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How to secure a retaining wall around a pond?

Posted by capkaren Nova Scotia (My Page) on
Sun, May 4, 14 at 23:31

Hello! And thank you for reading my post.

First let me say, I have NO IDEA what I am doing. Secondly, I need to explain that I am doing this without spending any money, if possible.

I have wanted a garden pond for years ~ have been daydreaming about it, trying to decide where on my crazy property to locate it. Out of the blue, I got an offer I couldn't refuse ~ a neighbour with a big tractor would come over today and dig my pond for free. Given my landscape obstacles (there are many), my lack of knowledge, the power reading I did last night, and my imagination, I plotted a design for him to excavate on the East side of my house. My house is on the top of a fairly steep hill. I live in Nova Scotia (Canada), Zone 5.

The pond is dug into the side of the hill in the shape of a C (with one side a little longer than the other so that it is not symetrical. The back curve of the C, closest to the house, is dug so that the bottom of the pond is about 8 feet from the edge of the lawn. The hole graduates down to about 1 foot deep at the shallow "legs" of the C. Some of the dirt removed was placed around the "legs" of the C to create a bit of a levee affect. The remainder of the dirt was gradually sloped further down the natural slope of my lawn to marry up with the bottom of my hill.

The "plan" (I use that term loosely) is that the water level of the pond will be approximately 1 foot deep, with a "deeper end" extending to 3 feet deep at the back. So, about 5 feet high of a cliff will extend above the level of the water at the back of the pond, sloping down to a 1 foot "cliff" at the shallow end.

I would like to build a rock wall at the back of the pond. I have accumulated a fairly good pile of rocks from another neighbour's throw-aways (someone thought they were "bauxlite". I don't know. They break off in straight pieces if you crack them together). At the top of the stone wall I would like to plant things like Cotoniaster and Juniper.

a) How do I need to approach this cliff? My excavator dude suggested putting in a couple of pressure treated posts behind the rocks. What would the purpose of that be? And is there something else I could use? I thought that pressure treated wood adds bad chemicals to the ground?

b) The rocks will only be at the back of the C. As the cliff becomes lower and lower, is there something I can plant that will adhere to the sides of the earth so they will become root bound and create a natural retaining wall?

c) The purpose of the pond is to add beauty and joy to my life. I would like to create a waterfall in the rock retaining wall. I'd like to have a few gold fish swimming around in it. I'd like some water flowers/plants. I'd like to attract frogs, peepers, dragonflies, and whatever other critters would enjoy it as their home. Can you have all of these elements in the same pond? Am I absolutely required to have a filtration system with gold fish or is there a way to create a natural ecosystem that will take care of that on it's own (with my maintenance, of course)?

I'm including a couple of very short videos to help depict what I've tried to explain here.

I would be grateful for any advise you can offer. But please keep in mind my financial constraints.

Thank you most kindly!
Katie
PS ~ I was not able upload the videos ~ sorry.


Follow-Up Postings:

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RE: How to secure a retaining wall around a pond?

I can't really get a good idea in my head on the plan. Drawings are good. But in general...

As soon as I hear house and pond in the same sentence I think - make sure the pond isn't too close to the house. I see a lot of people dig the pond right next to the house which can mess up the house foundation. A general rule is must be at least the same as the depth from the house. But your area may be different. I sure don't know code in Canada.

Likewise digging a pond on a hillside that may be keeping your house up is a red flag. Mind you I have no idea what kind of slope you have, your soil, etc., but I'd do some checking.

You didn't mention liner. Even in clay soil on flat ground a 3' deep non-liner pond might not hold much water. On a hill side...I'd be surprised. So I assume you do have a liner of some kind.

No plan so I don't know what you're retaining wall would need. But in general, just setting rocks on dirt at the edge of a near straight walled pond probably won't stay there very long. The soil will normally fall into the pond followed by the rocks. Depends on lots of factors, but in general.

Plant roots can certainly hold soil, but there is a limit. Depends on soil and how fast the roots develop. A native plant I assume would be the best choice. But I don't know your natives.

You can certainly have all those critters and more in the pond. Some critters may eat the Goldfish. I don't know how cold your winters are so not sure how well fish and frogs would do over the winter.

Absolutely you don't need any filter. The pond will be able to support a certain amount of life which will vary with time and seasons. Say to put in 2 Goldfish and they produce 100 young. Nature will reduce those numbers if needed. So that's the thing with bio filters. You only need them if you want to keep more fish than the pond can handle by itself.

Filters can be used if you want to force the pond into something. Like say you don't like green water you can get a UV filter. The critters would love green water = lots of food. So filters are really a human choice type deal.

A term for the type of pond you sound like you want is "Wildlife Pond". That's different from a Water Garden and really different from a Koi Pond. So consider that when researching. Context is important. Things that are desired for a Wildlife Pond are consider terrible ideas by Water Garden people and Koi Pond people even more so. Make sure advice is for the kind of pond you want.


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RE: How to secure a retaining wall around a pond?

I think one picture would be very useful.
First, you didn't mention a liner. I suppose you could be very lucky and your soil would hold water naturally, but it is unlikely. When you have time, read up on the EDPM liners. The liner will separate the pond from the treated lumber if lumber is needed. I don't really understand your retaining wall yet. Perhaps a small cement footing could be dug in and created by pouring a couple of bags of cement into the dug out area. Perhaps you could find a chunk of cement rubble to set in instead. Five feet high is a real wall and although it would lean against the berm, it would require some cautious laying of stones. I have recently been reading about walls. The main point is that stones are usually stacked similar to bricks where each layer of stones rests on the lower one so that each stone rests on two stones below so that stones are linked together rather than creating individual rickety narrow towers.


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RE: How to secure a retaining wall around a pond?

I guess you can only upload one pic per reply. I took a screen shot from one of the videos ~ it shows the general footprint of the pond (made out of white posts). It sort of looks like an inverted kidney bean; but the "legs" of the C ended up being more pronounced than that. I'll follow with a pic of the "hole".


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RE: How to secure a retaining wall around a pond?

The "deep end" (closest to the house) isn't quite at it's full depth in this pic ~ but you get the idea. That's a lot of dirt to hold back.

It's the morning after. It's been raining for 24 hours. And I'm wondering WHAT THE HECK I WAS THINKING!!

Yikes!


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RE: How to secure a retaining wall around a pond?

I think you're going to want to put some sort of shoring up before you lay your liner.

My pond design incorporated a permeable retension wall between it and a bog shelf. My shelves are already starting to slope and the retaining wall wants to fall in.

I've dug it out and moved them back as a temporary measure. I'm hoping I can get one or two more seasons before I need to take on another major project and redesign the pond. I'm going to shore up the shelves next time (my marginal shelf is sloping now as well). I haven't quite figured out the what or how yet.


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RE: How to secure a retaining wall around a pond?

Unfortunately, I suspect that your cliff is out of our normal experience and would require at least the advice of your local neighbors who are more familiar with the local soil and rain.

I had initially assumed that your wall was on the lower end holding water. I see that it would actually be a true retaining wall. Off the top of my not that well educated head, I would think you might need a drainage pipe (flexable landscape drain with punched holes) at the bottom and just behind the wall (and foundation). This would allow water in the hill behind the wall to drain out. You would need to curve it out thru a small trench in the newly created down slope berm. Perhaps gravel would need to be placed on top of that drain, and continue almost all the way up behind the wall as it was built, but I am now completely out of my experience. Obviously a google on retaining walls is called for.

For the time being(while you are looking for a local wise man), I would find a tarp to prevent rain from eroding that cliff.


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RE: How to secure a retaining wall around a pond?

I am feeling way over my head..... I've always been told I bite off more than I can chew.

Yes, a tarp for now. Definitely. Then perhaps a nap. I'm feeling over-whelmed. Maybe when I wake up it will be better. ;)

Thank you kindly!
Katie


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RE: How to secure a retaining wall around a pond?

I am feeling way over my head..... I've always been told I bite off more than I can chew.

Yes, a tarp for now. Definitely. Then perhaps a nap. I'm feeling over-whelmed. Maybe when I wake up it will be better. ;)

Thank you kindly!
Katie


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RE: How to secure a retaining wall around a pond?

I've added a couple of drawings and a pic I found on-line as "inspiration" that kinda depicts what I'm aiming at much better than I can explain it.


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RE: How to secure a retaining wall around a pond?

Here's a cross-section of what I think the pond will look like.


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RE: How to secure a retaining wall around a pond?

Here's the inspiration I found this afternoon ~ just an image from a pond company that somewhat reflects my situation.


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RE: How to secure a retaining wall around a pond?

I'm no landscape designer but I would imagine that this design includes some well placed drainage options for when the rain and snow melt head down the hillside. You will have to divert the flow from just washing the whole garden and retaining wall down into the pond. Maybe there is some free landscaping advice to be had - local agriculture extension office? A friend of a friend? Try to get some professional advice if possible cause you can only do this part once and it's so important that it is done right.


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RE: How to secure a retaining wall around a pond?

'I am feeling way over my head..'
Yes, a little rye humor: I was planning to use that line when I initially saw you in the hole, but then got distracted with the issues.

I am trying to think what You will need to think about. Do you have enough stone to do what you show in the drawing? I ask because I am concerned that more of that cliff needs to be covered than you drew. Can you get more? I know you don't want to spend a pile of money. Does anyone near-by have something else that could be used? I am back to thinking about using rubble: old broken cement driveway pieces in place of stacked stone for example. If nothing comes to mind, could you fill things in a little and raise the pond up a couple of feet: with a shovel; with your neighbor's equipment?


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RE: How to secure a retaining wall around a pond?

Funny Chas045! Thanks for the humour. ;)

Initially, I had intended to only put the stone at the back wall (as in the drawing). I had envisioned this lush, natural green perimeter around the rest of it ~ some vines, and plant roots all miraculously holding the vertical earth in place. [I think I have a wonderful imagination; but sadly it is not backed up by much practical experience or theoretic understanding.]

The "inspirational" image I attached previously made me rethink the stone work and now I'm thinking it will fill in the whole exposed cliff. I am lugging it (for free) from my neighbours property. It's in two piles on his land and, in addition to my ignorance on stone construction, I really am only guessing that it will be enough.

