BY PAUL BADALI

Since we’re still in the mainstream of the dredging season, I’ve decided to share a few tricks I’ve picked up in my experiences with dredging over the past few years. Hopefully they will help to make your dredging a little easier.

After several seasons of use, dredge hose becomes cracked and needs to be replaced. I have tried to repair the cracks and holes in my 5-inch yellow hose with silicone R.T.V. glue, that didn’t work; so I knew I would be replacing it. The only 5-inch hose I could find in the dry desert state of Utah was a very light duct hose called Spirolite, which is used to blow insulation into attics. The hose is so light and thin that I decided both the first and second time I went in to purchase some it could not hold up under dredging conditions. But the price was so good (about $3.90/foot for 5-inch) that I finally bought a 10 foot length just to see how it would hold up in the Klamath River. I liked it so well that when Tony Dilmore, who had originally recommended it to me, showed up in Happy Camp with some, I bought another 20 foot length from him.

Spirolite has definite advantages in some dredging applications. First of all, it is extremely flexible. It is ideal for creek dredging where the hose often must be wrapped around boulders. Secondly, it is extremely lightweight weighing only about half what the yellow hose weighs, so it’s easier to pack down the bank or into remote dredging sights. It does not show excessive wear as I had feared it might. When I first looked at this hose, I pinched my thumb nail and finger nail together on the thin clear material between the spiraled ribs and was able to pinch a hole in it. But I can’t see any holes in my 20 foot section of hose after half a season’s use in the Klamath River. So, it seems to hold up well. It does develop small holes where it is clamped to the nozzle and the jet, but these areas are at the end of the hose and can easily be cut off when they get bad. And at $4/foot, you can afford to take this into account and buy five feet more than you need. And as for beating out plug-ups, you don’t have to. This hose is so flexible that it rarely plugs-up. If a rock does turn sideways and plug, you simply deform the hose with your hands, and the plug frees with no hammering on the hose!

There is one application where a heavier, stiffer hose is preferred over the Spirolite, and that is in deep or fast water. Because the hose is so light and flexible, the water can grab it and keep pulling it out of your hole. When I used this hose in the gut of the “Glory Hole” on the Klamath in about 15 feet of water, I had to keep the dredge near the edge of the river, use 30 feet of hose, and anchor it to the bottom at two points on the way out into the gut. The nozzle still washed out each time I went up to knock a plug out. But for calmer more shallow water, it’s the hose I prefer to use.

You should be able to get it at most large hose supply stores in larger cities. If they don’t recognize the brand name Spirolite, ask for the lightweight clear spiral duct hose they use to blow insulation into attics with, and get prices at three or four hose supplies. You may get it even cheaper than I did!

Has your swivel nozzle stopped swiveling after two seasons of use? Mine had. Sand and small rocks work their way down into the joint, and rust accumulates in there over the winter. But if you have access to an arc welder, the repair job is simple. Just cut or grind off the weld beads that hold the swivel joint to the nozzle, and remove the swivel joint. Inside you will find two rubber O-rings or pieces of rubber cord cut to work as O-rings. Pull the whole assembly apart, and use a wire brush to buff rust and sand off of all the metal parts. Clean the rubber cord or O-rings in water.

You want to catch any sand that falls out, and pan it. I found one nice flake of gold inside my nozzle when I cleaned it. You may wish to use some type of non-oil lubricant in the swivel joint before you reassemble it, such as graphite or silicone. I haven’t done this yet, but I suspect graphite is the way to go.

To reassemble, simply match the old ground-off beads back up, and tack it in the same spots with an arc-welder. I would not gas weld these beads, as I suspect it would get the rubber O-rings too hot and damage them. When you are done, your nozzle should swivel as good as new. While you have the welder in hand, touch up any wear you see elsewhere on the nozzle.

This last winter, I got about 26 feet of 36-inch-wide miner’s moss free! You may be able to do the same. I noticed that miner’s moss was used on the floor as mats in every entrance at a local high school. I found the janitor and asked if he would keep me in mind, and give me any old pieces he might be throwing out in the future. He was curious as to why I would want old mats, and we got into an hour’s discussion about dredging for gold. At the end of our chat, he said, “You know, I think we have a few old pieces we’re throwing out in a store room right now.”

We went to look, and he helped me wheel out three six-foot pieces, and one eight-foot piece of miner’s moss. They needed some cleaning up, but hanging the carpets on the kid’s swing set and using the garden hose soon took care of that.

The moral of this story is ASK. If you want something, ask. If you think people will say no, nine times out of 10, then just ask 10 people, and you’ll get what you want. Everyone has seen miner’s moss being used for foot mats. The U.S. Postal Department uses it, supermarkets do, banks do, etc. They all have to throw out the old and replace it with new. So ask for the old mats, and chances are you will get some!

I would also like to give some advice on moving your small-size dredge around on a big river like the Klamath. If you are not a good swimmer, and you are scared to death to swim across; then listen to your intuition, and stay on the side you’re already on. Know your own limits, and don’t get yourself into trouble. But, if you’re an average swimmer, and just a little apprehensive, then here are some tips on getting yourself, the dredge, gas supplies, and concentrates back and forth across the river without a boat.

Number one, buy a good set of fins. Good fins fit over your wet suit booties and are fairly stiff. They are not so stiff that they feel like cedar shingles, nor so soft that you can touch the tip of the fin to the heel, but somewhere in between. With a good set of fins, you have about as much power in your legs as a 2-hp outboard motor, and you can really cruise across that river! Always wear your wet suit without weights when crossing, and take it easy. If you’re not used to pumping fins, you can quickly get a leg cramp from over exertion.

The current will pull you downstream as you swim. Pick a calm stretch of river to swim across, and start way up stream from where you want to end up. Don’t choose a calm spot immediately above bad rapids, because if you don’t make it, you will be going for a very bouncy ride. If you are crazy like I am, this can be lots of fun, but it can also freak out your wife who watches the ride from shore!

To swim across, just float on your back, point yourself towards the other shore, and pump your legs. Don’t try to head up- stream and fight the current! Just start way upstream from where you want to land on the other side, and take a relaxed ride. The fins do all the pushing, just let your arms dangle. With fins and a wet suit on, it’s easy as swimming in a lake.

To take my dredge across, I load everything onto it, and push on the tail-end of the sluice box while kicking with my fins. I do not like a rope tied from the dredge to the shore. I do not swim a rope across first, and let that rope pull the dredge in. I play outboard motor with my fins, and I propel the dredge to the other bank. I lie on my stomach if pushing, or on my back if pulling. I feel much more in control of the dredge this way. I do choose a very calm stretch of river to do this, and I give myself twice the distance upstream that I think it will take to get across. It’s easy this way for one guy to get a dredge across by himself, and it’s a breeze if you have a helper also wearing fins.

Supplies and concentrates are also easy to get across. If you use a large 30-gallon tub to dump your concentrates into, you already own a small boat. You can put your weight belts, winch, tools, towels, etc. into the tub, and pull it with you as you lie on your back and kick across. It will sink if you tip it, and an inflated inner tube around the tub adds safety and more buoyancy. You can pull people in dry clothing across in a small rubber raft as fast or faster than they can paddle. You can also very easily swim a motorized sluice (high-banker) across the river in a small raft or an inner tube. You can fit lots more cargo in a rubber raft if there is no one in the boat! Obviously, when you want to come back across the river, you have to walk upstream; because you will be washed downstream as you swim back across.

There really isn’t much to fear from a big river if you are careful. You float like a cork in a wet suit. Don’t fight the current! The current is stronger than you are, so “go with the flow,” and let it work for you. Get good fins, so you have some push, and have a good time with it. In most cases, there has been less prospecting and mining done on the other side, so you may reap great rewards for your investment in a pair of good fins!

Good luck, and see you out there!

 

BY MARCIE STUMPF/FOLEY

 

Bill StumpfMost miners have a season that is very special. Sometimes because they find a lot of gold, sometimes because of a very special nugget; but they all seem to have one year that stands apart from all the rest. We, too, have such a year, but not for any of the above reasons. Our year stands apart because it really put our love of mining to the test.

The year was 1979, and we were especially looking forward to it. We had a new motor- home; but more important to my husband, Bill, we were upgrading from a 2 1/2″ dredge to a brand new 4-incher. Our three teenage sons were staying home, and we were taking our first vacation alone, ever!

We tried to plan carefully, as usual; but due to our three sons, there was always an ever-present need to economize. We decided that we would carry our mining gear in our aluminum fishing boat on its trailer, which didn’t have really good tires. However, after looking them over, we decided they would make just one more trip. That was our first mistake.

Our second mistake was the date we picked to start our vacation. California was in the midst of a record heat wave, and we left home on the hottest day (anywhere in the State) in a decade. By late afternoon, heading up Interstate 5 near Red Bluff, the temperature was somewhere over 120 degrees. We were wilted; the left tire on the boat trailer had developed an alarming bulge; and the auto air-conditioning in our new motor-home had died. We pulled into a campground, showered, and collapsed under the rig’s air conditioner, too tired to even eat dinner.

A good night’s sleep helped, and we were at a tire store when they opened early the next morning. After they replaced the tire, we pulled out onto the main street and headed out of town-so we thought. We hadn’t gone a block when we heard a big “thunk!”, and our new tire went flying past us, up Main Street. I can still clearly see Bill slumping over the steering wheel, saying “Oh, no!..Oh, no!,” as cars and trucks swerved, trying to dodge the tire as it merrily sped down the street. It looked like something from the Keystone Kops ! Then, a glancing blow from a truck sent it spinning crazily off toward the sidewalk. And as I looked up, I saw that it was headed right for a beautiful little church with stained glass windows.

We could only watch and hold our breath as it jumped the curb, crossed the sidewalk, and started up the church steps. One big bounce, then two, and the next would send it over the top and right into the window! But the tire just didn’t have quite enough “oomph” to go over the top, and we gave a sigh of relief as it hit the edge of the top step to bounce back down and into the street where it finally came to rest.

Only then did we notice that traffic had completely stopped, and we had quite a large audience. Bill was really thrilled to have to get out and retrieve the tire and all the lug bolts, apologizing all along the way. Red Bluff was quite small, and the audience obliged by waiting and watching him.

The lug bolts were stripped, but he put it back together as best he could, and we made it back to the store. Bill had a few things to say the whole time he worked, but I wisely kept silent. In such a situation, I have found it is better to not even murmur sympathy.

Although they did not have what we needed to fix it, they managed to get it together well enough for us to limp along the shoulder to Redding, another 33 miles. There, they managed to make the necessary repairs, and Bill bought a replacement for the spare tire on the trailer.

By this time, we had lost what little coolness the early morning held, and we sped on our way in the heat. Our next stop, Yreka, came at about noon, and we quickly picked up groceries, gasoline and propane, and then headed on our way. About 15 miles further, we had to find a large open area back from the road to stop.

Our third mistake was in not making sure they did not overfill our propane tank. (We have found this is common, and can be very dangerous). By now, it was 114 degrees, and we were in the sun, of course. We gratefully climbed back into the rig to resume our journey. But unfortunately it was not for long. Soon, a passing motorist, by honking the horn and pointing back, signaled another problem. You guessed it! The other trailer tire was flat. There was no shade in sight, and I don’t exaggerate when I say that we sizzled each time we had to touch the hot metal of the boat to get what we needed. I stayed out to help as much as I could, but made sure I stayed out of the way, and behind Bill, in case he reached the stage of throwing things. He was seeing so much red by this time I was afraid he might not see me.

The tire-change went smoothly, however; and in another fifteen miles, we had reached our destination to join our friends, Ned and Dori. What a relief it was to relax in the shade, sip a cool drink, and visit.

When we’d finished our news, Ned told us theirs. They had made a deal for us to dredge on a private claim about 10 miles further up the mountain. We excitedly broke camp, and hauled everything up there, where we labored the rest of the day getting our rigs back into the thick trees, in the cool shade. We were going to be here a while, and we wanted it right.

There had been a cabin here at one time, and the cleared area where it had stood would be perfect for campfires at night. We also discovered, off a ways, a “Three- Holer .” For you city folks, that is an outhouse with three holes. Actually, I’d never heard of one, either. It had critters, and it was dirty; but was still sound. Dori and I decided we’d clean it up when we had time. That night, as we sat around a fire, the tension from our trip faded, and the wonderful peace that we always felt when we got away like this descended upon us. It was August, and the days were long. By bedtime, the guys had made plans to get going early in the morning, and be dredging by noon.

In the morning, Bill sprang from the bed, eager to get the day started. Unfortunately, his aim was off a little, and he smashed his knee into the cupboard next to the bed. Ignoring my offer of a band-aid, he quickly donned a pair of shorts and went out to get things ready. In an hour or so he was back. He had added a bee sting to his other knee, and a huge multi-colored goose egg to a shin. Now he was ready for band-aids and medicine.

After I’d done what I could, he put on his wetsuit. His fourth mistake was in not putting his wet suit on first thing in the morning. They are good protection! He then hobbled off to finish putting the dredges into the water with Ned’s help.

When they finished, we took a break for lunch; and as we finished, we had a visitor. It was the miner who had the next claim up the creek, and he was very nice about it, but…Ned and Bill had launched the dredges over the claim line. So they spent the rest of the day moving the dredges and setting up in a new location.

When we arose the next morning, Bill’s cut, sting, and goose egg were surrounded by rash and were inflamed. His fifth mistake was in not watching carefully enough for poison oak. From there, he proceeded right to his sixth mistake. He dredged anyway.

By the next morning it was obvious even to Bill that everything was infected, and his poison oak was rapidly spreading to cover his entire body. Reluctantly he stayed out of the water; we soaked and applied creams and ointments, as he stared at it all, willing it to go away.

Despite all of our efforts, Bill looked much worse the following day, and we were growing concerned. He still refused to see a doctor. Our seventh mistake was to use band-aids and tape, which Bill has always been allergic to. As I tried to remove them to put fresh ones on, each small tug of the tape caused Bill to say “~UGH!!!” The sound was approximately equivalent to the ones they make in a movie when having a leg sawn off without anesthetic. No matter how hard I tried to be careful, each tug brought forth another “~UGH!!!”. To make matters worse, I soon had tears flowing freely from laughing so hard.

Ned and Dori came running to see what had happened now, and when I answered the door with tears running, they were really concerned. As I tried to explain, they became very confused, since Bill had a huge scowl, and was at the same time telling them about the cruel and inhuman torture I was putting him through. Finally, I removed just a small piece to show them (and to shut Bill up), and his words changed to “~UGH!!!” Then they were laughing, too, and Ned insisted on staying to the end to get even for the many things Bill had done in the past.

