Hand-dug pond progress

First post! I wanted to share progress on the first of a series of hand-dug ponds in soil that is rich in organic matter for the top foot and a half, and after that becomes fairly compact with decomposed granite being a heavy component and certain areas having granite boulders underground. Area is near "Burrough Valley" in Central California foothills, with my lowest point being around 1500ft elevation and my highest point (majestic and biodiverse granite mountain landscape) around 1800ft. The topsoil is hydrated now so I have chosen a point with little to no tree roots and very few rocks, at the highest point of the "workable" (non-mountainous) portion. Hoping to never have to pump much out; I plan to do nothing that would stop it from being habitable for the local wildlife. It's the first in a series of ponds that I'd like to each be as close to 1/10 acre as possible; the parcel is 14 acres with about 7 of them being the aforementioned mountainous part.

It's about 20x10 feet right now after four days (focusing on digging down for the moment), and I want this to be at least 70x50 when finished if possible. Won't be upset if it can't be that big! Loving the process of hand-digging, including
-the critters saved unharmed such as tarantulas, millipedes, centipedes, and other helpful stuff for my area
-I'm lucky enough to have some friends helping me out certain days, it's a great time
-so satisfying to do by hand and exercise is good too
-I can't afford to hire an excavator at the moment and even if I could, I'd still want to hand-dig if at all possible :)

Anyway, I might ask questions that come up, but I feel like many of us enjoy seeing another hand-dug pond, either way!

Jonah,

Well that is an ambitious, long-term project!  I congratulate you on literally taking matters into your own hand as opposed to using machinery.  I can guarantee you that if I were digging a pond, I would use machinery, but I like that you are not.

Out of curiosity, how deep is your pond and how deep do you expect it to be?  If I were to guess right now, I would say it looks like about 4’ deep.  I am just curious as to how big/deep a pond can pragmatically dug by hand.

Good job!

Eric

4ft deep is plenty for a wildlife pond, although it may only end up filled seasonally. It is hard to tell from your photos, but is it well placed to take advantage of surface flows when it rains?

Jonah,
I take my (figurative) hat off to you! Welcome to Permies!
That is a great project. I don't mind the digging so much as the earth moving - for me that is the hard part: wheeling across rough ground. I have ambitions to dig a large pond myself, but other priorities and the fact we have virtually no clay locally puts me off a bit. Luckily my husband persuaded me that it was the law that everyone had a digger on Skye, so we do have a little Yanmarr 2.4 ton to make the digging bit a bit easier too.
I can see in some of the pictures that you have a little water standing there. Is your soil pretty clayey, or do you have other plans for lining the hole?

Cool project.

Your picture IMG_6122.jpg reveals a small valley in the background, have you considered building a pond there by making a dam?
Did you do a mason jar test to check the clay content to see whether you can seal it at all?
It is advisiable not to have any steep areas like you have now, because it is harder and sometimes even impossible to seal that.

Eric- Thank you! I am thinking it'll likely be about 4ft deep when finished, at its average "water-holding" level, but the bottom of the pond remains to be seen as I have funky downhill-ness to work with and will be building up and compacting the downhill side to retain the previously-downhill half of the pond, if that makes sense! More pics to come, which will illustrate what I'm talking about with this.

Michael- I imagine you're probably right about it only being full seasonally, unless in the future I decide to get a "proper" liner for it and shade parts of it really nicely, like I'm thinking about if funds line up later. Funds or not, plants will help me out as much as they can! In terms of surface flows, yes, it could be said to be at the bottom of the mountainous area, so I'm optimistic about catching surface flows that would have previously rolled on by, although it's been years since the nearby seasonal streams have visibly run according to the neighbors who've been there a few decades longer than I have.

Nancy, thank you! Yes, the wheeling it over the rough ground is a serious workout especially in this wetter season! We got a gentle drizzle of rain the night before I went up and took those pictures, I have very little clay there myself, but am optimistic about either natural methods when it works out for me to have something like ducks to seal the pond, or an abundance of clay trucked in from a friend or something, or if that doesn't work out maybe I'll buy a liner sometime. I sure wouldn't say no to a little excavator and I'm sure I'd end up using it a lot in reality! But, I'm thoroughly enjoying making what I can with stuff on hand for the moment :)

R. Han, thank you! I was just thinking earlier that it's high time I do a mason jar test on this area, planning on doing one soon. I am thinking I'll have steps leading downward from the high end of things to make it very secure against erosion, in a way so that rain can flow to the center/bottom of the pond which will be downhill from where it is now, although that may be hard to imagine until I post more pictures. But I acknowledge the difficulty in sealing the high parts and will continue making slopes as gradual as I can for sealing, for plants and for erosion control :) That valley is a bit of a thoroughfare for salamanders and other critters actually! Noticed all kinds of critters meandering down the dry streambed that's in that valley (kind of the biggest of the dry streambeds on my parcel). So, while I totally could make some kind of dam, for now I've chosen to simply be near that dry bed and provide a bit of a rest area for things meandering their way down if I can. There are some other promising valleys that I'm eyeing for future ponds, looking forward to sharing photos!

