an open excavation) around shallow places in the active river where they want to mine. They then pump the excess water out of open excavations, while processing gravels out of them. Whole teams of local miners (as many as 20+ people) are working together in these high-banking projects.

The downside is that tailings-water from some of the high-banking projects is allowed to flow back into the active waterway. This eliminates water visibility for some distance downstream. Depending upon where you go, underwater visibility can be lost by mid-afternoon. But even in those places, there remains an opportunity to do underwater work starting early in the morning – or possibly doing night operations with the use of flood lights from the surface. Or by dredging upstream from active high-banking operations.

Dive-miners on a floating platform

I also observed some mining activity where local divers are bringing up gravel from the bottom of the river and panning it at the surface. These divers do not have access to the right kind of air compressors for underwater breathing, so they are free-diving (holding their breath while diving down under the water) to excavate bottom-gravels from the active river. Because of this, their production-capability is severely limited. All of the dive-miners I observed were bringing gravels to the surface with the use of metal cooking pots.

As the purpose of my first visit to this river was to confirm the existence of potentially-viable gold deposits within the active river, these dive-miners are the ones we decided to spend some time with.

Local dive-miners carve their diving goggles out of hardwood or bone from some kind of big animal. Lenses are made from glass that is glued onto the goggles with epoxy. The goggles are attached to a diver’s face with a strap cut out of a piece of tire-inner tube rubber. There is no face-seal, and there is no way to equalize pressures inside the goggles. This creates a natural limit to how deep dive-miners can go beneath the water’s surface.

Nevertheless, local dive-miners are diving down to around three meters and bringing up gravel. And the gravel contains a lot of gold in proportion to the volume of gravel that is being processed. The local gold-buyer told us that around 5 kilograms of gold are being bought every day from local miners along this river. The going price is around $44 per gram. If the gold-buyer is telling the truth, that amounts to around $220,000 in gold.

To put this in perspective, a 10-inch dredge in experienced hands, with some underwater visibility, should be able to process about as much volume as all of the mining activity combined that I observed along the river.

All of the local miners we spoke with agreed that the richest gold is located in the deeper-water areas of the river where they are not able to reach using their methods. While divers can get underwater, they do not have the technology to excavate the deeper-gravel deposits that exist down there. A person can only get so much accomplished using a cooking pot on a breath of air!

So unless they are lucky enough to find rich deposits in the shallow spots along the edge of the river, existing technology available to local miners generally does not allow them access to the higher-grade areas located along the river-bottom. For the most part, local miners are working average gravels along the edges.

Confirmation

All of the images of the mining activity that were initially sent to me by my client showed high-banking activity that was taking place outside of the active river.

Sometimes, there can be high-grade deposits being mined alongside the river; but local conditions (deep gravel, dirty water, etc.) do not allow for a viable dredging opportunity within the active river. Therefore, the main purpose of my first visit to this area was to establish if there are high-grade gold deposits inside the active waterway, and to assesswhether or not we can perform a production dredging program there.

  

Approximately 5 miles downstream from the main town, we found a company of around ten local dive-miners who were swimming down to bring up gravel from an underwater excavation. We observed that they were recovering a substantial amount of gold in proportion to the small volume of gravel being processed. As this was an excavation project inside the active waterway, my client and I made a quick plan to complete our initial confirmation while working with this group of dive-miners.

After spending a little time getting to know these dive-miners, one of their leaders offered to take us on a short tour and show us some of the richer areas where they had done some dive-mining along the river. He showed us several places where he said their team-program had recovered as much as three ounces of gold per day at times. Each place he showed us was consistent with the types of areas where we find high-grade pay-streaks on the Klamath River in northern California.

According to our guide, the combinations of water-depth and/or gravel-depth usually prevent dive-miners from pursuing the richest deposits in the river.

  

This river is very similar to the rivers that we dredge in California. There are regular directional changes, a steady drop, and fast-water areas in the river, which create the natural diversity required to form high-grade pay-streaks. There is plenty of bedrock showing and deep water pools.

Our guide told us that the river gravels pay in gold-values starting from around a foot below the surface, all the way to the bedrock. He said the richest gold is often on the bedrock, and sometimes they can see gold inside the cracks when they are able to get down that far. He said that 1 and 2-gram gold nuggets are not uncommon. He said the biggest nugget he personally found was 10-grams (32.1 grams to the troy ounce).

In anticipation of the eventual need, several years ago, I shipped a T-80 air compressor, a dive-regulator and the required air-fittings over to this client in Sumatra from California. He arranged to mount the compressor with a small Honda motor. We brought that diving gear along with us on this trip.

So after getting to know our guide on the river, we volunteered to use the compressor to help his company of dive-miners excavate gravels from the deepest part of their ongoing excavation. I offered to allow them to keep all the gold we found, as long as we could buy it from them at the going price. They readily agreed. The purpose of this was to allow me the opportunity to get a direct look at the streambed conditions from which we would recover the gold, and to allow me to measure the amount of gravel that we would process so we could place a relative value on the raw material.

It did not take long to get me into the water, where with the use of a cooking pot as a digging tool, I started filling a wash-bucket with gravel from the bottom of their ongoing excavation. Filling up buckets with material underwater is a pretty slow process. It required three gold-panners to keep up with my progress.

The existing excavation from this company of dive-miners was pretty substantial, considering that progress was being accomplished using cooking pots while free-diving down to around three meters of water. They had worked down a face of bedrock along the edge of the river to around 6 or 7 feet into a semi-hard-packed streambed material. They had not yet reached where the bedrock bottomed-out (where the highest-grade material should be located). Even so, I did see some gold flakes in the bedrock along the face that they are following.

