Have to have a Screen?

Well I'm out in Hot Springs AR helping finish up a project. We have 14,000yds. of this fill we have to place. The specs are that any rock is 3" and less. The material to be used is tailing from an old Barite mine. We dug a few test pits in the pile before I arrived and the other super says it look ok. I'm not convinced. He always errors on the optimistic side to say the least, and the soil engineer has been by the book bending us over every chance they get. I took a walk around the pile today and don't really like what I see.

Below are some pics I have a 2lb hammer and linker rod in there for a little perspective. We have skimmed some of the bigger rocks off in the second pic, so thats some of what you are seeing. In the last pic: I'm guessing all/most those large rocks are from other projects they have dug into this pile for in the past that they kicked out. The rock is pretty soft in the it fractures easy.

We will be loading with a 20ton hoe no more the 1000yds a day by my guess. We won't have any other support equipment available. We just don't have a bunch of time to be kicking rocks out and it would be a real pain/slow to pick much anything smaller the 1' out by my guess. Not to mention I'm not sure how good my operator really is.

There has been talk about screening, but I think EVERYONE wants to chance it. Other then maybe the soil engineer. I don't really think we have a chance of getting out of here without a screen, but all of my limited rock experience was in Socal and never tailings.

Thanks

looks to me like you need to be finding a screen plant

I have worked material that looks just like that right here in SoCal. I had the same 3" spec, but only for the top foot. Tried without a screen, and the labor to pick rocks killed the job as we had a by the book soils guy.

I would recommend screening it. Look for an Extec Robotrack. You can feed the screen with the excavator and still load 1,000 cy of screened material into trucks in a day with the same hoe.

What's the depth of the fill and how big of an area? Put it all in, grade it out and go over it with one of these (if you can find a contractor in your area)? https://www.youtube.com/watch?v=h-oXIR_QOBA

I would not touch that job without a small screening plant. All you need is a small single deck scalping screen, something like a Power Screen would work well. I have worked in that area extensively in the past, and know the type of material you are working with. You are asking for problems if you have a by-the-book inspector and no screen.
Are you working at the old Vanadium plant by any chance??

If you have time to handle the material twice with a hoe I have slowly poured/shook the material out at the top on one side of a stockpile. The bigger stones roll to the bottom and you can skim them off. This was with dry common and rounder rock dont know if the trick will work with angular material

One question.... if you do go with a screening plant, can you find a market for the over's? It might make it pay pretty good if you could find a deal like that.

Trash to Treasure!

What are you using to compact the material? Will it break the bigger stuff up to spec? I am finishing a job that didn't have such a tight spec but the soil tech didn't want any rocks bigger than a humans head. I have a big cranium so I went with mine.

Anyway, the material was chert and breaks up easily when rolled in with a CS533E, almost making #57 sized stone. If you material breaks up easily, you may be able to handle it in the fill lift in conjunction with weeding out the larger pieces on the loading end.

Thanks guys thats what I was thinking. Just wanted to make sure it wasn't worth a shot. I tore it open today after my post. Started running down my boundary slope to give us an work area and to see what it looked like. Man this carp material is going to kill us when it rains. Like everything else on this job.


That little 3pt crusher is a sweet little rig and would work pretty good with this material. I will look into it a little more, but with that way our fill area is set up it probably a no go. Not to mention Safety wouldn't let us within 100' of that thing I bet.

I have picked lots of rock out out with a hoe and its just to time consuming. I don't have that kind of faith in my operator. Like all of our guys the closest thing to rocks they have seen is crushed concrete.

Not selling these rocks its not that kind of job site.




Pic of running down the slopes. Miss this kind of work. I just need a D8K and it would be like I was back in Socal. There are a few big rocks in there.

Once again I find myself agreeing with CM1995. I think I would just put in very thin lifts and beat the crap out of with with a vibratory padfoot before I got all fancy with a screen.

Who knows how they have it priced. Does everything have to picked out? even the stuff that's buried of is it just the top course? I would tend to agree with the compacter...but have never seen one break any rock around here...all granite and basalt. Not saying it can't be done..What about running a rake on a skiddy for the final lift? They are fast and efficient.

Regards, CD

True Colorado... CM and I operate in very similar geological conditions I suspect... Limestone, Sandstone, Shale, and Chert.

Acivil said:

True Colorado... CM and I operate in very similar geological conditions I suspect... Limestone, Sandstone, Shale, and Chert.

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Sandstone, shale and chert break up decent under a pad foot. Limestone can vary depending on how weathered it is.

Acvil are you agreeing about the compactor or that you have a big head too?:tong

Dozerboy said:

The rock is pretty soft in the it fractures easy.

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I think I would try a heavy pad foot or an 815, even one of those old pull behind grid rollers might do the trick if you could find one.

How does it break up running over it with the JD dozer?

What is the exact spec for the 3" rock? Is it allowable at any depth or only at the surface?

Can't use vibration on the fill we are just static rolling everything in with sheeps foot roller and it just bounces over most of this stuff.

Nothing over 3" at all.

The dozer you see is a 650LPG so it doesn't do anything but bounce over this stuff.

On the test pits a guess they found a good size area of shale, so for now we are using it. Still has some over sized rock up to 1', but I've made it disappear and no one has squawked yet. I manged to talk them into letting us get a D6n with standard tracks on the fill which is doing a ok job of busting up the sandstone and shale.

As you can tell this isn't your normal every day job site. We have other option for getting material, but we are already 5 months behind. I'm sick of being out of town and want to get this PITA done and get paid. Not build roads all over piles of tailings or hauling even more material a 2hr round to the site.

We really lucked out in that soil engineer is minding his own business since this portion of the job isn't his responsibility. Everyone else wants to see this thing done. None of this really matters it just going to be a nice grassy hill when we are done.

What about a skeleton bucket? Shake out the fines and load out the oversize stuff to be dumped in a waste area.

CM1995 said:

Acvil are you agreeing about the compactor or that you have a big head too?:tong

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Both I suppose...

Yup out here in Indiana we have the samething. We have to process the rock down to a 4inch material. We just shoot the hell out of it then run it through a crusher. Just picked up a job in Bella Vista Arkansas that requires a similar spec about the sizing of the rock. Is it a Sandstone type material or Limestone?

Sand stone, a D6N doesn't do to bad of job breaking it up. That is until you go back and cut finish and your popping the chunks out. No one is complaining yet. Been getting hammered by rain work 3-4 days spend 2-3 days dealing with rain and drying things out.