Pond Boss Forums POND CONSTRUCTION Soil questions Healer, heal thyself

h2Ofwlkillr response:
I ain't cuttin' ya loose on this one. Please expand a little and paint a clearer pic of your experience. Are we talking a 5000 cu yd dam made of a solid mass of good clay, then dressed with about 6" of topsoil? Can you describe the equipment and construction methods that got you there? You are presenting a very interesting and helpful case study here and your experience may/will help me and others to learn. Thx.

Brettski,

I believe it has been mentioned a time or two on this thread, and that is the importance of cutting 1:1 minimum side slopes on your core trench. It is impossible to compact soil onto vertical side slopes as per your core trench photo. Also mentioned was the fact that you can then compact the center of the trench if it is sloped back. This is a very important point and I don’t know how you can do this adequately with vertical slopes. It is difficult to adequately compact a trench that is cut the same width as your equipment, unless you use a sheepsfoot.

Also, on the subject of a non-continuous core trench construction. A continuous, monolithic compacted fill is preferred. However, I have seen core trenches completed in sections as you describe. A couple of my ponds come to mind. Why……basically it was the easiest way to get around a perennial stream flow of about 200 gpm. We cut and then compacted fill with a scraper on part of the core trench on one side of the drainage. This gave us a place to route the perennial stream as we cut and compacted fill on the remaining core trench. We essentially flip flopped the stream from one side of the drainage to the other. Worked great! I will mention however that both dams leak a little (about 2 gpm each). Most dams will leak or seep just a little but it is nothing to be concerned about unless the leak is muddy, and then you are losing fill dirt and the dam integrity may be compromised.


I guess the reason core trenches get so much attention on this site is because of their importance to the stability of your structure. Very difficult problem to remedy after the dam is completed and full of water.

Ed

Brettski...grab some coffee and a snack, this is a long one.

Actually the dam was closer to 8000 cu yds. Core trench is 16-18' wide and only about 24" deep, as the topsoil is very thin. The pond was dug to about 12', with no signs of any porous material, just very good yellow clay. The dam was compacted by a D7 dozer in 4" layers. When construction started, the clay was quite moist. We had to wait to start building because of excessive rainfall and very muddy conditions. After we got started, we went into a 5 month stretch of less than 2" of rain. This is where the problems started. Most of the dam has 6-8" of topsoil on it ( some a little more..some a little less ) The topsoil was used to level and smooth everything out and to give the grass something to grow on. About a month after construction, the cracks started to appear. Nothing too bad at first, but after 5 months of drought it got real bad. The cracks,3 of them, ran 6-7' deep, from inside the basin to the backside of the dam, and were about a foot wide at the top. I probably could have minimized the effects of the drought, if I wouldn't have been such a tight -ss and spent the money to water down the dam. But I didn't and so I've learned the hard way not only what I did wrong, but also how to repair some leaks. My NRCS agent and my excavator both thought the cracks would close and seal on their own, IF I got a few nice soaking rains before the pond filled. That didn't happen. The drought was broken by a 4" rain that fell in 3 hours. The pond filled to 3/4 full overnight. The clay didn't get a chance to swell before the water started running thru the cracks. My dam must be well constructed, because it didn't fail, nor did it wash big holes out of the cracks. The cracks didn't seal themselves.(can you believe it?) So, my quest to seal the cracks started. Crack #1 was the worst crack and really the easiest to repair. I spent a couple of mornings with a long rod and buckets of clay hand filling and packing the crack. it has never leaked again. Crack #2 didn't work that way. It still leaked afterwards. Meadowlark actually gave me the idea of how to fix this one....from the backside. It is now repaired. Crack #3 neither worked completely. It still seeps. Not alot , just enough to keep the ground moist. At this time I'm not too concerned about it. I plan to extend the dam in a year or two and the area of the leak is where the new section of dam will tie in. I will fix it then.
I hope this answered all your ?'s.

Ed,
Good to hear your input...thank you. Meadowlark would sing harmony to your statement regarding segmented dam construction. His posture was more geared toward allowing an opening thru the dam during construction to allow the release of any water build-up (expected or unexpected). Then, carefully pack the trench with good clay soil when pond excavation is done. Pretty much the same process, m/l. We are going to install a drain so this won't be necessary. For this reason, I continue to lean toward cutting and packing the core as one monolithic unit...why not? I also agree with the wisdom of sloped walls; that one comes right out of the books.

h2O....Nice monologue; it means alot to me.
You musta been sick...and scared! You noted in your previous post the hindsight of processing the soil by adding t-s to temper the clay. At the risk of redundency, I want to make sure that you meant the entire core mass....? Based on YOUR experience, would this have been wise for your project? It certainly synch's with Bob Lusk's post c/o Otto's expertise.