According to the dive-miners, they have been working that specific excavation for 2 months, and had so far recovered around 2 kilograms of gold ($80,000.00). To put the size in perspective, we could open an excavation that size in about half a day using a 10-inch dredge. Opening an excavation is much slower than continuing one that is already opened up. Conservatively, the local dive-miners had recovered 2 kilograms of gold in about 25% of a day’s ongoing production using a 10-inch suction dredge.

The local gold buyer weighed the gold recovered from our 20-bucket sample and offered to buy it for approximately $25.00 (US) in local currency based on the daily price of gold on April of 2005.

Since I was able to stay deep using the compressor, I extracted gravel from the bottom of the hole. I brought up 20 buckets of material, which were carefully panned by several helpers from the local mining team. In all, we recovered 1.1 grams (around $48.00) from my sample. This amounts to approximately $2.40 (US) per bucket at current gold prices. This was a typical medium-sized wash bucket. A single 5-inch dredge would excavate the volume of material contained in a wash-bucket in several seconds. A 10-inch dredge would scarf it up in the flash of an eye!

The thing that makes this so interesting is that the gravel I brought to the surface, for the most part, was material which had been sliding down into the bottom of the hole from the upper-side of the excavation. Although I did get some material that adjoined the bedrock on one side of the hole, I was forced mainly to extract gravel that was sliding down into the hole from further up in the excavation. The nature of scooping samples with a cooking pot underwater is that you take whatever you can get. Unlike dredging, you do not have an option to move top-material out of the way to get down to more productive stream layers located deeper in the river.

At the same time that I was taking samples from the deeper part of the excavation, the other dive-miners from the local company were bringing up samples from shallower streambed material. While I did not add it up, I did observe that their pans seemed to have just as much gold as we were getting from deeper in the hole. Most of the material I brought to the surface slid in from the shallower area where the other dive-miners were working.

While it still remains to be confirmed from a more organized sampling program using a suction dredge, this preliminary indication, along with the information given to us by these miners, indicates that the average gravels in this river almost certainly do contain commercial gold value.

More often, we are accustomed to finding that average river-bottom gravels carry non-commercial gold values, and that it is necessary to locate the high-grade gold deposits which usually form in the contact-zones between flood layers or on top of the bedrock. The existence of commercial gold-value in average gravels likely means that the pay-streaks will be even higher-grade.

We have confirmed that commercial gold deposits can potentially be dredged from this river. The next step is to follow up with a preliminary dredge sampling program.

Recommendations

First: I am suggesting to my client that he follow-up to see if exclusive commercial rights can be obtained for mining gold along this river. If so, I am advising him to arrange it as soon as possible. If the client is looking for a partner to develop the prospect, as long as the cost is reasonable, we can help arrange the financial resources to help pay for concession-rights.

Whether or not acquisition of exclusive rights (not excluding local mining activity) to develop the gold deposits along the river will affect the way we should proceed:

A. Quantification and marketing the proven reserves: If we can obtain the exclusive commercial rights, we should look hard at the concept of implementing a sampling program in concert with credible consulting-geologists to confirm and certify the existence of proven reserves. The purpose here would be to market the reserves to a larger public-traded mining company. In this event, we are prepared to help provide the funding and expertise to perform the sampling program. A good start would be to consider contracting with the same firm our client is using on the iron-ore project to perform the geological functions required to map and substantiate proven reserves.

B. Mining high-grade gold deposits: In the event that exclusive commercial rights on the river are not available, or a preliminary dredge-sampling survey convinces us that average reserves are not marketable, based upon what local miners are recovering from the river using primitive methods, it is a near certainty that money can be made using dredges to target high-grade gold deposits.

A preliminary dredge sampling program will be necessary whichever way we move forward with this project.

There would be several objectives in the preliminary dredge sampling program:
1. Determine if the average gold-values in the river will support a quantification program (outlined in A above) with the purpose of marketing proven reserves to a larger mining company.

2. Establish the value of high-grade deposits to get an idea how much money can be made from going right into commercial production.

3. Work out what recovery equipment will be needed to pursue either step A or B above.

4. Work out how we will harmonize a dredging program with local miners, general populations along the river, and others (government officials) who will take an interest in what we are doing.

It would be wise to allow no less than a month for the preliminary dredge sampling. To keep costs down until we confirm a commercial opportunity,if possible, I suggest we use the client’s existing structure as much as possible — meaning vehicles, local staff and the existing base camp.

To perform the preliminary sampling, we would need to hire several local dive-miners. I would like to choose them.

If possible, I would also like to hire an assistant/interpreter person who can stay with us throughout the project to help facilitate communication and coordination with locals. This might be someone that the existing geology-firm could provide. Having someone who is sincerely dedicated to projecting our intention and goodwill during the sampling project will go a long way to facilitate steady progress in the field.

Therefore, the next step is for us to find out:

A. Can we obtain exclusive commercial mining rights on the river? If so, at what cost?

B) Can we obtain permission to proceed with a suction dredge exploration program? If so, at what cost?

PumpsPumping systems used to support local high-banking operations.

If gaining permission to use a suction dredge is going to delay the project, we also have the option of proceeding with a system like what the locals are using in their high-banking operations. Just by adding an air compressor and an extended suction hose, we can adapt a sluicing operation (like what locals are using) to an underwater dredging program. In this case, we should allow a week to fabricate an improved recovery system. If we go this way, with just a little instruction, we can hire locals to do all or most of the work. So, for the most part, this would just be another local mining operation.

Having said that, using a floating dredge would be much more efficient for moving the gear around to each place that we want to sample. A 5-inch suction dredge in experienced hands will also out-produce one of those sluicing outfits about ten times over! Still, if necessary, we could get the preliminary sampling job accomplished using (for the most part) local equipment.

