Bentonite clay liner with wetland filter?

[mikeyb1978]

Hello All,
This is my first post. My wife and I are looking for help in the beginning stages of pond design and cost. In our backyard our vision is to have a 1300 Sq ft swimming pond with Koi, and a 700 Sq ft wetland filter using the aquascape centipede system. We don't want to use a synthetic liner and hope to use bentonite clay. One reason for this is so it's more natural. But the main reason is we have lots of moles and voles in our yard and I can see them making all kinds of holes in rubber liner in no time at all. We also hope to have a smaller pea gravel beach area for people to walk in and out. Here are some of my questions that I've searched and can't find answers to.

1- I know I can physically pour pea gravel on top of the clay but I would assume when someone walks on it the gravel it would be pushed down below the clay so eventually all the clay would be on top again? Does anyone have experience with a clay liner and trying to make a beach like area?

2- I've found geosynthetic clay liners which sorta defeats the "using something natural idea". It's half and half natural. I can find videos of people installing this and the liner is a white color. I can't find how this looks or feels once water is on it. I assume it expands out? Does it stay white? Or does the synthetic part keep the clay inside? If it keeps the clay inside more then I could see this being easier to lay pea gravel on top of it maybe the gravel staying on top. Not sure of this theory since I can't find how it reacts once water is on it? Anyone with experience on the geosynthetic clay liners?

3- I can find all kinds of videos of wetland filters using rubber liners but none on a clay lined wetland area. I would assume you would put down the clay, then gravel (if it wouldn't just push down through the clay), then the aquascape centipede system, then the layers of rocks. Like with the beach question from #1, I'm afraid that the rock weight on top of the centipede system would push it down into the clay liner and clog it with clay. Anyone made a wetland filter using a clay liner?

4- If we use bentonite clay then we can't do steep pond walls due to the clay overtime would slide down the walls. Lastly we don't want to spend money on tons of large rocks around the sides of the swimming pond. What other options could we use for a natural looking border?

5- If we did go with rubber liner, is there something that we could put under the rubber liner to stop moles and voles from chewing through it?

6- Lastly, the wetland filter is just going to spill over into the swimming pond. I would assume there would be about 20 feet length where the wetland spills into the swimming pond. I envisioned making a wooden deck/bridge/walkway that spans over that area. With a clay liner I can make concrete piers into the clay bottom to support the deck/bridge/walkway. With a rubber liner I couldn't put the piers into the ground and I would have to use something like the precasted concrete on ground deck block for supporting the deck. Any thoughts?

Thanks in advance for any help or ideas. This is my first diy pond project and am excited to get digging. Thanks Mike

 

[GBBUDD]

Hello All,
This is my first post. My wife and I are looking for help in the beginning stages of pond design and cost. In our backyard our vision is to have a 1300 Sq ft swimming pond with Koi, and a 700 Sq ft wetland filter using the aquascape centipede system. We don't want to use a synthetic liner and hope to use bentonite clay. One reason for this is so it's more natural. But the main reason is we have lots of moles and voles in our yard and I can see them making all kinds of holes in rubber liner in no time at all. We also hope to have a smaller pea gravel beach area for people to walk in and out. Here are some of my questions that I've searched and can't find answers to.

1- I know I can physically pour pea gravel on top of the clay but I would assume when someone walks on it the gravel it would be pushed down below the clay so eventually all the clay would be on top again? Does anyone have experience with a clay liner and trying to make a beach like area?

Yes it could push down through the clay/ bentonite. Easily fixed with layer of geotextile fabric . i would use the non woven as the strands from woven can be a on going pain.

2- I've found geosynthetic clay liners which sorta defeats the "using something natural idea". It's half and half natural. I can find videos of people installing this and the liner is a white color. I can't find how this looks or feels once water is on it. I assume it expands out? Does it stay white? Or does the synthetic part keep the clay inside? If it keeps the clay inside more then I could see this being easier to lay pea gravel on top of it maybe the gravel staying on top. Not sure of this theory since I can't find how it reacts once water is on it? Anyone with experience on the geosynthetic clay liners?

