Our farm is in a long term drought so I thought it would be a great time to dig some test pits in the location where we want to build a one-acre pond. The site is currently in tallgrass prairie. I had quite a surprise since the NRCS soil data for this area was dead wrong. (It is usually surprisingly accurate). Instead of nice sandy loam grading down into clay loam and then reaching clay at about 8 feet, I hit almost pure clay! I am sure it will be great for holding water, but it is going to be a b*tch to dig. I dug through about 10" of good top soil and then into clay with very little gradational transition. I could barely dig this clay with my mini-excavator! (Deere 26G: 6100#, 20 HP, 24" bucket) I would scrape and scrape repeatedly to get just a 1/4 bucket. The bucket teeth would leave little trenches and I had to work to get the edge of the bucket to bite any material. As I got deeper in the hole, the clay did have a little residual moisture and was easier to excavate. I made it down to max. depth at 8.5' and was still in clay to total depth. My holes did not start seeping water as usual, so I know the drought has significantly lowered our groundwater table. I thought I wanted to excavate this pond during a drought, so I wouldn't have to deal with wet clay in the bottom of the pond. However, did drying out this clay make it MUCH harder to dig? The original plan was to get an excavator in the 170-200 HP range and pair it with a dozer to excavate and push. The spoils are going to be built into a berm immediately beyond the perimeter of the pond. (We have a nearby groundwater pond in a water-bearing sand that will be the water source for this new "sealed" pond.) I am strictly a "property owner" level of operator, definitely NOT a professional! However, I would certainly appreciate some "best practices" advice from the actual professionals - written up with enough explanation for newbies and rookies to understand. Questions: 1.) Can a large excavator (like a Cat 320 or 326) break out full buckets of hard dry clay? My experience is with excavators is strictly in the mini sizes. However, I have noticed that when I have grabbed buckets of wet clay in a very small mini-ex (14 HP) that the machine did not have sufficient power to break out that scoop. However, just moving up to a 26 HP unit, the machine did have sufficient power to break out full buckets of wet clay. My related question: When moving to larger excavators, do the machines have much greater breakout power relative to the maximum bucket sizes, or are most excavators of any size pretty well balanced between the power delivered and the matched bucket sizes? If the larger excavators have more "excess power" than the much smaller ones I am used to operating, would the excess power also apply to their ability to scrape and cut down into hard, dry clay, or would I just have a bigger version of my recent test holes where the digging was VERY SLOW going? 2.) For dozer ripper operations, what are the best practices for dealing with hard clay? I expect the only way I am going to be able to excavate this pond will be to rip the entire surface with a dozer, then excavate as deeply as I can work, and then rip it all again. This is not truly a "clay hard-pan" situation, but I think it is probably going to act like that material. Advice from the people that have dealt with that problem would be appreciated. Related questions: If I can get a Cat 326 excavator for this project, what size dozer would be the best match if the job is going to involve extensive ripping? I have done the highly unenjoyable job of auguring holes in hard dry clay, where the only way to make hole was to fill with water, wait, and then augur while the clay had some moisture in it. Would watering the clay surface at the end of the work day make it easier for the dozer to rip the pond area the next morning? I am sure you all can think of additional problems that I have not even listed. Any advice on THOSE problems would also be appreciated. (It is much easier to fix screw ups during the planning phase than it is during the construction phase!) Thanks, Fishin'Rod
I'm no operator but I have seen and dug through some clay on my own property. The size of the machine and the teeth you use makes a big difference. I borrowed the neighbors Cat 312C and put on pointed rock teeth. It broke it up pretty good considering it was as hard as concrete at the time. Ripping with a dozer with pointed teeth does well too.
Thanks Vetech, I learned one new thing today. When I rent a little excavator, I always have them put on the bucket size that best matches my job requirements. Never even thought to ask about the options for the TEETH on the buckets! Hopefully, getting the right ones will make a significant difference in productivity.
A 24” bucket on a 2.5t mini is going to be really tough going in hard clay, that should definitely not be your barometer of performance. A 24” bucket on a 6-8t excavator or full size TLB should easily get a full scoop in anything but the worst conditions. The full size excavators have much greater breakout force, look up the specs and do the math for a given bucket size. With that being said, I try to avoid working in the conditions you have. Its really hard on equipment, burns extra fuel and wastes your time. If it’s one of those jobs that MUST be done when it’s extremely dry thats one thing, but building a pond isn’t necessarily so.
If it really is graded by depth, I suggest you do not mess around with excavators at all, to begin with. Get the biggest dozer with rippers out there for a day or two and rip and push off the top hard. Once it gets easy send him home.