Dave McCracken
Underwater Mining Specialist

 

BY MARCY STUMPF/FOLEY

 

Dredging below the chute

Bill Stumpf keeps a careful eye on dredging equipment while son David dredges 24 feet beneath a fast-water chute on the Yuba, River. The chute is out of sight to the left of current which can be seen at center-left of above photo. Bubbles at lower-left are from David’s hookah air supply, as he makes his way to the bottom of their hole.

As I sat in the sun on the bank of the North Fork of the Yuba River in California’s Mother Lode country, I basked in the warmth as I watched my 19-year-old son David swiftly cross the river on top of a small dam of rocks that someone had left below where we were dredging. Followed by his dog, Kona, he urged her on as she slipped and slithered her way across the slippery rocks. I didn’t know how he did it. I cursed and fell every time I ventured more than a few feet from the bank!

David was warming himself up by playing with Kona, preparing for the first dive of the day. My husband, Bill, gassed-up the dredge and made sure all was in running order.

We were working a “chute” where the river narrowed between bedrock dikes, pushing the water with tremendous force through the narrow opening, then dropping it into a large pool. We were set up in the pool, and had every inch of hose we owned on our 5-inch dredge to reach the bottom.

Bill began working in 18 feet of water, adding as much weight as he could to his weight belt to stay down. They had even fastened a chain to a piece of bedrock on the bank so Bill could “walk” down into the hole each day. They chopped, pried and levered their way through several feet of extremely hard hard-pack; and when they reached the bottom, they found a natural channel had been cut into the bedrock, about four feet across, and they weren’t sure how deep. Bill began suffering from nosebleeds at about 22 feet down, so David was continuing the dives on his own. We were giving him a couple of days to satisfy his curiosity as to what was at the bottom.

David and Kona ran back up to where I was sitting, and David laughed as Kona shook herself, spraying me with water and rubbing against me as I protested. He began adding all his gear for diving. This was a cold river, and he already had an acrylic bodysuit made for diving under his 1/4-inch wet suit.

David was thin and had a hard time staying warm any time of year in the Yuba, but this was springtime-the water was very cold. He wore boat shoes over his dive booties, work gloves on top of wetsuit gloves, and finally a hot water line to bring warm water inside his suit.

At last, he was ready, and I opened my mouth to complain about his weight belts, but could see that he could hardly move and decided to keep quiet. I had an ongoing thing about the weight belts. Being so thin, it was very difficult for him to keep the quick- release buckles in front; and wearing two belts compounded the problem. I knew from the past, that even if he had them on straight when he went down, he worked so fast and furious below that within 15 minutes, they would be working their way around his body. We’d “discussed” it often.

David adjusted his mask and descended; Bill went out to the dredge; and I settled back. It wasn’t often I had time to relax, and this was the last day we would be working here. We’d decided to pull out tonight. David was now diving at 24 feet; and as he started dredging, the dredge hose pulled the dredge out into the river a bit more–stretching to reach the entire length. Soon, material began flowing through the sluice box.

David finished the first dive, we had lunch, and he went down again. I was about to doze off when suddenly, a loud noise startled me. As I jumped up, I saw that David’s airline had blown off the air compressor. With a huge “whooshing” noise, it rapidly snaked across the river as air from the reserve tank rushed out of the open end.

I began to panic immediately. Bill did not have his wetsuit jacket or weight belt, and the swift current would force him downriver if he attempted to cross the current to David.

We waited for long moments on the bank for David to appear but, he didn’t.

Underwater, David gasped as he drew water instead of air into his mouth and quickly began fumbling through two pair of gloves for the quick-releases on his belts. He finally found one and dropped it but lost more precious moments looking for the other. He was fast running out of time and couldn’t find it!

He finally decided to force himself to the surface wearing one belt. But as he stepped out of the first weight belt, he stumbled and his boat shoe became entangled in the metal crate which he used to carry rocks out of the dredge hole! Now he had to fight panic as he worked quickly to extricate himself. It was dark and murky down there as he struggled to remove his foot from the shoe which was still caught in the metal crate. At last, he was free, but did he have enough air left after his struggles to make it to the top?

Up on top, I was already in tears. It seemed we’d waited hours, and Bill was rapidly descending the chain to see what he could do. He had to try something, even if it was wrong!

Just then, in a roar of water, air, coughing and shouting, David burst through the surface of the water and Bill dove for him, helping him out of the current and to the bank, where he lay a long time, coughing and spitting water.

We felt very lucky, and we were a sober and wiser group when we left that day. We’d learned several good lessons, and would like to re-emphasis them because they are important ones:

1) Always make sure your weight belt is tight and you can reach your quick-release buckle (and make sure it’s in good working order).

2) Make sure that any line connected to your air compressor is a “HEAT RESISTANT” line (usually red or black). Air coming out of the compressor is hot, and regular airline will NOT stand up to that heat. Remember: your life depends on the air from that line!

3) And, finally, we learned that curiosity that leads you into danger is best left to cats.

 

By Dave McCracken

This system combines two classification screens to more-effectively separate material-feed into three separate size-fractions, each which is directed into a different recovery system.

Dave Mack


Riffles in box Three sections of screen

Classification is the Key to Fine Gold Recovery

It is well-established that if you want to effectively recover finer particles of gold, you must first separate them from the larger-sized materials which are being washed through your recovery system by a higher-velocity flow of water. The small-sized material can then be directed to a milder-flow of water over a shorter set of riffles. The smaller you can classify the size of the material, which can be directed by and even milder flow of water over lower-profile riffles, the finer-sized gold that you can effectively recover.

This is all rather easy to accomplish with surface processing plants where earth-moving equipment can be used to feed a plant some distance above the ground. Feeding a plant well above the ground allows plenty of drop for water and gravity to direct material through multiple sizes of classification screens. Then, gravity can be used to direct the different size-factions of material to separate recovery systems with controlled water-flows and riffle sizes specifically designed to recover gold effectively from each size-fraction.

