Pond Boss Forums POND CONSTRUCTION Renovating a Pond or Lake? Applying Bentonite to sandy soil

Hello everyone !
I’m new here ( first post) and I am having trouble finding the “ How to add 44.5 tons (or more) of Sodium Bentonite to my 1 acre poorly constructed , leaking ,sandy soiled pond bottom thread. Can someone please direct me to the right section to discuss this topic? I have a million questions . Thanks!

This is it!

Ill sit back, maybe someone can get Otto or Lusk to come help.

Is draining an option?

First, draining and drying is the only option. Bentonite needs to be mixed into the sandy stuff. Have you considered a liner?

A PB mag article, don't remember which one but the PB office should have it, discussed this. As I recall, most of the issue was devoted to this. But, it has to be dry.

Maybe this is a situation where you'd be better off with soilfloc? Talk to TJ on here!

Marty, since you are in Oklahoma where the Oil and Gas industry has been active for many many years. Look for and contact any Drilling fluid companies around you. Contact them looking for what is called liquid mud. Some of these companies sell this liquid mud. This is or can be a bentonite mix or ask them if there are any drilling operations going on around you. When an Energy company is done with the drilling they have to clean things up and may have to haul off the drilling fluid for disposal. It might be cheaper for them to haul it off to your pond. This would be done with what is called vacuum trucks. They would pump the liquid to the pond where it might help to seal the ponds bottom. This could be at no cost for you. Over the past 30 yrs we have done this many times. The pond needs to be drained before applying it.

Yes , the pond nearly drained itself after a few weeks with little or no rain. It’s a storm water detention type pond. I seined the fish and pumped the remainder out a couple of weeks ago. There were about 20,000 (or more ) small green perch and 2 each 8 & 10 lb flatheads in there. Strange

I did consider a liner but for 3/4 or 1 acre a liner would be $30,000.00 or more?

I read a little about Soilfloc but wonder about the cost and ever changing water levels and how it would be affected on the banks during dry spells. However ,if I wasn’t losing so much water to seepage I may be able to keep it topped off with a fountain supplied by one of my 2 wells?

Marty, Is your soil sandy clay or sandy loam??

I’m not sure how to identify the soil . It seems like a very fine red sand. When I did a bucket test(With perforated bottom) it held water for 2 days then found a hole and washed out. When I put a small amount of the bottom soil in my hand and get it wet I can make a ball, roll it back and forth and form a “worm”. When it dries it becomes hardened but breaks easily. I have the soil conservationist for our county coming to look at it in a few days, but not sure if they do soil analysis or not .I know it’s important in determining the application rate for the bentonite. I think 4 lbs per sq foot might work but really am not sure how much is needed.

If you can make a roll or ball it's not loam. Sounds like clay to me, whether it's lean to fat I don't think it matters but when talking about bentonite and lbs per acre, that's mixed into existing substrate and compacted. Final layer should be high plasticity clay if available.
Plan 3ft deeper than what you want for finished depth is soil allows.
We did some hatchery runs NW of you in some lean sandy clay but we used a completely different method on those. Clay would not work because of frequent draw-down and re-fill.

Why not take that same bucket and then add the bentonite to see the results of adding the clay. Might also give you an idea as to how much bentonite to add. You could mix it in or add it to the top of your sample of dirt to see what works best for you.

TGW1 I sent you a PM

This is a mistake that happened in some areas SE of me.. Bentonite was used where it was not suitable for the soil type and IF you have lean sandy clay there is a much better option. I sealed a 2.2 acre impoundment with lean sandy clay with some areas of sandy loam and our core samples tested came back at less than .030 seep a day, which is the lowest our firms in this location can test for. Terracon is located in wichita, they do our testing. I push this hard because bentonite is a possible candidate but depending on soil type, there is a cheaper, better option.

Snipe, I don't know if I'm missing something or not understanding you but how are you treating the pond?

I use a common compound-dense soda ash-in Sandy clay and sandy loam. The secret is knowing the procedure and the rate.
Part of my living is wrapped up in this so I'm not going to be too specific for 2 reasons, #1, soil type dictates amount per square foot and #2, the rates vary by depth and we've found through many trials what works in "X" soil and what doesn't.
The advantage of this procedure is where ponds fluctuate widely, the soil does not "crack" when water is off of it and it's about 1/5th the cost of anything else out there.
It's incorporated into soil and compacted but much thinner layers than bentonite.
EDIT: I need to clarify my statement here.. I am reluctant to state the entire process because if not done correctly you can have serious pH issues and it can inhibit plant growth of desirable species. I don't want someone trying this and have problems without understanding the procedure.

