How high can i rock pond wall

[DerekOR]

I'm building a pond (detailed build post coming soon) and had a question about rocking in the pond.

I have a portion of the pond that is about 48 inches deep with just a vertical clay wall using underlayment and liner of course.

Is it ok just to stack a rock wall that high using waterfall foam and small river rock to put between the granite boulders?

I tried to start rocking in the whole pond with the boulders and mortar, and that turned into a bit of a disaster. The rocks are dark grey and the mortar is close to white when dry. Also, I think it dried way to fast, so it is cracked like crazy. I have a fair amount of work to do to salvage all of that.

The granite boulders I am using are anywhere from 20 to 100 pounds and randomly shaped.

I will try to attach two pictures, not sure if that will work.

 

[DerekOR]

 

[IPA]

I don’t know the answer to your question but Those rocks appear to have some sharp edges. Most people recommend river rocks. If you are going to use the ones you already have I would suggest protecting the liner with additional underlayment between the rocks and the liner.

 

[Lisak1]

Yup - wring rocks. To rock a pond wall the rocks should be smooth and round. The ones at the bottom course should be much larger than what you’re using. You need a very stable foundation. And most pond walls are dry stacked - no mortar. There are some pond builders who use foam between rocks but that’s not structural. They are just filling gaps.

 

[Mmathis]

First of all, why are you wanting to rock the vertical walls? Are you talking about floor-to-ceiling? Or do you mean from the shelf and up? Are you simply wanting to hide the liner? Once the pond is filled, the liner won’t be seen. It will eventually be covered with algae which will disguise the walls. I only rocked from my shelf to the top of the liner.

I can’t speak for general pond-building, but in my (limited) experience... Having a wall that is angled (rather than totally vertical) away from the pond will help. Also, using very large rocks seem to work better than smaller rocks. And agree with @IPA about sharp edges — that’s a fish accident waiting to happen.

 

[Mmathis]

@Lisak1 You beat me to it, LOL!

 

[GBBUDD]

The first thing to keep in mind in a pond build with deep waters is . What if there is a swimmer in the pond . What if they climb this wall, is it going to fall in on them? at a depth of four feet that can be big trouble .While lisa is right waterfall foam generally is not used as a structural aspect it can lock rocks in pretty well . Would i use it to hold in a rock that IF IT CAME LOOSE could hold someone down under water . absolutely not. It appears you have a good deal of liner left over i would look at making additional shelves. And as was mentioned i would also place some fabric under those sharp rocks . and if you are thinking on getting in the water those rocks maybe unfriendly

 

[DerekOR]

Thanks for all the quick replies guys. You are all very helpful and awesome!

Here are a couple answers/thoughts to some of the questions:

1) I do have an extra underlayment between the rocks and the underlayment plus a bunch of other stuff. So it goes: earth > 1inch mortar skim coat on upper portion> carpet > underlayment > liner > underlayment. It is probably hard to tell, but it is there! I was very nervous about stabbing the liner at all, so I figured it was worth an extra ~$150 for peace of mind. I was also nervous about chipmunks eating a hole in the liner, so I mortared around the top half of the pond all the way around (just a 1 inch think “shell” if you will) to keep them from messing it up. I also got a ton of scrap carpet from a friend. The bottom portion where I’d be rocking the tall vertical wall does not have the mortar or carpet…

2) I was thinking the ~48 inches would need some kind of rock to help with the structural integrity and not have the clay walls collapse in a bit. I live in Oregon (south of Portland) where it rains a lot. I was thinking the clay will turn to mud pretty darn quick…

3) I got 14.5 tons of class 100 granite rock delivered to rock the pond. Most of it is 20-100 pounds, but I do have some which are likely 150 – 200 lbs, but I think they will be too difficult for me to lower into the pond with just my wife, son, and me. I was going to save these for the upper shelf or around the border. I have a super-small yard, so I sort of am locked into using all this rock now at this point (at least I feel that way mentally). I understand you will NOT be able to see a lot of it ~40 inches down once the algae grows a bit.

4) I am planning to build a separate swimming pond on the other side of the yard sort of as a phase #3. I can do this one differently, and perhaps do cinderblocks with rebar and stuff under the liner if need be. But, we may try to swim in this one a bit if it can be done safely. The idea with the black foam is you could perhaps at least walk on portions without stuff collapsing or it would hold everything together so rocks wouldn’t fall into the pond.