Conventional Suction Dredges do not allow for Much Classification

I am not sure what the exact formula is, but I know from long experience that every inch you lift the feed of a suction dredge above the surface of the water, you lose a considerable amount of suction-power at the dredge nozzle. Therefore, since we have to accomplish both classification and gold recovery from a feed that can only be effectively lifted about 4-to-6 inches above the surface, our options are pretty limited.

Dredge manufacturers have worked out different ways to direct classified materials into slower-moving recovery systems. Generally these methods fall into three categories:

1) Placing a classification screen over top of a set of riffles. This way, smaller-sized material can fall through the screen into a slower-moving flow of water over riffles that are more-protected from higher-velocity water-flow. You see screened-over riffles in common use today.

2) Placing a classification screen towards the head of the sluice box, and then directing the classified material to one or two completely separate sluices which have a slower-moving flow of water over lower-profile riffles. This was most commonly seen in the form of side-by-side triple sluices during the 80’s and early 90’s. While effective, the problem with the side-by-side sluices is that the side sluice(s) normally have to be placed on top of the dredge’s pontoons. Therefore, in order for gravity to make everything work right, the initial feed to the dredge has to be lifted higher out of the water. This causes a power-loss at the nozzle. So you do not see as many side-by-side recovery systems in production on suction dredges these days.

3) Placing a classification screen somewhere towards the upper-end of the recovery system, and directing the classified material to a slower-moving recovery system which is located directly below the main box. This is commonly referred to as an “over-under recovery system, and remains in popular use today. An over-under system is most commonly accomplished in the same basic sluice box, which is constructed with a removable false bottom. By this, I mean two separate recovery systems, one sitting over top of the other, in the same sluice box.

I cannot go into which of these systems are better or worse; because there are too many variables in play, and experienced prospectors can work it out to get the best recovery possible out of any of these designs, each which would likely be comparable to the other. That’s because all three of these system concepts depend upon a single classification screen to remove some portion of the smaller-sized material from the higher-velocity water-flow which is required in a dredge.

This particular discussion has more to do with the effectiveness and size of material-classification. Remember, with conventional suction dredges, we are using water-flow to move all our material across any classification screen(s) that we are using. The larger the dredge, the faster and more powerful the water-flow must be to wash larger-sized rocks and a larger volume of material through the sluice. The faster the flow, the less time that smaller-sized material has to drop through a classification screen. The smaller the openings in the screen, the less opportunity smaller-sized material has to drop through the screen. The shorter the screen, the less opportunity smaller-sized material has to drop through the screen.

Each of these factors combine into to the effectiveness of the dredge’s classification. For example, the substantial flow of water to move 5-inch sized material over 10 inches of 1/8th inch punch plate does not present much opportunity for minus-1/8th material to drop through the screen. So while a separate slower-moving recovery system might be doing a better job recovering smaller-sized gold, perhaps the classification system is only allowing 5% of the finer-sized gold to be directed into the slower-moving recovery system. In other words, the effectiveness of your recovery system is largely affected by how you are attempting to classify and separate the smaller-sized material.

Therefore, on the subject of fine gold recovery with suction dredges, our first challenge is to try and accomplish effective classification as best we can out of a strong flow of water (strong enough to move the largest rocks you are sucking up through the recovery system).

Years ago, we overcame this whole challenge on commercial dredges by working out a mechanized shaker screen at water level which provided 100% classification of the dredge feed. Minus-sized material from the screen was dropped into a sump where it was redirected by a gravel pump to an elevated feed on a surface-type recovery system either on the shore, or on a separate floating platform.

But it is impractical and too expensive to try and place a mechanized classification screen on smaller-sized dredges — which also must remain more portable for sampling. Therefore, on conventional dredges, until someone comes up with something different (if ever), we must continue to make due with a water-flow to wash material across our classification screen(s). With this in mind, here are a few principles which I believe to be true:

1) The faster the flow, the more difficult it is to drop finer-sized material through the openings of a screen in your sluice box.

2) The smaller the holes in the screen, the less finer-sized material you can expect to drop through the openings out of the high-velocity flow required to move larger material through your sluice box. Example: Using the same flow of water and material, you could expect more fine-size material to drop through a 3/8-mesh screen, than a 1/8-mesh screen. This is because the larger openings provide a bigger doorway for material to drop through.

3) The shorter the length of a classification screen, the less fine-sized material you can expect to drop though. Therefore, we want the classification screens to be as long as we can get away with. Longer screen means more opportunity for finder-sized material to drop through.

4) Effective classification of finer-sized material can be accomplished better in stages. For example, first drop 3/8-minus material out of the fastest flow in the box. Then, using a slower flow of water, direct the minus-3/8 material over a 1/8-inch screen.

5) Since we only have 4 or 5 inches of drop to work with from the feed of a conventional suction dredge, there is only room for two levels of classification screen before we must drop the finest-sized material into a recovery system. Otherwise, we will be underwater where reduced gravity is not going to allow water-flow to work for us, anymore.

What to use for a fine-gold recovery system?

material in rifflesAs I have explained elsewhere, I believe it is necessary to direct finer-sized material over lower-profile riffles that will continue to remain fluid under a mild flow of water, even when they are full of concentrated (heavy) material. If you have not reviewed the theory on this, I strongly suggest you read “The Size of Riffles.”

There are different kinds of low-profile fine gold recovery systems on the market. Just take a look around and make your own choice.

We have been using the green, plastic Le Trap sluices to reduce the volume of our dredge and high-banking concentrates all the way back to the early 90’s. I cannot overstate how effective these Le Trap Sluices are. When set up with the proper water-flow, a Le Trap will recover all the visible gold from a feed of minus-1/8th material with losses that are so minimal as to be meaningless. We know this from panning the tailings hundreds of times over the many years.