I am surrounded by natural field stones (I live on a "mountain" so there are big rocks everywhere). They are not nicely chiseled stone; more curvy and irregular shaped. But I may be able to augment my resources with them.

As to MFLP's question about drainage..... I LOVE THESE FORUMS!!!!! Someone always comes up with issues that I would have never thought of. That is a really good point about the garden running into the pond come rain/snow melt. I would think that the roots would hold the plants in place; but what of all the mulch, etc?

However, I did cut a garden plot into an even more severe angle of the same hill last summer (it was impossible to mow) and it seems to be all intact this spring. I even placed the mulch on top of cardboard and it didn't slide off of that. So I don't know if it will be a problem or not. That said, my upper garden is not at the edge of a cliff ~ it "falls" into the lawn. So maybe that is holding it in place??

Hmmmm...... more to think about!
K.


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RE: How to secure a retaining wall around a pond?

I think most communities have laws about retaining walls; in California, if the retaining wall is more than 30" (about 75 cm) high, you have to have an engineer design it.

That said, I would put a ledge or short wall around the top of the cliff to direct water and debris to the sides instead of into the pond.

Also, there are net-like things that are used to hold soil in place on hillsides after fires or landslides. You could probably find something that would work in a similar way to hold the slope. (My brother works with this sort of thing, but he's far away from you. If you can find someone who does "remediation" near you, they may give you scraps).

Good luck!


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RE: How to secure a retaining wall around a pond?

I think I understand now. Measurements will be important because the difference between a 3' or 5' high retaining wall is a lot.

It does look like this is far enough from the house to not be a problem. But I'm not your local building inspector.

Based on the picture of you in the hole I'm guessing a 6' high retaining wall, it has to go all the way to the bottom of the pond. So the retaining wall weight will be many tons in weight, well over 10 tons I assume. That requires a very serious footing (wall in the ground big enough to support the weight. I don't know the frost line in your area, but I'd assume 2-4' below grade (grade = pond bottom). I'd assume the footer would have to be at least 2' wide and 1' thick poured concrete reinforced. I'm just making some wild guesses, these types of things are never standard and so an engineer has to do a specific design.

On top of that footer would be a stem wall type deal, poured concrete, about 2-3' tall maybe 1' wide. That gets you to grade (pond bottom). Then you can build the retaining wall. That's a whole deal by itself. A rock wall wouldn't be considered a retaining wall for anything over maybe 2' high. (depends on main things) except for places like Afghanistan. Retaining walls are engineered and there are many kinds, but most for a wall this size have anchors driven way back into the hill side. And I have seen DIY retaining walls that do this. They bury a railroad tie type beam parallel with the wall and maybe 10' back in the soil. They then tie the wall to those beams. But that for for maybe 3-4' wall. These things get exponentially (kind of) more complex and large the higher you go.

I'm guessing you don't want to spend $30,000 on this. Let me explain why these things have to be correct. If you just stack the rocks like in the picture they will sink into the ground over time. Water, snow melt, will run down the hill and down the back of the wall and water will collect at the base, causing very muddy soil (unless you hit bed rock which would be a great saving). A stacked rock wall doesn't have to sink much for stuff to start falling down.

That's just about a normal wall standing up, non-retaining wall.

Now lets consider the soil. When many soils get wet they slump. A rock wall has almost zero strength in holding back anything. You have the wall sloped back a little, which helps a tiny bit. When you're done one man with a pry bar could tear down the wall in an hour. 100 tons of soil pushing against the wall isn't even going to notice you have a wall.

I would expect a rock retaining wall to last just a few years and then a lot of erosion up hill as that area slumps over the years. However, it could fail the first month or last 50 years. Depends on many local factors. All this complex retaining wall stuff is to make a structure that is expected to last maybe 100 years. The reason we go to such lengths is because long term it's cheaper than trying to fix the problems of a collapsing hillside. A collapsed hillside isn't a one time event, it's an on going type thing.

In general the wall would be poured reinforced concrete and then rock could be mortared on as a veneer for looks.

Here in the US we would be required to put a fence at the top of the wall to stop people/kids from running down the hill and off a 6' cliff which probably would break some bones and could certainly cause death. So our code requires a barrier.

You're now in a kind of tough place because if you wanted to pull the plug on the project you can't just push the dirt back into the hole. Well you can but it's now disturbed soil. Water would fill all the voids and likely cause the pile to slump or even slide. The hillside doesn't look that steep and I don't know what's down hill from you but if I was a neighbor down hill from you I'd be calling every government agency I could.

It is possible to build a DIY pond on a slope like that for almost no money. The trick is lots of little pools and a stream connecting them. The stream runs parallel with the slope so almost no digging, and only a 1' high retaining wall is needed and dry stacked rock is OK. Where the stream turns to zig zag back the other way you put a small waterfall, maybe 1-2' and it can be stepped. When to get a half way decent flatter spot the stream becomes wider, like 2-3' or whatever. That section would need a pretty serious retaining wall so you can just have a stream. But somewhere at the bottom you do need a pond or basin, but that doesn't have to be huge. That can also be done in stages.


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RE: How to secure a retaining wall around a pond?

I would guess that folks from Nova Scotia are far less Litigious then in California. I also imagine that your slope goes a long way before neighbors become impacted. Even if you did nothing, I would guess your slope would eventually rearrange itself 5 to 10 feet further down the slope. If you managed to build a significant wall, it would also move in a few years, whether five or 30 years or so. But again, you might want a change anyway and if you did minimal repair, your hill would then be filled with rock as before; just a bit more concentrated.

My parents and I, lived in California near waterbug guy for almost a hundred years. One probably 30" garden wall of round stones lasted at least 60 years with almost no repair. On the other hand, several shorter garden stone edges required more attention. None of these constructions had much thought, no cement and no foundation of any kind. Unfortunately, your situation is much higher, far colder, and probably far wetter.

I really like waterbug guy's stream/pond suggestion in his last paragraph. For one thing, it would be closer to your original concept (and last picture), and of course, it would only require short walls. Also, I am a big fan of streams. I believe mine is doing almost all of my filtering, and you were initially asking about filtering. I am sure that WBG is right that disturbed soil is different than small cuts in another spot, (and you could start in another spot), but you could compromise and refill part of the hill and do the stream/pond deal with lots of bushes to attempt to retain the disturbed soil. You might even double compromise and try planting a couple of small trees (big shrub) in a slightly refilled portion or perhaps two stepped refilled portions, and do the stream/pond cut in almost adjacent on the hill so they look like it is one Japanese like garden cliff thing.


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RE: How to secure a retaining wall around a pond?

Not much litigation here in back woods NS..... even the drug dealers and poachers are left pretty much undisturbed. If the fellow across the road called a gov't agency, I think he would fare far worse than any concern they would have about my pond. And neighbours below my hill are a fair distance ~ separated by my woods/brook. But I'm open to whatever the universe delivers....it's all for my benefit.

I am intrigued by the stream/pond idea ~ I love flowing water and will eventually get to building a lovely woodland gallery/meditation garden in the back of the property incorporating the existing brook. But unfortunately I could not envision what WBG was trying to depict. I'm a visual learner; and a picture would be so helpful. Even better, if the picture incorporated my second drawing of the hole that presently exists.

My biggest hesitation about the stream (coming from a place of ignorance) is a) where does the source of water come from and b) does this require more equipment (power, wires, underground trenches, motors, etc = expense + more digging).

Any help you can offer with a drawing that would explain the stream/pond idea would be great!

Katie


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RE: How to secure a retaining wall around a pond?

I created a web page for you [here] which describes some the ways to build on a hill. The forum software here makes instructions difficult.

There has been a long time debate in some pond forums about whether people should post real info when a person asks for advice or should just act as cheerleaders and limit advice to "Yes that's a great idea." Many people do get discouraged when someone posts "that could kill someone". Many people get down right mad if any thing happens to not be what they wanted to hear...even though they're asking for advice.

In one very popular pond web site (not sure we're allowed to say which site) there are many threads that show the issues. Some times people get defensive and shutdown all thought and just plow ahead "just to show the haters" and many times the build goes really bad. That's probably 25% of the time I'd guess. Most people pick and choose what they want to hear and they do end up with a pond, but with lots of issues. And there are a couple of cases where the person actually listened and they saved a ton of money and got the pond they wanted. This was really tough for the owner because in many cases the build had already started, contractors had been paid. Telling the contractor they're wrong and work already done would have to be redone isn't easy. But in most cases the contractor was already aware they were over their head and was happy to learn. That web site has many professional pond builders posting. It's amazing that most people get really defensive when offered thousands of dollars worth of free advice from actual professtionals and instead turn to the Billy-Jo-Bobs of the world who just like to talk.

That is also why many pond forums don't have any build professionals, vets, etc., posting on some pond forums. It does no good. Make one post with reasonable advice and get followed by a bunch of "oh you don't know what you're talking about". An it's true. To a person with no experience good advice can sound really whacked. It's a Catch-22. Some people can only learn from experience. A new person can't tell which is which. So generally you only hear cheer leading. Which is perfectly fine.

The info I posted was just that...info. I wrote several times that I had no idea the specifics of this build. The info is to be used or ignored. I sure don't care which. At no time did I ever say you shouldn't build how ever you like. Personally I like to read both success stories and horror stories. Both are entertaining. It's none of my business what course you choose. You're an adult. However I do choose not to be a cheer leader just so I can watch a mess unfold. Sorry.

I'll bow out of your build now. I'm sure it will go great and hope you post a lot of pictures.


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RE: How to secure a retaining wall around a pond?

I had a long post started (now saved for the future) but realized that I really didn't know if any of it was of value. I am wondering if you could afford to even do the minimum.
You asked a couple questions about water etc:

Water initially comes from your garden hose if you are on well water. Yes, you need a pump but you needed one anyway if you wanted any waterfall. Yes, you need power, but now that we know you are in the 'boonies' that power can come from a Good grounded extension cord that hopefully comes from a GFCI circuit like you probably have in your bathroom or basement. Hopefully, you already have an outdoor circuit on an outside wall. If it doesn't have a GFCI installed, it is easy to install. A pump could be $200 but perhaps much less depending on your approach.

