Pond Boss Forums POND CONSTRUCTION Soil questions Need Opinions on Secondary Core Ditch

Hi all, and thanks for all the comments and suggestions in another of my threads "Clay or Pond Liner." There I describe the trouble I've had with a nice pond that continues to seek down about 6-8 feet every year.

I've done, and contiunue to, research bentonite clay and pond seal, which is a form of it. I've gotten a lot of info and now have an idea what works in certain situations.

The next thing I'm interested to learn about is a secondary core ditch. I thought about getting a track hoe on top of the dam and digging down to the elevation where the lake seeps down to each year, and then going a little deeper. I thought it might solve at lesat one thing, and that is to see if and where the sand pocket is. If we find one we can dig all of it our and pack it with good clay dirt. If nothing else we can back fill it a couple of feet wide with good clay dirt. The sheer volume of dirt required would probably make bentonite cost prohibitive. The area would be at least 200 feet long, 10 feet deep, and about 2 feet wide. That would be a lot of bentonite. Bentonite and pond seal would be fine for a shorted length.

I also thought about getting the track hoe to start on the water side of the levee at the peak water line and dig the core ditch from there. Packing it with clay dirt might seal it off before the water got to penetrating too much into the levee and finding more ways to seep out. I would also require less digging and less fill dirt.

In essence, this would not disturb the original core ditch, nor be right on top of it. It would be a secondary core ditch a few feet closer to the lake when it's full. I suppose a pond liner could be put in the ditch also if that might help more.

Any comments, suggestions and/or ideas will be appreciated.

Pictures of the levee and lake are in the other thread abuot hte pond liner. I'll see if I can link something here also.

don't know how this slipped through the cracks, experts?

i have always succeeded in fixing a leak with a secondary core ditch assuming the pond was cored the first time because most of the time i dont know if it was or not. i usually do it on the backside of the dam starting at the high ends of the back face working down. this way i can tell where the leak originates. if you start at the bottom (lowest elevAtion of back toe) and see water you might have to chase it up to higher elevations on the backtoe or backface to see where it is actually coming from. i also usually make a flat spot about half way down the dam height from one end to the other for the trackhoe to work from. this allows me to go deeper with a core if neccessary which usually is the case. going down on the front of the dam like you describe is better but i usually cant do it because of mud. good luck to you
and from past experience and goof ups on my part you cant always depend on the elevation the pond leaks down to to be the problem spot i have found it to be up to 8 ft below that elevation. i reckon its pressure related at times and when the pond gets low enough there is not enough pressure to force it out anymore. this is why i dont start on top of the dam. i start a little lower depending on dam height so i can go a little deeper if need be. i also segregate the good dirt and the bad while digging putting only the best back in and spending a lot of time packing it with the bucket on the way back in

under the thread building a easy pond i thought you will see a pond that i believe would have acted like the one you describe. its not quit half full now but i have faith in it not leaking after taking the core down 10 + feet. veins of sand surrounded by good clay can be quit the pain to detect and seal off

THanks Tim. After many weeks of studying the site, consulting with people experienced in these things, allowing the lake to seep down naturally till it slowed down, consulting aerial photographs, old construction pictures, and then draining it another 5 feet, we began work today. It will be months before I can tell you well this is going to work, but at least we're trying something different.

We can't detect any reasonable evidence of a seeping levee. It's all bone try and has been. We calculated that the lake was seeping about 30,000 gallons of water a day, maybe more, maybe a bit less. There is just no evidence of that amount of water getting through the levee. If 30,000 gallons was going through it would have blown a hole in the levee long ago. Water is not surfacing anywhere downstream of the levee either. None of the pasture is wet or mirey for a half a mile or more till the creek leaves my property.