Thanks Snipe, I thought maybe you was using something like soilfloc while water was in the pond. I haven't heard much but I've heard of using soda ash. I wish there was something else like soilfloc that was 1/5th the cost. Lol!

Don't take this wrong, Soilfloc has a strong niche to fill, in fact I've been in touch with TJ about using some myself in my own pond. I'm looking at this from a beginning approach, as-in IF I COULD DO IT from the beginning. And I believe TJ will back me on having a sound plan to start with is better than going back and trying to fill in our short-cuts.
And, if this is a situation where land based equipment cannot get access to the basin then I would strongly recommend we get TJ involved.

Snipe, I have a unit of Soilflock to use in our sandy soil as a test. I wanted to get the test done this Fall, but cold weather moved in and the ground started to freeze first. I'll do some testing this Spring with it as it relates to using in the pond basin and sides before it fills with water. Here our ground could be considered beach sand in a lot of areas in this county. Here on this property there is a mixture of Plainfield fine sand, rolling phase with some Clyde Fine Sand soil interspersed with the Plainfield. The land 50 yds to the S of my pond is considered a seasonal wooded wetland with Pin Oaks the predominate species growing there, with some Sugar Maple.

I see a couple of problems using Soda ash. First is what snipe said about increasing the pH. As it desolves on the ponds bottom there could be an increase in the pH and I could see where waves from the wind might increase the chances it could increase pH. The second problem could be as it desolves into the water it will decrease the waters hardness, calcium. We want some hardness in the water. at least 40ppm if memory serves me.

Snipe, I've talked to TJ a couple of times, he is very helpful. My pond is slowly doing better, but not as fast as I want it to. The next time my water level is high and I have the extra funds and my body is doing well and the weather is warm enough, I plan to try soilfloc if it isn't doing much better. A lot of ifs have to come together to make it work. Lol!

Bob, ponds do build up material that helps to seal them. Clays that settle from run off accumulate not to mention organics. In some parts of world, where clays are not part of the landscape, ponds are sealed on sandy soil with nothing more than manures. So this trend you see will probably continue. The fact that it is a trend is evidence supporting the notion that your leaking problem is diminishing.

I haven't given much consideration between costs of the different approaches one may take. So I don't know the cost of Soil-floc or bentonite for example. It seems like I have read that soil floc comes in two parts and I do wonder why. One thing that occurs to me is that one part floats. IIRC the polymer which absorbs water and is activated by water is what floats. So perhaps the other part is supposed to floc with it and sink the polymer. If this is so, then I do see other possible treatments that may work as well or perhaps even better than soil-floc at less cost.

One thing that comes to mind is bentonite especially in combination with a flocculant like gypsum. The treatment would involve mudding the water and then clarifying the water with the appropriate amount of gypsum. Such a treatment shouldn't adverse affect PH and should ensure the Bentonite makes it to the bottom without flowing out of the pond. The binding with the gypsum should prevent muddying by organisms stirring the sediment. My hunch is that this would work every bit as well as soil floc for long term reduction of filtration.

My father-in-law's place has a small pond on it that was built with box blade. It was built on a slope of a sandy hill and after they had constructed it never held water. A few years after construction, an oil driller asked if they could move a location to the pond (as it was already constructed) in order to dispose of tailings from the cable tool drilling. Now keep in mind, a cable tool doesn't use mud for drilling. But as they pounded their way through shales, a natural mud was created and these were disposed of in the leaky pond. The well was dry and they moved the rig away, but the pond there after held water and was still holding water 60 years hence when he told me about it some 30 years ago.

Guys, I think my intent was taken wrong here.. If starting a new pond basin in lean sandy clay or sandy loam, I can get a near 100% seal using my techniques as compared to using Bentonite. I can seal a 15' 1 acre pond for about 3,000$ for the material.
What I do after the seal is completed is what holds the pH steady. My pond is going into year 4. My pH is 7.8, my hardness runs about 120-140.
The trick is a 1 foot blanket of dirt over the top with riprap shores down to 3-4' in many areas, a lot of gravel and sand substrate.
My point of what I'm saying is there are other ways to seal a basin than bentonite alone. In my neck of the woods, the closest supply of high-end Bentonite has to be trucked out of Utah and besides not working good in a high fluctuation pond, it's cost makes it a bad option here. I think each area has soil types that bind in different ways with different compounds but the one constant is regardless of what is used, it has to be used properly, with proven installation/incorporation methods to have the best chance.