We decided we’d better leave it the band-aids off, which meant that Bill had to stay indoors to keep dirt out. With that development, and the seriousness of the infection, Bill finally agreed to see a doctor. We went to the hospital in Medford (Oregon) the next morning. The doctor kept his hands in his pockets the entire time he looked at Bill, said he had severe staph infection along with the poison oak. He prescribed several medications, along with many restrictions to keep it from spreading. This really sent Bill into the depths of depression, and it took us several days to get all the soaking, etc., worked out in our small motorhome. But then we came up with a plan to ease his problem. I became Bill’s “surrogate dredger,” and this is how it worked: (Until then, I had always participated in his dredging, but only as a dredge-tender, or by shoveling tailings.) Bill would stand up on the bank, about 30 feet high, and tell me where to dredge, and shout directions, which I was to follow. In most places here, bedrock was extremely shallow, only 2 or 3 feet deep, and I soon found that working the nozzle was actually a lot of fun. It sucked up all the stuff, and then I could fan the crevices and cracks; and most of the time, there would be some gold that I could see and pick up with my tweezers.

It was hard to hear Bill over the dredge engine, and he was frustrated because he could not see very well what I was doing. More often than not, he said that the gold I was recovering wasn’t good enough, and that I should move to a different place. Now this was the very first gold that I personally had ever found on my own, and I had a very special feeling for it. I was most-often content to stay right where I was. Also, one of the things I am not known for is my muscles or athletic ability, and dragging (the water wasn’t deep enough to float the dredge in many places) a 4-inch dredge over rocks is not a fun thing to do. Besides, I always believed he did not sample thoroughly enough when testing.

Naturally, this led to much “discussion,” something we are experienced at, having been married a long time. At times, in fact, I was sorry that we were no longer using tape. I’d have really enjoyed ripping some off. However, I would eventually realize, or be reminded, that I was only a surrogate dredger, and remember that I was supposed to be helping him; so I would usually move. Eventually, however, I lost all my understanding, patience, energy, and enthusiasm, and we gave up that experiment.

The next week, when we weren’t snarling and snapping at each other, Bill read and listened to the radio, and I recruited Dori to help me refurbish the “Three-Holer,” when I needed to get away. We cleaned out the nests, put a spare piece of outdoor carpet on the floor and contact paper down the seats, hung a lantern and fixed the latch on the door. Then we cleaned the path and lined it with rocks. Ned helped me fix a metal poker we heated in the campfire, and I burned “3-Holer” into a piece of picturesque wood that pointed the way. Then finally, the day arrived when Bill could go back into the water. We had four days left for dredging.

We set the dredge up in a deeper pool that he wanted to try, but we developed a problem right away. In dragging the dredge around, one of the pontoons was taking in water, and Bill was too anxious to take the time to fix it right. That was a mistake.

He hit good gold right away, but we were using every bit of hose we had. Each time he’d tug on the hose, the pontoon would settle a little bit deeper in the water. Eventually, the dredge would be in danger of sinking, and he would have to come up to pump it out.

Bill worked a very long day; and when he came out, he did no more than shower, grab a sandwich, and fall into bed. He got up early the next morning, put his suit on immediately, and we went to the creek. By this time, the heat wave was long gone, and it didn’t climb above 45 degrees until the sun came over the mountain, late in the morning. I did not argue, however. He was doing some serious dredging, now; and he was even angrier each time he had to come up to pump the pontoon.

I tried to build a dam under the dredge. But each time he pulled the hose, the rocks would fall, and I had to start over. By early afternoon, I had given up; and when I signaled him to come up about the tenth time, he came up boiling mad. He broke water like a fish on a hook, ripped the regulator from his mouth, and told us all just what he thought of his pontoon, the manufacturers of the dredge, dredging, and life in general. The whole time he was talking, he was shedding his gear; and when he reached the bank, he started pulling in the dredge, and proceeded to break it down.

Our friends quietly faded away, and I found a rock to sit on a safe distance away. When Bill finished, he told me I could pan the concentrates or not, he didn’t care. I did pan them after he went back to camp; and as I took a break before panning the last pan, I sat on my rock in the middle of the creek, and the beauty of the scene struck me, again. I listened to the creek as I watched the rays of sunlight shining through the trees to dance on the water. The black-berry bushes twined among the trees and ripe with big, luscious fruit, hung low over the water, and the air smelled so fresh and sweet I could taste it. The image is as bright today in my mind as when I sat there, and with the image comes the feeling of peace and contentment I felt at that moment.

We packed up that night and started home the next morning. Bill was very silent through the packing and the drive home. About halfway home, I was beginning to get concerned that he was really finished with mining, when out of the blue he said, “Next year.”

 
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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.

 

 
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By Dave McCracken

There can be a lot of gold deposited under and around the boulders located within a pay-streak!

Dave Mack

 

It takes an incredible force of water to move boulders in a river. Once they are moving in a flood storm, they can deposit in low-velocity areas, just like gold does. But, since boulders do not have a higher specific gravity, mass for mass, than most of the other streambed materials, they can be washed downstream just about anywhere in the river during a major storm. So you should not only use the presence of boulders to guide you in sampling. You would be much better advised to focus your attention on the boulders that have been deposited along the common path of gold’s travel.

In shallow streambed material, you can sometimes detect where important bedrock changes are located by noting where the boulders have deposited within the waterway. For a boulder, or a group of boulders, to be found in a specific location along the river’s path, there may be a sudden bedrock drop-off, a large crevice, or some other kind of lower-velocity condition in that area which caused the boulder(s) to be deposited there. Everything in the waterway happens for a reason, even if you cannot always see what it is!

If the boulder(s) is located somewhere along the common gold path, that would be a prime spot to do some sampling. In this situation, I suggest that you do not limit your sampling to the area just behind (downstream) of the boulder, though. Go around to the upstream side of it, as well. Look for any bedrock change which may have caused the boulder to stop there. If gold has moved through that area, that same bedrock change could also have caused gold to concentrate there. Finding the bedrock change that stopped the boulder, and following the bedrock change across the waterway, is a great way to locate the common gold path.

You do not always find boulders with every rich pay-streak deposit. But, it is not uncommon to find many boulders keeping company with a good pay-streak. When you do find them, most of them will probably have to be moved out of your way as you work forward through the deposit.

MOVING BOULDERS BY HAND

There can be a lot of gold deposited under and around the boulders located within a pay-streak. To get most of the gold out from under a boulder and into your suction nozzle, usually the boulder has to be moved at least a little bit.

One of the most useful tools that can help a dredger move boulders is a 5-foot (or longer) steel pry bar. If a boulder is too large to be moved to the rear of the dredge hole by hand, it can sometimes be rotated around to one side so that you can dredge out from under part of it. Then, it can be rotated around the other way to access the remaining gold and material beneath. A long pry bar can be a big help to you in moving boulders around in this way.

The key concern while working around boulders is safety! Loose boulders in and around a dredge hole are the gold dredger’s greatest danger, especially when working alone. Boulders resting up in the streambed material are usually more dangerous than those resting on the bedrock. But, those on the bedrock can cause trouble, too, if they are loose and able to roll – particularly, if the bedrock has any slant to it.

As they are uncovered in a dredge hole, loose boulders should be moved and safely secured as a top priority. They should be placed at the rear of the hole, if possible. But, wherever they are placed, they should be positioned so they no longer pose any threat of rolling into the hole and on top of someone working there. You can place smaller rocks and cobbles under the boulders as necessary, to make certain they will not roll or slide.

If you start to uncover a boulder that is resting up in the streambed material, do not forget about it. Until it has been moved and secured safely, a loose boulder should be foremost in your mind. If it is not yet ready to be moved, and you still need to dredge around it to free it up some more, it can be useful to place an arm or a shoulder against the boulder. This way, you can feel if it starts to loosen up in the material. Do not place your arm, head, or shoulder near the underside of the boulder, however. Because, sometimes a boulder will loosen up and crash down very quickly, without much warning. Physical contact with the boulder is helpful when you cannot keep your eyes on it at every moment. The face mask limits your visual perception underwater – especially when you need to watch what is going up the suction nozzle.

The main concern here is to take all necessary precautions to keep yourself from becoming pinned or crushed beneath a boulder in your dredge hole. If a boulder pins any part of your body to the bottom, it may be difficult or impossible for you to get the necessary leverage to move the boulder enough to get out from under it. And, if you are working by yourself …? I know of two dredgers who ended their careers in just this way.

Also beware of fractured bedrock walls that tower over you. They can fall apart and drop in your dredge hole as you remove the streambed material that holds them in place. I got pinned once by a slab of bedrock that broke free of a wall as I dredged away the material that was holding it there. Luckily for me, it landed on my steel-tipped boot, and that I was dredging with another guy on that day!

The second greatest danger to a dredger usually comes from a cobble falling off the side of the dredge hole and hitting the dredger in some way — like on top of the head. This can finish off a dredger just as surely as a boulder. Or, it may cause some serious pain/injury. Fingers and other body parts can get smashed if you are not careful!

Most trouble with cobbles and boulders can be prevented simply by taking your hole apart with safety in mind. The proper method of taking a dredge hole apart has already been fully covered in my Gold Dredger’s Handbook, so I will not repeat it again here. But, as a point of emphasis, the fastest way to take apart a streambed also happens to be the safest way.

Production dredging goes very smoothly and quickly when you have some area of exposed (dredged) bedrock between the non-dredged material in front of you and the cobbles, boulders and tailings behind you. When you start uncovering a boulder in the material, you should immediately begin planning where you are going to move it, once it is ready.

If you run across an occasional boulder that you cannot move by hand, sometimes you can dredge the material (and gold) out from around and under it without having to move it out of the dredge hole. You accomplish this by moving other, smaller rocks out of the hole to make room for the boulder. In this way, if there are not too many boulders, you can keep moving forward on the pay-streak without the few boulders slowing you down very much.

But, if there are a lot of large boulders down along the bedrock, you will likely discover that at least some of them will need to be completely removed from your excavation if you expect to uncover very much bedrock with your suction nozzle. Some boulders will need to be removed to make room for other boulders as you move forward on the pay-streak. If you cannot remove the boulders from your dredge hole by hand, then you will need some mechanical assistance.

DIFFERENT TYPES OF WINCHES

COME-ALONG: A “come-along” is a portable, hand-operated winching device that can be of considerable help to a small-sized digging program. It can be used to move those boulders that are not huge, but which are too large to be moved by hand. Come-alongs range in size. I recommend a larger version of the better quality, rather than the really cheap, imported models. Come-alongs have a great accessibility factor, because you can carry one just about anywhere. Their operation is somewhat slow. But, they will give you that extra edge when you need to move just a few boulders, and you do not own or want to set up a power winch.

GRIP-PULLER: Several companies make a hand-winching device that rides along on a steel cable. There is a handle that you crank back and forth, similar to a come-along. Each time the handle is cranked in each direction, the device moves an inch or two along the cable. These units also come in different sizes. In my opinion, grip-pullers are a substantial step up from a come-along, both in pulling-power and dependability. I have used these units underwater, but find that the water resistance adds substantial work to the cranking action. Still, when you are working alone, having this device in the hole with you allows you to see what the boulder is doing while you are winching it

Where you can buy winching supplies

USING YOUR TRUCK AS A WINCH: If your vehicle can be driven to a nearby position, you can stretch a cable from the vehicle to the boulder. The proper direction of pull can be rigged up by running the cable through snatch blocks (heavy-duty pulleys) which can be anchored to trees, boulders or whatever is available. Then you can use the pulling-power of your truck to help move the boulders out of the way. Four-wheel drive vehicles work better for this, especially when they are carrying a load to increase tire traction. Suggestion: It is better to connect the cable to something on the vehicle’s frame, rather than just the bumper!

When conditions are right for it, using a vehicle to pull smaller boulders can be much faster than using a come-along. One person operates the vehicle, while a diver is in the water, slinging the boulders. Safety becomes a greater concern when more than one person is involved in the pulling and the slinging of rocks. Communication and coordination between the “puller” and the “slinger” are very important to prevent serious accidents. Suggestion: If you turn the truck around and pull in reverse, you can better-see signals from your partner, and sometimes you get better traction, especially on a 4-wheel drive vehicle. Another suggestion: It is better to keep your vehicle a respectable distance from any drop-offs (like into the waterway), just in case the boulder gets momentum in the wrong direction. I know of guy who got pulled over the side of an embankment by a boulder gone wild!

Larger-sized trucks, tractors, bulldozers, and other heavy equipment can sometimes be used to move bigger rocks with even better results.

AUXILIARY TRUCK WINCHES: Auxiliary automotive winches are also able to move small to mid-sized boulders for a dredging operation with excellent results. Some of those little winching units have a wondrous amount of power. A typical 8,000 or 10,000-pound electric winch will move a surprisingly-large boulder!

If you are going to be using an electric winch, you may want to consider installing dual batteries in your vehicle. It also helps to keep the engine running while you are winching, so the batteries can quickly regain their charge between pulls.

When using a truck-mounted auxiliary winch to pull boulders, it is a good idea to block all four wheels. This precaution helps to keep the vehicle from moving, rather than the rock you are trying to pull. The front tires should be blocked especially well. If there is an embankment to worry about, it is also a good idea to run a safety chain or cable from the vehicle to some additional anchor behind, like a tree or another truck. This will protect against losing your vehicle over the embankment if the boulder happens to roll the wrong way. Sometimes this added measure is necessary just to keep the vehicle from sliding during the pull.

Probably the best kind of auxiliary vehicle winch for dredging purposes is one that can be attached mechanically to the “power take-off unit” on your vehicle’s transfer case, if it has one. With this kind of winch, you can use the full power of your truck’s engine to pull rocks. Not only will this provide you with more pulling power, but you will not have to worry about your batteries running down.

There is also a lot of good to be said for the portable electric and hydraulic winches on today’s market. I know of many smaller-scale and commercial dredgers who use them. They are quite powerful! Portable electric winches can be framed up to (1) attach to a vehicle, (2) be taken out to the dredging site, or (3) even be floated on a platform, where there is deeper water. All that is needed is an automotive battery and a means of keeping it charged up. The portable hydraulic winches can be similarly effective. The winch controls can be extended out on a longer cable and even modified to work underwater, which can be very helpful!

LOG SKIDDERS: Most gold-dredging country is also logging country. So there are quite a few log skidders around that can be leased or hired to pull boulders for you. Log skidders are usually equipped with powerful winches. They can really do a job in pulling the larger boulders! Also, you can drive them into some pretty difficult areas. Hopefully, you can work out a deal that will be ideally suited to your operation; a deal perhaps, where you pay by the hour and have the skidder arrive at a certain time each day, or whenever you are in need of it’s services.

PORTABLE POWER WINCHES: Gasoline-powered, mechanical and hydraulic winches are available in all sizes. Generally, the larger they are, the more winching-power that they produce. But, the added size and weight also makes them more difficult to pack into some of the less accessible areas.

If you find a widespread, rich pay-streak with plenty of large boulders that need to be moved, you should set up on your dredging site the most powerful winch that you are able to haul in there. The more pulling-power you have available, the smoother and faster winching will go.