Thanks MG. I had no idea how my experience in little excavators scaled up to big excavators. Was hoping they would perform better breaking out that hard clay. I know the spec numbers look MUCH better for the big boys. However, real world experience beats "numbers" in most situations where the forces can be observed. As to your second paragraph, picking the best soil moisture conditions was also part of my set of questions. However, when the groundwater returns to its more typical elevation then I would be working in wet clay in the bottom of the pond. (And I know how much that sucks.) In your opinion is there a Goldilocks scenario for the moisture content? (There is no hard deadline for this project so I can pick the conditions to some degree.) Is digging a water storage pit beside the pond project and spraying the clay not going to work because the water would just pool on top and get very little depth of penetration? I think I am going to need a water pit anyway because when I scarify and compact the material for the final contours, this clay is so dry I would have very poor compaction.
I built my pond recently and used my NH 555E to do so. I have a 36” bucket and while it takes a while, I had no issue. My ground was solid clay from 10” down all the way to my bottom depth of 13 ft. We had a d4 that helped push and I dug the dirt into piles. With a bigger machine or excavator it would have went faster, but it’s all about not biting off more than the machine can handle. I think a dozer with a ripper is overkill. Also at least in my Ohio area, I’ve never seen one with a ripper.
Remember, clay doesn’t absorb water very well, so spraying it is just going to cause a slippery muddy mess. Leave it dry and bust it up. When I did mine I thoroughly enjoyed watching the clay flake off into little pieces.
Thanks for throwing me that curveball to consider for this project! I thought this project would require an excavator and dozer working in combination since I was going to be working in some wet clay at the lowest pond bottom elevations under "normal" conditions. However, we are in a pretty serious long-term drought and our little creek has gone dry. My test holes were not weeping any water at total depth. Would it be possible to do this project with just the big dozer? Just keep ripping in moderately level passes as needed and then push out of the pond basin? My grades will be ugly anyway. I was going to come back in with a tractor with box blade and a sheepsfoot vibratory roller to do the final grade and compaction. P.S. To add additional information related to your project proposal: I have seen many photos/videos of people that have constructed beautiful dish pan ponds. I do NOT want that! Bass like hanging out where there is lots of vertical structure. I am planning on excavating much of the bottom down to around 8' deep (below normal pool water level). I am then going to cut slots 4' deeper and leave all of those clay benches in the pond. That will be fewer total yards to move and more structure and features for the fish. My pond is going to be ugly before the water fills it, but hopefully the aquatic creatures will think it is beautiful afterwards!
Take some pictures of the dirt so we can see.
EDIT: Nobody answered your questions. 1.) Can a large excavator (like a Cat 320 or 326) break out full buckets of hard dry clay? That is a hard no. 2.) For dozer ripper operations, what are the best practices for dealing with hard clay? Keep ripping and dozing until it gets to greasy make headway, then excavator toss it as you work your way out. If you don't plan on doing any maintenance work your plan is fine. If the material is as hard as you describe, then a dozer with rippers will be faster than any excavator. There is no magic to hard excavator digging, unless you have a single shank ripper for it. I have dug in plenty of hard clay, it feels more like you are machining it. The teeth get too hot to touch and you change them out every other day in the hard.
That is part of my problem - I have no good barometer for what actually constitutes "overkill". I will say that I have dug lots of test pits and expanded or deepened our old dragline ponds using a mini-excavator. I have never before had any trouble whatsoever digging a little strip trench down to the max depth of the machine I was using. However, I always had some soil moisture when I got down to the layers that were at least 80% clay. I deliberately tested one spot on high ground last weekend. I estimate that it took about 40 minutes to make 3 feet of depth in the clay after I scraped off the top soil. I gave up on that hole! I guess I need to ask the forum: Is slowly desiccated clay much, much harder than clay with a decent moisture content?
Thanks skyking, your edit items are spot on for clarifying my problems! There are definitely not any money trees growing on our property. A one-acre pond project where the work is so hard that I am replacing the excavator bucket teeth daily is not within our budget! When you were "machining" out the hard clay on your excavator, was there abrasive sand mixed into your hard clay, or was it merely the heat and pressure of the hard work that was causing the severe tooth wear? Also, when you were on excavator jobs that were THAT tough and the supervisor finally had to relent and bring in a dozer with a ripper - could the dozer rip that material in one pass with a standard three-shank ripper, or did they have to go down to the single, deep ripper? (All of this ripping work is going to be on level ground. If I set my ripper bar depth correctly, and my shank angle correctly, is "hard clay" still easy work for a large dozer? Are the single shank rippers for breaking permafrost and rock ledges?)
Pictures of the material wouldn't do it justice. If my kids had been "helping", I am sure they would have filmed a comical video of my pathetic efforts scratching through that hard clay. I did take multiple samples. I am going to send them to our ag university soil lab and get a particle size analysis done. However, I frequently got out of the cab and worked samples through my hands. Only one location had any significant sand in the clay samples. I think the really hard crap was 90-100% clay content!