But you also need a liner and at least right now you have a fairly big pond that would probably take at least $200 if I remember semi correctly, and perhaps double that. You really don't need anything else, especially if a stream were included, but that would probably require some more liner.

So: doing this would require at least $500 US. And then.....if you wanted to do things the right way, it could become astronomical. If you want to do things 'the cowboy way' as we sometimes say down here, you can probably find a way without much additional expense, but it is likely going to be experimental and might require your neighbor's help again. Anyway, I was wondering if the 'oh never mind' approach was something to consider?


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RE: How to secure a retaining wall around a pond?

It's been a rough day. Probably not the best time to be adding to this thread; I'm sure things will be brighter in the morning. But I didn't want all of your generous contributions to go without a response.

I am very grateful for all of your input, advice, suggestions, and encouragement. I appreciate, WBG, your comments w.r.t. giving professional advice vs being a cheerleader. Frankly, I have needed (and continue to need) both! The link to the website you included touched my heart ~ it is impressive and so very helpful. I certainly hope I didn't say anything to make you feel unappreciated by me. The facts are simply over-whelming.

Here's the thing: I have no income, no help, no partner. It is astoundingly impractical for me to consider putting in a pond ~ let alone a pond of this magnitude. My socio-economic situation is better suited to a bachelor pad with a quiet cat; not six acres, three animals, and a dream.

The reason sometimes people don't adhere to the sound advice of those of you with correct expertise is not out of any intention to dismiss or snub your generous, well-intended input. I know I'm over my head; but I want to believe that it is possible for me to have my dream anyway. I do want to do things correctly ~ I want a well constructed, safe, beautiful, long-lasting, well maintained pond for me and a bounty of nature's critters to enjoy for years to come. But I am not in a position to do it all the right way. So while I want to do my best and end up with a great result; I don't have the wherewithal to do it the way someone with money, a Kubota, and a husband could do it. I have two hands and a big heart (and really nasty herniated discs in my lower spine ~ a direct result of the big heart).

The cheerful, toothless farmer with the big front-end loader that dug my hole recounted some of the history of this rural area to me while he dug. The old-school way of doing things didn't follow today's standards by any stretch of the imagination; and my house stands sturdy 120 years later with a weird fangled septic system and all kinds of "improper" eccentricities that are, in some ways, far superior to the new standards. So I was just hoping, with the bevy of expertise available in this forum, that maybe there were ways that you could help me figure out how to have my dream despite my lack of money, know-how, husband, or Kubota.

When a toothless grin with a big tractor offers to dig a big hole for free and the next door neighbour has a big pile of pretty stones they'll let you lug away for free, it just felt like the stars were lining up for me to have my pond. What's a girl to do!


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RE: How to secure a retaining wall around a pond?

I'll bow back in and try not to say anything negative.

When I do any project if I don't get a lot of people telling me I'm crazy I figure its not worth doing. It is a way to learn. I've built many kinds of ponds that weren't the standard method. So I'm all for plowing ahead.

You want to go old school. That's cool. We've been building these structures for more than 5500 years so it is time tested. Here is a great video on how to build a stone wall. Now mind you this is for a stone wall, free standing. But the basics are right and they go into detail which is important.

A retaining wall is different. I don't know how 6' tall stone retaining walls were made but I assume similar to the shorter retaining walls we build today, just more mass. Like maybe a 3-4' wide base. It's a mass thing. You have a hillside wanting to push down so you need a greater mass pushing up.

I only know how to build say 3' high max stone retaining walls. 2' max is better for a beginner I'd say.

If you changed your design to a terraced wall instead of a single massive wall it would be much easier, much less stone (maybe 1/3 less). Like I said back at the beginning, the higher you go the more expensive it gets.

A terraced design is basically the design on the web page I gave you, except you don't need the streams and the terraces could be say 2' high instead of 1'.

There is a fair amount of info on the web about building stone retaining walls, and it's all pretty good. There isn't one that stands out to me. Just stay away from the videos of the dudes in bare feet building their first wall.

It's worth doing the calculations ahead of time for the amount of stone needed. Better to know that up front and scale back if needed than run out of stone 1/4 done.

Consider building the walls a bit above grade at the top. That reduces the danger of people taking a header because they can see it when walling down the hill.


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RE: How to secure a retaining wall around a pond?

Thank you WBG for your response..... your idea of terracing the high slope sounds promising. I envision that means cutting out more of the hill to make the terraces (as opposed to building up terraces from within the hole with dirt). Is that what you mean? And thank you for including the link for the video! I am very grateful for the time and thoughtfulness you have given to me.

And I do like your idea of extending the wall above grade ~ funny the things you don't think of before hand...... The first night after the dig, when it started to get dark, I was suddenly struck with terror at the thought of someone/something walking along my slope and unwittingly taking a headlong dive into the abyss. Since then I've put up a rim of posts and some solar lights; but I know that is far from adequate!

I hope you have a wonderful day. I'm off to lug another couple tonne of rocks across the way!

Cheers, Katie


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RE: How to secure a retaining wall around a pond?

I notice that you didn't answer my question. I assume that is because you don't want to quit your project and I gather that you didn't want to think about the expenses at the moment. BTW, I think you are right on what BG would be suggesting IF you continue in the same location. You would need to cut back further. Perhaps two separate cuts (slices) into your cliff. I assume that the cliff is now six feet deep and slices would be two feet each. This would make the whole (hole [;-] ) project much bigger. My concern is that it is already way too big.

I initially wondered if changing location (or quitting) was good idea because you might not even be able to afford a liner and insidentals And because you said you already have a natural stream somewhere. For one thing, the current area is already down and away from the house and I wonder if it was just out of view and perhaps just too far a walk for morning tea or whatever.

Anyway, I just wanted to again suggest the possibility of a compromise that would exactly create your inspiration photograph above. Your slope was perfect for it and the only reason you didn't achieve it was that your friend cut too deeply into the slope and only took essentially one cut. If he had taken an initial horizontal slice of eighteen inches just reaching your upper stakes; and then moved down another foot or 1.5 feet and sliced off another chunk but leaving an 18" area as a terrace and then finally digging a one foot deep hole again inside that lower area (leaving at least a foot at the back again) you would have achieved the outline of that photo.

As it turns out, this is essentially how most ponds are drawn up, but they may be done by hand and are not on a slope. The inner deeper areas are just little terraced semi concentric depths. Since they are only a foot or so high, they don't normally have any support. The inspiration photo just suggests a bunch of blocks piled up and that is probably what it is. BTW you only need a three foot deep area if you have goldfish (winter cold protection) and it doesn't have to be big. I think these cuts would make a small pond that would take a smaller liner (less cost). BTW if there is a roofing supply nearby you might be able to pick up liner from them and skip shipping charges that are a major part of the cost.

OK: coulda, woulda, shulda; but it seems to me if your hopefully still friend would be willing to come back and try again near the current area With Terraced Cuts and also scoop up almost all of the initial dirt and dump/push it at the base of the cliff and stick a couple of potentially big bushes or small tree into that slump, you would probably hold it from sliding very much. Some dirt from the new hole and current one could raise the lower area up a few inches as you have presumably done the first time.

I just looked up gravel pits for a picture of terraces.

Here is a link that might be useful: gravel pit


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RE: How to secure a retaining wall around a pond?

"your idea of terracing the high slope sounds promising. I envision that means cutting out more of the hill to make the terraces (as opposed to building up terraces from within the hole with dirt). Is that what you mean?"
Well at this point it's a little tricky because you already have a huge hole, disturbed soil, I'm not on site. But yes, the correct way is for the wall to be set on undisturbed soil because it needs to act as a foundation. Disturbed settles a lot and very easily.

Still think controlled slope is the easiest option unless you really want a 6-8' waterfall.


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RE: How to secure a retaining wall around a pond?

Okay, let's regroup!

Sorry Chas, I did not mean to ignore your question ~ I reckon I didn't have the emotional stamina at that point to go any further than the response I gave.

So, today I've moved another tonne of rocks, my step-brother-in-law (who just got a new job as a foreman at a pool/stonework company) come by for the once over and he enthusiastically said "this is gonna be awesome!", and I've had a big glass of wine. So I'm ready to tackle anything. [Btw, he knows nothing about stonework, just knows how to manage people, I guess.] Sad face.

Yes, you are correct! Quitting is not an option. I know some things are going to cost ~ and may have to wait for later down the road. But generally the pond will be made from salvaged material and grunt work. Both of which offer their formidable challenges. I guess, however, the biggest challenge is that I don't fully understand the process (where do pipes go? how am I supposed to design a berm when the hole has already been cut without a berm [i.e. build a berm out of disturbed soil or cut out more top-soil from the perimeter of the existing hold to create a berm]?, etc.)

a) I am calling roofing companies tomorrow to ask about liners. A friend of mine got a big piece when they tore off the roof at the local community college. He has a tiny pond ~ miniscule. So obviously I'm going to need a LOT of liner. SBIL says they are doing a pool repair in the next couple of weeks and he will try to get the pool liner for me. It will be hard to handle as it will be wet and heavy. Well, even if it were dry it would be hard to handle.

Question: Is there any reason why I can't make a "quilted" liner out of more than one piece? Surely there is some substance that I could use to "glue" them together. I used to have this spray-on rubber (it came in an aerosol spray can, sprayed out like paint, but dried as rubber). Would that create a seal between two layers of liner?

And I agree! I need to cut out more hill and make a terrace! I will call tractor man and see if he is willing to make a couple more cuts. If not, it's just me an my shovel.

Sooooooo, with that in mind, I need to understand the waterfall operation. If the water starts at the top terrace (assuming I add two terraces), travelling down along the second terrace, and landing in the pond below, what needs to be on the "floor" of the terrace to keep it from eroding? And please don't say gravel because that costs $$.

Here are some potential options:

a) I use some stones to create a stone floor and use the rest to build the retaining walls. Pro: It would look nice. Con: I'm not sure I have enough rocks (but it MAY actually cut down on the amount of rocks I need). Would it serve to maintain the integrity of the ground below or would I need to have liner underneath it to keep the flowing water from washing away the earth? If I need liner, what do I put around the rocks so that you don't see the liner?

b) A modified version of WBG's idea of mini pools leading to the bigger pond below (except without the streams): What if I turned each terrace into a little pool surrounded by rocks? Pro: Sounds cool. Con: I don't have the logistics envisioned in my head.... How would the water flow from one pool to the other? What about the waterfall?

c) Something else that I haven't thought of yet. (This is where you come in.)

