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kurt_Blumberg
03:22:30 Tue
Jul 7 2009

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damming and selective dredging of a small creek

The creek I'm beginning to work here in Colorado is quite small and in a narrow rocky gorge. I have come up with an idea for working it that I want to run by you all and see if anyone has done anything like it.
Currently I have opened up a pool that extends from one side of the canyon wall to the other...about 20'. The stream width at the entrance to the pool is about 4'. High water season is waning so I won't have an over abundance of flow to contend with. I now have a hole begun on one side of the pool. My plan is to build up a dam that separates off the hole from the remainder of the stream. By this I could substantially lower the water level in the hole to make removal of all material easier. I could control the level of the water to allow full suction with my 5" hose or make it almost dry to really get at stubborn boulders with a winch or blasting.
There are probably some factors I'm not realizing and taking into consideration, so if any of you has any suggestions that might assist me in this plan, please feel free to offer them. thanks

  
Vance_in_AK
05:48:04 Tue
Jul 7 2009

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Re: damming and selective dredging of a small creek

No advice, just picturing your project.
You will have the dredge itself outside the dam you build & have the suction nozle within the confines of the dammed area so you are pumping the water out of the dredge hole right? Then you will let a controlled amount back in to keep enough to work.
Biggest hurdle I see is that you will be pumping your material way above the water level you are working to get it over the dam & to the dredge, but if it's just a few feet it may not matter much. I don't have the experience to know.



---
Vance in AK
PS119:72. The law of your mouth is better to me than thousands of gold and silver pieces.
 
 
kurt_Blumberg
06:06:28 Tue
Jul 7 2009

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Re: damming and selective dredging of a small creek

You've got it right. I will most likely need to bring the material up about 5' at most I expect. As long as my jet tubes are under water in the pond I should have enough lift. to bring the material out of the hole and up to the box.

  
LipCa
14:27:55 Tue
Jul 7 2009

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Re: damming and selective dredging of a small creek

two things...


your boulders are going to weigh a lot less in the water so don't lower the water level to expose them.

and, you're not going to lift your material anywhere near 5 feet from your lower water level up to your dredge. maybe two feet. once it gets above the water surface, it gets heavy.

where are you going to put the waste? back in another hole?

  
kurt_Blumberg
03:06:41 Wed
Jul 8 2009

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Re: damming and selective dredging of a small creek

I thought that as long as the material was suspended in water even if that water was just in the hose it weighed the same as if it were actually under water.
I realize the boulders will weigh more in the open air but what I mainly want to do is to loosen things up while the water level is low and the rock is easy to get to. Then I can let the hole fill with water and dredge it out. Yes, I'll move the material to the back end of the hole.

  
overtheedge
00:09:50 Fri
Jul 10 2009

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Re: damming and selective dredging of a small creek

Building a small dam isn't a small undertaking.

For each foot of difference in the water line, there is a substantial increase in the hydraulic forces at work. You can have problems with the seal against the canyon wall. You can have substantial hydraulics coming from the bottom of the hole.

Rivers and streams are at the level of the water table. The greater the porosity of the ground, the greater the flow in the bottom of the hole. This is not just downstream, but the water table (in the hole) will return to the stream level.

Now the biggy. If you are successful in the design and construction of a temporary dam, imagine the effect if you are in the hole and it gives way (it is temporary, right) for some unforseen reason. Your choice, but think safety first. Gold has little value to the dead.


  
kurt_Blumberg
05:06:57 Fri
Jul 10 2009

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Re: damming and selective dredging of a small creek

Well, as a "go to it" kind of guy, yesterday I went about chucking rock, rolling boulders and shoveling gravel till I had a dam going. Most of the material came from the little channel I was encouraging my stream to flow in. The deeper it got, the higher the dam went till I had just enough flow into the dredge hole to keep it fresh. I also made an outlet from the hole that is about 2' below the level of the stream. So, at this point the water level of my dredge hole is stable at 2' below stream level. I'll be taking photos and a video tomorrow of what I have going so far. It looks to me like it's going to work. More tomorrow.

  
overtheedge
01:26:22 Tue
Jul 14 2009

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Re: damming and selective dredging of a small creek

Oh 2' shouldn't be a problem. I was thinking more on the line of 6-10' water level difference.


  
Au_Seeker
02:52:14 Sun
Jul 19 2009

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Re: damming and selective dredging of a small creek

Kurt,

I sure hope you are Ok, it has been 8 days since you posted last!!!

"It looks to me like it's going to work. More tomorrow"

Geo,

That is a wild video, I wouldn't want to be driving down that road late at night after that washout!!!:gonetoofar:


Skip
[1 edits; Last edit by Au_Seeker at 02:55:02 Sun Jul 19 2009]

  
kurt_Blumberg
05:34:20 Sun
Jul 19 2009

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Re: damming and selective dredging of a small creek

Hey, not to worry. If I stop to take a drink from my creek, the water line goes down a bit. Sorry about not posting the next day. I'm having difficulties with Photobucket but should have pics up soon. I actually have three levels in the creek bed now. The upper carries the majority of the flow which used to be in the middle and the lower, which is the dredge pool. I can suck the pool dry, work on boulders or bust up bedrock and then just reposition a 6" pipe from the upper channel to fill up the dredge pool in a few minutes. So far, so good. I had to order a larger engine for one of my pumps and that won't arrive till Tuesday. When I get back to dredging I'll get some video footage and try to post it along with some stills. During the interim I have been expanding my pit with pick and shovel and hydraulic water pressure. Also built the new upper channel and am working at beefing up it's banks so next year's spring flood won't wash all my efforts away. Though after seeing that road get torn up I'm not sure even a bunch of well placed boulders is going to do much good, Best thing I can do is try to make the stream a straight shot through the diggins.
I've been having great success with my big hand winch.
Drilled a 3/4" hole in one big boulder[maybe 600 lb], pounded a threaded forged eyebolt in place, hooked on to it an sucked it right out of the bank.
What about the gold, you ask? That's comin' soon I hope.