Jpsdad, thanks for the info. You're one of the few people I've heard say you can use bentonite to seal a pond that has water in it. I've had a few people tell me that it worked for them, but most on here say you have to till it in and compact it.

Snipe, thanks for the info. I figured you was talking about a new pond or at least one that had been drained.

I can see where soda ash might seal the ponds bottom. If done correctly it could form a layer that would set up much like cement. I would have to give it a little more thought if I was going to attempt it. Looks like snipe has already figured out the formula.

Tracy, your earlier suggestion for the pond on sandy soil is a good one. Bentonite mud from a drilling company will no doubt decrease filtration on a sandy bottom and the solution may be an acceptable one that provides what is sufficient for the poster's needs. I need to add my thumbs up to it.

Soda ash has been used for a long time to seal pond bottoms but the soil must have clays to work. As Snipe mentioned, it depends on the soil. In soils (with clays) where the clays are bound in granules that don't stick together well, the soda ash disperses the clays making them behave more like bentonite does. They become mobile and plastic. In a soil with little clay, the soda ash would offer much less and perhaps no benefit. An example of such soil is my father in law's soil which in every practical sense is almost nothing but sand and organics .

Where clays that are already dispersive are available for lining the pond, there is no need for any sealing additives at all. In these cases one might need to offset the clay's dispersive properties in order to lower turbidity.

I've worked on hundreds of leaking pond projects over the past 6 years and there's a dozen or so cases where bentonite was applied to a hydrated/full pond in hopes to seal slow the leak - some of these projects cost into the five figures and unfortunately, for these guys, bentonite didn't improve the leak issue. This doesn't mean it won't work, just means it didn't work for them. I think half the project cost was due to freight costs per Snipe. Closest source for us in NE is WY or TX - we've bid a few jobs and freight was cost prohibitive and blew out the budget. If I lived closer to a source and it was cost effective heck I'd try anything to get a seal.

I am typically the last gasp call made before folks are about to abandon their sealing efforts altogether. I try to talk them off the ledge and in some cases we try a polymer, in some cases I try to convince them to live with the seepage, or [last resort] fill in the pond. Whatever lines up with the person's goals and budget is the solution I recommend - I'm just here as a volunteer to try and help whomever I possibly can with pond related issues.

Regarding Bentonite application - I have always deferred to Mike Otto/Michael Gray direction which states it must be tilled into the dry basin and compacted with 4-6" lift of high plasticity clay. I've worked with polymers to seal dry basins with great success in a similar manner, but have no personal experience using Bentonite as, again, it's not cost effective for us in the Midwest and the polymer is far more efficient and friendly on the budget. There may be other ways to apply bentonite, but I'm not familiar with either of these pond builders ever discussing it.

To make matters a bit more confusing, Kenny comes along in the last few years and relates his success using soda ash [sodium carbonate] as a sealant. I'd never heard about this process before - and he's definitely the resident expert on the subject. I have no ideas on application process, application amount, or cost - but I always defer to guys who have directly worked with said materials on site and have practical, personal experience with the results. I would like to learn more so I can start providing it as a possible solution for leak issues, but I'll need to lean on Kenny until I understand it better.

These discussions are valuable as there may exist multiple strategies to help slow or seal leaks - and identifying the most cost effective method is everyone's goal. Good stuff.

It would be great if we had a section just for threads about sealing ponds and such.

From what I know right now, Soilfloc is in first place for my personal case and as I said before I will probably try it when the stars all align if not holding well enough at that time. But I'm always open to learning other ways.

TJ can you tell me what is the minimum water temperature and what is the best water temperature for Soilfloc to work?

I agree with Tj on using polymers for some leaks. I have purchased soil floc from Tj for sealing off leaks in my sediment pond and it was easy to apply and I saw some bennifit from the product. And he is a good guy and will help you out if he can. I also agree that shipping cost ( if you have to ship it) would be way cheaper for the polymer because it takes alot less of the product. As for using bentonite, it is a clay and can be used to help reduce fluid loss. You just have to remember it is not a plastic liner nor is it a conctrete pool. In my opinion, after using bentonite most everyday for 40 yrs, it will reduce the fluid loss if applied prior to filling the pond with water. It is not so easy to get enough of it in place to seal a leak after there is water in the pond. Can it be done i think it can. But it would require a premix but again it will reduce the fluid loss and may not completely seal off 100% of the seepage. Another thing is you can use most of those types of polymer products mixed together with bentonite in a premix.