Small but cool updates: did the bentonite "bucket test" some have certainly heard of; I heard about it on Permies originally: drill 25-ish holes in the bottom of a bucket and fill with layer of native soil, then add bentonite above it covered in another layer of soil until it seals and no water drips through over time. I did this and tried 3lbs/sqft at first. Too many drips for a pond that's supposed to hold water, so I went to 3.5lbs of bentonite in the bucket (I am using 40lb bag Saf-T-Sorb from Tractor Supply @$7.87 a bag) and that amount is working perfectly, 26 hours later! Not ready to be buying large amounts of bentonite yet, and the pond digging still has to be done, but it's encouraging to know.

Another thing: Realizing I should not put steps on the side, at least not as dramatically as I have one going at the moment- an issue R. Han made me think about more carefully. Bentonite would slide down for sure, I can see how even after just working with a small amount.

Question for anyone who knows: with a bentonite-sealed pond, I'd like to place a couple things in the pond like a couple big mossy granite rocks (already on my parcel) and maybe a downed tree for aquatic life, but I'm worried about piercing the bentonite layer that I'll have worked so hard to keep solid. Can I get around this by placing a good sized layer of the native earth on top of the bentonite, and then putting stuff like rocks on top of that earth? I think that should work, right? I know some of the native soil is traditionally tamped/packed on top of the bentonite anyway, as I did for my bucket test, so thinking it should be fine to simply put a bit extra as a cushion for objects sitting above the bentonite.

I'm hand digging a pond as well, although I've got a bathtub sunk in the middle, so I can get a bit of extra depth in the middle without such tapered sides the whole way. Mine will be smaller than yours, since I'll be growing edibles and want to be able to reach most stuff from the edges. It'll be about 4' deep in the middle so I can have a few goldfish for mosquito control and not have them freeze over winter.

Did you tamp the soil in your bucket when you did the perc test? That makes a huge difference.  When I did mine, I used soil from my pond hole - silt with no organic matter. At 3lbs clay/ft2 mine leaked very slowly. I didn't tamp it at all.

We got the bathtub lowered in and I filled in around it. I was planning to tamp the soil under the drain hole really well and put in a plug of bentonite once I finish digging the rest next year. After we got some rain built up in the tub, I could see I could probably get away without doing it, though. The silt under the tub is already so hard packed, it doesn't seem to be leaking at all. So packed silt > unpacked with bentonite layer. I'll still do the clay plug, just to make sure, though.

I would do a layer of native soil on top of the bentonite for protection. That's what I'm planning on doing anyway 😁
I was actually planning to tamp native soil really well, add bentonite layer, add bentonite and soil mixture layer, tamp well, add final layer of sand and small rock, tamp gently.

I'm fully expecting gophers to tunnel in from the sides and ruin the whole thing anyway. They ruin everything else I do, why not a pond too?😂

Good luck with yours!

That's an exciting project, Jan! Thank you and good luck with yours too! Many burrowing critters where I am too... hoping that various leak-sealing methods like the "sprinkle method" of dumping in a bag over the leak and having the flow plug it up, will work to eventually create a clay layer that they're less interested in :) purely wishful thinking/guesswork, I won't be surprised if they continuously mess with it!
Definitely planning on a thick layer of native soil above the clay now, not that that'll dissuade them.

You know, I tamped it well, and 3lbs didn't work while 3.5lbs was clearly a different level! One other thing to consider for me is that when I added the 3.5lbs and put the bucket test back together, the soil layer at the bottom of the bucket mixed at least a bit with the clay layer. I've seen people on pond sites say it's best to do a "blanket" of clay and only do the "mix with native soil" method if one's soil requires it, but there's a chance the mixing played a real role in the seal with the .5lbs of clay added the second go-round.