2. No clue

3- I can find all kinds of videos of wetland filters using rubber liners but none on a clay lined wetland area. I would assume you would put down the clay, then gravel (if it wouldn't just push down through the clay), then the aquascape centipede system, then the layers of rocks. Like with the beach question from #1, I'm afraid that the rock weight on top of the centipede system would push it down into the clay liner and clog it with clay. Anyone made a wetland filter using a clay liner?

3. As you your self know clay or bentonite require gradual sloped walls/ floor. the aquablocks can be made in any configuration you would like . but to have a 40 foot long bog just to get 4 feet in depth sounds impracticable.

4- If we use bentonite clay then we can't do steep pond walls due to the clay overtime would slide down the walls. Lastly we don't want to spend money on tons of large rocks around the sides of the swimming pond. What other options could we use for a natural looking border?

4. shaped concrete https://www.gardenpondforum.com/threads/some-very-impressive-pond-builds.26353/page-3

Where you are obviously doing your home work you might enjoy these pond builds https://www.gardenpondforum.com/threads/some-very-impressive-pond-builds.26353/

5- If we did go with rubber liner, is there something that we could put under the rubber liner to stop moles and voles from chewing through it? There are three products i can think of two are others ideas.
A. chicken wire obviously small holes . But as i see it even if galvanized it will eventually rust and fall apart.
B. Concrete cloth you install it like a semi flexible sheet but once water hits it its a thin reinforced layed of concrete
C. is a product i have been using on my build . i used it in the wetland bog to protect the liner from the sharp edges of the mafia blocks i used. And i am now in the process of using it again to stop tree roots from puncturing a rain water harvest system using aqua blocks. This is fiberglass infused with a coating that is used in roofing to protect rubber roofing from sharp objects. These run about 15 dollars a sheet. 1/8 fiberglass protection board. i have some pictures of it in my blog https://www.gardenpondforum.com/threads/going-for-it-phase-one-12-000-gallon-pond.22563/

6- Lastly, the wetland filter is just going to spill over into the swimming pond. I would assume there would be about 20 feet length where the wetland spills into the swimming pond. I envisioned making a wooden deck/bridge/walkway that spans over that area. With a clay liner I can make concrete piers into the clay bottom to support the deck/bridge/walkway. With a rubber liner I couldn't put the piers into the ground and I would have to use something like the precasted concrete on ground deck block for supporting the deck. Any thoughts?

6. i myself would make a footing under the liner in the location i wanted my piers make it flat with rounded edges Compact the h-ll out of the area place a heavy duty fabric your liner and an other layer of fabric and the liner will be fine it's like a gasket it can take more downward force then you could ever imagine.

That will be $500.00 consultation fee

Thanks in advance for any help or ideas. This is my first diy pond project and am excited to get digging. Thanks Mike

 

[Mmathis]

Hello and welcome!

I don’t know anything about clay-lined ponds, but I wonder if where you live and the type of local soil you have would matter.

If you plan on having koi, 1300 gallons is on the small side for koi.

 

[j.w]

@mikeyb1978
Check out this thread from a member here who is doing a bentonite pond in Canada: https://www.gardenpondforum.com/threads/bentonite-lined-pond.25521/

 

[mikeyb1978]

Thanks for the replies/suggestions/links. Gdbubb just send me your address and I'll put the consultation check in the mail! MMathis I'm thinking my pond will be around 1300 square feet not 1300 gallons so I think that will be enough room for Koi.

 

[GBBUDD]

Thanks for the replies/suggestions/links. Gdbubb just send me your address and I'll put the consultation check in the mail! MMathis I'm thinking my pond will be around 1300 square feet not 1300 gallons so I think that will be enough room for Koi.

Ahh i'm feeling generous this one is on the house.

 

[GBBUDD]

@Mmathis Thats roughly a 26 x 50 pond

 

[addy1]

@Mmathis Thats roughly a 26 x 50 pond

lol might be big enough for one koi!

 

[sissy]

That also depends on depth .Your soil conditions and water table will factor into if you can do clay or not .I would check all that out first .