Yes, I would have and have done with 2 ponds built since. I have very heavy rich in clay soil. My topsoil alone probably has enough clay content to safely use in dam construction...minus the sod of course. My last 2 ponds we just scraped the sod off and didn't bother with the topsoil. It was mixed with the clay and used in the entire dam construction...core and all.

h2O reflects:
My dirt-guy would shake your hand and buy you a beer for that one. Did you core the dam on these last 2 ponds (embankement ponds, I presume?) and did you use similar build/compact procedure with the D-7?

Yes, they were both embankment ponds. We used a D4 on both of them. Same compaction method. Both holding water well.

The boss and I just took a trip to the project to shoot some elevations into one of the draws to prep for excavation, throw out some grass seed along the new driveway, and roll a few truck and tractor tires to the top of a knoll overlooking the basin area. All fun stuff...even the tires :rolleyes:
As I stand and look out and dream in my mind's eye, I am still thinking alot about this dam construction thing. It dawns on me that earlier in my short-lived PB existence, ML sparred with me on dam construction. Any thoughts, ML?

Brettski,

First thanks for pointing out this thread...it is one of many I missed completely during my hiatus from the Forum....which you ended with your breadcrumbs.

I had to smile great big at H20's reference to the back-side filling of cracks and stopping leaks which I wrote about many months (years?) ago. I'll never forget a whole bunch of experts on here saying that technique would never work...and my skoal chewing East Texas operator laughing so hard when I read him some posts that he couldn't stand-up. The skoal man was right on...he said get on that da*n dozer, push up clay on the backside, pack it as you go, make it a minimum of two feet thick and it will never leak again. He was absolutely right and asked me to post it here and see what folks would say.

Were all those outside experts wrong who said it wouldn't work? No, I would not say that at all. Rather, I would say that my skoal buddy knows the soils in this area better than anyone not in this area...hence he knew from years and years of experience that the back-side packing technique with my small dozer would work in my particular soils...and it worked perfectly, saving me hundreds(perhaps thousands) of $ and very likely the entire dam and pond. That pond now is one super F1 bass pond.

So why am I rambling about a technique in which you have no interest and certainly hope to never use in your project? The moral of the long story is that a really good local dirt guy knows your dirt better than anyone outside your area, anyone.

I wouldn't do things exactly the way your contractor has, but pretty close...the thing I respect is that you have checked him out, seen his work (I presume), talked to his past customers and know that he is a good contractor who has worked extensively in your soils. You have also made yourself a "smart buyer" and are now qualified to question his technique. Trust his judgement until he proves to be untrustworthy.

I respect the inputs you have received on this thread...but if I had been afraid to use a dozer to pack my clay, I never would have built the three ponds I've built with three more on the way....not a single one was built with anything but a small dozer which was assisted by a track-hoe, a loader and dump trucks when the serious dirt moving was going on.

Get the very best local dirt man you can get, check his work, talk to his customers and if everything checks out, trust him to do the job until he proves to be untrustworthy...and always, always be a smart buyer.

You probably wanted me to give you a much more technical input....but my input to you, at this point in your project, is to enjoy the journey. You did your homework and if you hired the best man for the job, let him do it under your watchful eye.

Interesting post. It reminds me of all of the times I didn't bother doing something because I knew it wouldn't work.

I'm reminded of Mike Otto's story about a dam he wasn't going to build because there wasn't enough moisture in the soil to pack the clay. A local dirt expert of some kind told him that if they waited for moisture in that area, they would never build a dam. He said to go ahead and build it. It would work. Mike built it and it did work.

Thanks, ML; good story, helpful input...the wise stuff from you that I hope for and appreciate.