  
JOE_S_INDY
00:06:22 Sat
Dec 1 2012

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Re: damming and selective dredging of a small creek

Hey Kurt,

How did you ever do? :confused:

I have a similar situation in Alsaka that I am considering something similar.

So, how'd you do on this 2009 posting? :confused:

Joe
[1 edits; Last edit by JOE_S_INDY at 11:32:39 Sun Dec 2 2012]



---
Wiser Mining Through Endless Personal Mistakes
 
 
klondike_jake
23:54:48 Sat
Dec 1 2012

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Re: damming and selective dredging of a small creek

if i understand this rite.you are going to raise and lower the water level in your working area.more water to suck and less water to hook up boulders.
so actually you want to make like a caisson. im thinking that it might work using 4 mil plastic barrier out side of a sand bag built wall. you will still get water coming in ,but could control it with a med size pump.
i would want more water hight to float out the big rocks.

  
flintgreasewood
05:02:57 Wed
Jan 2 2013

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Re: damming and selective dredging of a small creek

Hey, guys, sorry I never got back to respond to the questions and report on my progress. Work in Alaska took priority the past two years. But here's where my Fourmile Creek project sits. I was very successful in establishing a very solid dam after pitching many tons of rock on it as I progressed upstream.
At one point I even had to remove rock in the middle to place lengths of 6" pvc pipe for the outlet from my suction hose which returned it's contents to my sluice box down stream. With great difficulty I hand dug a 100' long ditch on one side of the canyon that is able to handle all the creek flow even at high water. Upstream of the workings at the start of the ditch I set in another length of 6" pipe that I use to divert water into the pond when I need it. It will fill the pond in about 15 minutes. When it is full I shut off flow and let the ditch take all the water. That is where I get my supply for the two dredge pumps, and in low water season I use just about every drop. Then I begin suctioning gravel from the upstream end of the pond. When I have drained the pond I remove one of the pressure hoses from the jet tube and connect a fire nozzle. But before I turn that loose I hand chuck all the big rock and boulders on to the dam or ditch bank [soon it will all to to back filling the pond]. Then I turn on my hand held Giant and blast away. It's about all I can do to keep from being knocked over by the force. It's a part I really enjoy. Soon the pond is full again and ready to have the loosened gravel sucked up. So, at this stage I have a pretty good section of bedrock cleaned off. Last summer I was not able to work the creek as the Alaska project took precedence once again. Don't know when I'll get back to it, but the gold isn't going anywhere.

  
flintgreasewood
05:19:01 Wed
Jan 2 2013

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Re: damming and selective dredging of a small creek

Forgot to mention. I had my monster hand winch fixed upstream and had been dragging all over sized boulders upstream a ways, and there were some that weighed at least 1500 lb. Well I had enough of that and relocated the winch downstream of the pond so when I get back to work there I'll be dragging those same boulders as well as the others I encounter downhill and through the pond [where they will reside till the end of the world...which I hear was supposed to happen today!!] I also positioned my sluice box far enough down stream to a steep drop which will carry away all my tailings and I won't have to waste a lot of energy reshoveling material clogging up the little stream. By the way, my method for dragging boulders is to drill a 7/8" hole with my hammer drill about 6" deep. Then I pound in a large threaded eye bolt and hook on to it with my winch. To remove the eye I just stick a big pry bar through and screw it out.

  
Coeur_D_Alene
07:00:29 Thu
Jan 3 2013

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Re: damming and selective dredging of a small creek

Kurt Still nice to hear that old winch is working well. Seen videos on the Colo and Ak claims. Are you going to post any more video on the Alaska ice mining project? Glad to see you still mining. Vance in Idaho.

  
Golden_Bear
04:45:27 Sun
Feb 24 2013

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Re: damming and selective dredging of a small creek

The way we did it once,for a temporary dam was this: we put some material down to start with. Then we layed a plastic pallet cover down. Big sheet of visqueen will work also. Then throw some dirt in back of it, with rock. It worked good to supply water for high banking, and small dredging. One note. Remove the plastic sheet when done. So just remember. You don't want to throw much support rock/ it on it. Just enough to keep it from floating away. drop some on the bottom when starting. then pull the plastic up.You will have to move that off it when done. GLTU.

  
geowizard
18:17:12 Sun
Feb 24 2013

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Re: damming and selective dredging of a small creek


Update:

Kurt announced on another forum that he contacted DNR about his dam project. DNR doesn't have a problem with small i.e. less than 8 ft dams.

My claims on Esperanto Creek in the Innoko mining district look like Vietnam. The best dam builders are available all over Alaska and they work for free! These guys made terraces over a two mile long section of creek and the dams are on the order of 1000 feet wide!

- Geowizard

  
Oregonguy
05:46:09 Mon
Mar 18 2013

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Re: damming and selective dredging of a small creek

cool thread to read through!

  

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