 

[Mmathis]

@Mmathis Thats roughly a 26 x 50 pond

Oops! I read the 1300 sf as 1300 gallons! Math has never been my strong point, but now my reading skills are being put to the test!

 

[Dbarr1575]

I have no ideas or experience to share other than when you search bentonite in this forum there are numerous threads about the topic. Good luck and I think a swimming with koi pond sounds absolutely amazing. Can’t wait to see the finished product!

 

[mikeyb1978]

Thanks for all of your replies! A local excavator thinks that he'll hit clay when digging to use as a liner so he thinks buying bentonite clay is overkill. I guess we'll see on that. I've moved into my planning of a wetland/bog filter and I'm finding confusing information. It looks like my pond will be roundish with a 40 ft diameter. Using one formula to find the gallons of water I found was - Diameter x Diameter x average depth x 5.9 = gallons. I did 40x40x3x5.9 and I get just over 28,000 gallons. I've been reading through this forum and other websites and places say I want the pump to be able to turn over the water at least once per hour. Then in other places on this forum there was lots of discussion about the slower the flow rate in a up flow wetland/bog the better to have more retention time in the bog for the plants to absorb the nutrients.
I'm stumped as to how big of a bog I need and then what flow rate I want to achieve going through it. My plan would be to either buy the aquascape centipede system or make my own like the one found here ( http://bogfiltration.com/making_your_own_upflow_bog_filte.html ). On this diy setup link (on webpage before the page link) the guy states that I should use 1 foot of diffuser per 1000 gph flow plus an additional foot. He gives an example

"In this case, we're going to take a 10' by 16' pond, with an approximate volume of 1800 gallons, and use a 2800 gph pump. Based on simple math, 3000gph pump=3' of diffuser plus 1' extra= 4' minimum length diffuser. In this case, we used a 5' diffuser, as we had the room, and the client may want to upsize their pump down the road. This upsizing will give them the option to go up to a 4-5000 gph pump. This 5' diffuser, with clean out chimney, will create a bog filter approximately 6' wide by 8' long by 3 ½ ' deep. "

If I used a 12,000 gph pump I beleive it would turn over my pond once ever 3 hours after head loss, etc. By using the equation above I would need 12,000/1000 = 12 feet of diffuser plus a foot so 13 feet of diffuser. The size of my possible bog would need to be around 6' wide by 20'long? If I wanted to add second 12,000 gph pump, so have 2 pumps going into a wetland filter then I would need a bog around 12'x40' bog running 2 diffusers each about 13' long.

For the centipede setup I found the chart that is at the end of this post. It uses pond size in sq ft. The sq ft of a 40 ft diameter pond would be around 5000 sq ft. I'll go with an over estimate and use their pond size of 7200 sq ft. By their chart I would need an filter area of 8'x20' and use 3 centipede modules. Each of these modules are about 5.5 ft long by 13" wide by 11" high. So the centipede would be about 16.5 ft long. Now the centipede is wider than the 8 inch diameter diffuser being used in the diy option so I would think I would need more length in the diy option than centipede to slow the rate of water but it's opposite. The centipede module setup would be longer but the centipede would have a smaller bog filter area. Also in the centipede setup it's showing that I would use a 7,500 GPH pump which is much smaller than my diy example. I'm not sure which route I should go and would love some input. Thanks

Constructed Wetland Filter System Requirements
Pond Size (in sq. ft.)	Actual Filter Size	Number of Centipede® Modules	Liner, basic configurations minimum sizes	Pump Flow GPH
600	8′ x 10′	1	15′ x 20′	3,000
2,400	8′ x 15′	2	15′ x 25′	4,500
7,200	8′ x 20′	3	15′ x 30′	7,500
10,000	8′ x 25′	4	15′ x 35′	10,000
20,000	8′ x 50′	8	15′ x 70′	20,000
40,000	25′ x 50′	12	35′ x 70′	30,000
80,000	50′ x 50′	16	70′ x 70′	40,000

 

[GBBUDD]

Your in a category well outside a garden pond . All i have ever seen people do is to add aeration, or There is a couple aquascape videos https://www.gardenpondforum.com/threads/some-very-impressive-pond-builds.26353/