We had to dig it with excavators, 34' straight down inside of H-piles with lagging. Not sand just hard work. Those tooth grooves are really annoying eh? "There are definitely not any money trees growing on our property." All the more reason not to mess around with the wrong equipment and expectations. Do the math: 1 acre is 43000 square feet, 8' cut is 344,000 cubic feet. If you did an 8' cut and moved the material away, that is 13240 cubic yards. 1324 solo dump truck loads of material. Did you come up with those numbers? you don't need to dig 8' to make an 8' pond. The spoils build the berm around it. It is still a bunch of material. Try getting a quote from somebody to get an idea of what the pond is worth.
Your mini x was 20hp you said. My backhoe is 78ish. That’s like comparing a Chevy cavalier to a corvette and expecting the cavalier to win a race. Not going to happen. Can it dig the clay, yeah sure but as you said it’s going to take 40 minutes. I used my backhoe and dug for 4 straight 8 hr days to HELP with my pond. I wasn’t using it to be the main piece of equipment. Clay is hard, especially when it’s virgin ground. You need to get a bigger machine flat out. Something around 100hp minimum. Will a dozer work, sure. Will an excavator work, absolutely. But you need to pick something that will work for you and go from there. Also consider if someone is going to help. If I didn’t have my dad working along with me, it might have changed how I built my pond.
We need more info on the pond itself. Is it going to be a completely dug pond or can you build a dam across a low area? When we build ponds around here it’s always daming up a creek or a low area. In our area a pond of any size is built with dozers and scrapers. Some guys use an excavator and trucks but that takes a lot of labor to do efficiently.
I was trying to simplify the scenario to keep the questions and replies directly on point. However, you guys are too sharp for that, you want to analyze the whole job! (Which of course is the correct way to do it.) The pond will be roughly "delta" shaped since there is a little bit of a sloped bank on each side in the current topography that matches that shape. Current working proposal is to strip and stockpile the top soil just beyond the boundary stake line. Will then scarify the top of the clay horizon and start building the berm with clay spoils from the pond basin. Will spray light water on the bulk portion of the berm and only do light compaction of the clay with the dozer treads. After reaching the final configuration, I will scarify the pond bottom and the sides. Will then water to the proper moisture content and beat the hell out of it with the vibratory padfoot roller until we walkout the sheepsfeet. As suggested above, I was NOT going to dig to total depth, but rather do some version of excavate six feet deep and build a clay berm six feet above grade to get an average water depth of 12 feet. There will not be any "dam" per se. The final pond will be built above the surrounding ground level and be supplied with pumped water from a nearby groundwater pond. (That pond is too variable for recreational use, but all of our wildlife love it!) There are no nearby property line boundaries, utilities, or anything of that nature that complicate the design. If I screw up my math too badly, then I can easily make the pond slightly larger or slightly smaller to accommodate my error. The pond shorelines will be cut at around a 1:3 slope. I will make some steeper cuts and even some vertical banks in the deeper portions of the pond. More questions for the forum: What fluff factor would you estimate for dry clay to calculate my spoils volume? My "final seal" on the clay berms above the original ground level will only be approximately a 6" compacted clay blanket. Will that be sufficient? (See the attached drawing of the berm profile. There will be a lot of clay bank behind the final blanket to help seal the berm.) The final question is really the most important for the design. My current calculation estimates that the spoils berms will have a base that is 60' wide and a flat top of 18' for a design berm that is 6' tall. How high would you build the berms using a D6 dozer? Or phrased another way, how much would you push out compared to pushing up?
I think you’re over thinking some of this. As someone who designs, builds, and repairs ponds here’s my take on it. First off, wait until conditions are better. You’re beating your head against the wall with all the extra steps, ripping, watering fill etc. We try to do most of our pond work in August and September when it is dry, but not during a terrible drought. Your design of the dam (berm) looks good although you probably don’t need a full 18’ across the top unless you are just trying to get rid of fill or are using it for a roadway. You need to cut in and compact a core trench the entire length of your dam, compact in lifts the entire dam. Don’t mess with the bottom of the pond, a smooth cut from a dozer blade is going to seal better than ripping and recompacting. You can go over it with a compactor if you want but ripping first is counter productive. Figure minimum 1.25-1.3 loose yards vs bank yards.
Thanks MG! Valuable to have an actual pond builder in the replies. All of our local guys that are good enough to build ponds that don't leak, are ALSO good enough to land big construction contracts at this time and our pretty much tied up long term. The only places I have where the topography creates enough watershed for a typical pond with cored dam lie in the floodplain so I cannot do any dirtwork in those areas. The 18' wide "top" to the berm is just based on my calculations of the volume of spoils. There are a lot of spoils for an excavation type pond compared to an embankment pond! I agree that I am "overthinking it". However, it is much less painful to me to have people point out bonehead moves while still on the forum compared to me finding out something was boneheaded after the dirt was already moving!