*** UPDATE ***
I had another great phone conversation with my contractor the other night. One thing for sure, when I want to talk, he calls me back within 24 hours and spends all the time I need (sometimes I need alot ) Anyway, after we discussed a buncha plans for this year's attack, I told him that I wanted to address his plans for the dam construction once more. I hit him with all my concerns...we have jousted like this before and he is receptive. He assured me that his plan to finish both ends of the core will ultimately wind up being similar to running the entire core at once. As TN HB said, in order to get down into the sides, you gotta ramp in, ultimately cutting back into the center area to do so. We discussed his rolling back the TS with the clay he dug out. Response; suitable method of processing excellent clay subsoil. I asked why he even cut that little section of the core. Response; the bottom/center portion is going to be left as complete, but it allowed him to glimpse at a wide swath of what is down there. I told him I was concerned for use of the D6 to compact. We discussed the lack of compaction of a dozer; he said his D6 weighs 46K and thought he remembers the number "70 psi"...couldn't swear by it without looking. He quickly redirected me; they will use his E-mover to place and compact the core soil in thin layers. He noted that he thinks he is going to bring in a 2nd E-mover due to the amount of soil to move. Knowing full well that I was focused and intent on the dam, he said "I'll tell ya the same thing I have told all my pond clients. Providing there is good clay in this site, we are going to take all the very best material and it is all going to be packed into the core and the upstream side of the dam...period. If it's not here, you will have to bring it in. Best stuff up front...lesser soils go behind". He also added "now, make no mistake, there is going to be soil that gets pushed into place with the dozer on the dam...that's just the way it is during construction, but where is needs proper compaction on the dam, it will be thin layers and run over by the E-movers". I told him that I wanted to see a 1:1 on the edges of the core. He did not object and readily admitted that this is, indeed, standard practice. He said that he didn't normally make an effort to cut his cores back that much, but will be happy to do so for me.
My project will be a short but substantial dam mass. It will be 15 feet high, 20 ft wide roadbed, about 300 ft wide across a valley. The back side is .7 acres and the valley will be filled with pond waste soil. I figure the slope on the back side at about 12:1.
Lastly, my NRCS agent went out and GPS'd the perimeter of the proposed pond, my new driveway, and a couple of property corners. He was able to drop it onto an aerial photo for my latest motivation

That is going to be one nice pond. Now to help us out you need to take the map and add on the cleared areas and the possible future location of the small pond , the nature areas and what ever else we are missing so we can get the total effect. Then we might be able to add about 100 more things to think about.

.7 acre pond below the lake. Sounds good to me. Maybe you can add a pond above the lake, too.

I'll say!

Whether you're goofin or not, you gotta know that I'm gonna do exactly that...sans the .7 ac pond. The GPS points were taken following the remaining treeline after all the timber was extracted. The entire pondsite and behind the dam is bald, waiting for phase II. The .7 ac behind the dam is gonna be loaded with waste soil. But, never fear...I have been shooting elevations thru the balance of the timber and I have a .5 - .75 ac hole waiting in the main timber block, south-east. (ssshhh..the boss might be wistening...be vewy, vewy kwiet)

I was not "goofing" at all but was serious. I envision this ( all you have done) to be an excellent learning tool for many on how to plan and learn about starting a pond. A good place to send prospective pond builders to in a future frequently asked questions area. A trip through the process from a to z. So we need to gather your story (by link if that will work) in one place and plats/pics/plans will really help. How about that idea ?

I just wish I had been as thorough as you are. I think the results will speak for themself.

Thanks (again) for the many prop's, guys. This is one big deal for me. I have never undertaken anything this big before, and I'm only starting. It may send me to the poor-house, but I'll never look back and wonder if I didn't try hard enuff.
Eric, you are one "house icon" away from a complete chronology. If you are having trouble falling to sleep, my website should help. If nothing else, it will prove my manic commitment.
An interesting note (at least to me, it is); I prepared a couple of projected maps of the proposed pond based on the topo maps I took from the USGS Terraserver. When I put this new actual GPS map against them, they are very different....evidence of the potential "low detail and accuracy" of the on-line topos. I think the surface area is close, but the shape...fuggedaboutit.

I don't understand. Are you getting a 5.5 acre pond?

It looks awesome.

...God and my loan officer willing, datsdaplan. I will likely lose about .3 - .5 ac surface from a small building site bump-out peninsula and a shoreline road that will follow about 75% of the perimeter (tying into the the dam roadway).

That is great, Brettski. I had thought your were originally planning for just about an acre.

Great news!. Congrats.

The wound has been healed! Da core, she be done...and done right! Based on the edumacation from my valued PB associates, I was able to bend my contractor's standard procedure to meet my construction requirements. Quite simply, he removed the topsoil from the damsite area. Then he cut a continuous core from one end to the other. Per my request, he "laid open" the core trench to about 1:1. Then they used the dozer to select the clay soil from 2 areas directly adjacent to the damsite that contain killer clay. They laid is the clay with the dozer in thin layers while they compacted it with a loaded earthmover. They stopped at natural grade. Tomorrow, weather permitting, we are going to lay in the drain pipe, valve, and valve well. The day after, good chance the balance of the core (above grade)and the dam start taking shape.
I'm satisfied. Thanks to all for sparring with me on this one. It made a big diff.