The contractor has fixed leaky lakes before but does not claim to be an expert in this speciality. Still, he felt we should start digging near the emergency spillway and dig a trench for a good ways to see what was down there. He has a trackhoe that will dig probably 15-20 feet deep and we went about 15 feet, using a bucket 4 feet wide. He may have been right. Just under the topsoil layer about a foot or so down we hit good hard red clay that was almost like concrete in places....then a huge sand pocket. It was about 4-5 feet in depth and about 30 feet long. Just pure sand. Then we hit red clay again. Above the water line was all red clay. We then took the backhoe and raked tons of that hard red clay and had a big John Deere with a 17 yard dirt pan and also a bulldozer and backfilled the trench. The trench was about 100 feet long, about 15 feet deep, and 4-8 feet wide depending if we doulbe dug it wider where the sand was. We also had a bulldozer and backfilled all of this, then kept scraping good red clay from above the water line and plated over the whole thing about 2 feet deep. We only hit that one sand pocket, but it was a doozy. He said that no doubt a sand pocket that size could suck out 30,000 gallons of water a day.

We are going to plate over part of the area that will be on the bank side of a cove, even down where the water will be 4-6 feet deep. Tomorrow we also plan to move directly across the cove to the area I hit sand with a probe and see what's down there.

That's the latest upsdate. I should know my noon tomorrow if there are any other big sand pockets to core and pack. I know that liners and bentonite and pond seal are excellent for a lot of things. This project has gotten way beyond the economic feasibility of any of that now. He brought some big equipment and we're moving an incredible amount of dirt and covering a lot of ground (literally) in applications that just would not be very practical for any method other than what we are doing.

I'll keep you posted. And thanks for all the suggestions and encouragement.

BillLake

Bill,

Good luck and it sounds like you are going about this as logically and intelligently as you can. Those sand lenses can be a real pain. Even in my area where we have clay deposits as deep as 200 feet due to prehistoric glacial action, occasionally you will run into sand lenses.

I dug a pit for my well distribution box (where I can feed water to each or all of the four ponds on the property with gate valves), and there was a perfectly round pocket of sand in the side of the pit. Fortunately I was putting a liner in the pit, however it's not unusual to have water elevate the liner when the pit is low of water, probably due to this sand lense bringing in surface water.

The way I understand it, up here is, the sand lenses are glacial streams where sand was deposited, but could be wrong.


What's really cool up here is on a couple of occasions that I know of, two different well drillers have brought up wood shavings from around 100 feet which indicated they are drilling in to a tree which had to be from the last ice age about 10,000 years ago. I find that very fascinating!

It's incredibly fascinating! My contractor was dicsussing in very general terms today about land formations and how they occured over the thousands of years. It's also amazing to listen to water well contractors talk about the weird things that water can do underground.

This update pretty much finishes up the project. We dug and back filled a core ditch as I mentioned above. This would be on the NW corner by the emergency spillway. The contractor said he would guess the sand pocket was about 4-5 feet deep and about 30 feet long as I mentioned above. We then plated over it with about 2 feet of good clay soil and covered that whole area from the water line out about 50 feet, totally covering all the suspect area. We extended that 150 feet or more I would guess down that side of the cove.

Today we went to the opposite side where I hit all the sand with a probe in late summer. I predicted it would be a solid sand vein all the way. It wasn't. It had a layer of fine white sugar sand on top for 2-3 feet and then good red clay. I couldn't have asked for another better underneath. We didn't find one suspected trouble spot in maybe two hours of trenching. We trenched about 125 feet and stayed in red clay all the way. We went down 8-10-12 feet in some places and stayed in red clay. We also spot checked some other areas and always hit good hard red clay every where we went.

We also checked an old beaver run in the back of one cove that would be about two feet under the water line when the lake is full. I don't have a feeder stream coming in so the beavers did that a good while ago and left. The tunnel was fairly shallow and not much to it really, and even if it had led to a sand pocket the whole deal would have been too near the water line to have caused any significant seepage. We saw no evidence of that whatsoever. We excavated all of that and it just made a shallow circle and came back out. We dug all that out and packed it good with clay.

Other than the shallow coves I've now cored the rest of the lake's water line. We did some in 2008 so we were eliminating suspect areas even back then.

We rode around it and in it on four wheelers, walked where we could, and spent the morning doing this. We didn't miss a visible spot. No evidence of any seepage on the lake floor. No sink holes, no mysterious low places, no nothing like that.

I asked time and again if there was any other pre-caution I could take while he was there with the big equipment. He said I had done practically all I could do other than just drain it dry and plate the whole thing. We decided to let the dirt pan take some more dirt farther into the cove on the side where the sand pocket was, and that will make it a solid plating another 50-75 feet.