I never recommend that a dredger buy a portable power winch just because he or she will be dredging. It is probably better to wait until you know exactly what your needs are. I have worked many pay-streaks where no winching was needed at all. And, in many of the pay-streaks that did require winching, a number of the boulders were so large that the small, portable store-bought type of winch would not have been adequate for the job.

You can find some pretty heavy-duty used winches for sale at about the same cost as a lighter-weight, new portable unit. I advise waiting to see what you will need before putting your money into a winch.

Having said that, here is something to consider: Mechanical winches seldom have a control mechanism which can allow the operator to stand away from the machine where all the wrestling is going on (and in the line of fire if a cable breaks). While I have used some wonderful mechanical winches, there was never a time that we were pulling a big rock that I was not worried about something going wrong with all those tons of energy happening right next to me. There is a lot to be said about electric or hydraulic units that will allow you to step away from the danger with the controls in your hand.

WINCHING COBBLES IN DEEP MATERIAL OR SHALLOW WATER

As I have stressed in other articles about dredging, the main limiting factor to progress is in how quickly oversized material (rocks that are too large to be sucked up the nozzle) can be moved out of the ongoing excavation. In deeper streambed material, there can be so many cobbles that there is no longer any room directly behind the dredge hole to throw them. You can run into a similar problem in shallow water, where the cobbles must be lifted out of the water (where they become a lot heavier) to get them behind the dredge hole. In these types of situations, it is common to fill cargo nets with your cobbles and winch them out of your dredge hole in bulk. The following video sequence was taken in an operation where we were removing big lots of cobbles from a deep excavation in just this way:

SETTING UP A HOLE FOR WINCHING

Before you start winching boulders, it is a good idea to first make sure that you have located the lower (downstream) end of the pay-streak. You do not want to winch boulders onto any part of the pay-streak that you will be working at a later time. While the winter storms could possibly move some of the cobbles and dredge tailings which were placed on a pay-streak in error, it takes much more than a winter storm to move boulders from where you winch them. Believe me; it is much better to plan ahead, so you only need to move boulders one time!

BUILDING A RAMP

It takes a tremendous amount of winching-power to pull a boulder up and over another boulder from a dredge hole. The direction of pull is all wrong, and the second boulder will act like a barrier. The winching is much easier, smoother, and far less dangerous, if a ramp is built so the boulders will have an inclined runway to be pulled along. Cobbles can be used to make an effective boulder ramp. Therefore, an important part of setting up your dredge hole for winching is to construct a ramp/runway that can be used to easily remove the boulders, without them encountering difficult obstructions.

It can be really tough to pull a boulder out of a hole without a ramp.

Cobbles can be used to make an effective ramp for winching boulders out of a dredge hole.

One approach to setting up your hole is to dredge around a number of boulders as much as possible to free them up for winching. This way, more boulders can be pulled out of the hole once winching is begun. Then you can come back later to clean up the bedrock with your dredge.

To perform winching effectively, you will need plenty of air line attached to your hookah system. This is because it is necessary for the diver to sling each boulder and follow it to its final destination where he will disconnect it. Then, the sling and cable must be pulled back and attached to the next boulder. Since this process requires a lot of movement, depending upon the distance involved, you may need to attach an extension onto your air line to accomplish this smoothly.

FEASIBILITY OF MOVING BOULDERS

A dredging operation that requires a lot of boulders to be winched is going to move slower than if little or no winching is required. A winching operation almost always requires the involvement of at least one other person, sometimes even two or more. Those “extra hands” will usually expect to get something for their active participation in your dredging project. So you will find that when you need to use a winch, you will be moving slower through the pay-streak, and it will usually cost more to run the operation. Therefore, a pay-streak that has lots of boulders usually needs to pay pretty well to make the additional effort worthwhile.

The following video segment will give you a look at an organized winching program where multiple persons were involved:

Sometimes, you may discover an excellent pay-streak, but find that it lies beneath many boulders that have to be moved. Even though there may be plenty of gold under the boulders, after figuring the time and expense involved in winching, you may conclude that the gold recovery, though excellent, is still not sufficient to make the project economically feasible. Big boulders are not easy to move. Moving them takes time and money; more, sometimes, than the gold is worth. So, to avoid getting bogged down in an unworthy project, keep track of your daily expenses and your daily gold recovery. Then you will have some basis for calculating whether it is financially worthwhile to continue dredging in that specific location.

If your winching helpers are not full-timers on your dredging operation, and if the location is not too remote, you might arrange to have them arrive at a certain time each day to help pull boulders. That way, you can spend the morning setting up the hole to winch as many boulders as possible. Then, when your help arrives, the boulders can all be winched out of the hole at one time. After winching is completed for the day, you can let your winch helpers go, while you go back down and clean up the hole with your dredge. This way, you are not paying helpers to stand around with nothing to do while you are dredging. It can make a difference.

SETTING UP A WINCH FOR OPERATION

When you are using a portable power winch to move boulders in a dredging operation, the winch must be set up on a solid and stable foundation. It takes a tremendous amount of force to move a boulder. Sometimes, the boulder will move quickly. Or, sometimes, the sling will slip off the boulder, causing the cable to suddenly go slack. Maybe the boulder will loosen up and roll the wrong way, causing a sudden, heavy stress on the cable. When these things happen, and they do happen, you do not want your winch bouncing around or sliding off the platform. That could be extremely dangerous! The winch must be stable!

The winch also should be anchored to a solid object behind it which will hold its position much more securely than the boulders that are to be moved. A fair-sized tree, or a large boulder, directly behind the winch platform can work well for this purpose.

Also, the cable or chain being used to anchor the winch must be considerably stronger than the winch’s capability to pull. The last thing you need is your anchor chain or cable breaking while you are pulling a large boulder! This could cause the winch, and the winch operator, to be yanked off the platform, resulting in a serious accident. Undamaged, heavy-duty truck tow chains with the adjustable end-hooks are excellent for anchoring a winch. Make sure you get chains that are strong enough.

Your winch should also be anchored to a point which is lower than it is. If the winch is anchored from a low point, when boulders are being pulled, the winch will be held down more solidly onto the platform. If the winch is anchored to a higher point, during pulling the winch can be lifted off its platform. This can also be dangerous.

Sometimes, you will not be able to find a good location for your winch along the streambank. You prefer a location where the winch can be set up to directly face the boulders to be pulled, and which provides a level, solid foundation with a properly-located, fixed object from which to anchor the winch. But if that is not available, you can almost always find an acceptable foundation somewhere between two large objects along the bank. The platform may require a little concrete work to get it right. The winch can be anchored to one of the objects, while the other object can be used to attach a snatch block (heavy-duty pulley). The cable can then be run from the winch, through the snatch block, to the boulders that need to be moved. One advantage to this rigging setup is that if the cable does happen to break under a great strain, it will be less likely to fly directly at the winch and its operators.

Positioning the winch between two anchors on the bank,
because there is no easier way to get a straight pull with the winch.

When you set up a winch, it is usually best to position it so the boulders will be pulled as much as possible in the desired direction. The boulders will also need to be pulled far enough away from the dredge hole that they will not have to be moved again at a later time. Often, you will not be able to set up the winch in a position where you can directly pull the boulders in the desired direction. For example, you may want to pull them downriver, rather than toward the stream bank. This situation is most commonly corrected by using directional-change snatch blocks. A snatch block (pulley) can be anchored at a point from the exact direction that you want to pull boulders. The cable then runs from the winch, through the snatch block, to the boulder. In this way, you can usually move the boulders in any direction that you desire from a stable winching position along the bank.

Setting up the proper direction of pull by anchoring a snatch block directly downstream in the river.

Directional-change blocks for winching should be very heavy-duty. They need to be stronger than the cable being used, or the capability of the winch to pull. The best pulley is one that can be quick-released from the cable. This way, you do not have to feed all the cable through the block to get rigged for winching. Good winching pulleys are generally available at industrial equipment supply stores and at marine equipment shops. Directional-change blocks can be attached to trees or boulders with the use of additional cable, chokers or heavy-duty chain. You will find that a few extra tow chains (long ones) and chokers will come in very handy when setting up a winching operation. Chains which have the end-hooks on them are best, so you can adjust their length to meet your needs.

To minimize damage to the environment, you can place pieces of wood between the cable or chain and the trunk of any tree that you use as an anchor. When you anchor a directional-change block to a tree or boulder, you are almost always better off anchoring to a low point. This will reduce the chances of rolling the boulder over or pulling down a tree.

When you use a cable to anchor a winch or directional-change block to a boulder, set it up so that the pull will not cause the cable to become pinched (between two boulders or between a boulder and the bedrock) or be pulled into the material underneath the boulder. Otherwise, after the winching, you may have trouble retrieving your cable without having to move the anchoring boulder as well.

At times, you may need to set up a directional-change block, to pull boulders in a desired direction, but cannot find a downstream boulder that is large enough to use as an anchor. In this case, you can run an additional cable out from a fixed object further downstream on the opposite side of the waterway, and attach your directional-change block to the cable. Then, by increasing or decreasing the length of the cable, you can position the block right where you want it.

Setting up a directional-change block by extending it out on a cable from the other side of the waterway.

It is not a good idea to winch boulders with rope, even the smaller boulders being pulled by your truck or a come-along. When you use rope for winching, the rope stretches even if it is doubled-back multiple times for extra strength. And, it stretches. And, it stretches. Then, it breaks. Such breaks can be dangerous when working around boulders. Also, it can quickly exhaust your supply of rope. Rope is just not strong enough for the job. Steel cable is best. You might get a deal on good, used steel cable from the scrap metal yards. Call around to find out who has it when you need it. Scrap yards usually sell it at scrap prices, by the pound, even if it is in good condition.

The cable you use on your winch should always be considerably stronger than your winch’s pulling capacity. The last thing anyone wants to see is a bunch of out-of-control steel cable flying wildly back in his direction. Faulty or worn cable should be replaced immediately and never used thereafter for winching.

Winching boulders involves an incredible amount of force. So does hauling logs by cable. Similar cables are used in logging operations to pull trees to the loading area. I have heard stories of logging cables snapping, flying back, and cutting a man in two. You are dealing with a similar amount of force when winching the larger boulders in a dredging operation.

WINCHING SIGNALS

During a winching operation, it will be necessary to have a diver in the water to set the sling on the boulders. The diver will also need to remove the sling from each boulder after it has been moved, and then return the sling and cable back to the dredge hole for use in moving the next boulder. This process will continue until all the boulders for that stage of the dredging operation have been moved.

Unless the diver is slinging boulders and operating the winch (a very slow way to go, unless the controls to the winch are in the water with the diver), another person must operate the winch, truck or other device that will be doing the pulling. Once you have more than one person involved in the operation, communication becomes a critical part of the process.

If the winch is a smaller one, or if a truck is being used to pull boulders, and the pulling position is in sight of the target boulders, the job might be accomplished with only one winch operator. On the other hand, in a normal two-man operation, if the winch operator is unable to maintain constant eye contact on the area where the winching is taking place, perhaps a third person will be needed to help with the communication. Each situation will be different. Since this need for immediate and accurate communication is a safety matter which requires on-site judgment, you will have to decide how many people are needed to winch safely.

Sometimes a truck can be turned around to pull backwards, and the driver can directly see and simultaneously carry out the diver’s signals. The controls on an electric winch will often allow a second person to be positioned well enough to see what is happening where the rocks are being moved.

While a boulder is being moved, the diver can watch its progress and signal the winch operator to stop pulling and/or give slack on the line so the boulder sling can be adjusted, if necessary, to successfully complete the movement as planned. The main point is that the diver must be able to communicate to the winch operator quickly and without error. The greater the pulling-power and/or speed of the winch, the more important it is that these signals be accurately received and acted upon quickly. Imagine that you are using a powerful winch to pull a large rock with a heavy steel cable and solid anchoring objects. If your boulder gets jammed against something else in the dredge hole so that it will not move, and you continue pulling with great force, something is eventually going to give. And, it might not be the boulder! This uncertainty is what you want to avoid.

If you are using a winch that does not automatically feed the cable evenly onto the drum, the operator will sometimes need to manually guide the cable. Otherwise, on hard pulls, if the cable starts crossing itself and is allowed to pinch itself on the drum, it may become damaged and thereafter be dangerous for further winching. For this reason, the winch operator may need to focus some attention on the winch, rather than on the diver. In this type of situation, it is wise to include an additional person to help relay communication. Someone needs to be watching for the diver’s signals at all times.

Gasoline-powered winches make noise. So does a gasoline-powered hookah-air system supplying air to the diver. The diver also usually has a regulator in his mouth. With all of this noise present, and the diver having his mouth full, verbal signals are usually not very dependable – especially, if there is a substantial distance between the diver and the winch operator. For these reasons, I have often found visual signals to be more trustworthy, particularly when there is a person positioned at the winch to relay the diver’s signals to the winch operator.

In shallow water, hand signals can usually work pretty well. You really only need three of them: “PULL” , “STOP” and “GIVE SLACK ON THE CABLE”. I highly suggest you take a look at the standard set of signals that my partners and I use in our own dredging operation. These can be found in a special video segment included with an article I wrote about teamwork. Otherwise, create your own signals so that they can be quickly and clearly understood, and one signal cannot be confused with another. There is also a section on winching and signals in my video, Advanced Gold Dredging & Sampling Techniques.” You might want to check it out to get some ideas.

At times, you may be faced with the need to winch boulders out of a dredge hole located in deeper water. In this case, the diver will be heavily weighted down to stay on the river-bottom. He may also be some distance from the streambank. In this setting, it may be nearly impossible for the diver to surface to give timely signals to the winch operator. The process of getting up to the surface can simply take too long! When this is your situation, and if the water is not moving too fast, you may consider using a buoy, tied to a rope that is anchored near the dredge hole, to relay your signals. I personally have found the best and safest signals to be: (1) buoy underwater means, “PULL” (2) buoy floating at the surface means, “STOP PULLING” and (3) buoy bobbing up and down in the water means, “GIVE SLACK”.

This method of buoy-signals is relatively safe. If the buoy is anchored a short distance from the boulder, in order to pull the buoy underwater and hold it there, the diver would have to be away from the boulder on the “PULL” signal. If the buoy is floating, the diver can be anywhere, which is why it is the best choice for the “STOP” signal. You need to make certain, however, that nothing is allowed to snag the buoy’s rope (like the pull cable or an air line) which could pull the buoy underwater and cause a false “PULL” signal!

One other safety note:All divers must always watch their own hookah air lines during winching, to make sure an air line (or the signal rope to the buoy) is not snagged up in the cable or rolled over by the boulder as it is moved.

BOULDER SLINGS

When slinging boulders, try to make sure the pull cable will not rub too heavily or get crushed against other boulders. It is always best to protect the pull cable and let the boulder sling take the pounding. The boulder sling is going to be pounded anyway. Because of this rough duty, boulder slings should be replaced or repaired periodically.