Attaching a couple pics from the end of day 5 of the digging! And bonus trail cam shot of one of the bobcats that sometimes passes through- I'm lucky to have native wildlife to manage the gopher/ground squirrel front!

Pictures taken yesterday, moving more topsoil! More of a terrace than a pond at this point; mostly focusing on making sure to keep sides sloping super gradually as I've realized just how important the gradual slope will be in terms of keeping the bentonite where I want it to be.

Update on bucket test: no drainage out the bottom still- emptied the water so I can see how it performs after drying fully and then being re-filled.

How deep are you planning to go?

John, I'm thinking when it's finished it'll be an average of 3-4ft! But before it's done, the "center" of the pond will move gradually downhill as I dig, if that makes sense. I have to move earth down the slope I'm working with, and compact everything well, moving topsoil away to sort of create the area where the final pond can be. Top edges will stay looking similar to how they do now (very gradual slope so they can still hold clay), bottom edge will continue to be expanded down the hill.

Hello,

So With this pond, Do you know what your doing design wise?
I am not trying to be rude, I would just like to know what kind of berm is going to be at the lower section!

for me the grades, and levels of the earthworks in the images appear Steep!

I figure its work asking and trying to understand!

Regards,
Alex

Alex,
I have a plan, yes!
The berm will be made out of the earth that I'm scooping out as I go "downhill" with digging- the shape of the pond as it is now is not the final shape, and the "higher" edges may end up being simply additional catchment for the pond going downhill. That's why I'm making sure to start by having the upper edge very gradually sloping, so it won't cause erosion. The "bowl" of the pond will not extend to the piles of soil I'm compacting downhill from the pond- the process now is similar to a terrace with regard to moving earth, and I am prepared to build/move the "final" berm to be wherever I need it to be, using the soil I've moved. The variables/what remains to be seen is how much of a berm can be created with the excavated soil, and how much lower on this hill I'll be able to go. I won't be disappointed even if the final area isn't much bigger than what you see now.

I bet this is all very tricky to imagine without showing exactly how it'll be done, hence the thread to share the pictures as I go. :) Bottom line though, nothing is final at this point in terms of the way the earth piled at the lower area looks, or the size of the hole being dug. When I first had the idea for a pond here, I had a more rigid idea of how big it should be, but realized by now that due to this hillside, the size and shape is variable depending on reducing erosion of walls and halting any slippage of bentonite clay.

Jonah Bassman wrote:Alex,
I have a plan, yes!
The berm will be made out of the earth that I'm scooping out as I go "downhill" with digging- the shape of the pond as it is now is not the final shape, and the "higher" edges may end up being simply additional catchment for the pond going downhill. That's why I'm making sure to start by having the upper edge very gradually sloping, so it won't cause erosion. The "bowl" of the pond will not extend to the piles of soil I'm compacting downhill from the pond- the process now is similar to a terrace with regard to moving earth, and I am prepared to build/move the "final" berm to be wherever I need it to be, using the soil I've moved. The variables/what remains to be seen is how much of a berm can be created with the excavated soil, and how much lower on this hill I'll be able to go. I won't be disappointed even if the final area isn't much bigger than what you see now.

I bet this is all very tricky to imagine without showing exactly how it'll be done, hence the thread to share the pictures as I go. :) Bottom line though, nothing is final at this point in terms of the way the earth piled at the lower area looks, or the size of the hole being dug. When I first had the idea for a pond here, I had a more rigid idea of how big it should be, but realized by now that due to this hillside, the size and shape is variable depending on reducing erosion of walls and halting any slippage of bentonite clay.

Isn`t this just an earth works calculation of volume. or is this about discussing how to keep a berm from washing away,



It seams like a great learning experiment in soft engineering!

I will keep watching, Your journey!

Regards,
Alex

I plan to basically see how much volume I end up with after doing everything necessary to make sure the dam wall is securely constructed, so both of those concepts are involved, we'll see how it goes.
That is a great video, I'd actually seen it once before during the early stages of thinking about where to put the first pond, but it was a good time to rewatch! I definitely need to incorporate a core trench for the future dam wall among other things, just a matter of where the "bottom end" of the pond will be.
I agree, I think it'll be a great experiment and I'm already learning more about the land I'm on, at the very least!

Jonah Bassman wrote:I plan to basically see how much volume I end up with after doing everything necessary to make sure the dam wall is securely constructed, so both of those concepts are involved, we'll see how it goes.
That is a great video, I'd actually seen it once before during the early stages of thinking about where to put the first pond, but it was a good time to rewatch! I definitely need to incorporate a core trench for the future dam wall among other things, just a matter of where the "bottom end" of the pond will be.
I agree, I think it'll be a great experiment and I'm already learning more about the land I'm on, at the very least!