Okay, let's sleep on it!
Thanks for sticking with me folks!
Katie


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RE: How to secure a retaining wall around a pond?

"Question: Is there any reason why I can't make a "quilted" liner out of more than one piece? Surely there is some substance that I could use to "glue" them together. I used to have this spray-on rubber (it came in an aerosol spray can, sprayed out like paint, but dried as rubber). Would that create a seal between two layers of liner?"

Yes, for most materials. Each type of material, PVC, EPDM, vinyl, etc., has specific chemicals, equipment and methods. We call it "seaming". That's the good news.

The bad news is these things aren't free, some aren't very easy to apply, and the longer the seam the more likely the failure.

There are plenty of people on the net who will suggest all manner of goops. Gooping up stuff is the first thing first timers reach for. I wouldn't suggest any of these.

Another thing to consider is the life expectancy of the recycled material. Trying to seam together a swimming pool liner that was removed because it was the end of it's life may not make much sense. So try and find out the age of whatever you get.

If you can get EPDM that would be a total score. They have a seaming tape for that. You do have to clean the overlap really well you really need to do it on a flat surface, but if you follow the directions (there are videos and written instructions from the manufacturer) it can be done.

All line kinds can also be seamed using a mechanical fastener. This is a strip of metal (aluminum or SS) with bolts every so many inches. The 2 liners go between 2 strips and bolted together. Find for short runs, I wouldn't recommend it for long runs.

Another option, and this is always my fav is instead of seaming liners consider making multiple pools. No cost for seaming and multiple pools on a hillside could go a long way to reducing the retaining wall needs because pools can act as a retaining wall as long as the walls are sloped. I like it too because I think the result is more interesting, but that's my tastes.

BTW, my entire home from the studs is all used materials off Craig's List. So I'm all for reuse. My fav cheap/free liner are billboards. They're huge and almost brand new. They only keep a billboard up for a short time, couple of months max, and then take them down and landfill them. You're out in the boonies but if there's a highway nearby there might be billboards too. They sure don't last as long as EPDM but can last 5-20 years (maybe longer) if covered by gravel/soil.


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RE: How to secure a retaining wall around a pond?

"And I agree! I need to cut out more hill and make a terrace! I will call tractor man and see if he is willing to make a couple more cuts."

So you're getting tractor man back to do even more tearing up of the hill...still no plan...you didn't watch any of the stone wall building videos did ya? Cause if you did you'd know why that really isn't a great idea.


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RE: How to secure a retaining wall around a pond?

"a) I use some stones to create a stone floor and use the rest to build the retaining walls. Pro: It would look nice. Con: I'm not sure I have enough rocks (but it MAY actually cut down on the amount of rocks I need). Would it serve to maintain the integrity of the ground below or would I need to have liner underneath it to keep the flowing water from washing away the earth? If I need liner, what do I put around the rocks so that you don't see the liner?"

Yes, liner is required. Liner is laid on the soil. No reason to put down rocks first then liner. Rocks are placed on top of the liner to hide. For EPDM underlayment isn't needed. when you get into weaker liners like PVC, swimming pools, underlayment is more important both under the liner and on top when adding rocks. The liner doesn't have to be protected on top if mortar is used, but that doesn't seem to be the case here.

A great underlayment is used carpet padding. Carpet is good for underlayment, less good to protect the top because as it rots the little bits of yarn go everywhere. Underneath you can use newspaper, cardboard, old clothes. If your soil is sandy and rock/stick free you could risk no underlayment. I wouldn't for the weak liner types.


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RE: How to secure a retaining wall around a pond?

"b) A modified version of WBG's idea of mini pools leading to the bigger pond below (except without the streams): What if I turned each terrace into a little pool surrounded by rocks? Pro: Sounds cool."

Yes. It's way cooler imo than the pond pic you posted as inspiration. You have something very few other people have and would kill for...a hillside. You won't see a lot of examples because so few people have hillsides.

And it's way, way, way, way easier and cheaper to build. You'd still have to deal with that giant hole, but yes, way easier. Especially for using free materials. Score a pool liner...add another pool to your hillside. Score another one a few months later...add another pool. Pretty soon you have something really spectacular.

And consider the viewing angle. The giant pit pond will look great when you walk down the hill and view. But from the house will you see anything? But with terracing you'll be able to see all your pools from the top of the hill. That's way more enjoyment imo. With trees, plants, paths, sitting areas, multiple falls, little streams, it's a wonderland.

What you've been trying to do is stick a flat ground pond into a hillside. That's super hard and really expensive ($$$ or labor wise). You've been trying to stick something up nature's butt. Nature don't like that and will fight back with erosion and slides and collapsed walls.

Terracing you're working with nature. Nature will reward you.


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RE: How to secure a retaining wall around a pond?

"Con: I don't have the logistics envisioned in my head.... How would the water flow from one pool to the other? What about the waterfall?"

That's the easy part. Now we're back into the world of standard pond building.

You overlap liners. No seams are need and actually they aren't desired.

You just need to add a little space between the liners. That stops water from wicking up and out of the pond.

Waterfall is just liner on the ground and then rocks. There's things that are done to keep the water on top of the rocks like spraying Great Stuff foam into the voids. I prefer mortar for several reasons, one of which it's cheaper.

No point going into a lot of details at this point unless you have a specific question.


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RE: How to secure a retaining wall around a pond?

"c) Something else that I haven't thought of yet. (This is where you come in.) "

That's the easy one. Building a successful pond is really pretty easy in 3 steps. You haven't considered steps 1 & 2 yet.

1. Learn about ponds. At least the basics. What kind you want, how they work, how they're built. That way you have an idea of what you're getting into and can scale the design to your desire.

2. Plan your pond. You did a little bit on paper but you have a much more challenging site than 99.9% of people. Things like measuring are a big help in figuring out if what's in your head will work or has to be changed.

3. Dig.

Many people skip 1 & 2. And for many people that's not a big deal. It's really hard to mess up a pond on a flat lot. The water will end up in a hole which isn't going to slide down a hill. But there are also many threads in forums that were monster builds that went really badly. I'm talking homes damaged, property value lost and a ton of money spent. Kind of hard to watch, but darkly entertaining too. And a great way to learn. I've read maybe a dozen real disaster build threads where the person plugged away for months. Most giveup pretty quick. But the long disaster builds are a great learning experience. I feel like I was there, like I was the one making one bad choice after another. Because it sure could have been me. Taught me a lot.

You will do steps 1 & 2. That's not really an option. The option you do have is which order you do the steps. Doing them in the reverse order is possible. But the larger the project the harder it is exponentially.


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RE: How to secure a retaining wall around a pond?

Good morning!

Actually, I've watched the video twice ~ have downloaded it and plan on watching it again and again until I can do it in my sleep.

Problem: I'm more of a visionary and less of a strategist..... That is, I can "see" the end product but have no clue as to how to step-by-step create it.

For example: "So you're getting tractor man back to do even more tearing up of the hill...still no plan...you didn't watch any of the stone wall building videos did ya? Cause if you did you'd know why that really isn't a great idea." Nope. You lost me. What is the connection? I would think having multiple small retaining walls would be much more stable than one mammoth retaining wall (well, theoretically, if I were a stone mason I'm sure that might not be true ~ but I mean given the reality of my situation.).

Now, on to this "giant pit". Are you thinking I should fill it in? That it is too big or undesirable? I don't see that as an option. It's not really as big as it looks. When you stand in the shallowest end of the hole, you can see that the mammoth cliff in front of you is mostly underwater. It is 8 feet from bottom to top ~ but only about 4 feet of that is above the water level (i.e. requiring retaining). I'm assuming the liner covering the remainder acts to retain the ground from eroding further. Is that correct?

I also think I'm not really understanding the multiple pool ideas. What I picture in my head would require way more land than I have between pit and house. Or am I mis-judging said pools. What would be their dimensions? Depth?

Thanks for all the good info w.r.t. liners. There is a highway nearby, but no billboards; only in the city (2 hours away). And I don't have a truck. How do you find landfills that you can access? Cool to hear you have a salvaged house! My barn is full of material just waiting for my dream house build!!

Btw, what are you using to create your awesome pictures. They are great and very helpful! Good point about water wicking out from between the liners. But how will a spacer stop that from happening (sorry, I never did get physics very well). Wouldn't the spacer need to be adhered to both liners to keep the water from going through?

Sorry I'm asking so many questions. It will help me build a better pond if I understand the mechanics of it all.

Have an awesome day!
Katie


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RE: How to secure a retaining wall around a pond?

Good morning Chas, I took a look at the gravel site you linked me to. And certainly, when farmer clem agreed to dig my pond (I had specifically used the word "excavate") I wasn't aware that he was going to show up with a ginormous tractor with a four or five foot bucket on the front of it ~ didn't even have tines on it, just a big scoop. Ergo, the cutting job is not very refined or what I had hoped for. It is, essentially, a pit. I had seen enough pond videos to know that I wanted a "step" system cut out. But the question is HOW do I create that after-the-fact, given that I'm left with a big vacuous pit?

A merrily we go.....


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RE: How to secure a retaining wall around a pond?

WBG.....one more thing (okay, well a dozen more things, but one for now!) ;)

In your web design image of Retaining Wall vs Erosion Control you showed plants planted within the actual slope (image on right side) in addition to the tree at the top. I like that very much. Make it look even more natural.

If I stone the floor of the terrace OVER TOP of a liner. How can I include plants in the mix? Or is it one or the other?


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RE: How to secure a retaining wall around a pond?

Katie, I first anted to agree with you on a couple things. Yes, WBG what program were you using for the nice drawings? I attempted to use Paint to make a sloppy drawing and couldn't make it do anything. I remember having good success with Paint 30 years ago with our first Mac, but now.......
and WBG, I didn't see what lesson from the stone wall video you were referring to either. Perhaps you were just talking about acting before planning.? Katie,no matter what, it is nice to know that your neighbor is willing to help, and I would agree that things should be thought thru before much more action.