One type of boulder sling often used out in the field is a long, heavy-duty tow chain with end-hooks which allow the chain to be quickly and easily adjusted to any length. This system gives you a fast set up. Just wrap the chain around the boulder in the proper place, connect the end-hook to give you the right fit, and she’s ready to go.

Tow chain boulder sling with end hook.

However, some boulders are smoother and rounder, which makes it more difficult to get a good “bite” with a sling made out of chain. Every time you start to pull, the boulder might move just a little and then the chain slips off. You can waste a lot of time working on a single boulder in this way; it can get quite frustrating.

Logging cable-chokers are also useful for making a cable sling that will tighten up on the boulder as you pull. This may improve the situation, but still not work problem-free on smooth, round rocks.

For round and smooth boulders, I have found the best remedy to be an auxiliary “boulder harness.” This homemade boulder harness consists of heavy cable, chain, steel pipe and cable clamps. It is very easy to construct. The sections of steel pipe slide onto the cable to protect it and to keep the cross-chains properly positioned. The harness is set up like a lasso. It pulls tighter around the boulder as stress increases on the line. And, it generally works well in pulling even the most difficult boulders.

How to put together an excellent boulder harness for winching.

PULLING BOULDERS

Some boulders come easy and some do not. A lot of the problem is in breaking the boulder’s initial suction/compaction in the streambed. If your winch does not have the power to pull a boulder the way you have slung it, sometimes you can break the boulder free by using a rolling hitch A “rolling hitch” is rigged by slinging the boulder backwards, then running the chain or cable over top of the boulder. This places the winch’s pulling-power along the most-leveraged position on the boulder. This will sometimes free a stubborn boulder by rolling it.

How to sling a rolling hitch.

When pulling boulders up and out of a dredge hole, you should pull them some distance away from the hole. Otherwise, if there are more boulders to be moved, they may begin backing up along your ramp and block the passage of any more boulders. This could require you to move them all again, which is a time-waster that you can avoid with proper planning in the first place. For example, take a look at the image at the beginning of this article. That is a top view of a winching operation we did on one of our Group Mining Projects a short while ago. See how we were pulling the boulders back well out of our ongoing excavation?

If you are dealing with relatively deep streambed material and a lot of boulders, you may want to set up an adjustable, directional-change block behind the hole. This way, the boulders can be winched out of the hole in several different directions. This will prevent them from backing up so quickly.

Setting up an adjustable directional-change block to pull boulders in several different directions.

Once the dredge hole has been opened enough, some of the boulders can be winched or rolled to the backside of the hole, rather than taking them up the ramp. Winching will start to go faster when you get to this stage. Depending upon the situation, it may be necessary to winch some of the boulders up the ramp and out of the hole to prevent too much jamming. Be sure to keep access to the ramp free and clear. Otherwise, you may get closed in with too many boulders in the rear of your hole. The more boulders that are jammed up, the more difficult it can be to clear them out of the hole.

Sometimes, when you have winched your boulder to its destination, it will end up on top and pin your sling underneath. If you are using a tow chain as your sling, you can usually just unhook it and have the winch pull it out from underneath the boulder. But, if you are using a sling made of cable, you may not be able to pull it out from under the rock without damaging the harness. For this reason, it is a good idea to have a second sling on hand to help move the boulder off the other harness when this happens.

DIVER’S SAFETY

A diver will be safest by staying well away from the area where a boulder is being winched, and the path it will be taking as it is being pulled. The forces involved in winching are more than enough to cause a very serious accident. Since the diver is underwater, the winch operator sometimes cannot see what is happening where the bolder is located.

What can happen down there, though, is when the diver sees the boulder getting hung up on things as it is being pulled along, he wants to move in and help it along with his pry bar. The less power that your winch provides, the more the diver will naturally feel the need to help the boulder along in this way. Never forget that your safety margin is considerably reduced when you get near a boulder while it is being pulled! A safer course of action would be to stop the pulling and reset the harness, or reset the direction of pull, or improve the boulder ramp, or find a stronger winch for the job. Or, you can increase the pulling power of your existing winch by double blocking…

DOUBLE BLOCKING

“Double blocking” is accomplished by attaching a snatch block to the boulder sling, running the pull cable through that block, and then back to the last directional-change anchor. This type of rigging will nearly double the amount of pulling force that can be exerted against the boulder by the winch and pull cable.

Double blocking back to the last directional-change anchor
will nearly double the winch’s pulling power against the boulder.

If even more power is needed, another block can be set up on the line to run the pull cable back to the boulder sling. The pulling force of any winching device can be increased by continuing to double block in this way. There is a disadvantage to all this rigging, however. It takes much more cable to pull boulders any significant distance. Also, it is equally more difficult for the diver to pull the boulder sling and cable back to the dredge hole after each boulder has been moved. With all that cable going back and forth, it can get pretty complicated – especially if you are dealing with a limited amount of visibility. Quick-release snatch blocks are a must when double blocking. This way, you can detach the pulleys from the cable without having to feed it all the way through.

Actually, one double block is not that hard to manage as long as you have enough cable. It is when you double block a second time that it starts getting difficult to keep track of which cable is going to where? But, this alternative is available to you if you need the extra pulling power to move a particularly large boulder.

Directional-change blocks, by themselves, do not give you an increase in pulling power. For a power increase, the cable must be doubled back so that the boulder is moved only half the distance that the winch is pulling on the cable.

 

 

By Dave McCracken

As far as I’m concerned, if you are going to spend a lot of time dredging in cold water, a hot water system is definitely the way to go!

Dave Mack

Cold Water 1
“Photo by Tim Cook”

Can you recall ever standing alongside an unheated swimming pool or just next to the water’s edge on the beach, trying intently to muster the nerve to jump into the cold water? Perhaps you even tried to build up to the big leap by counting, “One, two, three.. .jump!” — only to find yourself still standing at the edge of the water after the countdown and feeling like your body is not quite under your control. This can often be the case when you are dredging in cold water. The key to successful cold water dredging is having the proper equipment — particularly those items needed to keep your body from getting too cold and uncomfortable.

Wetsuits

Wet-suits are designed to allow water to get inside the suit. Your body-heat then warms the water up, insulating you from the colder water that remains outside the suit. In really cold water, the main problem with a wet-suit is that initial frigid shock which shocks your body as the initial cold water rushes into your suit when you first enter the water. This happens again every time you re-enter the water after knocking out a plug-up in the jet tube or every time you take a break. This “cold water shock” has an accumulative affect on the body; and even the toughest people often find ourselves going “one, two, three” on the bank and have trouble making our bodies jump back into the water.

Some wet-suit divers lessen the pain of cold water shock by having a hot tub of water on the bank. They pour the hot water into their suits just before re-entering the water to help bring up their body temperature. Hot water systems that provide a steady flow of warm water into a wet-suit are even better — but we will address that topic below.

There are different types of wet-suits, some which are designed especially for cold water use. Cold water wet-suits are usually made of thicker rubber, have few or no zippers, and almost always have the hood directly attached to the wet-suit top. There is also the “shortie,” which is like a pullover wet-suit sleeveless T-shirt with or without a hood attached. A shortie can be worn underneath or over top of a regular wet-suit to create added warmth. In addition to the added thickness of rubber around your upper torso, a hooded-shortie prevents a lot of the cold water shock from running down your neck and back!

Important note: The more rubber you add for insulation from cold water, the more lead you must add to your weight belt(s) so you can remain firmly anchored to the bottom of the waterway when you are dredging. Also: The more rubber that is added around your upper body, arms and shoulders, the more constrained your arms and shoulders will be. Dredge work underwater is mostly stomach, arms and shoulder-work (movement). Therefore, adding more rubber increases the amount of effort required to get the work done. Effort in dredging is like money in your wallet. You only have so much. So it must be managed as efficiently as possible. Because, once you have used it up, your day is over.

Dry-suits

For cold water dredging or diving, dry-suits are definitely a step above wet-suits (when there is not a hot-water system). A dry-suit is designed to keep all of the cold water out. Basically, there are two different types of dry-suits available on the market: Those that use the rubber or nylon shell as insulation, and those that require additional insulation to be worn inside the suit. Both types work well; it is a matter of individual preference as to which kind is best for you.

Dredging activity is very hard on any type of suit. There are many different models and makes of dry-suits available. Some are designed more for sport diving rather than dredging and hard work. Dry-suits generally are quite a bit more expensive than wet-suits. However, you cannot rightfully put a price on comfort and warmth when you are spending many hours underwater working for a living. If you are cold and uncomfortable, you will not get in as much dredging time; and you will not make as much gold (money). So, my advice is to spend the extra money on getting a quality dry-suit if you are going to buy one.

Dry-suits generally require more maintenance than wet-suits. Mainly, the seals at the extremities and the zipper must be properly maintained. Most dry-suits have zippers which should be coated with bees wax every several uses and sprayed with silicone each time the suit is used. The seals should be sprayed just before each use. This allows them to slip on more easily, and prevents unnecessary stretching. The zipper is the heart of a dry-suit and must be handled with care. You have to be careful not to get sand in it, and not to sit on it or rub it heavily while moving rocks around in the dredge hole. I always glue a rubber flap over my dry-suit zippers to further-protect them from dredging wear and tear. Most manufacturers stress having a second person zip it closed rather than doing it yourself. This is because it is difficult to pull the zipper straight when it is behind you, as many dry-suit zippers are. If you damage the zipper, the suit is no good until you get the zipper replaced.

You will find that even the smallest puncture holes in a dry-suit need to be patched when diving or dredging in extremely cold water. Otherwise, you are constantly uncomfortable with cold water entering the suit from that location.

Hot Water Systems

Cold Water 2As far as I’m concerned, if you are going to dredge long hours in cold water, a hot water system is definitely the way to go! Water is usually heated with a heat-exchanging device mounted to the cooling or exhaust system of the dredge motor. The dredge pump is tapped to provide a water supply, which runs through the heat-exchanger, then through a steam trap/mixing tank, and then down through a hose to pour a constant volume of warm water into the dredger’s wet-suit. Some dredgers are using propane continuous-demand hot water heaters, but most use heat exchangers mounted to their engine exhaust systems.

Hot water heat-exchangers are available on the market. They are also reasonably easy to build. Most homemade exchangers are built with a long length of copper tubing which is either wrapped around the existing exhaust system or is coiled inside a separate housing through which the engine’s exhaust is channeled.

Photo By Tim Cook

The key to a hot water system is to provide an abundance of hot water. If you do not have plenty of hot water for all of the divers working on a system, then you will most likely end up pumping cooler water into each diver’s suit, which can be worse than having a wetsuit with no hot water system.

Hint: You can never have too much hot water — because you do not necessarily have to use it all.

Most ordinary wet-suits are adequate as hot water suits — particularly with the addition of a hooded shortie vest. Dry-suits normally do not make good hot water suits, unless they are modified. This is because the seals prevent the hot water from exiting the suit. After a while, all the excess water inside the suit cools down and makes the diver cold. Removal of the seals on a dry-suit would probably make it a good hot water system (as long as it is a tight-fitting dry-suit) — but this seems a waste of money when a far less expensive wet-suit will accomplish the same purpose.

The main problem dredgers can have with a hot water system is being scalded by extreme hot water or steam. This problem can largely be solved by adding a steam trap to the system. Some prefer to call this a “mixing tank.” A mixing container can be made out of PVC plastic tubing. One of the primary purposes of the mixing container is to be a holding tank for water and steam. So, if extreme hot water or steam is created in the system, it will have a chance to mix with the warm water in the tank before being pumped down to the diver. The mixing container should be mounted vertically on your dredge with the input coming from the top, and the output to the diver being on the bottom of the container. This way, steam is prevented from being pumped directly to the diver(s). Some systems contain a low-pressure relief valve at the top of the container to allow air and steam to release.

mixing containerThe mixing container must be large enough to absorb a shot of extremely hot water, but not so large that it allows the water to cool down before it is pumped to the diver. The mixing container allows the diver to feel the rise in water temperature much more slowly, so that the hot water hose can be removed from the wetsuit before it gets uncomfortably hot. Sometimes, the water can be so hot coming out of a heat exchanger, that a special steam hose must be used. In fact, just for safety, I always use heat hose on the connection from the heat exchanger to the mixing tank.

If the water coming out of the heat exchanger is too hot to pump directly to a diver — which is often the case — a source of cold water can also be tapped from the pump and directed into the mixing tank through a valve. By regulating the amount of cold water, you can adjust the temperature of the water being pumped down to the diver. This also increases the volume of warm water available to all of the divers.

Warm water is usually pumped down to the diver through the same kind of hose being used for air line. The hot water line and air line are usually taped together to prevent tangling and additional underwater confusion. The hot water line can be slipped into your wet-suit down through the neck. I usually poke a hole in my wet-suit near my chest where it is easy to slip the hot water line in and out of my suit.

Or, in extremely cold water, you can devise a splitter system which will direct some of the warm water to your chest, hood, each bootie, and each glove. This is the best way to do it if you are dredging in ice cold water. However, sometimes the splitter system can be avoided simply by having a hot water system which provides so much volume, that the warm water is forced out into these same extremities.

When dredging in ice cold water, if you do not have warm water directed to your hands, it is usually necessary to use three-finger wet-suit mittens. Otherwise, your hands can go numb from the cold. Three finger mittens are bulky; they prevent you from picking up larger cobbles with one hand, and they generally slow you down. With a good source of hot water to the hands, you can often get by with a good set of slightly-insulated rubber work gloves with the openings loosely rubber-banded around your wrists to prevent cold water from entering.

Dredge with snow on the decksAuthor was developing some of the early hot-water heaters on his first dredge in 1981 while working in the frigid waters of the Trinity River in Northern California.

It is necessary to warm up your dredge engine to normal operating speed for at least several minutes to properly set the temperature of the water directed to the divers from the mixing container. Once you get the temperature working right for you, you normally do not need to make any further adjustments on subsequent dives, as long as you are running the motor at the same RPM.

If you stand around for a few minutes with hot water pouring into your suit, there is usually no shock at all when entering the cold water. As a matter of fact, it can be a pleasure to enter the cold water after you run your body temperature up to the uncomfortable stage when you begin sweating.

A hot water system should be removed from the dredge when not being used, like during the warm summer months. Otherwise, the heat and vibration will tend to wear the heat-exchanger out unnecessarily. Also, even when not in use, if a hot water system is attached, water should be allowed to flow through it any time the engine is running. This will prevent unnecessary overheating of the heat-exchanger.cold water 3

Photo by Tim Cook

If you are tapping your dredge pump for a supply of water, be sure the water output is either closed off or underwater when priming your pump. Otherwise, there may be an air leak which can prevent priming.