I think Snipe nailed it when he said soil issues and adapting to their peculiarities should be addressed in the construction. Nothing beats a liner constructed from clay with good plastic properties. He is able to transform his troublesome loams with soda ash into an acceptable clayish liner with acceptable plastic properties. The filtrations results of his cores do tell us that it doesn't take 100% clay to have a good pond bottom.

I don't know what Soil Floc is made from but I think it likely that its polymer is polyacrylamide or what is widely called PAM. I have no doubt it will work and I think it works for similar reasons that bentonite works. It forms an layer of low permeability at the interface of permeable soil/strata. I see a much greater benefit with a polymer when there is things like rock seams taking water. Bentonite is very dispersive and it will tend to stay dispersed in pond water, which is why I suggested it may work better if precipitated with a flocculant. In the end, if there is filtration, the bentonite or the polymer will be drawn to it and they will bridge the interstitial spaces near the boundary. I think a polymer works better when these spaces are large (eg rock seams, vugs, and fractures). A blowout? Its probably better to reconstruct IMHO.

I think Bentonite should only be used when the soil is primarily chemically inert components (e.g. primarily sand). It should not be used where the soil chemistry is coagulating clays already in the soil. The tendency will be to do the same thing to the bentonite reducing its performance. Snipe's method of constructing a liner treated with dispersant is appropriate for these soils.

I have a unit of Soil Floc here that I will be using as a test in VERY sandy soils and incorporating it into the soil before the pond is filled. I had hoped to do the test this Fall, but the weather turned too cold too fast to get the test done. I think I have figured out how to get water into the pond without causing erosion which would disrupt the Soil Floc compacted area.

Going to dig a few small ponds here and need to find the most cost effective way to seal them. No clay in the area unless I dig down 21 feet.......

Here locally, the water table is high enough and the soil porous enough that digging any pond deeper than 8-10 feet result in water upwelling into the pond during construction. That precludes easily incorporating any "sealer" into areas of the pond that are deeper than that, but maybe if a deep sump is dug to let the seepage accumulate, and the material incorporated as best as possible into the surrounding soil. then Soil Floc applied to that sump area after the pond is full, may be a way to seal new ponds locally.

The biggest unknown is the groundwater table. I believe that if the water level in the pond is high enough (i.e. higher than the water table level outside the pond) then the water pressure inside the pond will prevent the water outside the pond from seeping into the pond, and pushing the sealing material out of the soil and into the water in the pond. I think that will be a problem that needs to be considered in locations where a well cannot be used to initially fill a pond.

I will follow this with interest, esshup. You are correct that if the water level of the pond is higher than the table the pressure in the pond will prevent inflow into the pond from ground water.

How big a pond in surface area are you going to be testing this on? What is a unit of soil floc? I mean in terms of weight and volume? How much does this unit of soil floc cost?

I have used at least 10 different polymers to control fluid loss. I would suggest a pilot test to determine how to apply the polymer to the soil to seal a pond. My first thoughts are to just add it on top of the soil and not blend in with the sand. If you look at some of soil floc earlier reccomendations were to dust in on top of the water and let it sink to bottom. That would put the product on top of the soil on the bottom of the pond. And from my experience i think that would be better than blending it with sand. When people have used the polymer they talk about how it is gooey and slick and how it sticks to the side of their boat when they add it to the water. And that is exactly how it acts, Keeping this in mind, when it is added to a soil it forms a slick, gooey film that water will not pass through if the goo is thick enough. To pilot test it use a bucket, drill holes in the bottom of the bucket and blend it with soil add water and see how long it takes before the bucket leaks. Then do another test with adding it to the top of the sand/soil covering the sand and then add water. See how long it takes for the bucket to leak.

+1 to Tracy's suggestion to perform experiments to estimate effectiveness. I was going to suggest the same but wanted to understand the amount to be used and how much surface area of the pond bottom so that the density of polymer could be estimated in preparing the experiment. My impression from your thoughts, esshup, is that you are contemplating use of the polymer in lieu of bentonite in sandy soil where construction techniques are similar to that of using bentonite to construct a liner.