I think I can explain the stepped pool, liner separation thing but WBG has far more experience than I and may have an additional point. First, I don't think 'wicking' is the correct term. Wicking would be putting a cotton tee shirt between the two liners and the shirt would absorb water that could reach dirt in the upper area. If you just have liner to liner contact, the potential problem is capillary action from possible wrinkles in the liners that could act like little vertical thin straws. I believe you could see this if you had a thin but clear straw like a coffee stirrer (but most are colored); I believe the rise is caused by air pressure.


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RE: How to secure a retaining wall around a pond?

The liner does not work well as a retaining wall. And your other wall needs a very solid support. If the base starts to go, you're wall will start to go. I'm on a much smaller scale than you, but I learned this the hard way :/


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RE: How to secure a retaining wall around a pond?

Chas!!!

Does my MacBook Pro have Paint? I just started using a Mac and am still learning it's features; but I miss Paint ~ used it all the time on my old Windows PC. Do I have to download it or is it an App from the App store?


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RE: How to secure a retaining wall around a pond?

Katie, as I hope I implied, I don't know what I'm doing with computer graphics anymore and am therefore not a reliable source. However, I think my sil had one and I thought I saw it on her machine. I didn't realize old Macs needed to go through the app store. I would bet it is just hidden in some pull down menu, but I have been away from macs for years and am generally better on PCs although why I couldn't get my new version of Paint to do anything is beyond surprising.


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RE: How to secure a retaining wall around a pond?

Sil.

Cute!


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RE: How to secure a retaining wall around a pond?

Okay, getting lots and lots of rocks. More than I had anticipated. Yay!

For the back of the big pit, I am thinking that I should use large field stone behind the smaller angular face stone (there's not enough angular stone and ~ following the video design ~ I will need to have the wall double width (plus core). Is this good?

Even though I am adding terraces, I can cut them so that their "cliffs" gently slope instead of being vertical. This will mean (I assume) that I would NOT have to double those walls and can simply follow the up-slope with face stones. Yes?

So the big question that remains is......

How do I add a berm now that the big hole has already been cut straight down?

Any suggestions?


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RE: How to secure a retaining wall around a pond?

chas045 is correct, capillary action is a more correct term imo. Ccapillarity, capillary motion, or wicking are all terms for the same thing. I see wicking used almost exclusively in Water Garden forums so I go with the flow. The tee shirt thing is also capillary action.

Capillary action requires a small (tiny) gap to work. So make a wider gap with a stick. bead of silicone, whatever, makes the gap too wide for capillary action to happen. Trees use capillary action to raise water more than 100' vertically so it is powerful. In most ponds it isn't a problem even if it happens. But it's so easy to build so there's no risk I think it's a good idea.


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RE: How to secure a retaining wall around a pond?

I don't really want to hog the thread. When we're talking about a 6-8' nearly vertical soil wall or stone retaining wall we're in the world of unusual and dangerous. That is kind of a specific experience and as I mentioned is beyond my experience. I only know enough about it to mention some things that would worry me, that I think should be looked into.

If you switch to a terraced design then we're back in the world of more standard type pond building. You can get advice from lots of people. Of course a lot of that may be pretty bad too...but at least you'd be in the same boat as everyone else.


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RE: How to secure a retaining wall around a pond?

OK, why letting tractor guy loose is maybe not that great an idea to start the terraces.

And maybe this isn't supper clear in the video. The problem with videos and text is things get explained once. When you work with a mason they yell at you...a lot. That gives you feedback about how important the 100 things he told you are. In the video they say it once and you might not get how important it is.

Everything about a stone wall is about settling. Every step, everything. Why is the base 21-30"? Settling. Why are tie rocks used? Settling. Why are rocks placed long side into the wall? Settling. Why are the rock fill in the middle set with as much care as the facing rocks? Settling. We know for a fact that the wall is going to move. So do what we can to minimize that movement and do things to reduce movement damage.

This all starts with the soil. In the video they show scraping the soil bare and probably say things like "undisturbed soil". Undisturbed soil and disturbed soil is extremely important in building. There's an entire science devoted to how to create undisturbed soil. Like when we build a house, or a sidewalk the city comes out to inspect the hole before concrete is poured. There only a couple of things they're looking for and one of the big things is undisturbed soil. You can just tamp it down and call it undisturbed. You have to dig down more, use more concrete than should have been needed.

Undisturbed soil means the soil hasn't been moved, loosened.

Now you're getting ready to let tractor dude loose. You've done no measurements, no elevation plan at all to know where the terraces should be right? What exactly do you think tractor dude is going to do? He's going to tear the hill apart. Spinning tires digging holes, dirt everywhere. A terrace is what, 5-10' apart. How is the tractor going to fit on that?

You end up with a nice big mess of disturbed soil. If you were working for a mason and he came back from lunch and saw that he would punch you right in the face, girl or not. Then he'd throw you off the site. Then he'd sit down and start crying because now he has 4 times as much work to do. He's going to have to dig down to undisturbed soil, order a lot more rock and spend a lot more time builds a much taller wall, most of which will be below grade. And if he ever sees you on the street he's going to punch you right in the face again.

I'm really trying very hard not to be negative, but wow. You just went thru this digging the giant hole without a plan. You said you felt maybe you were over your head...but now you're getting ready to do the exact same thing again. At least that's how it looks to me.

The other thing you will hopefully see in the video is how little digging is actually needed. If you're build a 3' high wall you don't dig 3' into the hill. Maybe 2'. That's easy with a shovel. After the wall is built you back fill the top 1' or so. Look at how the wall is tapered at the top.

OK, yes, a tractor would be faster...if you have 3 things. The proper equipment. Farm tractor with a bucket on the front isn't. You need someone driving the tractor who has been screamed at by masons for the last 10 years so the start to understand tearing the crap out of stuff is not good. And last you need the dude that's going to be building the wall to be there to scream at the driver to stop tearing the crap out of everything.

That's why a shovel is way better for a first timer. You can't do as much damage. You'll dig one footer instead of trying to do all 3 or 4 at once. So you'll dig that one footer and want to start laying stone. Good. So you'll start laying stone and you will quickly learn why all these other things are important. Experience.

I don't know how long each of your terraces will have to be, I'm guessing pretty long. Make a plan, lay it out. Then instead of digging a 50' long footer just dig a 10-20' footer and start building. That experience will be so valuable to you. It will save you so much work later. Keep going in 10-20' lengths. Start with the shortest wall first. Give yourself a chance to learn and improve. By the end of the project you will be a pretty good stone wall layer I'd bet.

So I guess what I'm saying is learning from a video is pretty great, but you have to really study every word.

Just FYI...there are other methods for building stone walls. In the video the footer is only a couple of inches deep. It depends on the soil. You want hard soil. You don't want loam. From your pictures your loam looks really thin, so no problem. But there are builders who create a much deeper footer and fill with stone. The idea is the lower you go the harder and more stable the soil. The less effect of freeze/thaw. In the video they go shallow but wide. Just saying this in case you run into different building methods and wonder which is right. They're both good imo, it's more about soil type and stuff like that.


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RE: How to secure a retaining wall around a pond?

For drawing diagrams I use GIMP. Not the best but it is free. Way better than MS Paint imo because it has layers.


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RE: How to secure a retaining wall around a pond?

This forum software makes these kinds of long and detailed builds pretty difficult. Pictures are hard to post, no way to quote, etc. The other forum you posted in has way better forum software but in the main forum there's really a lot of people who post who will get you into serious trouble. They have a "showcase" area that can be quieter.

There are some forums with professional pond builders who are great, very helpful. They do long build threads there all the time. Great place to read. Posting might be a problem because they build a certain way, the money way. You need a thick skin there. So not sure how much help you'd get that you could use. But it is free to post so why not try it out. This forum doesn't allow me to even say the name of other forums (I think). You can email me or PM me in the other forum and I can give you that info. My email is on my web site.

I'm already kind of having a hard time following this thread.


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RE: How to secure a retaining wall around a pond?

Good luck on digging out such a hole on the down hill side of your house foundation. Pile driving or drilling some vertical steel pilings deep into the ground with treated 6x6 or 8x8 behind them to hold back the retaining wall is about the only thing that will hold on a slope that has been disturbed.

Ask the guy that I am making a killing off of after he tried the same thing with nothing more than 8x8 treated post with 1" x 8' re-bar to hold it.

This did not last a year before it gave way and nearly took the entire year old barn with it. He is listening this time. For once I get the mess cleaned up and out of the way. There will be 20' 12" I beams driven into the ground before the retaining wall is even started on.




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RE: How to secure a retaining wall around a pond?

Expensive way to learn. And how tall a retaining do you think he started with?


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RE: How to secure a retaining wall around a pond?

Good morning!

a) Yay! You came back!

b) You should write fiction or a weekly editorial for a good magazine or something.

c) I know you aren't trying to be a nay-sayer ~ you are trying to be helpful. But it isn't actually helpful to chastise the mistakes I've already made ~ made before I started this thread (oops, there's another mistake). :) That just feels discouraging, like there's no hope. And of course there is hope, as long I don't lose my gumption. And you can and are helping me not lose my gumption by instructing me on how to move FORWARD from here. Cause here is where I am.

d) Okay, so no more tractor dude. Shovel it is (for the upper terraces). But I'm still not clear as to what to do in the PIT to create undisturbed soil to put the rocks on. Is the answer to that in this paragraph:
"You'll dig one footer instead of trying to do all 3 or 4 at once. So you'll dig that one footer and want to start laying stone. Good. So you'll start laying stone and you will quickly learn why all these other things are important. Experience.

I don't know how long each of your terraces will have to be, I'm guessing pretty long. Make a plan, lay it out. Then instead of digging a 50' long footer just dig a 10-20' footer and start building. That experience will be so valuable to you. It will save you so much work later. Keep going in 10-20' lengths. Start with the shortest wall first."

If so, then what I understand from that is that I am to dig (with shovel) around the OUTSIDE of the entire perimeter of the pit ~ out, say 1' and down less than the height of the intended rock wall (which will be higher and higher as I head toward the back of the pond..... Dig some. Lay rocks. Dig some more. Lay more rocks. And on and on and on.
Is that correct?