The nice thing about a hot water system is that it will supply a continuous feed of hot water into your suit. This way, your body’s energy reserves are not being constantly used up to keep warm. As a result, you can be comfortable and get in more dredging time.

Important note: You can also be so warm that your body doesn’t want to work — like being in a hot shower. The solution to this lies in the amount of cold water you valve into the mixing tank, or how far down you zip your wet-suit jacket! Believe me, “too warm” is a much easier problem to solve underwater than “too cold.”

A common question people ask is, “Should I get a hot water system, or a dry-suit?” The answer to this lies in what you intend to do. I suggest having both systems available, depending upon your activity. For production dredging and sampling in extremely cold water, I would use a hot water system. For swimming across the river to stretch a rope, or for swimming down the river with mask and snorkel to look at the bottom in extremely cold water, I would recommend a dry-suit.

Other Things To Know About Cold Weather Dredging

If you are working in freezing temperatures above water, there are certain things that should be done on your dredge each day before knocking off. Your pump should have a drain plug tapped into the bottom. This way, you can drain the water at the end of each day to prevent your pump from freezing solid. It is not a bad idea to bring some hot water with you everyday in a thermos, because sometimes the pump will freeze even with the water drained. Be careful not to crack the pump housing by pouring too much scalding water directly over it when it is freezing cold.

Also, in freezing weather, the concentrates and water must be completely cleaned out of your recovery system at the end of each day. Otherwise, they will freeze solid and prevent the system from working until it thaws out the following day — if it thaws!

If you are not going to process them directly, your concentrates from the day should be stored well underwater to prevent them from freezing on the bank. Your mask, hood and gloves should be brought back to camp each evening and kept warm. Otherwise, you have the misery of putting them on when they are ice cold — unless you have a hot water system on your dredge.

Winter Dredging

Eric Bosch and author displaying nuggets pulled while diving together.

Dave and Eric holding nuggetsEven if you are able to handle most of the cold water problems with the use of good equipment, another factor winter dredgers often have to deal with is higher and faster water. While the higher water will allow you to mine further up on the edges of the river, in many areas it will prevent you from mining out in the faster and deeper water areas-which may provide easy mining during the summer months. If, due to the faster, higher water, you are not able to get out and sample in certain sections of the river, you will not be able to run a full testing program on that section of river; and you will miss pay-streaks. So, it can also be more difficult to locate deposits during the faster and higher water months of the year.

On the other hand, if the river edges are paying, the winter months may be the only time they are available for dredging. The location of deposits are going to vary from one place to the next.

While wet-suits, hot water suits and dry-suits do make for good insulation underwater, they generally provide poor insulation to the cold air above water when you are wet. Therefore, it is good to have a warm winter jacket to wear over your diving suit while taking breaks on the surface.

Tents in the snowAs a side note on this, my commercial dredging buddies and I ate many hurried lunches on deck during the winter months (even while it was snowing) while the dredge continued to run at operating speed (with a rock placed over the suction nozzle to slow the water in our recovery system), pumping warm water into our suits.

If you are mining in extremely cold conditions, it really helps to have a warm and comfortable camp. A person can put up with some pretty cold and miserable conditions if he or she knows there is a warm shower and hot meal coming later that evening. There are few things worse than freezing all day and then going back to stay in a wet and cold camp!

Author’s campsite during his first several years as a gold prospector.

How Tough Are You?

It takes a pretty tough person to dredge in extremely cold conditions. Even with the best equipment, there is still a substantial amount of cold water exposure on your hands and face. You spend quite a bit of time working on the dredge, tying off lines, swimming the river, cleaning up concentrates, making repairs, etc. This all adds up to exposure which can be painful or uncomfortable. Some people are gung-ho enough to dredge in extremely cold water on a short-term basis. Few people are willing to do it long-term.

We all have the potential to be tough enough to dredge in extremely cold water. What it always comes down to is whether or not we desire to be that tough! A lot of people think they are, and then realize they are not willing to do it!

Talk is cheap!

I was mining with several guys in 34-degree water one winter. One of the divers and I were sampling for a new deposit while the other two guys were actively dredging out a rich deposit we had already located. They were recovering several ounces of nugget-gold each day, while we were knocking out sample holes. One day, we helped get the production operation started and then headed out to do our sampling. We soon realized we forgot our lunch, turned around and drove back to where our partners were dredging. We had not been gone fifteen minutes, and they had already gotten out of the water and were in the truck with the heat turned on — drinking hot coffee! These were tough guys; that water was cold!

A partner and I were dredging in Alaska in October when things started to freeze. We’d had a very good season, but I wanted to put more ounces into my bottle before returning home. Ice had already formed on the edges of the river, and my partner had been ready to leave weeks before. I was determined to spend one more week dredging, because the gold was good and I had plans for what I was going to do with it. One day, with a week to go, I could not make my body go underwater again. “One, two, three, go!” — but my body refused. So, it just wasn’t worth it, anymore! I walked over and tugged on my partner’s air line and asked him if he was ready to go — home, that is. We were on the road later that afternoon in a warm truck with the heat blasting. In that area of Alaska, three feet of snow fell that night!

There is a point where the body just takes over and says, “No!” And, this is probably the point where it is smart for you to listen.

 
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This story first appeared in Gold & Treasure Hunter Magazine
Sep/Oct, 1996 on Page 14. This issue is still available! Click here.

By Dave McCracken

“Having the Gold Mining Adventure of a Lifetime!”

Dave & Alley
Author’s note: This story is dedicated to Alan Norton (Alley), the lead underwater mining specialist who participated in this project. Under very difficult conditions, Alan made most of the key dives which enabled us to make this a very successful venture.Alan lost part of his ear to a hungry fish one day; and the following day, Alan was making a key sampling dive again because we needed him to. There are very few people I know, if any, with more courage, dedication and enthusiasm to successfully complete a difficult mission than Alan.First came several Toyota Land Cruisers. Then, a couple of Isuzu Troopers, followed by a number of small pickup trucks. These were just in front of two large Russian troop carriers, all filled with armed troops. They came in on us fast, carrying along a big cloud of dust from the dirt road. Even before the vehicles came to a stop, soldiers were jumping out of trucks and running out to secure perimeter positions. They were carrying AK-47 machine guns, M-79 grenade launchers and Chinese rockets. I had seen these guys before. I had fought with them, and I had fought against them. They had that unmistakable look in their eyes. They would kill with little or no provocation.

Once the perimeter was secured, three generals stepped out of their Land Cruisers and enthusiastically approached us, their personal bodyguards close behind. The generals looked friendly. Their bodyguards looked seriously unfriendly! The generals, whom we had not met until now, hurried right up to me and each of my men and gave us big hugs, hand shakes and slaps on the back, like we were long lost sons. The bodyguards stood there with machine guns pointed in our general direction, doing what they were supposed to do to ward off any potential menacing threat to their leaders–which, by the way, never crossed our minds. We did the natural thing; we acted like long lost sons!

We had not been in Cambodia even for one hour before we were packed into Land Cruisers of our own and driven to Kampong Saom on the coast–which was almost half way across Cambodia. The end of the dry season had caused the water levels in the Mekong River to drop so low that deep-water ships were no longer delivering cargo to Cambodia’s capital, Phnom Penh. Therefore, it was necessary for us to go to Cambodia’s only other deep-water port in Kampong Saom to take delivery of five full ocean shipping containers of mining and additional equipment, supplies, boats and vehicles that had been shipped over there from America to support our project.

Since nothing happens immediately in Cambodia, we ended up spending about a week at a gorgeous beach while waiting for the shipping containers to be released by Cambodian Customs. Our hosts were taking good care of us. The hotel was comfortable, the beer was cold and the crab meat was freshly cooked on the beach–and it was all we could eat. In fact, we were just about getting bored. That’s when the generals showed up.

Isn’t it amazing how fast boredom can turn to fear? After hugs and handshakes, the generals agreed it was time for target practice. They had their bodyguards throwing beer cans out into the water so they could shoot at the cans. Pretty soon, lots of people were shooting at them. The few civilians that had been enjoying the beach scurried off quickly and respectfully. Everyone was laughing and having a good time except us. We were laughing, but not sure if we were going to be the next targets! It was all too much at once. We didn’t even know these people and they were all enthusiastically shooting their guns off. We were surrounded!

Pretty soon, one of the generals handed me some kind of machine gun I had never seen before and challenged me to shoot a fresh beer can. It was the only beer can remaining on the beach! This was a tough position for me to be in; those guys were not the best shots. I calculated whether I should try to out-shoot them, which might cause the generals a loss of face in front of their men, or to miss the can and perhaps lose their respect? On an impulse, I clicked the machine gun over to full automatic and fired a short burst to find a mark, adjusted slightly, and hit the can, knocking it up into the air on the second burst. No one had used automatic fire–probably to conserve bullets. All the generals burst out in a roar of laughter, followed by all their men. Deciding to quit while I was ahead, I handed the machine gun back to the general with the clip still half-full of bullets. That was the end of target practice and the beginning of my very warm friendship with that general. About a week later in Phnom Penh, this general and his very kind family, with great ceremony, adopted me as their number-one son.

The beach was just the beginning of 60 days of non-stop adventure which took me and three of my men from one end of Cambodia to the other in search of gold and valuable gems.

As it turned out, the generals were directly involved with this exploration project–which, by the way, was the first precious metal exploration project in Cambodia since the United Nations returned control of the country to a Cambodian coalition government in late 1991. During the course of the project, it became abundantly clear that our presence, and our successful venture, was very important to these generals and the Cambodian government. Cambodia is just getting back on its feet after decades of war and agony. The country is hungry for capital investment from the east and west. Successful ventures such as ours would help facilitate that.

Our project took place in northeastern Cambodia on one of the three main tributaries of the Mekong River. We were hired to help this operation put its suction dredging equipment into production and to help find high-grade mineral deposits.

The area is remote. In fact, it is the same area America bombed in the early 1970’s (with B-52’s) to prevent the Viet Cong from moving supplies on that portion of the Ho Chi Minh Trail. You just would not believe the number of bomb craters; I have never seen anything like it. In fact, up until the time of our project, I don’t believe a single bulldozer had visited that section of Cambodia since we bombed it! While these conditions probably never did slow down the Viet Cong very much, they certainly did slow us Americans down a lot! It took literally weeks for us to transport our equipment to the work-site. Trucks and trailers would disappear into craters and then come back out, one after the other, like a big roller coaster ride–only in slow motion–for hundreds of miles! It was one of the most amazing things I have ever seen!

All the while, our security troops were worried about being ambushed by Khmer Rouge rebels–roving bands which were still occasionally shooting up taxis, burning bridges, robbing various business establishments and causing other acts of terror around the countryside. Our generals were very concerned to make sure there were no embarrassments on this operation. Therefore, they sent along a 300-man military force to provide security. Each of us was also assigned several personal body guards. They also issued each of my men and me our own machine guns–which we gladly took. You kind of feel naked without a weapon when everyone else is walking around with some kind of heavy fire power! Here follows some video segments that I captured of our interaction with our bodyguards and some of the troops that were assigned to our project:

By the way, the people of Cambodia are the kindest-natured people I have ever associated with. Everyone is very polite and friendly. Unless it is worth dying over, you never see an argument in Cambodia! During the entire 60 days of our project, there was not a single person I smiled at that I did not receive a heartfelt and sincere smile in return. They seem to genuinely like Americans. In fact, any product or item that says Made in America is in great demand in Cambodia–especially hats and insignia which carry American flags and symbols.

One night, we had to make an emergency dash through rebel-held territory so that we could meet a production deadline. We were driving like madmen through bomb craters, up and down, with grenade launchers and machine guns hanging out windows. Our security people were very concerned we would be ambushed. Better to be safe than sorry, I suppose. But, I never saw any direct sign of danger. Even so, the eminent concern–with guns and grenades pointed out windows, with everyone on moment-to-moment alert–created a charged atmosphere which we usually only experience on television in America.

We received incredible hospitality from native villagers in every community that we passed through or stopped to visit. Many villagers had never seen white men before. You have to remember that Cambodia, for the most part, lost an entire generation of people to the Khmer Rouge regime. Locals told us the ratio of women to men in Cambodia is five to one, because the men were either killed in war or murdered. That ratio is about how it appeared to me.

The equipment we sent there to use for sampling took a very heavy beating during the trip across Cambodia. The axles we mounted on the dredge platforms were badly bent from being dragged through hundreds of craters, and there was quite a lot of other damage, too. So we found ourselves staged for about a week in the last town before we would reach the river. This was a place where various supplies and services were still available. There, my men and I supervised final repairs and preparations for our sampling program. It is very challenging to do this sort of thing in an environment where most of your helpers do not think the same as you do, and do not speak any of your language:

Between the delays at Customs, the painstaking trip across war-torn Cambodia with the equipment, and the time we had to spend repairing gear at the final staging area, we only had about 2 weeks remaining to accomplish what we went to Cambodia for in the first place. A final distance to the river of 35 kilometers does not sound like very far; but in Cambodia, where anything and everything can go wrong; this last 22 miles still seemed like a long way to go. Even so, there was a lot of excitement when we had everything ready and began our final journey to the river from the last bit of civilization that we would see. The following video segments demonstrate the excitement that we were all feeling to finally get started on our dredge sampling program:

Along the way to the river, we started seeing lots of diggings alongside the road. We thought the holes were water wells at first, because they were perfectly round and uniformly about 2 ½ feet in diameter. Then we realized they must have been something else, because there were so many, and they were positioned so closely together. We stopped to take a look as soon as we saw some locals actively working inside one of the holes. These turned out to be sapphire miners! They were digging about 10 meters down to bedrock and recovering handfuls of pretty blue stones from the bottom gravels. These miners were selling their gemstones for mere pennies (Me and my guys were buying!). We found out these miners were from the Cambodian hill tribes; jungle dwellers that pretty-much are the same as they have been for hundreds or thousands of years. A number of humanitarian groups are now present in Cambodia attempting to prevent the modern world from impacting too dramatically upon these ancient tribal people. The following video segment captured some dialog that we had with a few of the sapphire miners. It presents a good example of how simple and kind the people are from the Cambodian hill tribes:

Immediately upon our arrival at the river, we realized that we had 2 serious problems to overcome. The first was that there was about a 10-meter drop from the bank down to the active river. There was no ramp or other simple way to launch the 10-inch dredge and special recovery platform that we brought with us for this job. Not wanting to use our security force for this, we immediately set out to hire around 30 men from the local hill tribe village to dig a ramp. That exercise took about 6 days to accomplish. So we were not going to have use of the big dredge until the final week of our project.

Our second serious problem was that the (sizable) river water was running mud-brown. We did not know it at the time, but there was some active dam construction happening upstream in Vietnam. The ongoing construction was turning the river to mud-water. That meant that we were not going to have any visibility underwater. There is a way to get the work done in dirty water; but besides the serious safety problems associated with dredging blind on the bottom of deep tropical rivers, you have to do everything by feel. This slows you down to just a fraction of what you can accomplish with some underwater visibility. This was going to be a difficult mission to accomplish!