5) I plan to make a suction grid with a 3 inch main pipe and 2 inch branches under 6 inches or ¾ inch river rock and have it flowing with air-lift. So, if any of the small/medium/large rocks do fall, they would just be falling on that bed of gravel.

6) I do plan to put in some Koi and Shubunkins. Phase #2 will be a 10 foot by 15 foot by 12inch deep bog – so this will help with the filtration.

Is this whole plan a disaster waiting to happen, or do you think I can make it work safely for family using it for some swimming (with the fishes) and will it be safe for the fish???

 

[DerekOR]

The first thing to keep in mind in a pond build with deep waters is . What if there is a swimmer in the pond . What if they climb this wall, is it going to fall in on them? at a depth of four feet that can be big trouble .While lisa is right waterfall foam generally is not used as a structural aspect it can lock rocks in pretty well . Would i use it to hold in a rock that IF IT CAME LOOSE could hold someone down under water . absolutely not. It appears you have a good deal of liner left over i would look at making additional shelves. And as was mentioned i would also place some fabric under those sharp rocks . and if you are thinking on getting in the water those rocks maybe unfriendly

GBBUDD,

Are you thinking of removing the liner, taking a bunch of dirt, filling back in portions of the hole, compacting it, then putting the liner back down? Is that what you mean when you say build more shelves? That would be a ton of work, but if it is the ONLY safe solution, then so be it... My wife will probably kill me - so if you tell me that's what I need to do and you don't see any more posts from me, you know what happened !

I've read your whole pond build post, so I know you are a super expert when it comes to this stuff .

I also thought about renting an excavator similar to what you did and getting some of those 200lbs rocks down in the whole - perhaps they would make a suitable base...

 

[GBBUDD]

2) I was thinking the ~48 inches would need some kind of rock to help with the structural integrity and not have the clay walls collapse in a bit. I live in Oregon (south of Portland) where it rains a lot. I was thinking the clay will turn to mud pretty darn quick…

if you have true clay and in the pacific north west i would definately think long and hard about placing a couple drain tubes under the liner. it will give any water that gets under the liner a way out without trying to bubble into your pond

 

[DerekOR]

if you have true clay and in the pacific north west i would definately think long and hard about placing a couple drain tubes under the liner. it will give any water that gets under the liner a way out without trying to bubble into your pond

GBBUDD,

There is a drain tube (3-inch perforated plastic drainage) on the end with the shelf (left in the first picture) and the side with the waterfall (top in the second picture). This is because it is sitting in the corner of the yard.

Do you think it will be necessary in the bottom of the pond if I have 6 inches of river rock in the bottom - or will that be enough weight to keep the liner from bubbling up?

Also, maybe if I'm trying to make the rock wall 48-inches high with foam the rule will be no one is allowed to swim in it if you really think it is a safety concern.

Damn I really should have sought your guy's advice much sooner !!!

 

[GBBUDD]

I've read your whole pond build post, so I know you are a super expert when it comes to this stuff

Hardly an expert as that was my first pond build but i have built many things in my day . same principles apply.

T

Thanks for all the quick replies guys. You are all very helpful and awesome!

Here are a couple answers/thoughts to some of the questions:

1) I do have an extra underlayment between the rocks and the underlayment plus a bunch of other stuff. So it goes: earth > 1inch mortar skim coat on upper portion> carpet > underlayment > liner > underlayment. It is probably hard to tell, but it is there! I was very nervous about stabbing the liner at all, so I figured it was worth an extra ~$150 for peace of mind. I was also nervous about chipmunks eating a hole in the liner, so I mortared around the top half of the pond all the way around (just a 1 inch think “shell” if you will) to keep them from messing it up. I also got a ton of scrap carpet from a friend. The bottom portion where I’d be rocking the tall vertical wall does not have the mortar or carpet… The one inch concrete could create a problem as it will crack if it is sandwiched in a secure it maybe fine.