I've watched and thought for two days and I can't think of anything else either. I think I'm going to keep them there till noon tomorrow and we might haul more red clay to the bed of that cove, but when we dig in the cove we hit clay, so I just can't think of anything else we could try.

We calculated the water loss again. My well does 60 gpm which is 86,400 gallons per day. When I turn it off the lake seeps about half that rate until it gets to a certain point and then it stops. This stopping point appears to be at the bottom elevation of the sand pocket, about 6-8 feet below the water line when it's full. The lake drops about half as fast with the well off as it rises with well on. So, we figure 25,000 - 40,000+ gallons a day would have to be going somewhere, and my contractor says that the 5 x 30+ sand pocket could easily do that. He owns a huge sand pit in the neighboring county and has told me quite a few water and sand stories this week. Some of it is just baffling to think what water can do underground. The water is naturally running in that direction to the levee and he thinks it hits that pocket and then runs on into the hill and may hit a deeper pocket and just goes where it goes with no visible evidence within my property, which extends over half a mile to the highway.

So gentlemen, you are my witnesses. I have done everything humanly possible short of plating the whole lake bottom. I've researched, I've studied, I've consulted, and I hired the best dirt man I know and we both agree there's not much else to do but hope for the best. I turned my well back on today. I calculated that it takes around 7-8 million gallons to fill the lake, so it will be running for a while. I also noticed the last time I filled it from this low of a starting point that it also rises pretty fast till it hits that same elevation where we found the sand pocket and then the filling shows down dramatically. We knew the water elevation the lake naturally tends to settle at is a certain set point, and the bottom of the sand pocket we found is approximately at that elevation, within a few inches. I'm still so cautious as to claim a solution until I fill the lake that I'm still leaving open the possibility that it's something else. But if it is it's going to be so deep and complex that nothing short of a solid plating of clay would fix it. We spent a lot of time in the lake bottom and examined every square inch visually and tested probably 300 feet with trenching. The only suspected problem we found was that sand pocket. I hope we finally got it right.

I wanted to have a secondary project that I knew would work and improve things in general, regardless of what the lake does. We cleaned off a lot of brush and made the hills look really good. Now I have 3-4 acres I can plant for deer and have it right across from the center of the levee so I can see them. I took back at least 5 acres of land total just with brush clearing. We pushed all that into the lake bottom so now I've increased my underwater cover several times over.

We also hauled some more dirt to the backside of the levee and now I'll be able to mow more of it in the conventional way. I also got to haul more dirt to level out some ground behind the cabin where I can now put another shed or workshop if I want to, and we got rid of some dry land brush piles along the way. So, at least I'll have made some permanent improvements I can enjoy long term regardless of the lake and we were able to work most of this into the project. We had basically finished the lake project shortly after lunch so I had them fill out the rest of the afternoon with some of these long needed and long wanted improvements. If the rain holds off we might go till noon tomorrow to clear some fire lanes and take back some corners with a little light brush cleaning. Then it's going to be a long wait and see until the lake is full again around January, and then to see how well it holds on into July.

Thanks guys. I'll probably add to this as a later follow up, but it will be months before I know anything on the holding capacity. I hope I hope I come back in late July and say....It Held!

Thanks again...and PRAY that this works!

Bill

Bill:

It sounds like a well thought out plan. I think you did everything that you could and I believe it will hold. You might see some water loss (or a slow down in the water filling the pond) until the new dirt is saturated.

Keep us posted. Do you have any pictures of the work? We like pictures!

Thanks! I've probably taken 200 pics of all angles, positions, and lighting conditions. The pictures I took the last time it was drained helped with this project, so I wanted to be sure I had detailed shots of the whole lake this time.

I never could figure out how to post pictures here. I still have a link to some earlier pictures and I'll see if I can add some more. I'd rather just post them here if anyone has some additional explanations on how to do it.

Personally, I've found it easier to use my photobucket account and copy/paste a direct link. There is a how-to thread here somewhere.

I did the same with Flikr. I'll sort through all these and pick a few to link to. Might be this week-end.

Thanks again.