So when we needed something to recover overwhelming amounts of fine gold using a dredge on a river in Cambodia, I started giving a lot of thought to how we could more-effectively classify dredged material down to minus-1/8th, and direct the material in a controlled flow over Le Trap-type riffles.

Dredge 1Dredge 2

Several very experienced dredge-builders and I created the prototype several years ago from a Precision 6-inch dredge. To accomplish our objective, we assembled two layers of classification screen, each which could be independently raised or lowered, so that we could adjust the water-flow over the riffles, and over each of the screens. The top screen is 3/8-inch mesh. This is to allow the larger-sized material and strong water-flow to wash through the box without affecting the plastic riffles along the bottom. Minus-3/8ths material drops through the top screen onto a 1/8th-inch mesh screen, where the water flow is substantially reduced. Slower water-flow then allows finer-sized material more-extended contact with the 1/8th-inch screen.Double screens over riffles

Material that drops through the 1/8-inch screen is then carried over the Le-Trap sluice by a mild flow of water. By adjusting the height of the lower screen over the plastic riffles, and the slope of the sluice box, we are able to control the amount of water-flow over the lower-profile riffles.

Since the sluice box in the 6-inch Precision was much wider than a normal Le Trap sluice, the prototype required quite a lot of work in a cut and paste project (using of 4 or 5 Le Traps) to create the first underlay recovery system for a dredge.

Fine goldWe invested quite a lot of time and energy into the prototype. All you have to do is look at how much (very fine) gold we found on that river in Cambodia to understand why we did it. We were shipping this 6-incher over to resume (sampling) where we had left off on that earlier project.

 

During trials on the Klamath, I was amazed at how much (very) fine gold we recovered out of just a minute or so of dredging loose material off the surface!

Our trial run on the Klamath River near Happy Camp in March several years ago turned up so much fine gold out of the lose surface gravel, that I hesitated over sending the 6-inch prototype to Cambodia!

I have been told for 30 years that there is so much fine gold in the river that we are losing out of our conventional dredges, if we could just recover it, we could make the river pay just by pumping any gravel! This new system seemed to prove that theory may be true, especially with these higher gold prices. But it was March and the Klamath was cold; so we shipped the original prototype dredge to Cambodia.Cambodia Dredging

I devoted plenty of time in Cambodia (underwater) observing three separate flows of material coming off the back-end of the recovery system; and it was poetry in motion!

I have a non-disclosure agreement with our clients in Cambodia, so I cannot go into details or images of how well the new system performed over there. But I can say that I devoted a lot of time underwater watching water and material exit the sluice box in three separate flows; and the double-screen system is by far the best thing I have seen on a conventional dredge for effectively classifying material into three separate size-fractions.

Because of that, my experienced buddies and I invested quite a lot of time during the 2009 mining season to adapt the double-screen system to my 8-inch dredge. 8-inch dredge

Building double classification screens, so they can be adjusted up and down to allow you to set three separate water-flows through the sluice box, requires quite a lot of labor! But getting this right is the foundation of this whole concept.

Here are some video links which demonstrate the system being used on my 8-incher. These give you a much better look at how we created a double-screen classification system over top of the fine gold recovery: Take a look at the size of the gold we were recovering!

 

As (bad) luck would have it, the State of California imposed a temporary ban on suction dredging just as we completed the double-screen refit on my 8-inch dredge. This forced us up onto the Rogue River in Southern Oregon, where we are limited to smaller-sized dredges. So my 8-incher had to be set aside.

Picking up on the idea of my double-sluice conversion over a plastic sluice, one industry-fabricator was recently promoting the idea of refitting conventional sluices (using the plastic sluice underlay) which do not include the double-screen classification, and do not allow the screens to be adjusted. I would advise caution on short-cutting these concepts. That is what prompted me to write this article. Since these conversions must be accomplished through custom shop work, I wanted to provide you with some background so you can make your own decisions.

While there is still a lot to learn, for the reasons I outlined above in points 1 through 5, I personally do not believe that you can classify raw material effectively from a 4, 5 or 6-inch (or larger) dredge being washed across an 8-mesh screen by high-velocity water.

I believe effective classification must be accomplished in stages; first to drop the 3/8-minus material out of the higher-velocity flow which is needed to push the larger-sized material through the sluice. Then, drop the 1/8-minus out of the much slower flow necessary to wash 3/8-inch material across the lower screen.

I believe you have to be able to adjust the height of each screen (set the water velocity) in order to get a workable water-flow over the riffles and over the 1/8-mesh screen. The water-flow cannot be so much that you boil-out the riffles, and it cannot be so little that you load the riffles. You also must not pack up the space between the two screens!

Eric Bosch and I first experimented with this double-screen concept in the early 90’s. But we made the mistake of fixing both screens (welded them where we estimated they ought to be). Our estimate of how much water-flow was needed between the screens was incorrect; the space between the screens packed solid with material; and the whole system failed.

Also, if you cannot adjust the water-flow over the riffles, and between the screens, you cannot compensate for different conditions in different areas.

Dave's goldAs an example, there is an overwhelming amount of heavy black sand and small iron rocks (and lead) along the Rogue River in Southern Oregon. We do not encounter this magnitude of heavies on our properties along the Klamath River in northern California. The heavies along the Rogue completely overwhelmed my fixed recovery system (buried the riffles on my 5-inch conventional dredge) at the beginning of last season. This prompted me to place smaller riffles below my (fixed) screen, spaced further apart. That worked better, and I recovered a lot of gold. But I believe I lost most of the (very) fine gold (I could see it in the last riffle) that was fed into my sluice box. This has prompted me to refit the recovery system on one of my 5-inch dredges for the upcoming season.