If so, then here's my question: To maintain the integrity of the present undisturbed soil at the back, I'm wondering about this idea.......
So I dig out the berm starting at the shallow ends moving around toward the back. When I get to the high part of the cliff, can I build a footing on the existing bottom (undisturbed soil) out of rocks, concrete, etc. and marry it up with my dug berm? Thus avoiding the need to cut out more of that cliff (disturbing more soil)?

e) Also, when you say that my berm is not as deep as my wall, do you mean this: At the shallow end I want the rocks to rise six inches high above water level. So I dig the berm down from ground level, say 6". Place my liner to extend out onto the grass over the berm and into the hole. Set rocks on top of the liner on the berm, building up to a height of 10" so that 4" of rock is submerged below water level and 6" of rock is above water level. And then carefully tamp in dirt behind the wall (between the wall and the undisturbed soil). From the ground view, the rocks would sit 4" above ground level. Is that correct?

f) Thanks for the info on Gimp. I'll check it out.

g) I will check you out on other site. Same name?

h) I'm heading into the city today and am checking out some roofing companies re: liners. Are there chemicals on roofing liners that would be harmful for my pond life?

Have an awesome day!

K


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RE: How to secure a retaining wall around a pond?

The question of what to do about the existing pit...I haven't really said anything specific about that because that's really hard. If I was on site I could get a feel for the slope and the soil type and maybe the answer would be clear. But here's how it would be handled in general.

You have to start with the terrace highest up the hill. To know where that should be you have to measure. You need to create an elevation map, a cross section, at least a couple.

The problem with winging it is if you're off a little placing the first wall then the lower walls won't be right either and you end up building a lot more wall.

You see if the pit wasn't already there this would be a lot easier. You could just wing it. For example this could have been the first wall. You see there's room to get equipment in there to excavate and it doesn't matter much where you start.

Then the second cut can be made with an excavator (Bobcat, blade, whatever).

And the third.

Where these all ended up on the hill wouldn't have mattered much. But because you have a pit everything has to be positioned so it comes out right. If the first wall is too far up the hill you won't lower the pit wall enough. To close to the pit and you're really screwed because the pit wall won't be reduced enough and the walls you just built will have to be removed and you have to start over. Spending an afternoon measuring can save you a lot of work.

Straight talk time..I believe in learning by doing. If I were in your shoes I would proceed with the terraces. But my goal is just to learn. This project is a very serious learning opportunity. Lots of masons I know couldn't pull this off. They would be in too much of a hurry and make a bad measurement or a math mistake. That's OK for them, they also have the experience, equipment and crew to fix stuff and they'll know something isn't right before getting too far.

And I doubt my result would be very good either, but that's OK with me because learning is my goal. I'll just rebuild it all again. To me rebuilding the same wall 5 times is just as good as building 5 different walls. But I don't know if that fits your goals. I don't want to talk you into something.

Having said that I'm worried for you. This is a huge job. I'm willing to bet this is 20-30 times what you think. Taking on a job that's 2-5 times what I thought it was is something I can put my head down and plow through. 20-30 times is rough. Corners will be cut, its just a question of when. The earlier in the project the more options you have.

The other issue is time. That 8' (or whatever) vertical soil wall isn't going to wait for you. If you start to have an erosion problem it could bring down your first walls before you can complete the job. I mean this looks like a multi-year project and I don't think Mother Nature will help. But I don't know your climate or soil type.

And I'm not sure you have the right kind of rock for making a dry stacked wall. These are pretty flat rocks, many need to be at least 12" long. You'll need a fair number of large rocks for the cap. You'll also need a lot of small stones, like as much as the bigger ones.

I'm concern is you haven't done the calculations yet to know how much rock you need but instead you're spending your time carrying rocks. That's a huge red flag. These things are built with brains, not muscle. You know how to carry rocks so that's what you're doing. It feels like you're making progress. That's natural, but it's also a trap. Where are you piling these rocks? Probably right where you need to dig. So you get to move 20 tons of rocks 2,3,4 times instead of 1 time. If you dig the cut first then you can carry the rocks directly to where they are needed you can make good guesses what kind of rock to carry and just carry what you need (kind of) directly to where they're needed. At least you'll know where to stack them so they're close at hand and out of the way.

I would seriously consider a plan B, C or D. Those would all still be enough work that during the project you'll wish you never did this but be proud of in the end.

Plan B is the controlled slope I've already shown. It moves the least amount of soil, uses the least amount of rock and is the fastest way to secure the site. And you can to a combo of maybe a 2-3' retaining wall at the top and a controlled slope below. Plus you can always come back and add more retaining walls on the controlled slope if you want.

Plan C is a controlled slop but you build ponds on the slope instead of just rocks. Still plenty of rocks. It's a way of doing terraces with ponds. These really wouldn't be ponds as much as they'd be streams, but maybe 2-3' wide and 1-2' deep. So in between pond and stream. That's pretty easy to do but you need a fair amount of liner. Doesn't have to be big pieces or all the same kind. You can get waterfalls in there too. Basically the liner would help protect the soil and the weight of the water would help compact disturbed soil. It's a much faster fix. You can bring in rocks to make short sloped walls. That's easy, just setting single rocks on soil. Doesn't matter what shape rock.

It just depends on what you want.


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RE: How to secure a retaining wall around a pond?

"h) I'm heading into the city today and am checking out some roofing companies re: liners. Are there chemicals on roofing liners that would be harmful for my pond life?"

No harmful chemicals. I have a web page that discusses that myth, link below if you're interested. My web host is being flaky today. Used to be a huge myth in the forums. Today pond EPDM and roof EPDM are about the same price, but prices for both do vary a lot. So today you don't see the myth very often because there's no savings. Water Garden forums are always full of myths. Someone writes something scary, which people love to read and repeat. Becomes a "fact" over night. It's a really problem. People come to these forums thinking people know a lot about ponds but it's mostly a very closed world of repeating stuff they heard from each other. The poor newbies think it's all true. Heck the people writing it think it's true too. And what a flame war you get should dogma be questioned.

Sure hope you're not buying a liner for a pond that isn't even planned.

Here is a link that might be useful: EPDM myth


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RE: How to secure a retaining wall around a pond?

Wow!

Double wow! You are really helpful and generous!

Nope, not "buying" anything. Trying to get my hands on as much free liner as possible as soon as possible; NOT because it will ultimately be used on the pond, but I thought it would help cover some ground while I'm working on this multi-year project and protect it from eroding.

I'm not opposed to switching from two terraces to a gradual slope. I'm exhausted just reading your above post (although the pictures make it look so awfully pretty! And I cannot believe how accurately you depicted my hill/pit. That's exactly what it looks like!!!).

I know this is a LOT to ask..... but any chance of you drawing a picture of that too? In particular, how the back slope connects to the gradually declining sides of the pit.

I do have one concern: Given that the present cliff is so steep; I'm worried about just how much more hill I will have to cut out to make the slope.

Although I haven't really internalized this yet; I am starting to get the enormity of this project. Dealing with moving the rocks is more practical than just a form of denial and avoidance (although it is helping with that). My neighbour is selling his house ~ has an offer on the table with a sale date of July. Which means, I need to get the rocks before the new owners move in and decide they want to build a garden pond. I'm placing them about thirty feet away from pit.

I love the idea (plan C) of mini pools. I just don't understand it.... How does it help with the current cliff situation? What is on the down side of the pools? Where do the rocks go? Stacked (wall) or on the ground? What transitions between the pools?

Thank you so much for participating so willingly in this conversation. I'm trying to take it all in!!

:) K.


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RE: How to secure a retaining wall around a pond?

I see, you have to get the rocks while the getting is good. Makes sense.

I'm not exactly sure what you would like drawn. I'll draw what I'm thinking and go from there.

But basically for the plans B & C there really isn't any "correct" way except for hiring a soil engineer. So what I would do is take a shovel or bar and just poke the soil, hopefully not so you get killed. So maybe start at the sides. You're just trying to speed up erosion. You should get a sense for how stable the soil is and that will kind of tell you how steep you want to chance it. That will put a bunch of soil into the pit so that won't be as deep so you won't have to cut as far into the hill.

At the top there will have to be a wall. That can be 6" to say 24" high depending on what you want. Because as you break down the slope you will be able to stand on it and then you'll be into undisturbed soil where a wall can go. Personally I'd shoot for a 12" wall at the top. That's pretty simple to do, less skill needed, less risk. It will be good experience.

I'll a diagram.


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RE: How to secure a retaining wall around a pond?

Awesome! I'm excited to see what you come up with.

Thanks again for help! Night night.

Katie


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RE: How to secure a retaining wall around a pond?

The pit.

Start sloping the wall.

More sloping.

More sloping and a cut at the top for a wall, maybe just 1'. Make it sloped instead of as vertical as I show. That way you just have to stack rocks in the dirt instead of actually making a free standing retaining wall. Unless you want the free standing wall.

Top "wall", but more like rocks on the dirt to protect the soil.

Pond/stream starting at top. Stream is very little digging, could be just 12" wide. Pond would be more digging.

Use rocks to protect the up hill soil and liner covers and protects the down hill side.

Water. The actual depths will be determined by the slope and amount of work you want.

The pictures aren't perfect, just a general idea. Details are important but we get into that later. Soil will want to erode down and can wash into the stream so you try to position the liner to be a kind of dam on the uphill side and covers the downhill side.

At the top you want water coming down the hill to be able to go around. No way to make that perfect, but you sure don't want an uphill valley in the middle of this.

There's 4" black drain pipe that comes in 100' rolls, cost about $50 US here. If you could swing that then putting it in a trench at the top to catch and direct water away would be good. These have to be covered with rock. Should have some geo-fabric down first, but old carpet will work.

Pardon the pun but there is a downside to this. You see the lighter brown soil that came off the slope and the ponds/streams are all set on top of...that's loose soil which will settle, which will cause leaks. You'll just have to keep an eye on everything and add rocks as needed to keep water in place.

So there's a choice. More digging so each pond/stream contour is on solid soil, or way less work using loose soil to build up a berm on the downhill side. If you use loose soil tamp as good as you can in 2-3" max thicknesses at a time.

In 3-5 years you might have to redo it all, but it will be much easier. Liner can be reused. Hard to tell how long something like this will last.

The upside is this is what nature will do on its own over the years if nothing is done. So you wouldn't be making it worse imo.