I've had the well on a few days now and the water is rising really good. I still have a ways to go to cover our construction area but since my last post I think I may run the well untill the water is about 2 feet deep over the entire sand pocket area. I asked the contractor how deep that particular track hoe would dig and he said around 32 deep and we dug about 20 feet in some places around the sand pocket. The area directly across from this is where I suspected most of the sand to be, but as I mentioned above I was wrong. We hit some fantastic red clay about 2 feet down and we stayed in it as deep as we dug. Before treated the sand pocket area first and the contractor wanted to dig really deep in case there was a sand pocket directly across (where I just described) and that it might drop indefinitely and theoretically the water could run back into the hill, drop, and follow a sand vein under the cove which most likely would have connected with the sand pocket we found. SO...he made the core ditch especially deep at the sand pocket to solve both problems --the sand pocket itself and the possibility of the water flowing under the cove in the same sand pocket. Thankfully we didn't find sand on the opposite side, but we should be double covered where we found the problem.

I think I will raise the lake about 2 feet over this whole area. We plated it with clay about 2 feet thick in a very wide band and went probaly 150 feet or more down the cove tikll we hit the area where the shallows are when it's full. I think I'll turn the well off here and punch a yardstick into the mud and see if there is any significant seekage. If there is I can drop it back down and maybe plate some more in the other cove if necessary. This will save from filling it full and then waiting till late July to see what it does.

I've got a ton of pictures but I have more to make, so I'm going to wait and do it all at the same time.

Thanks again.

Good luck. I hope you have the seepage problem fixed.

Hi eveyrone, I'm back for an update.

The water is rising a little better than expected despite lack of rain, but the well is running fine. We have rain in the forecast 11-2-10 and the lake has risen almost to the elevation where we did the work. It will have to rise a few more inches then it will start backing over a flat shelf, then up to capacity. The flat shelf is where the core ditch is and then we plated over it with clay and smoothed it up. I'll have a big long drop off there, which will be good for fishing. I also added a lot of brush, probably increasing the amount at least 10 times. That lake just never had a lot of cover, but now it does.

I went through a lot of pictures and picked about 20 to show here. I just got them re-sized and uploaded to my Flickr account. I hope this works.

Thanks again for all the suggestions and encouragement. This was a hunt-n-find-n-fix, so we dealt with things as we found them. Some of you mentioned wanting to see some pictures so these give a pretty good idea of what all we did. If you have trouble getting to my Flickr link or if you have trouble viewing, let me know and I'll see what I can do to fix it.

http://www.flickr.com/photos/tomatodon/sets/72157625295164032/

I hope that works! And thanks again!

Back again. I closed my Flickr link and re-opened it from here, so the link I posted above should work. I corrected some typos, but each picture has a brief caption below it. There is a "Next" button with an arrow in the upper right of the picture area to help you scroll through them. I added 22 photos, so that should give you a pretty good idea of what I did, and the progressive stages of construction. I may add to that, but for starters there are 22 pictures.

All of this work was done the week of October 18, but I think there is a time stamp on one or more pictures that says "11" for November, which is wrong. I used two cameras and obviously I didn't have the second (new) camera's time and date set correctly.

I didn't note the specifics of the equipment but I can get that info if any of you are interested. All I remember is that the contractor said that the track hoe could dig around 32 feet deep and the John Deere tractor was pulling a 17 yard dirt pan. The track hoe bucket was 4 feet wide I think. We dug wider than that where we hit sand, but the rest of the core ditch was about the same width as the bucket, so the core ditch is basically 4 feet wide when we had a good clay backing, and 8 feet wide when we dug out sand and packed with clay.

The link works for me when I click it here in Pond Boss. Let me know how it works for you.

Here is the link to the previous set of photos, taken to show the lake draining and during low water stage after it had seeped down in late summer to the evelation that it usually stops. These were taken to show the lake and terrain before I began construction.

http://www.flickr.com/photos/tomatodon/sets/72157624817825264/

Thanks again!

PS. I'm hoping by 11-10-10 that the water will start flooding over the actual construction area where we suspect the leak was. When it gets over that a foot or so deep I plan to cut the well off and see if it seeps down any. If it does I can drop it back a little and try to plate over other areas with clay. But am hoping for the best and that we solved the problem. After at least 15 years of dealing with this I'm still praying we got it right this time. After this, we're running out of options other than a lot of clay plating.

Looks good. I'm assuming that the clay in the core trench was packed down with the track hoe?