The images at the beginning of this article show an early version of the double-screen system that was designed for deposits we located in Cambodia. We did not find a single particle of gold on that river that was larger than the size of a pinhead. Since larger-sized gold was not present, we did not want to waste the (very) limited amount of room we had to work with by installing riffles for larger gold. Those images are helpful in showing the plastic sluice underlays (there are two of them, one following the other).

The images at the beginning of this article show the Cambodian version of the double-screen refit. Those images are helpful in showing the initial plastic sluice underlays that we were using (there are two of them, one following the other).

Header areaHeader with screen and miners moss

The images in this article also show a header section near the upper-end of the box. My initial theory was that the initial impact of the water and material must bottom-out on something other than plastic sluice underlays. We experimented with a combination of different kinds of heavy screens over top of miners moss or ribbed rubber matting to absorb the initial force of the water and material where it bottoms-out at the head of the sluice box. Fortunately, nearly everything we have tried in the header section seemed to work really well. As you will read below, we have since evolved completely away from using plastic sluice underlays… Header area after running

This is what the header area looked like under the screens when we shut the dredge off while dredging at production speed. You can see how classified material kind of mounds up there before flowing onto the slick plate of the riffle system. We are finding that quite a lot of (very) fine gold also gets trapped in the header section!

We have noticed that while in production, material tends to mound on top of the header section under the 8-mesh screen, and then wash off the mound onto the first sluice underlay. This is really good, as long as the mound does not rise up and pack-up the whole space between the screens.

While we were still using them, the plastic sluice underlays followed just behind the header section. This allowed water-flow and material to settle out and slow down before being washed across the lower profile riffles.

 

 

 

Two kinds of rifflesriffle section

Notice that the shorter section of riffles (remains protected by the top screen) are present only to process classified material which washes across the 8-mesh (lower) screen in the box.

Adding larger riffles for bigger gold

We have since evolved the system, adding two sets of different-sized riffles to catch larger-sized gold. We accomplished this by replacing one of the 1/8-mesh (lower) screens with a solid bottom that supports both sets of the added riffles. The false bottom continues to allow an under current to wash minus 1/8th material across a low-profile underlay, just like in the Cambodia version.

The first set of riffles on top of the false bottom is designed to process the material that drops through the 3/8-inch screen, but is too large to drop through the 1/8th-inch screen (1/8th-to-3/8th size-fraction). This would be for small nugget-sized gold. That size-range of gold is very easy to recover.

As I discussed in The Size of Riffles, the height of a riffle necessary to recover a piece of gold normally does not need to be much taller than the size of the gold you are trying to trap. So the first set of riffles for larger gold can be rather short. Notice that the first set of riffles continues to be protected by an extension of the top screen.

Then we added a final set of open riffles (not covered by a classification screen) to catch any gold we might suck up that is larger than 3/8th-inch (larger nuggets). For example, depending upon where you dredge, the Rogue River in Southern Oregon can produce a lot of gold in these larger sizes. But the river is loaded with fine gold, as well.

It is kind of hard to see in the images; but if you look close, you can see the plastic sluice under the false bottom where we placed the riffles for larger gold.

Since you cannot buy these double-screen systems ready-made, you either have to refit your own sluice, or arrange with a capable fabricator to do it for you. With this in mind, I will follow with some basic directions which we have learned from building several of these systems:

Building the System

If you look at a Le Trap, you will see that it has 3 important sections: There is a slick plate at the top. This is vital; because it allows the water-flow to smooth out before material encounters the riffles. Then there are some short riffles. These capture all the gold unless you over-feed the box with too much material at once, or unless you completely fill the short riffles with gold. Then there are some deeper riffles which more-aggressively capture all the rest of the gold when you do over-feed the short riffles up front. “Overfeeding” has more to do with the amount of heavy iron material, than light sand or gravel. I will talk more about this down below.

Close-up of rifflesThis image shows two sluice underlays following the header section (with no screens on top)

When we planned these sluice underlay riffle-panels, we included the slick plate up front, and then went about 50/50 the rest of the way using short and deep riffles. We did this because I wanted more of the short-type riffles that work so well in the Le Trap. But I did not want to eliminate the deeper riffles which create such a strong back-flow, especially at times when lots of material is being fed across the box. But through extensive trial and error using the third evolution of this system this past season, we discovered that the higher velocity flows that are necessary to move volume-amounts of classified material across the plastic riffles were also causing some of the trapped fine gold to boil out of the system. Too bad! We then tried Keene’s new ribbed rubber matting (good stuff!) and ended up with the same result (we were losing some gold). So it appears that these plastic and rubber riffle systems are better suited for final concentrating work, rather than being used in the volume production setting inside of a dredge recovery system (more on this below).

Because the double-screen assemblies are heavy, in order to manage them, you have to divide your sluice box into several smaller sections. How many sections depends upon how long your sluice box is. You will notice in the images at the top of this article that we divided my 5-inch dredge into three separate sections. One section is over the header area. The other two sections are over top of two identical sluice underlays. It is wise to divide the sluice underlay sections into exactly the same sizes. This way, the parts can be interchanged when it is time to reassemble your recovery system.

We build the double-screen assemblies so they rest exactly upon the sluice underlays. This allows us to take apart one only portion of the sluice box if that is all we want to look at or clean-up.

The screen assemblies are built so the aluminum side supports slide down inside the sluice box and sit directly on top of the side rails of the sluice underlays. This pins everything down snuggly against the bottom of the sluice box. Then we snap the screen assemblies down tight to make sure everything stays in place when we are running the dredge or moving it around on land or in the river.

Sluice Underlays

Close-up of matting
Close-up of both

Through a very substantial amount of trial and error this past season, we discovered that both the plastic sluice material and also the new Keene rubber matting were losing gold from under the twin screens.