2) I was thinking the ~48 inches would need some kind of rock to help with the structural integrity and not have the clay walls collapse in a bit. I live in Oregon (south of Portland) where it rains a lot. I was thinking the clay will turn to mud pretty darn quick… And you are probably correct but for small rocks to stack 4 feet high the walls should be angled back so much that they are laying in the angle but resting against the lower rock or they could create a wave from the weight of the rocks above and colapse.

3) I got 14.5 tons of class 100 granite rock delivered to rock the pond. Most of it is 20-100 pounds, but I do have some which are likely 150 – 200 lbs, but I think they will be too difficult for me to lower into the pond with just my wife, son, and me. I was going to save these for the upper shelf or around the border. I have a super-small yard, so I sort of am locked into using all this rock now at this point (at least I feel that way mentally). I understand you will NOT be able to see a lot of it ~40 inches down once the algae grows a bit.
check 4:17 minutes and seconds in the video

and i would strongly recomend Aquascape videos and atlantis garden and tussey landscaping for how to build a pond before you continue . There are many ways to build a pond as you will see i didn't take too much of my own advice and follow those folks with the video but i did in practice i went with large boulds as you saw in the blog . i do have 4 and 6 foot walls but i also had 3 and 4 foot tall boulders an i stacked rocks behind eachother locking them in. and if you are realy thinking or a swim pond then i'd watch about 40 hours of you tube videos both on how to build and completed builds for ideas and ticks. i would also think about your now project as a bog and build the pond. thats would keep a good size pond nice and clean .Look for a blog here some seriously impressive pond builds.for ideas

4) I am planning to build a separate swimming pond on the other side of the yard sort of as a phase #3. I can do this one differently, and perhaps do cinderblocks with rebar and stuff under the liner if need be. But, we may try to swim in this one a bit if it can be done safely. The idea with the black foam is you could perhaps at least walk on portions without stuff collapsing or it would hold everything together so rocks wouldn’t fall into the pond.

5) I plan to make a suction grid with a 3 inch main pipe and 2 inch branches under 6 inches or ¾ inch river rock and have it flowing with air-lift. So, if any of the small/medium/large rocks do fall, they would just be falling on that bed of gravel. I could not figure out a effective uplift using air through layers of gravel .

6) I do plan to put in some Koi and Shubunkins. Phase #2 will be a 10 foot by 15 foot by 12inch deep bog – so this will help with the filtration. good size for sure i myself would go a bit deeper then 12 as many plants can send roots that deep i'd go just below what they can reach but many have 12" and i am not expert. just my two cents

Is this whole plan a disaster waiting to happen, or do you think I can make it work safely for family using it for some swimming (with the fishes) and will it be safe for the fish??? there are easier ways with some shovel work to work with what you have but like i said id lean toward that being the bog iif i was doing a swim pond

 

[Mmathis]

I can only speak for my own situation, but we have clay, clay, clay “soil,” in addition to a high water table. We also have a lot of rain. A year after we built our pond, the side walls were collapsing.

 

[GBBUDD]

GBBUDD,

There is a drain tube (3-inch perforated plastic drainage) on the end with the shelf (left in the first picture) and the side with the waterfall (top in the second picture). This is because it is sitting in the corner of the yard.

Do you think it will be necessary in the bottom of the pond if I have 6 inches of river rock in the bottom - or will that be enough weight to keep the liner from bubbling up? the 6" will low water to run under the pond and drain a little but if you have clay it drains very slowly and a relief tube coming up along the side of the pond the water will rise under pressure and a open tube is that path compared to lifting your liner and water . they call it a hippo


Also, maybe if I'm trying to make the rock wall 48-inches high with foam the rule will be no one is allowed to swim in it if you really think it is a safety concern. ALL WATER is a safety concern not to be paranoid but its a fact. if the wall was all baseball sized rocks and it collapsed odds are it wouldn't hold anyone down if they were loose rock . mortar them together a nd a section let go then yea it's a issue to think about but it may a child . who knows its just better to think about before you build it is all

Damn I really should have sought your guy's advice much sooner !!!

It is just that advice many said my design had some concerns but it's working pretty well . what works for one may not for another but the ideas should be in the same idea. your design could work but how often will you need to address ideas what didn't work out over the years or have an accident in swimming

 

[GBBUDD]

@Mmathis
can you draw a quick sketch with the shelves aquascape way each shelf a foot to a foot and a half high ? with the top shelf only 4 inches deep ?