Don't be suprised if the water doesn't rise as fast once it hits the newly constructed area. Those areas tend to soak up water until they are saturated.

Absolutely it will have to get saturated, even clay.

I hope this works for you Bill! You've definitely done your best and thought it out vs. the haphazard approach some people make in putting in a pond!

Definitely keep us posted!

We're getting that good soaking rain right now with some heavy showers mixed in. This will give plenty of water for all this dry ground to soak up. I hope we get 2 inches or more, enough to help the pump raise the lake since I have so little watershed area. We were so dry here our whole state was under a burn ban (brush piles, etc.) until November 5. Either way, this rain helps and the ban should be lifted by Friday.

Yes, we packed it with the track hoe bucket. The only other option was to dig the whole thing 8 feet wide and bring in a small packer that an operator could drive in the ditch, packing as it was being filled. I thought that was dangerous, having a machine and driver off in a 15 foot ditch and all that commotion might make the ditch cave in. So we packed it back all the way, but went a lot wider in the sandy area, and then plated over the top with about 2 feet of clay. It might continue to seep, but I doubt seriously it will be in that area. The contractor and I both closely supervised the digging and packing the core and we dug out a lot of sand and put back a lot of good clay, so it shouldn't seep.

Looking at those pictures as I was re-sizing them for the internet, I can tell the water has already come up a lot. I'm hoping this rain will put it up to the shelf and I will know soon how well it's holding.

Thanks again and will keep you posted. I assume you didn't have any trouble getting to the pictures.

I think you have it licked. Nope, getting to the pics was easy.

I added another section to the feeder docks on the levee, to extend it another 6 feet. Got the post in and plan to deck it this week. The water is raising back very well so far and now I can stand on the dock and feed the fingerlings. With the extension of the feeder docks, and another few days of the water rising I should be able to use the battery powered feeders again this week.

The water is now starting to slowly rise onto the area where we dug the core ditch and plated over with clay. I'm guessing it will be 2-3 more weeks before the whole area is covered. At that point I should be able to turn off the well and see if it holds.

Everything on schedule and following plans for now.

Thanks again. Will keep you posted.

"Bill"

PS. I see a lot of you listing the abbreviations of the fish you have. Some I can figure out, some I can't. Is there a link that shows all that, or can someone list them here?

In the old Lake I have Florida largemouth and also northern strain. Florida bluegill, redear, and a few crappie. In the new lake I only stocked black crappie, Florida bluegill, redear, and fathead minnows. As I remember, redear and shellcrackers are the same thing?

203 weeks! I must say you are very patient!

Just ribbing you. I'm sure you meant to type in 2 or 3 weeks!

Here's the list of acronyms. It's in the "commonly asked questions (archives)" portion of the forum, 2nd page.

Yes, 203 was supposed to be 2-3. The 0 and - are right beside each other! Dangp thet typoooss!

Thanks for the acronyms! I had no idea there were so many!

Water is creeping up more and more. Getting more pictures as it does.

Bill

The water continues to rise, and I continue to photograph and monitor the whole project.

The water is now above the level it was in September, the level it was due to leaking and late summer evaporation.

Previously it would rise evenly and fairly fast until it hit this point and then it would slow down. I have not noticed that this time. The water is now creeping closer to the spot where we dug the core ditch and there is visible settling of the ground here. I hope it settles, packs, and seals. So far so good.

I uploaded a few more pictures to illustrate this, found on my Flickr site:

http://www.flickr.com/photos/tomatodon/sets/72157625490961286/

This should be Set (C) November Water Level. If you have any trouble with the link, please mention it here.

BillLake, we all hope it seals well for you. Seeing visible settling means there was a lack of proper compaction though. We'll continue to hope for the best.

I agree. About all we could do is use the trackhoe bucket to push and tamp the clay in the ditch, which is OK, but not true compaction. But we did plate over it with a good bit of clay and also made the core ditch through the sand pocket extra wide, hoping to compensate for any settling.

So far the water is still rising at a steady rate, which hopefully means it's sealed, or is sealing off, without water running through the sand pocket. The water is getting to the right level to do that, if it's going to.

I'll keep you posted. I marked the water level yesterday, and today it made another nice little jump.