Expanded metalWe finally found the right combination by using a wide, raised expanded metal over top of deep ribbed rubber matting. The aggressive expanded metal was dropping the gold out of the classified feed. Once it was in the ribbed mat, the gold was not getting away. This combination was so effective, we even replaced our header section with the same expanded metal, though we used miners moss underneath, rather than ribbed rubber matting.

We did multiple checks; and we were never able to find a single speck of gold in the final 25% of our recovery system, even though we were mostly dredging in fine gold pay-streaks (loaded with fines in the front section of the recovery system) all season.

This is important: The width of the sluice underlays (and screen assemblies) have to be a bit narrower than the inside of your sluice box. Otherwise, it is too difficult to get them in and out when you want to perform a clean-up or reassemble the recovery system. I always allow a margin of around 1/8th or 3/16ths of an inch, maybe even ¼-inch on a wider sluice.

Note: We have since replaced the sluice underlay in the drawing above by welding some 3/4-inch angle iron on both sides of the expanded metal to create side rails that the double-screen assemblies can rest on top of.

The following video sequence should give you a better idea of what we have ended up with as a sluice underlay:

The width of your side rails needs to be greater than the margin you are allowing between the sluice underlay and the side of your sluice box. This is so you will be sure that the sides of the screen assembly are going to slide down and meet the rails of the sluice underlay.

Double-screen Assemblies

Sliding the second screen into the frameThese add up to some weight; so you have to plan how to divide your sluice box into small-enough sections that you can lift the screen assemblies out of your sluice box without too much trouble. On the other hand, you want to minimize how many sections you have to make, because these are very labor-intensive to build.

The length and width of the screen assembly should match the sluice underlay, so that they will marry-up exactly when you set the screen assembly down on top of the underlay.

 

Screen LatchYou have to use aluminum plate for the sides to keep the overall weight of the screen assembly from adding up too much. The height of the sides needs to be at least as tall as your sluice box. I build mine high enough that I have room to adapt a latch to snap everything down tight.

Once you have the aluminum sides of your screen assembly cut to size, bring them all to your local machinist, and ask him to mill slots so that you will be able to raise and lower your two screens. If you bring the machinist one of the lag bolts you are going to use, he can mill the slots just wide enough to allow the lags to slide up and down freely, but not so wide that the lag is allowed to turn in the slot when you are tightening or loosening the nuts that hold the screens in place. Just to make sure I will have the full range of adjustment, I have the slots milled nearly the full height of the sides, to within about ¾ inch of the edge, equally at the top and the bottom. Each aluminum side needs three slots; one on each end and another in the exact middle.

You can source thin-headed lag bolts from fastener supply outlets. If you look, I’ll bet you can find them on line. If you cannot find them, then you have to grind the heads down on regular lag bolts, because normal heads are too thick and will take up too much space between the screens and the sluice box.

Helpful hint: The head-thickness of lag bolts on both sides of the screen assembly need to be included when you are deciding how wide your screen assembly and sluice underlay need to be for everything to slide in and out of your sluice box without too much difficulty.

Another helpful hint: If you cut the side plates all the same size, and have the machinist mill the slots exactly the same on all the plates, all the pieces will be interchangeable, and then you can jig-up to drill standardized holes in the side rails to your classification screens.

The lag bolts need to be heavy enough to support the weight of your screens (perhaps 5/16ths or 3/8ths). Different boxes have different widths, meaning heavier screens. It is better to go a little heavy on the lag bolts. The bolts need to be long enough to extend through the aluminum side, through the side rail of the screen, and have enough room for a flat washer and self-locking nut.

Screen frameStacking screens

Ideally, you build all your screens exactly the same size, so they can be interchanged. We accomplish this by rigging up a jig to cut all the side rails exactly the same; then to weld the frames all the same; and then to drill all the bolt holes the same. We drill the bolt holes in the side rails a little large to allow some margin for error.

Side rails for the screens need to be heavy enough to support the weight of your screens with you standing on top of them. By heavy, I am discussing rail thickness. Because, if you go too wide, you will limit how close you can adjust the distance between the screens. Thicker 1.25-inch-wide strap has worked well on my refits for the screen side rails.

Unless you want to buy whole new sheets of screen (expensive), I suggest you source used screen at your local metal scrap yard. The one we go to in White City, Oregon nearly always has a large supply in all mesh sizes. I gather that commercial screening plants replace their screens pretty often – most of it still in good enough condition to meet our needs.

The top screen (around 3/8th-inch openings) needs to be heavy enough to span the length and width of your screen assemblies without needing additional support, and without bending or sagging when you stand on top of the finished screen.

The lower screen (around 1/8th-inch openings) needs to be heavy enough to span the length and width of your screen assemblies without needing additional support.

Helpful note: I experimented with a finer-mesh lower screen (about 1/10th-inch openings), and had trouble with small particles of rock plugging up all the holes. We call this “blinding.” It’s when the holes in a screen all become plugged-up (or overwhelmed by too much feed), preventing the screen from doing its job. So it would appear that you do not want to use a mesh on the lower screen much smaller than 1/8th-inch.

Cutting screenWe have had good luck cutting the screens to size using a cutoff wheel on a hand-held grinder. If your side rails are made of thick material, you should be able to cut the screen to size and weld it down directly on top of the side rail frame. Grind all the edges nice and smooth, so your hands are not getting cut up once you start working with these screens on your dredge.

Helpful note: If you weld the bottom screen on top of the side rails, and the top screen on the bottom of the side rails, you will be able to loosen or tighten the center bolts in the side plate much more easily. I am talking about the lag bolts which attach the screens to the aluminum side plates. If you end up with your center bolts between the screens, it is much more difficult to get at them!