All travel on the river from our base camp had to be accomplished by boat. The boat that we arranged broke down on our first trip downriver to survey the area. As it was just before dark on our return to camp, and the mechanical problem seemed pretty serious, we actually started making plans to sleep on a sand bar that was located out in the middle of the river, maybe 5 miles away from our camp. With no dinner and no shelter from the mosquitoes, it was a pretty bleak feeling out there. I captured the following video segment just as our guide was suggesting that we spend the night there on the sand bar. Fortunately, they got the boat motor operating just as darkness was almost complete. It sure felt good to finally arrive back at camp that night where there was a hot meal and perfectly good tent waiting for each of us:

While we were doing our initial survey downriver, we came upon a local river mining operation that was using a long-handled (about 15 feet long) shovel, suspended by a floating platform made of bamboo. This dredge was being used to excavate sand off the bottom of the river. The locals called this a “Vietnam dredge,” because the river mining technology had been imported by miners across the border in Vietnam. Almost the entire dredge was made out of materials from the jungle. Even the lines being used to tie off the dredge out in the river were made from jungle vines. The only part of the dredge we could see that was from our modern world was the head of the shovel. That looked to be fashioned from the car hood of a bombed-out jeep. This river location was part of the Ho Chi Minh trail. So there were plenty of bombed-out jeeps around, and some ruined Vietnamese tanks, too. In fact, there was a lot of painful history here!

Author and several team-members trying out a “Vietnam Dredge,” made from bamboo, which local miners use to bring gold off the bottom of the river.

Upon discovery of the local river mining program, we immediately took the opportunity to make friends with the local miners and the elders of their village. This is standard procedure anytime we are performing an preliminary evaluation in a new area. While their methods might sometimes be somewhat primitive compared to ours, I have found more often than not that hundreds (or thousands) of years of local mining experience has given the miners who occupy an area a strong perception of where the richest gold areas are located. We did not have much time remaining to make a rich discovery for our clients. Any head start the locals could give us would surely be a welcome development! Ultimately, the locals told us that their dredge was positioned along the strongest line of gold that they knew of in the river. That was a big help!

To get an idea of how much gold they were talking about, we accepted their invitation to go down and operate their Vietnamese dredge for a little while. The following video segment captured my guys running the local production equipment. It worked by pushing the shovel down into the sand, and then using a make-shift windless to raise the river-bottom material to the surface. There, local wooden gold pans were used to process the material:

While the local miners were recovering a fair amount of gold from the river-bottom sand deposits, their success did not appear to help us very much. This was because we wanted to sample for the high-grade gold deposits which are almost always located at the bottom of hard-packed streambed layers. In working their Vietnamese dredge for awhile, it did not take very long for us to realize that the long-handled shovel would not penetrate the hard-packed streambed material that was under the sand. Too bad!

5″ Pro-Mack Sampling Dredge

Still, knowing where local miners were supporting their villages with gold from the river gave us a starting point. The following day, we moved two 5-inch special sampling dredges onto the river some distance downstream from where the locals were mining, but directly in line with them so that we had a better chance of sampling on the strongest path of gold in the river

My guys were initially quite challenged by going down into the pitch blackness along the bottom of a muddy, tropical river. Because there is zero visibility down there, everything must be done by feel. This is not easy to do, because your imagination cranks up into overdrive about what might be lingering around down there to bite or eat you in the dark. Remember those horrific nightmares you had when you were a kid? That stuff doesn’t ever go away. The terror is still present; it is just buried. Going by yourself down to the bottom of a tropical river in total darkness, and having to feel your way around to figure out what is down there, energizes all you nightmarish fears right back to the surface. It is difficult to do what you are supposed to do down there with all this internal fear playing out inside of you! It takes courage and a lot of discipline.

So my guys challenged themselves with acquiring some preliminary sample results using the 5-inch dredges, while I was pulling the 10-inch dredge together and installing a special shaker table in the base camp that we would be needing to process large samples. The table needed to be anchored in concrete. All of this took several days. Time was running out!

On the second day of sampling, our lead diver, Alley Norton, touched down in some hard-pack and came up with a pretty good showing of gold. The following day, I encouraged Ally to go back down and open up the hole (get a bigger sample). We had to keep dredgers separated while sampling, to avoid someone getting smacked with a cobble being tossed in the dark. There simply is no way to tell where anyone else is when you are dredging in muddy water. Alley’s hard work and enthusiasm paid off. Considering how small his sample actually was because of the dirty water, he recovered a lot of gold! We had located high-grade!

I captured these following video segments towards the end of the third day of sampling:

As we had less than a week remaining to accomplish our mission, we all focused the next several days placing the 10-inch dredge and platform into the water. The local help had completed our launch ramp according to plan. Wow, was that a lot of work! Once the big dredge and recovery system were floating in the river, we still had to dial it all in to get it working right. This was particularly important with the sophisticated recovery system that we had brought along for this job.

Before opening up Alley’s discovery with a production sample, we needed to make sure the recovery system was working right. This all took another two days, because the large volume of sand from the bottom of the river was overwhelming the gravel pump that was supposed to transfer classified material to the recovery system. This problem required us to get very creative in the middle of the jungle. Through some trial and error, we constructed several water blasters to inject water into the feed of the gravel pump. This made sure that enough water was going into the feed to keep sand from packing up in there. While all of this took up valuable time, we had to get the big dredging system fully functioning before using it to perform the final production samples in Alley’s rich discovery

We only had 2 days remaining on the project when we finally floated the big dredge over Alley’s rich discovery. Talking about racing against the clock! So while Alley went down in 6 meters of underwater darkness to suck up the sample, I stayed up on deck to fine tune the dredge’s recovery system. You can only put one diver down on a big, powerful dredge in dark water. So our other guys helped where it was needed. Alley spent several hours opening up a large hole through about 2 meters of loose sand. Our plan was to first pump most of the sand off the hard-packed streambed material where Alley had found the gold. Then we were planning to flush the sand completely out of the recovery system before dredging up the pay-dirt. This was to minimize gold losses because of too much sand overwhelming the system at once.

We were making good progress on our plan. But about half way through the day, Alley climbed back onto the dredge with a lot of blood flowing down the right side of his head and face. A pretty sizable chunk of his right ear was missing and it was bleeding profusely! Blood was actually squirting out with the pulse of his heart! He said while operating the dredge’s suction nozzle on the bottom of the river, it felt like a submerged log with rough bark brushed by his head, scraping his ear. When he reached up to touch where the pain was coming from, he could feel that a part of his ear was gone. That’s when he came to the surface. Seeing all that blood and the bite out of Alley’s ear was very dramatic for everyone that was present.

Back at camp, we bandaged Alley up as best we could. We always bring a substantial medical kit with us on these projects. We applied antibiotics just to be safe. Alley said the pain was not too bad. He was mostly worried about how ugly it was all going to look later. I would have been worried about that, too! There wasn’t anything else we were going to do about that situation out in the jungle, though. So we decided to set aside that problem for another time. We were going to depart Cambodia in a few days, anyway.

Collectively, my guys and I decided it was wise to not do any more diving in the river until we found out what bit Alley. Whatever it was, there was a chance that we could still salvage the sampling project by wearing more protective gear while underwater. We still had one more day available to perform a final production sample!

As none of our bodyguards or the other military guys in camp seemed to have any idea what bit Alley, we decided to drive the motor boat up to the hill tribe village where the Vietnamese dredge was operating. We had already made friends with the villagers and elders there. Once there, we removed the bandage from Alley’s ear to show the elders, and they immediately knew what bit him. They told us that there is a fresh water blow fish that lives on clams at the bottom of the river. Apparently, this type of fish must have come alongside Alan’s head; and in the very poor visibility, thought his ear was a clam. One bite and there it went. The villagers assured us we would have no further problem with that fish if we started wearing hoods, gloves and full face helmets in the river while it was muddy.

Afterwards, we heard the story of one of our military men bathing naked in the river and losing his vital organ. Apparently, the man had just been married several weeks before. Luckily, we had been taking our showers up on the bank!

When we arrived at their village, the local people were busy preparing for a “grand celebration” that was to take place that evening. All of us were invited to attend, and it would have been impolite for us to decline their kind hospitality. The celebration turned out to be a funeral ceremony for one of their important elders who had died 3 years before. I have seen similar traditions in Madagascar, where the big celebration of someone’s life happens by the whole village several years after the person dies. These hill tribe people were busy decorating a whole shrine that would be dedicated to the person, carving all sorts of symbols relating to the important things the person lived through. Interestingly, the biggest symbols I recognized were American military helicopters and B-52 bombers. No doubt, the later part of the Vietnam war must have been a very traumatic time for these very simple hill tribe villages, with the Viet Cong using their river for a highway, and the Americans dropping thousands of tons of bombs all around.

These people seemed nothing but pleased to have us Americans present, so we accepted their invitation to participate in their party that evening. Indeed, the party turned out to be one of the most interesting events I have ever been part of. A center covered circle had been built for the people who wanted to express their grief over the loss of a loved one. Inside that area, there were around 20 people who were crying and almost howling in deep grief. Outside the circle, the rest of the village paraded round and round in a dance in joyous celebration of the person’s life.

My guys and I jumped in with the outer group. They were beating on different-sounding chimes to make their traditional music. The sound was so interesting that I captured it on tape. The occasion was something I am sure that none of us will ever forget. We were honored that they allowed us to participate in such an important tribal event. They were honored that we joined in with them. It was a wonderful bonding experience between us and remote villagers of the deep jungles of Cambodia. The following video segment and audio segment capture some of our hill tribe friends as they were preparing for the party, and then capture some of the music and feelings that we shared together that evening:

The following morning found our team back on the 10-inch dredge, preparing to perform one last production sample. This was our last day to accomplish what we went there to do. So much effort and money had been invested to transport this fantastic equipment halfway across the world, through some of the most difficult circumstances on the planet; only to finally arrive on our last day right over top of what appeared to be a very rich gold deposit.

It was so important that we get the best possible production sample, Alley insisted that he take the first dive. He had started the sample on the previous morning, so he knew the layout of the hole in the total darkness of the river bottom. Total darkness down there would have required either of my other two guys to spend valuable time figuring out what Ally had already done. As this gold deposit was really Ally’s personal discovery, we agreed that he would take the first dive of the day to open up his hole. I would spend that time dialing in the recovery system as well as I could. Then I would finish the sample during the afternoon with a second long dive. My other two guys were content to support us from the surface. I don’t think they were quite over the emotional shock of Alley’s blood and guts from the day before. Who could blame them?

As I knew this would be a memorable occasion that none of us would ever forget, I captured some video of Alley bravely overcoming his fears and going back down into the deep black hole that attacked him on the previous day, something very few people would do. You will see from the following video segments how good the production dredging equipment was that we managed to place on top of that rich gold deposit. I believe the recovery system was the most sophisticated that had ever been used with a suction dredge up until that time. It was truly a miracle that we ever got the equipment there, or that we found such a high-grade gold deposit under those difficult conditions. With all that we had been through, in my world, there was no other choice but to perform that final production sample:

After a few hours of diving, Alley came to the surface; because his ear was throbbing in so much pain, that he said he could no longer focus on what needed to be done on the bottom of the river. By then, the recovery system was dialed in as well as we were going to get it. So I suited-up and went down into Alley’s deep, black hole. This was actually my first dive on this entire project. During the week or so that we had been on the river, there were just too many other things that needed to be accomplished which only I could do to bring everything together in time for this final production sample. So there I was, taking the last and most important dive of the whole project!

I will never forget in military jump school, the first time I bailed out of an airplane. It was one of those situations where I really did not have much of a choice. But looking way down there at the ground made jumping feel totally wrong. My body did not want to do it. So it was necessary for me to flick some internal emotional switch, override my natural instincts, and just force the body to make the jump. Going down into deep muddy water is much the same; the body does not want to do it!

I have actually done quite a few dredging projects where it has been necessary to perform the underwater work in muddy water. It is never easy! Especially when the water is deep! It was around 6 meters just to the bottom of this dirty river. That is a long way to go down in the dark. I worked my way down there slowly by following the suction hose, which is where I knew that Alley had left off. When I reached the suction nozzle, I rotated my body around it in a circle, feeling around with my legs and feet to try and find Alley’s dredge hole. Letting go of the nozzle was something I was not prepared to do, because it was the only thing that gave me a reference point down there in the total darkness. Also, feeling around tentatively with steel-tipped work boots felt safer than reaching out in the dark with my hands!

I soon found that Alley’s hole was just off to one side of the nozzle. Experienced dredger that he is, Alley knew better than to leave an unattended suction nozzle down inside of a dredge hole in the sand. The walls never stop sliding in on sand-excavations or loose gravel. If you leave a suction nozzle down inside of one, within just a short time, the suction nozzle and hose will be overwhelmed and buried. That would have been the end of this project. There was not enough time remaining to dig a hose out of the sand in the dark!

Once I found Alley’s hole, I memorized where the suction nozzle was positioned several feet away, and then I followed the edge of the hole all the way around to get some idea how big it was. This was the hard part, because it meant that I had to reach out and feel everything with my hands. All that blood pouring down the side of Alley’s face the day before was vividly on my mind! There were creatures down there with serious teeth! Here is where I had to flick another fear-switch off and just do the work. These fear switches are not really turned off. They are just suspended. I speak from bad experience. Depending upon how many of your internal fear-switches are in suspension, it just takes one small event to turn them all back on into nightmarish panic and terror. I have been there. It is not fun!

Reaching out meant feeling out as far as I could outside the outer edge of Alley’s hole to make sure there were no boulders up there that would roll in on me in the dark. I did not find any. Slowly but surely, I explored all of Alley’s hole by feel. It was pretty big; maybe 30 feet in diameter at the surface, funneling down to a center point about 2 meters deep. Alley had pumped a lot of sand! Before I went down, he told me that he touched down on the hard-pack streambed at the bottom of his hole, but that the sand kept sliding in on him. So he had not been able to get a sample of the hard-pack, yet. This was for me to do!

I invested about 2 hours into taking a sizable cut off the front and one side of Alley’s hole, working the sand back step-by-step in the darkness. I wanted to uncover enough surface area of the hard-pack as possible. This was so that further sand-slides would not prevent me from getting a good sample of the hard-pack. With time, I started uncovering the hard-pack. This is where the loose sand met the cobbles, boulders and gravel that were tightly compacted together. Though I could not see it, it felt just like the hard-pack we dredge along our properties in California.