Tracy makes a good argument that a film on the surface might be more effective than trying to integrate the polymer through a volume of sand. With experiments, one could determine the costs of different approaches and which are most effective. The long term benefits in the unique challenges you face in those sandy soils could not be determined from such short term experiments however. This something to consider as well. I think in much the same way that Snipe protects the liners he constructs with an overlay of soil ... you might also want to do the same so as to protect the liner from crayfish and such. Another thing to consider is whether you can obtain soils a reasonable distance away with sufficient clay so as to improve it for liner use with a clay dispersant (eg soda ash). Such could be mixed with sand to increase its thickness. In a case with ground water flows under a clay liner, some gradual erosion of the clay liner must also be expected.

While I've sealed sand/gravel veins and glacial till on my ponds using polymer, I have no experience trying to tackle a proper sandpit. Scott and I have discussed this project for years - I related I don't have much confidence anything can seal a sandpit but a compacted, high plasticity clay liner, but Scott elected to give it a shot using a single unit. I am also concerned with the rising water table pressure potentially working against the hydrostatic pressure of the pond volume potentially affecting a seal down the road, if indeed one is even achieved. This should be educational at the very least. Wish you lived closer - I'd love to treat some test sand holes and see how things go.

Agree Tracy - good observations.

In case anyone is interested, I did discover a few things about soilfloc. Its polymer is anionic polyacrylamide (PAM) and a unit is 1 55 lb bag of part A and 1 55 lb bag of part B. Don't know if both bags are polymer or if 1 bag is polymer and the other inert (in terms of being a polymer). So assuming 110 pounds of polymer per unit and a recommended rate of 1 unit per 3000 sq ft the application rate is ~.59 oz. of polymer per square foot. So roughly 1.2 % the weight recommended of bentonite when constructing a liner using bentonite (3 lbs/ft^2). The cost to treat with soil-floc excluding shipping and application is ~ $8000 per acre which is a fraction of the FOB source cost of Bentonite > $26000 but just not sure about the cost of bagged mud nowadays. There is a big difference in the weight. 130,680 lbs dry bentonite per acre compared with to 1597 lbs of soilfloc. If only half the soil floc is polymer, then 799 lbs of soilfloc polymer. So either 81 or 162 times the sealant by weight is recommended for bentonite.

I would personally love to do some testing with soil floc and report the findings. If any one has a small batch of part A and part B leftover from a treatment, and can spare it, I'd be happy to pay shipping for a small sample to work with. Same goes for bentonite but I don't care to do any testing with granular bentonite.

TJ is a dealer.. He works with the parent company and has done hundreds of jobs using the product. If you have questions or want to obtain product I would ping him on soilfloc.

I have a hell of an Idea.. I have 3 cells to build in the next couple of months.. How about we do one with soilfloc, one with soda ash and the 3rd with bentonite??

Jpsdad, I've seen enough Soilfloc to treat a 1 acre pond (1,320 pounds) for $5,700.00 delivered.

Are you convinced they will all leak? Considering cost, availability and your professional experience I’d recommend your soda ash application. I will help you all I can - I’m down for the road trip.

Ken,

I think we already know your soils work best with soda ash. My thoughts are to measure filtration under different treatments. In particular, I would like to test cost equivalent application of soilfloc and bentonite to see how their filtration compares with sand as the filtration medium. Neither could perform better under field conditions and we could at least learn the best possible performance in sand one might expect from each. I also want to test the soda ash with our caliche underlain clay soils. I think they may respond well with this treatment where bentonite would not. I notice many of the ponds constructed near me noticeably filter water and are maintained by pumped water. So I think I will learn something that I can apply later when constructing a pond.

Another thing that interests me is how each might perform if the interface is punctured equivalently. Would they both filter away or would one or the other be less prone or perhaps have self healing properties?

Bob,

To be sure there will be different prices depending on vendor. I just did a google search and that is the only site I visited. They recommended one unit per 3000 ft^2 and their cost was 557 (I think) when buying 15 units. Anyways, I will defer to 1320 lbs/acre at a cost of $5700/acre. Thank you for sharing this.

My thought was although I already know soda ash will work in my soil (less than 3% clay particulates of any sort), I have the complete soil logs of the last 3 jobs I've done, 1 is lean to fat sandy clay, 1 is heavy Loess content and 1 is very much the same as my own at primarily Fine sandy loam.
All 3 have what I consider acceptable loss at less than .100/day. 1 is .033/day, .057/day and the hardest to seal was the heavy Loess and came out at .097/day which just barely exceeds guidelines set in Doc 509. But I also shorted the second layer by 3lbs per 100 sq ft. Had I done the second layer slightly heavier, the seal may have well fell into 509's acceptable limits.