Clay has a bulking factor of about 20-40 percent! after excavating! The rest is just space and specific weight, water ratio, void space, particle size.
When you compact it back as a berm, it will shrink in size!

Thank you, I've read that about clay as well. There isn't a lot of clay in the native soil and I will be bringing in clay as well as moving out a great deal more soil than is currently dug. So, simply a matter of eventually choosing the final lower border of the pond-- I'm not sweating the final size, at this point the plan is to slowly go about constructing a hand-dug pond the safe way and see what it ends up looking like. Going to make sure the berm is plenty solidly anchored as well as compacted and extra earth brought there to account for shrinkage. Apologies if I'm misunderstanding something about what you're saying :)

Update: based on realizing I'd have to remove a couple small oaks that I'm fond of, and realizing the challenge here with keeping the top sides gradually sloping enough to hold bentonite as the "lower" side gets deeper, I'm now thinking this first pond may not get much bigger; working on deepening/smoothing sides/keeping everything gradual, and once it's the proper depth with smooth sides, I'll start to remove/reserve the topsoil that's in the area where the core trench will be on the downhill side. Feeling good about all this and glad I have plenty of earth to use in making the dam! Might still have to remove those small oaks, but I'd be happier if I didn't have to.

I am glad the trees may get a chance.
I dont understand people refusing to change a design to accomodate tress etc.

Yeah, I agree. I think I can save all of them. Few things are more valuable than a strong tree in the landscape that doesn't even need me to water it.

John C Daley wrote:I am glad the trees may get a chance.
I dont understand people refusing to change a design to accomodate tress etc.

I think a lot of times, while trees are nice to keep, if they impede the form or function of a design, why keep them?

At least in our situation, if I just have a couple trees in the way, I have plenty of other trees, I'll take the ones in the way out, use the wood, and if I'm missing some shade, add some in when the project is completed.  

In the case of a pond, having tree roots right near an area that you're trying to seal is a tough proposition, especially with soil that has a low clay content.  

Done some more work on it since last update! Looking forward to being able to start prep for the dam soon; definitely not getting much bigger with this project other than for that. Cool weather and wet ground are working to my advantage now, whenever I get a couple hours to put into this :)

Did the water stay long or soak away?

You know, it actually stayed a while! This stayed at least a couple days and this is after me scooping out much of the original puddle from that day! That's how it's been going- digging to make it a bit more of a gentle/deeper bowl after each time it rains, but scooping out most or all of the collected puddle each time. We've gotten some more rain since I was last up there, so I'm looking forward to checking how things are tomorrow! May be a bit of clay beneath the topsoil soil after all-- never done a "jar test" with the soil actually, just gone by look and feel of things, so I should do a jar test just to see.

Please keep us posted as it might get interesting.

I always followed the golden rule: chose the lowest spot and obviously you have chosen the highest spot of the land.

Good luck and let us know how it works out..

I appreciate the kind words, but it sounds like you're making some incorrect assumptions about the topography of the parcel, or what I am doing with this project. This is about 1570 ft. The high point of the land is around 1800.

The pond is slightly elevated from the rest of the "workable" land, as I mentioned in the first paragraph. Plenty of things going on in the higher elevations, and I also wanted to account for gravity feed.

Will definitely keep posting updates! :)

I'm interested to see how you got on with this, Jonah. Digging by hand is not for the fainthearted and seems to take way longer than you think. My pond project is always going to be "next year" and then something else comes along that takes priority.....Did you get it finished to your satisfaction, or is there a way to go yet?

Thank you, Nancy! You're right on the money re: digging projects-- it's still underway, looking very similar to how I left it with the most recent pictures... For the most part, I had to focus on matters that took me away from the land in spring, and then the summer came with its nearly-100-degree temps which bake the earth, leading the digging to be less of a priority. Still very excited about the project though, and looking forward to finishing it including adding bentonite clay so it can hold water! I'm thinking I'll get some great work days in on it this fall once things are slightly cooler and wetter again, and hopefully I can finish it before the spring rains! :)

Alex Moffitt wrote:https://www.youtube.com/watch?v=AadLCOqalFk

It seams like a great learning experiment in soft engineering!

I will keep watching, Your journey!

Regards,
Alex

Great video! I found it on YouTube and came to Permies to see if there was a discussion about it here.