If possible try to give yourself some paths in there following the contours to make maintenance easier. Places for plants.

The waterfalls are easy. At end end of a contour the liner on the downhill side just overlaps the next contour down. Details when you get there.

This is important. Each contour pond/stream has to be level, or sloping down very slightly. If you slope it down, because each contour is long, the low end will require a lot of rock on the uphill side. So I'd mainly go for level, following the contour. Don't really want a perfect curve, just follow the natural contour. Less digging and looks better.

Getting these level isn't exactly easy. For sure you want to use a water level. Easy to make, instructions on Youtube or wherever. Perfect for the long distance. A 4' bubble level won't do it. 2x4 and level won't do it. Water levels are more accurate than even a laser level. Good tool.

Another huge help if you can swing it. 1/4" or 3/8". You drive short lengths into the ground and then cut a long length on top so it's horizontal. That allows you to make sure that's level the whole length. That defines the downhill side of the stream. You pile rocks and or pack soil to form the berm. The liner goes over that. You can leave the rebar in place or remove it after the berms are in place. It is way good to leave it in place. That will greatly reduce the downhill side settling and leaking, animals stepping on it and sinking it. Liner goes over berm and rebar. Heavest rebar you can afford for the stakes, but 1/4" or 3/8" for the horizontal. It will last a very long time but does rust. I'd say 3/8" min for the stakes, 1/2" is better. How long the stakes have to be depends on the soil. Don't have to be super hard to pound in, but not loose either. The stake can go into the hill at a slight angle to get a good byte. That's just an overview to give a general idea. We can get into more detail if needed later.

You may not have enough liner for a single piece to span the entire length of a contour. No problem. A slight drop can be placed anywhere and a small waterfal (more like rapids) added there so 2 liners can overlap.

Long term you might not like all the streams. Clog with leaves, animal issues, whatever. You can just abandon the upper parts. The liner will still protect the soil. Just pile soil, gravel, rock into the unused stream to not have standing water.

Or you could just lay a liner over the entire upper section and cover with rock. I'd still do the terraces because the entire rock covered liner would likely slip down the hill. Terraces would help keep it in place.

You really want to use your imagination when on the hill and placing this all. Picture where a tree might go, or plants. Consider some dry stream beds too. That's the art part.


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RE: How to secure a retaining wall around a pond?

Holy catfish, waterbug! That post is spectacular! I don't mean to gush artfully, but you sure are an example of someone with a tremendous gift; and you give it so freely as a gift to others. I can only hope the words "thank you" will express my gratitude. Wow!

I get it. And I reeeeeeeallly love it.

I need to learn how to draw perspective because I want to be able to map/measure this out with accurate dimensions. But never having seen my land/pit, I cannot believe how closely you reflect it in your drawings. Fantastic.

I am still uncertain about the sides; but I will try some drawings to see if I can get it. And I have a couple of questions about the drain pipe ~ the first one being..... in what order does that need to go in (if not immediate, than my other questions can wait).

I am going to print out multiple copies of your drawings and pin them up all over my house as inspiration and as a clear message to the universe as to what I want. It will come, without question!

Anyway, I need to read this a few more times until I have completely internalized it; but as soon as I saw it I felt a clear resonance that THIS IS IT!!!!!

The thing that I am most happy about (and most surprised) is that I can build the upper pools in "disturbed" soil. I'm happy about that not only because it means less work and easier to manipulate/control to get what I want ~ but also because I'm leery about doing too much more digging up the hill ( a) the pit is big enough as it is and b) I don't want to eat up my land......I was driving my lawn tractor with a load of rocks on the wagon up above the pit and the momentum of the wagon load kinda propelled me toward the edge of the cliff and gave me a real burst of fear. A bit too close for comfort, yikes!) I've decided hand mowing around the pond is the order of the day!

Meanwhile, I'll download gimp and try to figure it out or do some hand drawings and scan them and see if I can't "look" at the hill straight on to see what the sides will look like and the dimensions of the upper pools.

Thank you so much for going into such detail with this. You are a real gem!

Gratefully, Katie


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RE: How to secure a retaining wall around a pond?

You are welcome. I have a confession. I am a recovering pond addict. I do not understand why, but just enjoy designing and building them. So I appreciate you letting me add my two cents.

I do want to be clear that building the pond on disturbed soil is not good. There will be settling, there will problems. But I think it is the most reasonable choice at this point. And you will learn a lot, not spend a lot, will get to use all the rocks you can move. And nothing is very permanent which is good. This may all slide down the hill next spring. But you'll know how to put it back and it won't be a big deal and you'll be able to make improvements.

The trick is out much of a slope you end up with. Less digging = steeper slope.

Plan D, I think we're up to, is to have tractor dude push some/all of the dirt back into the hole. If you could get him to add 6-12" at a time and run the tractor over it to pack it down that would be great. Then you can build your ponds on that and have to break down the hill even less. The weight of the water in the ponds would help settle the soil and each year the spot would get more stable. You could still have a pretty big pond at the bottom. Trouble for me is I can't know exactly what the site looks like. You could take more pictures with you standing in the picture. That's how I guessed at your slope and pit, the one picture with you standing in the hole. I guessed you were about 5' 3" give or take.

I think you're smart to not drive near the pit. I had one friend killed by a farm tractor rollover and another maimed for life. A lawn tractor isn't as big, but I'm guessing one falling 8' feet onto to you isn't going to be good for the tractor. You would only break it's fall a little.

The drain pipe would basically go by the grass line of the cut, follow the crescent shape so the 2 ends are on the sides and down hill. Just trying to catch some water coming down the hill from getting into disturbed soil. One big problem with disturbed soil is it holds a lot of water. It could look fine on top but if you step on it you could sink to your waist. It can become like a bubble of muddy water sitting on a hillside. Then suddenly just break loose into a mud slide. It depends on the soil.


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RE: How to secure a retaining wall around a pond?

Quick question before I draw my plan.....

I will be removing the turf around the outside perimeter of my pond for planting trees, shrubs, grasses, etc. (On second thought, I'm wondering about the merits of NOT actually removing the turf, just killing the grass instead and then digging individual holes for my planting ~ thereby disturbing less ground and keeping it more stable. Yes?)

a) Does the drainage pipe run between the planting and the cliff or between the slope of my grassy hill and the planted area?

b) I've never used drainage pipe before. Home Depot's video on it shows it with an inlet grate. I'm assuming I would not need an inlet grate ~ the pipe is just to allow excess rain/snow water in/on the ground to seep in and be wisked away, correct?

c) Could I use sand from the side of the road/beach in the trench (as opposed to buying pee gravel)?

Thanks! K


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RE: How to secure a retaining wall around a pond?

One more thing. (This is premature, I know; but it would be helpful as I get this all squared away in my head if I knew the answer in advance.)......

If I want to put any plants in the terraced area with the upper pools, how do I get them in the ground if there is a liner covering the ground?

Sorry, I'm sure that is a dumb question, but I don't know the answer. :)


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RE: How to secure a retaining wall around a pond?

Funny story:

I have mentioned, at some point throughout this epistle, that I was trying to find a way of determining a level line along the perimeter of the pit to determine the lowest point. And in response to my post, a couple of very nice people have made mention of a "water level"...... even leading me to YouTube for an easy instruction on how to "make" one. And I kept thinking, "okay, so eventually I'll make a water level; but what the heck do I need a one of those for..... once the water is in the pond it will automatically find it's own level!"......
So my friend comes over today with a great long piece of clear tubing and says "Let's make a water level." And again, I'm thinking, "that is really thoughtful of you, but I don't need to find the level of the water, I need to find a level point on the ground...."

Then he show's me how it works. And I say "Ohhhhhhhh, it's not a WATER level, it's a water LEVEL!" Now I get it.

Gee, for a smart girl, I can be pretty dumb sometimes. :)

Cheers! Katie


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RE: How to secure a retaining wall around a pond?

I will be removing the turf around the outside perimeter of my pond for planting trees, shrubs, grasses, etc. (On second thought, I'm wondering about the merits of NOT actually removing the turf, just killing the grass instead and then digging individual holes for my planting ~ thereby disturbing less ground and keeping it more stable. Yes?)
Yes. Now you're getting it. A lot of what I say may sound overly complex, but really the basics are pretty simple. When build on a hillside stable soil is the most valuable resource you have. Everything that's made unstable has to be made stable and that's time and $$$. Less you dig the better.

Building on flat ground this is way less of an issue.

a) Does the drainage pipe run between the planting and the cliff or between the slope of my grassy hill and the planted area?
I don't know where the planting area is. Basically the drain pipe goes on the uphill side where ever you've started removing soil. All parts of the pipe has to be sloping downhill, no sags where water will collect, so that will determine exact placement. Mainly you should be concerned about low spots on the hillside, kind of valleys, were water collects. Those are the main areas you want drained.

In a perfect world you'd be putting drain pipe on each terrace. But that's a lot of $$$.

b) I've never used drainage pipe before. Home Depot's video on it shows it with an inlet grate. I'm assuming I would not need an inlet grate ~ the pipe is just to allow excess rain/snow water in/on the ground to seep in and be wisked away, correct?
Yes. There is 2 kinds of pipe, one with little holes all over it and solid. You want the holes. It goes into a small ditch and covered with rock/gravel which acts like the grate you saw. In a perfect world the trench is fairly large and fabric is placed in the trench first, then the pipe, then covered with stone and the fabric sides are pulled over the stone to cover. Soil can then go on top but better is just more stone. Sometimes a fabric sock is pulled over the entire length of pipe. The fabric is to slow down soil filling in around the stone and filling the pipe. How far you want/can go is your call. Mainly I'm concern about next month, next spring. As time passes slide risk reduces as soil compacts and plants grow. So even if the pipe is say 3/4 below the ground and you pile stones over it that hopefully will help. The drain pipe could even act as the uphill wall of your highest terrace/pond/stream.

When doing things on the cheap we're trying to get the biggest benefit for the least $$$.

c) Could I use sand from the side of the road/beach in the trench (as opposed to buying pee gravel)?
No. Sand would get into the pipe. You can use your rocks. Gravel is normally used because it's cheap, easy to shovel, easy to even out. But rock works too. Any material larger than the holes in the pipe and doesn't float.