Another helpful note: You might want to drill your holes just off center through the side rails. This way, you can still get a socket on the nuts after the screen is welded on.

These helpful notes are things I have learned the hard way!

When you assemble the screens, a good starting point would be so that the bottom screen rests maybe just a little more than an inch above the plastic sluice.

Helpful hint: If you make the side rails on your sluice underlay too tall, it will limit how far down you can slide your lower screen.

We have had pretty good results lifting the upper screen about 1.25 inches above the lower screen.

This is important: To add more flexibility, if not already present, we modify the sluice box supports on the dredge so that we can raise and lower the slope of the box. This creates a very helpful mechanism for adjusting flow rates.

Once in the field, you can make adjustments to sluice slope and height of each screen to work out the needed velocity in three separate water-flows: First, the water-flow across the sluice; then the water-flow between the screens; and finally, the water flow across the top screen.

I already discussed above how to replace the lower screen with a false flat bottom which you can place riffles on top of to recover the larger classifications of gold. In my view, it is more effective to do this in the lower section of the sluice box (though, I mounted the riffles for larger gold in the upper-end of the sluice on my 8-inch dredge). I know this viewpoint is not popular with some prospectors, because they do not want to chance losing a bigger piece of gold that is allowed to get so close to the end of the recovery system. My answer to this is that gold is really heavy stuff! If there is some anomaly (like the gold is attached to quartz rock which makes the piece lighter) that would keep it from trapping in a set of riffles in the back-end of the box, it probably will not drop out in the front portion of the box, either.

Other than in a very rare occasion, the vast majority of the gold you will recover is small enough to drop through an 8-mesh screen. Some important part of that gold is so fine as to be difficult to recover using the recovery system on a conventional suction dredge. The journey of fine gold through 20 feet of suction hose, and then up through a diffuser (flare jet) places most of this fine gold right on the bottom of the material as it first flows into the sluice – right where you want it; right where it is most likely to drop through the classification screens out of the higher-velocity flows, which otherwise can wash it through your box like sand. Better, I think, to get the minus-1/8th gold into a safe holding area as the first priority.

If you look closely at the diagram just above, you will see another reason to put the larger riffles towards the rear-end of a double-screen system. See how all or most of the fines are directed through an undercurrent below the larger riffles? This means the larger riffles will not be getting flooded and loaded up with fine-sized material. So, while fine material gets more exposure to low-profile riffles (where it belongs), the deeper riffles remain more open so that larger gold has a place to drop out of the flow.

But that is just my view. You guys can do it any way you decide to!Riffles just after shut-down

The reason you see rocks on top of the double-screens, is because we turned the dredge off while we were pumping at production speed. See how the riffles are working? They are not loading up, and they are not boiling- out. This means the system was working!

I do my classification and sluice flow adjustments when running the dredge at normal operating speed while I am feeding the nozzle at production speed in hard-packed streambed. I arrange for a second person to kill the motor without notice. Then, when I disassemble the system, I can see how the sluice and screens are performing while I am pumping gold and gravel into them at production speed.

Between these explanations, the drawings above, the images and the video segments, you guys (or the fabricator who will help you) should be able to see how these systems come together, and how they work. They provide you with a whole lot more than I started with!

Here follows a video segment we put together at the end of this last season which demonstrates the most recent evolution of this very effective dredge recovery system:

Other Considerations

Trial runPossible need for added floatation: As I mentioned above, these double-screen assemblies are heavy. So if you do a refit of your sluice, you may also consider adding some floatation to your dredge. When I refit the original 6-inch Precision dredge for Cambodia (image above), I also had new, larger aluminum pontoons made up to provide enough floatation so that I could also stand on the dredge while it was running. Nice!

Having enough water-flow to make double-screens work: Every dredge is a bit different. Before refitting your dredge with a double-screen system, you might turn the dredge up and watch the water-flow across your existing recovery system and estimate if you will have enough water volume to provide sufficient velocity to meet the needs of three separate flows.

Overfeeding the system: Every recovery system has its volume-limits! Since I find nearly all of my high-grade gold associated with hard-pack, I design my recovery systems to process average material which makes up normal hard-packed streambed that was put in place during the evolution of a major storm event. Normal streambed consists of rocks which are fitted together, with smaller rocks and pebbles in-between, with gravel, sand and silt filling the smaller spaces. When taking apart normal hard-packed streambeds, the smaller-sized material only comprises a small fraction of the overall volume. Therefore, I have yet to overwhelm one of these double-screen systems while production-dredging in hard-packed material.

On the other hand, if you go out on the river and just start pumping sand or loose, classified gravel (like tailings), a much-higher percentage of the material will penetrate the screens and you will almost certainly overload (blind) the sluice with too much material – and perhaps even pack-up the space between the sluice and the bottom screen. Let me be clear: This double-screen system is not designed to process sand or loose gravel deposits or tailings from some earlier mining activity!

This same concern is true for any type of recovery system used on a suction dredge. So it is important for you to be mindful of the material that you are feeding into your suction nozzle. If it is a layer of sand or loose gravel, you should either slow down; or you can speed up and pump it through as fast as you can; and then go up and make sure your system is no longer packed-up before you start feeding pay-dirt into your dredge.

The fine gold needs to be present: The only good place to test the effectiveness of your recovery system is when you are feeding high-grade into your dredge. The more gold you feed into the recovery system, the better you can see how well it is working.

Effectiveness cannot be discounted just because you see a speck or two of gold down towards the end of your box. The thing to look at is where most of the gold is stopping.

So many times, I have watched others decide their recovery system is not working, only because they are not recovering much gold. You cannot recover much gold if it is not present in the streambed that you are dredging! So I suggest you reserve judgment until you test your system in high-grade.