While the dredge was plenty powerful enough to pull apart the compacted streambed material, my progress was slow. This is because I could not see the oversized rocks that had to be moved out of the way, and I could not put my hands out in front of the nozzle in the dark without getting them hurtfully banged up. Mainly, I just poked around down there in the dark to suck up anything that would go up the nozzle. Each time a loose cobble would block the nozzle opening, I would wrestle it off and put it behind me. It was not long before I had more loose cobbles behind me than I could manage. It was too far to throw them out of the hole, and trying to pack them out would have caused more sand to slide in. So I just juggled everything around down there the best I could, determined to get as much of that hard-pack up the nozzle as possible. Ultimately, my progress became overwhelmed by loose cobbles in the hole and sand sliding in from the sides. I had not reached bedrock, but I did get a fair sample of the material that Alley had touched down upon with the 5-inch dredge several days before. By my measurements in the dark, I estimate that I sampled less than a cubic meter of hard-packed material. That was all we were going to get under those difficult circumstances. It was a good feeling to finish what we had traveled so far to do.

The guys turned the dredge down when I reached the surface. I had to wait at the ladder for the longest time to allow my eyes to adjust to the bright sunny day. As I was waiting, my guys were making a lot of enthusiastic noise about visible gold in the recovery system. When I finally was able to see again, I climbed up onto the dredge to see that the entire recovery system was inundated with a thick layer of small golden flakes. It was, by far, the most gold I have ever seen recovered out of such a small volume of gravel. This place was rich!

We had just enough time before dark to run our concentrates over the shaker table back at camp. Everyone there experienced an incredible feeling of pride. Under very difficult circumstances, against all odds, we stuck it out right until the last hour to make this project a success. Watching all that rich gold flow across the shaker table had all of us in awe about how rich this river is. Who would have ever guessed? Right there on the Ho Chi Minh trail! While I am sorry to have missed capturing the gold-laden recovery system on the dredge, I was able to recover myself enough to capture the following video segment of the final clean-up. To put it in perspective, our small sample caused that shaker table to flow gold like that for a full 15 minutes!

We returned to civilization the following morning, and departed Cambodia a few days later.

Follow ups:

A short time later, our clients met with some serious misfortune by aligning themselves with the losing side in a power struggle over who would control the government in Cambodia. While they survived the events, they have been banned from the country forever.

Shortly after my clients found themselves in big trouble, all of the equipment and supplies we sent over (that they paid for in advance) were taken away. The only thing remaining there today that shows we were ever even present is part of a steel frame from one of the large floatation platforms. Everything else is long gone.

The wars in Cambodia are now long over. The people there are very friendly. You do not see guns there anymore. People are focused on getting ahead in business. They want to be like America. The government is trying hard to attract foreign investment.

Nothing since our project has been done to develop the deposit that we located. Although the government of Cambodia has offered to make an exploration license available, I have yet to raise the high-risk capital necessary to go back over and do something about what we found

I made a special trip back to the site of our discovery 2 years ago. The bad roads have been replaced with a highway! Schools have been built in the village communities. The people out there were happy to see me. Most importantly, dam construction in Viet Nam was finished and the river was running clear!

While I was out there, I hired a local boat to take me downriver to see if anyone was doing anything with our deposit. Nobody was there. Even the Viet Nam dredges were gone! It appears that my guys and I were the only ones whoever really understood the significance of what we found there. Local miners cannot access the rich material using their technology. With clear water, we could process hundreds of times more hard-pack in a day than what I sampled down there in the dark.

The following video segment was taken in the very place where the earlier segment showed us operating the dredge:

Alley and his brother are now managing a successful concrete business in Phoenix, Arizona. He never did anything to fix the bite out of his ear. Now he says the tattered look gives him personality and character. Since nobody will believe he had his ear nearly bitten off by a clam-eating fish while prospecting for gold at the bottom of a muddy river in the jungles of Cambodia in the middle of a war along the ancient Ho Chi Minh trail, he now just tells people that his ear was bitten off by someone while fighting in a bar on the north side of Phoenix. That’s already more adventure than most people can handle!

Note: This story was pulled together from the non-proprietary portion of an initial report from a preliminary evaluation of a potential production dredging project in Northeastern Cambodia. The opportunity to do something with this prospect still exists.

 

 

BY ROBERT MILES

Two brothers, Roger and Richard Bogan, share the dream of striking it rich…together

Theirs is a partnership that is unique, a friendship of two brothers, the kind you would generally expect to exist in a storybook or television script. And on the Klamath River in Northern California they are known as the team who know how to get it….get the gold, that is. Not an easy reputation to obtain, and even a more difficult one to maintain. Gold is elusive, and keeping a partnership viable and working for more than one season means not only putting in long hours under water moving the overburden of rocks, sand, and gravel, it means having the ability to find the pay-streaks.

Their long time dream of putting an 8-inch underwater dredge to work became reality, and in a matter of approximately 31 hours of diving, the Bogan brothers netted $4,000 in placer gold from their very first clean-up. Sound easy? Well let’s take a closer look at all the hard work, preparation and planning that went into making this very demanding and difficult task actually work.

“I had the dream way back in 1982 to start gold mining,” Roger reflected. “Even then, before I ever found a single nugget, I felt a kind of intense excitement. Of course at first it was only a hobby. Then, I got my brother Richard interested in 1983 when he flew to Arizona to visit from Illinois. We took this little prospecting trip with a 3-inch dredge up to Bumble Bee, about 45 miles north of Phoenix. I remember Richard caught the fever right away. In fact he literally beat the water to a froth the minute he saw the first couple of colors. Since that time we’ve found quite a bit of gold, seen a lot of country and had some fantastic adventures.”

In 1984 the Bogan brothers journeyed to Alaska for the summer, staying three months in the back country, 200 miles, from the nearest telephone in an area near Jack Wade Creek on the south fork of the 40 Mile.

“The country was spinetinglingly beautiful,” remembered Roger, “but Mother Nature didn’t cooperate very well. In all the time we were there, we probably had only 18 days when we were actually able to dredge for gold. When it would rain, which it seemed to most of the time, the rivers would rise 5 to 6 feet overnight and it would become a real tempestuous situation. Even though we had a 5-inch dredge that was really outfitted, we just couldn’t dive in those conditions.”

Throughout that summer Roger and Richard recovered enough gold to pay expenses they saw some magnificent country, and were mining only 1 1/2 miles from another hardworking miner who struck it rich with a 54-ounce gold nugget.

After Alaska they decided to try California. “We’d heard rumors about rich rivers and they were true, but you have to really go for it. Even small dredges have the capability to actually bring up the gold, but it al1 depends on how hard a person wants to work. You just can’t sit on the bank and make that gold jump into your sluice box; you’ve got to work! The bigger the dredge the harder the work, but you get more production of course.

“One thing about California, it’s a lot cheaper to mine there than Alaska, so we took a 4-inch, a 5-inch, and an 8-inch dredge with us all at the same time. We figured we could sample with the 5-inch, use the 4-inch in the creeks, and do the real production work with the 8-inch. We spent about a month working the creeks, and that’s where we pulled our biggest nuggets — one was a really nice quarter-ouncer which Richard immediately laid claim to. We also found a lot of nice coarse gold.” In that first month the Bogans recovered 6 ounces, and then decided to move the “big guy” into the river.

“We had picked what we believed would be a really productive spot,” recalled Roger. “We had spent a lot of time talking to the old-timers. They really know the lay of the land and where the gold is likely to be carried in the river during the high flood waters. Those people are great; they have so much knowledge if you just listen to them. We had also taken some mining seminars from Dave McCracken, and we felt we’d hit a pay-streak if we could just keep in mind the old miners’ rule: “If you were the heaviest thing in that river where would you be?”

In the spot they chose, the 5-inch sampling dredge hit pay-dirt, bringing up 3/4 of an ounce of gold in the first set of sample holes. “We knew right then we were on to something, so we turned on the 8-inch and spent the summer doing what we’d been dreaming of doing for years. The dredge we continued to use throughout the rest of the season was that same 8-inch. We had built it ourselves, using a 1600cc Volkswagon engine and Precision machine components. So far we’ve built five different dredges, and we’ve been very happy with our ability to recover both fine and coarse gold.”

The energy I felt when spending time with these dynamic and dedicated miners was nothing short of spellbinding, and it’s definitely contagious. “Our goal for the next six months,” Roger reports, “is to actually recover 500 to 600 ounces. That way we’ll not only cover expenses, we’ll be making a very comfortable living doing what our entire team loves the most.”

 

By Dave McCracken

Finding wild adventure, wonderful new friends, and riches in gold inside one of the most remote locations on the planet!

Dave Mack

 

This story is dedicated to my long-time, trusted friend, Mark Chestnut. He and I teamed up to perform a preliminary assessment of the gold dredging potential in the deepest remote jungles of Borneo, Indonesia. The ultimate success of this mission was largely the result of Mark’s professionalism and dedication to getting the work done under some very difficult conditions.

On his own, Mark led sampling expeditions with his team of Dyak helpers for days at a time into places where I am entirely certain that no outsider has ever been before, living under fly camps with the natives, eating the food they prepared from the jungle, running down through narrow gorges in long boats where the ride was so violent, that all of the boat paddles were broken along the way. I am very careful who I take along with me on these projects. Those that go must be of the highest caliber. Not only would I take Mark with me anywhere, but I would be comfortable in sending him to manage a project. There are only a few people I have worked with in our industry that I would trust with that responsibility.

Indonesia’s 13,677 islands stretch across 3,000 miles of ocean. Only around 6,000 of these islands have been named, and only 900 of those have been permanently settled. The principal islands of Indonesia are Java, Sumatra, Sulawesi, and Kalimantan (Indonesian Borneo).

Three-quarters of the island of Borneo is called Kalimantan, and is part of Indonesia. The northeastern part of the island is owned by Malaysia.

Throughout history, Borneo, which is the world’s third largest island, has been a mythical location of indescribable riches and unfathomable mystery. Early explorers and traders sailed the pirate-infested waters of Indonesia and Borneo for many centuries, trading for prized jungle products, diamonds and gold, but generally staying clear of the forbidden unknown interior, which was known to be prowled by savage headhunters and cannibals.

The natives of Borneo, known as Dyaks, believed that the power of any individual was contained in his head. To cut the head off, and to possess it, was therefore to possess that individual’s power. The power of a head diminished over time, making it necessary to obtain new, additional heads; the more heads, the more power. While most often, Dyak tribes battled against each other, any outsider was also fair game.

Usually, head-hunting raids were well-organized ventures led by a supreme commander, in which hundreds of men would participate. The main weapon was a mandau (machete), which was made by Dyak blacksmiths, working with native ores and primitive forges. Early explorers reported these machetes held an edge capable of slicing a musket barrel in half! Shields were made of ironwood, following the longitudinal grain, so an enemy’s mandau would become wedged deeply enough to become lodged and pulled out of his grasp.

After a war party was fully organized, a Dyak medicine man would perform a ceremony to weigh and balance the different omens. If all was in order, the war party would usually travel by native long boat to a distance which was several hours on foot from the enemy village. Sometimes, the enemy would be pre-warned by their own hunting parties; and they themselves would mount an ambush on the raiding war party. In this case, the ambush was usually begun by firing poison darts onto the unsuspecting enemy with blowguns, and then hand-to-hand combat with spears and mandaus.

Captured women and children from a village were forced into slavery, and the village was looted of its valuables, especially traded goods from China and India. A celebration always followed a successful head-hunting raid. Those who brought back heads were heroes.

Head-hunting was practiced widely throughout the interior of Borneo up until the Second World War. Now, it is a thing of the past.

Because of the impassable mountains and rivers, much of the interior of Borneo is not accessible by automobile. Access to a portion of the interior can be accomplished by riverboat, but waterfalls and severe rapids prevent deeper penetration. Access to the most remote locations generally is accomplished by the use of helicopters. There are some landing strips in the interior. Small planes can be chartered, but quickly changing weather conditions can make even this type of access unpredictable.

Our mining venture was into one of the most remote and least-explored sections of Borneo’s interior. Going in by helicopter, we crossed over hundreds of miles of impenetrable jungle. There were mountains, having sheer cliffs hundreds of feet in height, extending for miles. We crossed over hundreds of rivers, many which were raging white-water. I remember hoping, as I always do when traveling by helicopter, that we would not crash. Because if I managed to survive the crash, I was gauging the magnitude of the effort it would take to return to civilization. It would be next to impossible!

The reason we were in Borneo was to perform a preliminary evaluation to gauge the potential success of a production gold dredging operation. Some base camps had been already built in the area by the company that hired us; some dredges were already on site; and the local natives were using the dredges when we arrived. We spent 30 days in the jungle, living and working with the native miners, learning their way of life and survival in the jungle.

The natives involved on our project were from two different villages. They were all very friendly and helpful. All were in excellent physical condition and used to hard physical work. Most were already familiar with basic gold mining techniques, since they have been mining gold by primitive methods for many generations.

Generally, no matter what else they wear for clothes, the natives wear nothing on their feet. Often, all the men wear is a pair of underpants. On one occasion, I went on a nine-hour prospecting/hunting expedition, where the terrain was so slippery and steep, most of the climbing was done with our arms. We scaled sheer cliffs with narrow, slippery walkways, where the bedrock was so sharp it cut into the soles of my jungle boots. The clay-like ground was so slippery, it was like walking on ice during most of the hike. I like to think that I personally am in pretty good shape. The pace was very fast, but was only a third of their normal speed. They had to slow down to allow us to keep up. I almost wore out a good set of authentic military jungle boots, and I had blisters on my own feet long before the expedition was finished. The natives were all barefooted, and not one had a cut or a bruise at the end of the day!

You have to be careful where you stick your hands at the bottom of tropical rivers!

The native men in the jungles of Borneo have a simple, adventuresome life–the kind that every little boy dreams of in America. Their responsibilities consist of hunting, fishing, finding gold and raising their families. For lack of any exterior form of entertainment, the family unit is very close there. These people create their own entertainment, excitement and adventure.

We found that while they were all very strong and helpful, they were also always fun to be around. Operating gold dredges was a new adventure for most of them, and they were having a good time learning how to do it.

The natives also have a high level of self-preservation, probably because their lifestyle is so closely connected to the basics of survival. On one occasion, after we had shut down a production dredge, one of the divers was bumped off the dredge into fast, deep water wearing a full vest of weights and no air. He was connected to a 100-foot airline. The airline was wrapped around something under the dredge, so no one could get at it. We all stood there and watched while this native pulled himself 100 feet up-stream, underwater, against a strong current without ever coming to the surface. We felt him frantically tugging one pull at a time. It never occurred to anyone that he might drown. When he reached the dredge, the look of agony disappeared into an uproar of laughter as he took his first breath. After that, we all used the same signal of frantically thrashing for air every time we wanted to communicate the danger in dredging a particularly difficult location. We always laughed when using the signal.

On one expedition, it was necessary for our guides to cut down a large hardwood tree to replace most of the paddles we needed to continue our journey.