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RE: How to secure a retaining wall around a pond?

If I want to put any plants in the terraced area with the upper pools, how do I get them in the ground if there is a liner covering the ground?
That's where the art comes in. Natural is cheaper than formal. The more this all doesn't look man made the more natural. That all sounds like duh, but it's surprisingly hard to pull off. It's easier for us to do the same thing over and over.

So while you're on the hill positioning the liner you look for opportunities for different kinds of plants. But basically between terraces there will be/can be a gap between the up and down hill terraces. Plants can go in those seams. Grass, other plants. That gap maybe can even be wide enough for a small path for you to get in for maintenance. Paths can be just grass. Basically each terrace can be all stream or part stream and part path/planting area. How much of each its the art. For example, a path doesn't have to be contiguous. Like maybe you have to step over the uphill stream to get to another path and then down again in a bit. Or you have to step over a rock or whatever.


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RE: How to secure a retaining wall around a pond?

Good you're getting the value of the water level. Probably the most useful tool you will use on this project. They're even better than a laser level for this type of project. It will help you plan the project and then also get the details dead on when building. And dead on is super important with this type of project. So good deal.


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RE: How to secure a retaining wall around a pond?

I guess it is time to hop back in and point out a couple things about inexpensive streams. You obviously wish to do this with minimal expense. The general approach is to buy a decent pump that can probably pump over 2000 gal/hr. The more expensive ones are called mag drive pumps and they are far less costly to run on a continuous basis (something in the range of a couple of old light bulbs; 200 watts). They probably cost ~$200 US and up. But you could probably scrounge an older sump pump or something, for almost free, but the wattage will be 3 times higher.

Better pumps can usually pump higher. Some kinds just won't pump high at all or the flow rate just decreases. I mention this because you would be attempting to pump a taller amount than in many ponds. Of course, you don't have to start the stream at the top (or even higher and closer to your house) but then you would lose the advantage of the retaining effect of a big water trough as a retaining section. On the other hand, in the higher sections, you could be digging into undisturbed soil, and you probably wouldn't need the extra retaining value.

One cheap approach would be to turn off the pump sometimes, but this causes some of the stream water to run down and overflow the bottom pond. BTW a power failure has the same effect. That then requires partial refilling. Many people are often doing partial refills for a water freshener so that is not a total waste. One extra concern: you are in a cold area and ice dams that cause unpredictable spill-overs could cause severe water loss. There are water level switch floats that should shut the pump off if the bottom pond drains too much, but they should be set up so that the switch wouldn't freeze and fail too. I suppose the only pump system that would work in freezing areas like yours are submerged pumps so the pump wouldn't freeze and crack if water wasn't flowing. BTW, when the pump is stopped you would want to be sure that All of your plumbing would drain all water from the pipe or the pipes will break too. You probably knew that already, and it was just this ignorant California boy who had to learn it the hard way after moving to North Carolina.


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RE: How to secure a retaining wall around a pond?

All valid points. When the time comes and the elevations are known, picking a pump will be important. But yeah, there are ways around this. Liner streams can be dry with just rocks. More than one pump can be used. Etc.

But I'm guessing this will probably have a lot of streams. They'll clog with leaves, animals will walk in them. I imagine the actual amount of wet streams will be scaled back. It was never part of the inspirational pond. But who knows.

I don't see the overflowing thing being a problem. I'm guessing the bottom pond would be pretty large square foot wise which is what matters. Maybe if the pond fills almost to the top with rain there could be overflow. Hopefully there will be an overflow on this pond. Important for all ponds, but extra so for a hillside pond.

I hope OP never considers ever running water into the streams in winter. That would be a serious problem. In just the past few years the forums have gone a little crazy imo on the pumps in winter thing. The downside of cold water seems to be completely ignored.


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RE: How to secure a retaining wall around a pond?

Good morning,

I went out yesterday and found the highest point of the lowest point of the ground (if that makes sense) and used my handy-dandy water level to find the equal point at the highest point of the cliff. Then measured down from the cliff. This determined that the water level will be 4.5 - 5 feet down from the edge of the current cliff.

Then I picked a random number and measured up along the slope of my remaining hill 9 feet. I chose this number for three reasons a) it needed to be short enough not to eat up my entire hill, b) it needed to be long enough to make a substantial difference in the angle of the cliff/slope, and c) it needed to be big enough to fit three small pools. I'm not sure it will satisfy C, but it's a starting point.

So then I did a little calculation. I'm not sure why I'm doing the calculation. But those 2 sides of the imaginary triangle leave me with a 10.3' slope up from the 4' mark.

That would mean, if I built the lowest rock wall 2' high, it would have 1' submerged (approx) and 1' above water level. That seems much more doable.

That also gave me a more accurate measurement of the "deep end". It is a good 4' down from the top of the water. That is more than ample.

My first concern is STILL creating a stable berm for that area of the rock wall. My thoughts are to start work by cleaning up the shape of the pond and throwing all medium and small sized rocks into the deep end. Then, as I start to cut into the cliff to make the sloped terraced pools, I will throw the dirt onto the rocks and create a new floor of the pond.

When I tried to pound a rod in the ground to measure the water level at the back of the pond, the gravel/dirt fell away as soon as I touched it. So I am anticipating that I cannot "sculpt" out a berm back there. So I'm wondering about using the big rocks (10" to 14" in diameter) to create a foundation (on top of this new floor) for the rock wall instead of a dirt berm. Does that make sense?

Will write separate post regarding the pump.

Cheers, Katie


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RE: How to secure a retaining wall around a pond?

Sorry, I don't know how you got your images to appear larger on the forum. I hope you can zoom in with your computer.

:)


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RE: How to secure a retaining wall around a pond?

I may be showing a severe ignorance of different soil types (and your description of crumbling is a concern); but I had not been concerned at all about your berm because I didn't think it needed to be all that high and I just like to think of it as a pile of dirt. From your original post, I thought it was essentially already there. My method for a small pond with a missing wall was to throw the dirt I dug out onto that end. Then I covered the pile with that end of my liner. The pond water pushes on the liner and keeps the inside from sliding in, and the liner covering keeps the back side from eroding. I imagine, if I only had a big pile of sandy soil, that might not have worked, but your soil didn't 'look' sandy.


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RE: How to secure a retaining wall around a pond?

Sorry, I'm not following. Text isn't very good when talking numbers, drawings are better.

The triangle you drew has to be a right triangle to help, so you can figure the terraces, know the slope. You pick a point on the hill, point A, and then move your water level some place downhill, point B. So A and B are level. You measure from A to B for one side and from B to the ground using a bubble level or plumb bob for the other side of the triangle. The 3rd side can be computed. Where the plumb bob landed then becomes the new point A and you repeat going down the hill. It's takes some time but once on paper you can make better plans.

I did think of one thing, I know you want this on the cheap but you're talking about buying liner...so maybe you should consider concrete block. Figure how much you need, it might be doable. 6 courses would get you 4', that's about $2/ft for material, might be cheaper than liner. If you skip the footer. I mean it's not good, but better than loose rock. And then terrace with block too. Not sure how long the walls are but could be maybe $300 for block, rebar and concrete. Might be cheaper than covering the hill with liner if you're buying it.

Worth figuring out imo.


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RE: How to secure a retaining wall around a pond?

I've been reading this post tonight and I feel that I need to say to you, capkaren, 'Stay out of that pit until you get the soil stabilized from the top!'

What if the crumbling that you mentioned when you tried pounding in rebar had been the outer 12 inches of the entire excavation? Can you imagine being buried alive?

Safety, please :-)
I got really scared looking at the original picture of you standing there with the cut out towering over your head.

I had an environmental engineer friend killed in a much smaller dig when the sides collapsed and nobody knew he was there. He did this type of work every day as a profession. He ignored the first and second rules of excavation, never go into a dig site alone and never underestimate the weight and power of soil sliding down a hill.

I don't mean to be a buzzkill, but you really need to be watching for your own safety.

I found a beautiful stream/waterfall on a high slope, about halfway down this linked page.

Here is a link that might be useful: Garden of Whimsy

This post was edited by pkponder on Mon, May 19, 14 at 0:01


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RE: How to secure a retaining wall around a pond?

Sorry I've been out of touch for a few days.....busy times.

Thanks pkponder for expressing your concern w.r.t. the dangers of working in a deep hole. I would have guessed that was more of an issue in sandy soil; but I really know absolutely nothing about soil ~ including the make-up of my own.

However, I do like safety and will heed your warning. In fact, I've ceased driving the ride-on mower above the hole to cut the grass ~ just makes me a bit too nervous (well, to be honest, riding side-ways on a hill is scary enough without the addition of a cliff below) ~ not to mention, I wondered weather or not it could agitate the dirt that's been cut into below.

We've had several days of rain in the past week and there hasn't been any mudslides or noticeable erosion.

On another note: I had my eye on a large pool liner that was being replace but the pool guy said that pool liners cannot be used in ponds as they are toxic. Does anyone know if this is actually the case?

I hope you are all enjoying your lovely ponds and whatever critters and plants they host.

Cheers, Katie


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RE: How to secure a retaining wall around a pond?

I am so happy to see you post! I was beginning to worry :-)

I have never heard that pool liners are toxic. Anyone else?


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RE: How to secure a retaining wall around a pond?

Pool liners are fine, just another plastic. I have read in forums people saying the chlorine on the liner will kill fish. Or just "chemicals" in general. But that's just imagination running wild.

Another issue that comes up is these things are sometimes advertised as being "algae resistant". That has lead some people to assume there's a poison in the plastic that leeches out to kill algae. And if it kills algae it probably kills fish. This myth was very popular 10-15 years ago in the Roof EPDM wars. But the deal is these are all "algae resistant" only because they're a slick surface, algae doesn't stick that well. It can stick, which is why marketing people said "algae resistant" and not "algae proof". It's just something marketing people say sometimes. Glass is "algae resistant", your skin is "algae resistant", pretty much anything can be called "algae resistant".

Swimming pools with liners are commonly used at Koi shows to hold fish.

That's a pretty good sign the rain isn't causing erosion. Maybe to don't have to cut back too much at all.


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RE: How to secure a retaining wall around a pond?

Hey Capkaren,
How is the pond building going? I can't stop thinking about your grand waterfall!


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