The natives are also very adept with the use of a chainsaw. They are able to cut down a tree and slice straight boards out, without the use of any guides whatsoever. Compared to other jungle expeditions I have been on, we lived in luxurious base camps, with showers, sleeping quarters, meeting areas, dining areas–all on stilts ten feet off the ground. The base camps were clean, dry and comfortable–put together from lumber sliced out of trees solely from the use of a chainsaw. The long boats we were using also were made from the same lumber.

Because of the steep, rough terrain in the Borneo jungle, almost all travel is done by boat on the intricate river system. Consequently, all of the native men are skilled in the handling of their keting tings (native long boats). These boats are usually around 30 feet long and about 3 1/2 feet wide. These days, they are powered by 4-stroke engines, 8 and 10 horsepower Yamahas were being used in our area of operation. A long shaft mechanism is connected to the engine with a propeller on the end. The boat operator is able to manipulate the long shaft and propeller around like a rudder, but is also able to control how deep the propeller extends into the water. In this way, the keting tings can be maneuvered through
We went down through rapids which, as we approached, I thought the natives were just playing a trick, with a plan to turn around at the very last minute. Rapids with waves nearly 4 feet higher than the gunwales of the boat on both sides. And then, afterwards, we would come right back up through these rapids. At first, I thought this was reckless and chancy. Later, I realized it was routine. In thirty days, we never saw a single boat get into trouble.water only inches deep, even when transporting 1500 pounds or more of personnel, equipment or supplies.

It did not take long for me to realize the long shaft mechanism is the most effective means developed to propel long boats on shallow rivers. These long shaft propulsion systems are used all throughout Asia.

On one particular prospecting trip into the headwaters of a river, we rode these boats down through whitewater canyons so narrow that the sides and bottoms of the long boats were scraping the sides of the canyon on both sides–and we were going faster than a roller-coaster ride. What was most amazing to us, was that somehow, the natives were able to get the long boats up through those canyons! We were personally dropped in at the top by helicopter.

The operation supplied us with bottled water to drink, rice to eat, and the other basics which we needed. The natives had gardens and supplied us with fresh vegetables. There was a hunting team which supplied us with fresh wild boar and deer meat on a daily basis, and fresh fish from the river. Native cooks prepared the food for us, and we could not have found better food in most of the restaurants in Indonesia or elsewhere.

Notice the slash across the pig’s head?

Hunters use dogs to track down wild game–usually the babi hutan (wild boars). Often, a hunter will go out alone with a single dog. The dog catches the scent of a boar and starts barking. When the dog catches up with the boar, the boar will turn on the dog and stand there to defend itself. Meanwhile, the native hunter catches up and will either attack the boar with his spear; or more often, the boar will attack the hunter. When the boar attacks, the hunter sidesteps at the last second, and slashes the backside of the boar’s head with his mandau in a single downward stroke. This is kind of a ritual, like bull fighting in Mexico. The hunters take pride in returning with wild boars having the familiar slash on the back of the head. Most boars that were brought in were killed in this manner. Some hunters brought in two and three boars on a single day to feed the whole crew.

They also brought in payau (deer)–sometimes killed with a spear, and sometimes brought in alive. The natives and their dogs have a method of running down a deer alive, so it can be preserved until the meat is needed.

The natives also hunt bears; but this is usually accomplished also with the use of their blow guns. They weaken the bear with poison darts and go in for the final kill with a spear.

My earlier experiences in remote jungles always involved animal life which was dangerous to us while dredging in the river. I expected no less in Borneo. However, while we did see some very large buaya (alligators), the natives assured us that they have never been known to attack a man. Apparently, they like their meat dead and rotten.

The main river was actually pretty large in size!

During our prospecting, the natives did show us one specific area where the water runs muddy all the time–even when the water is running clear just upriver. The natives explained that the muddy water was either being stirred up by dragons or alligators. Needless to say, we did not bother to sample in that location.

The natives did tell us to be careful of the kujut (huge catfish) at the bottom of the rivers. While we did not see any underwater, native fishermen did catch one catfish which weighed around 60 pounds. It was large enough, and had big enough teeth, to take a man’s hand away. The natives said this was a small fish! Apparently, on the larger rivers, the natives have trouble with losing their dogs to these catfish. Some villages use full-grown live ducks as bait to catch these big catfish. They told us there has never been an occasion where a full-grown man has been attacked and eaten by a catfish. This, however, didn’t make us feel all that much safer while underwater.

We set up fly camps alongside the river when we prospected distant areas from the base camp.

Actually, as far as wildlife goes, it was the pacer (ground leeches) that had most of our attention. Luckily, there were no leeches in the river! But, if you needed to go up on the river banks, or if you were going to take any kind of hike through the jungle, you were going to get leeches on you. They were everywhere! Some bushes had blood-sucking leeches on every leaf–on every branch!

The biggest problem with leeches is psychological. They are slimy, sleazy creatures. You just naturally want to get them off you as quickly as possible. When you try and brush a leech off with your hand, it then sticks to your hand like glue. When you use your other hand to get it off, it ends up on that hand. Meanwhile, there are two or three more sleazing up your legs–or maybe a dozen, depending upon where you are standing or walking. Leeches move pretty fast!

Leeches have a very strong sucker-mouth, which attaches to your skin and sucks the blood right out. It doesn’t take long. In fact, they can attach to the outside of a thin pair of pants, or on the outside of a T-shirt, or on the outside of a cotton sock, and suck the blood right through the garment. It is all pretty slimy business! The nice thing about these leeches is that they do not carry any disease.

When we started, I figured we had it together over the natives with our lightweight long-sleeve shirts, tucked into our thick Levis, which were tucked into our jungle boots. All most of the natives were wearing on the hikes was a pair of shorts or underpants! However, it soon became obvious that the natives could easily find and remove the leeches from their own bodies. Sometimes, we didn’t find a few of our leeches until we got back to camp. Generally, a leech will drop off you once it has had its fill of blood.

“Leeches do not hurt you. What’s a little blood? We found the best way to get them off was by scraping them off with the sharp blade of a knife.”

A small red mark on your skin is left where a leach has been sucking. It goes away after a few weeks. The natives told us leeches are used regularly to suck the infection from injuries in their native medicine.

Overall, the adverse animal conditions were very mild–compared to the crocodiles, piranha, electric eels, African Killer Bees, black flies, mosquitoes, and poisonous vipers we have encountered in similar jungle conditions in the Amazon and elsewhere. I was only bitten by one mosquito in 30 days! A few leeches are not a bad trade-off for not having to deal with truly dangerous critters.

Our guides and helpers were a good bunch of guys to have on the team.

We did have several very amusing experiences having to do with leeches. Where is the worst place a man can get a leech stuck onto him? One day, we were riding upriver in a keting ting. These long boats usually have one person operating the motor, and another person in the bow with a paddle to help keep the boat pointed in the right direction, and to signal the boat driver to watch out for submerged rocks and logs. We had just finished a short prospecting hike, and thought we had removed all the leeches from our bodies. It always seems, however, that no matter how thorough you are, a few more show up afterwards. We were going upstream through a boulder-ridden section of river, when the bow man jumped up and yanked his shorts down. Right there, in the worst place imaginable, was a leech hanging off the man. One of the other natives pulled out his machete to give him some help. Just at that time, the boat rammed into a submerged log, and the bow man flew overboard. We all just had to stop and laugh for the longest time before we could get going again. Needless to say, this was a subject we all laughed about right up until the time of our departure.

During our sampling operation, we spent a great deal of time traveling many, many miles around in the long boats. It was a great way to get a good look at the jungle and the wildlife. In many places, the trees grow out across the river from both sides to make a natural tunnel.

One day, we were traveling by boat along the river’s edge, when a large biawak (lizard several feet long, with sharp teeth and very fast) jumped off a tree limb directly into the boat in front of me. He would have landed on top of the native in front of me, but the native, ever alert, saw it coming. I saw it out of the comer of my eye, but thought it was just a branch falling out of the tree. The native jumped up just in time, and the lizard fell into the bottom of the boat between his bare feet. Then, yelling like a mad man, the native and lizard both danced around quickly, trying to get out of each other’s way. Finally, the lizard went over the side. All this, about three feet in front of me; and so fast, I didn’t have a chance to react! We all laughed so hard that we almost had to pull the boat over to the edge of the river.

One day, while prospecting, we came around a bend in the river, traveling by keting ting, and a million fruit bats took to the air. Known also as “flying foxes”, these are huge bats with wingspans of two to three feet. There were so many that it was like a dark cloud above us as we traveled beneath them on our way downriver.

Mark Chestnut poses for a photo with his sampling team after returning from a 5-day sampling project deep into another world where no outsider has ever gone before or since.

Some of the local natives also hunt a certain breed of monkey, not for the meat, but for a particular healing stone possessed by only one special monkey in each tribe. Apparently, these healing stones are in great demand by Chinese medicine men, and a very high price is paid for them, much more than the price of gold by weight.

According to the local natives, if a monkey becomes sick, the special monkey will pass the stone to the sick monkey until he or she is healed. The problem for the monkey hunters is in determining exactly which monkey is carrying the stone. A sumpit (blow gun) is used to fire a poisoned dart at the monkey. Blow guns are made of a single piece of ironwood at least two meters in length, with a straight hole bored through its center. The darts are made from bamboo, and are dipped in a deadly poison made from the sap of a Tajom tree mixed with the venom from a cobra.

We ran into a few monkey hunters during one of our expeditions. These men hunt for gold during the dry periods when the water is low in the rivers. They hunt for monkey stones during the rainy periods. We noticed immediately that the monkey hunters each had almost a full mouth of solid gold teeth. When I inquired about this, the natives told us the poison used on blow gun darts is so toxic, that just the vapors near the mouthpiece of a loaded blowgun will cause a person’s teeth to fall out after a period of time. Besides, solid gold teeth are fashionable in Borneo, similar to clean, white teeth in our culture.

I noticed that many of the natives had gold teeth. I never did find out exactly how gold teeth are fashioned and how dentistry is performed deep inside the Borneo jungle. Many of the older men and women have tattoos on their hands, legs and arms. We were told the tattoos are made with tiny metal needles dipped in a particular tree sap, or in charcoal, leaving permanent black marks.

The predominant religion in the area of our operation was Christianity. The natives preferred to take Sunday off to conduct their own religious services. This was added to by other, more ancient rituals and customs. For example, after we had arrived and began our dredging activities, the rains started picking up. One of the natives had a dream that the local jungle guardian spirits were angry because of the loud noise of the engines brought in by the foreigners (us). Many of the natives worried over this dream, considering it might be a bad omen. Word reached the main village many hours up river. Within a few days, a whole delegation came down to our base camp led by the village chief.

The following day, they put on a ceremony along the edge of the river, while sacrificing the heads of two chickens to appease the jungle spirits. All of the local natives showed up to participate. All work was cancelled for the day. The following day, the weather cleared up, and operation conditions were improved until the time of our departure. Coincidence? The local natives didn’t believe so. Me? I choose to go along with the local customs of the natives of any area which is providing the hospitality. Who am I to challenge the beliefs of others? The natives believe Borneo is an old land, and that old spirits still linger around to help control the weather and certain events to protect the animals and local people. We found that different villages had this same belief, but had their own rituals for making peace with the spirits.

We had fried chicken for dinner on the night of the ritual. Uhm uhm good!

The local miners are recovering gold from the rivers by panning with their Tulangs (gold pans). These are similar to the Sarukas used in South America. They also use their keting ting motors to wash the streambed material from bedrock, so the flakes and nuggets can be exposed and removed from the bedrock cracks and traps. Some of the natives were using hoes underwater to rake gravel off the bedrock. They would then dive down using a facemask to recover gold from the bedrock traps. Sometimes they hit hot spots and do quite well.

One native told us he recovered over four kilograms (around ten pounds) of gold, mostly nuggets, in several months of hard work by primitive methods. But they don’t really need to recover a lot of gold. The jungle provides for most of their needs. Their villages also produce woven baskets and other products from the jungle which are exported to the outside world. A little gold allows for extra luxury items which improve their standard of living.

Long Shaft System

Local miners are doing very well by blowing gravel off the bedrock using their long-shaft propulsion systems!

I think the thing that impressed me most during the entire expedition was the friendliness of the people. Children ran out and waved at us when we went past their villages by long boat. Adults invited us to stay with them in their homes. The Chief of one village gave me his own favorite blowgun, one which he had personally used for the past 12 years.

Dyak sampling team

The natives were excited to dredge with us, because it was explained to them that we were “professionals, gold prospectors from the outside world.” They pretty-much had taught themselves to dredge from scratch during the two months prior to our arrival. Except for when the water was muddy, they would insist on going down to help us. They wanted to participate also in the muddy water, but we insisted that it was too dangerous, because someone might get hit in the head with a rock.

Just like during any other activity, these natives dredge barefooted. Even the individuals who were wearing wetsuits wore nothing on their feet!

Instead of lead weight belts, they were wearing jacket-like vests, tied together with fishing line, with big pockets. River rocks were stuffed into the pockets to weigh down the diver. It seemed to work alright for them, but I’ll stick to my lead weight belt and steel-tipped rubber boots! Of course, we had to be very careful to avoid throwing rocks on unprotected toes.

And we found gold; lots of it. We intend to return to Borneo with a larger sampling team and do a much more involved sampling program. If this project goes well, the company is interested in our bringing over an even larger team of experienced dredgers to work on a gold- sharing venture.

  

There is a lot of gold in East Kalimantan (Borneo). In the deep jungle, because of a rather steep gradient, the gravel inside most rivers I observed was generally very shallow to bedrock. Just like in California, some rivers had lots of fine gold, and some had jewelry gold–two ounce-sized nuggets, and much larger, are not uncommon. In the areas we sampled, the smaller-sized tributaries all seemed to carry a steady line of nugget and jewelry-sized gold, usually under a foot or two of hard-packed streambed material. Huge sections of exposed rough and cracked bedrock are common all along the rivers and creeks, which have never been prospected with a metal detector. We found gold lying all over some exposed rough bedrock in one area we were sampling. And we found deposits in the main river which could potentially yield pounds of gold or more per day to a production-dredging team. Because of the complete lack of modern suction dredging equipment during the past, many river channels are completely virgin of earlier mining activity and the opportunity is extraordinary.

Because of the inaccessibility of the gold bearing areas, Borneo is probably not a good place for the casual, small-scale dredge operator. However, with the proper infrastructure set up (expensive), Borneo could be a modern gold dredger’s dream come true!

One of the consultants on this project told me he first went to East Kalimantan about nine years ago, He said he has known many people who have never been able to get it out of their system, He himself pretty-much has lived there ever since. He told me “once you drink from the waters of East Kalimantan, you will always need to return again.” There is something about the area, the natives, the lifestyle–measured against the fast-paced rat race of our own lifestyle that makes one wonder… Whether it is because of the adventure, the kindness of the natives, the gold nuggets and great mining opportunities, or the water—or maybe a little of each of these things, I know that I personally will be going back!