How high can i rock pond wall

[GBBUDD]

The pond digger is a good guy for sure . The only problem with all mortar like that is the cement is going to play with your ph it may help depending on your water or it may hurt. one tip for you if your buying sakrete or quickcrete from the depot or lowes buy a bag of portland cement and add a scoop or two two your mortar tub with the trowel it will make the concrete much stickier and easier to work with if you have some big voids don't be afraid of putting waterfall foam or even gravel filling in the spaces behind. while the intent is to have clear water and see your rocks and gravel quite often many live with just seeing the shape and never seeing the colors of the rocks in their ponds. The algae puts a film / peach fuzz over the rocks so a little mortar on the rocks may not be a game ender. If you want to clean it muratic acid can clean it right up with some elbow grease the fresher the easier it is to remove.

 

[Lisak1]

What if I tried something like this where there is more than one rock on the very bottom and foamed the whole thing in. Is that workable, or would it still be very unsafe?

Each of those blue blocks is supposed to be a rock .

I have watched probably over 200 hours of pond construction videos from Greg Whitstock, Pond Digger, Tussey, Jaak Harju, etc. I guess a lot of it didn't really sink in and get into my shoveling hands when we were going to town though....

View attachment 132436

The top of your wall needs to be stable enough that someone or something can walk on it... because eventually it will happen. One big rock is always going to be better at providing that stability than any combination of small rocks. Also - I know it's just a drawing, but you want that vertical wall to have a slight lean backwards.

 

[addy1]

My pond is straight wall, with a tiny slant. Our dirt is clay with shale. Still holding well 10 years later. Here in MD

My pond in AZ I had straight walls, clay dirt and I put a lot of rock in bottom, after the first year could not even see the rocks. I did not do a clean out every year or vacuum the bottom. The algae nicely covered them and they just disappeared.

 

[DerekOR]

The pond digger is a good guy for sure . The only problem with all mortar like that is the cement is going to play with your ph it may help depending on your water or it may hurt. one tip for you if your buying sakrete or quickcrete from the depot or lowes buy a bag of portland cement and add a scoop or two two your mortar tub with the trowel it will make the concrete much stickier and easier to work with if you have some big voids don't be afraid of putting waterfall foam or even gravel filling in the spaces behind. while the intent is to have clear water and see your rocks and gravel quite often many live with just seeing the shape and never seeing the colors of the rocks in their ponds. The algae puts a film / peach fuzz over the rocks so a little mortar on the rocks may not be a game ender. If you want to clean it muratic acid can clean it right up with some elbow grease the fresher the easier it is to remove.

GBBUDD,

Thanks for all the advice.

I think I am going to try and work on just a small section continuing with the mortar, adding in the waterfall foam and small gravel/river rock in the cracks as you suggest. I will try to take out some of the smaller rocks and introduce larger ones. I will also try to create a slant with the rock similar to some of the diagrams Phaewryn made (thanks for those).

If I can get this small area to work OK, then I’ll expand out and do the entire pond. If it doesn’t work well, then I’ll fall back to ripping everything out and backfilling with more dirt and trying to add back in a shelf behind the liner.

One other idea I had was to perhaps build a shelf inside with some retaining wall blocks and river rock (behind the blocks) to make maybe a 20inch tall shelf by 12 inches wide. More expensive for sure, but perhaps moving forward vs. ripping out underlayments, liner, carpet, mortar shell, etc….

Also, very good to hear Addy1 that your clay soil simply held up without any rock wall on the vertical at all. Good to know perhaps I am being too paranoid about the whole thing and rocks may not even be necessary. As Phaewryn pointed out, if the dirt wants to move it is going to move. Some crappy little rock wall of mine isn’t going to stop it . So the name of the game is what looks good, and what is safe for family and fish.

Thanks again everyone for your ideas!

 

[Mmathis]

Finally found it - this is the video I was trying to go for. Has ~4-5ft tall shelves with mortared rock. About the same size rock as what I have - just need to remove some of the smaller stuff I think.

Anyone heard of a pinterest fail? That's kinda what my stuff looks like right now compared to Eric's 25+ years of experience!

The thought that always comes to my teeny little brain....yes, he did it, but he has an experience and knowledge level that I lack!

But all you can do is try it and see. Sure, it’s a PITA, but you can always go back and change or tweak things if it doesn’t work out.

One thing I have learned is that every pond is different. Every situation is different. What works for one may or may not work for the next guy or gal.

My motto is: look at the science, in this case, I guess that would be physics and fluid dynamics — consider the safety factor — assess my own skill set, and since I am involved in Scouting, the Scout motto: “BE PREPARED!” Because when things go south, it always seems to happen at the most inconvenient time!

 

[WaterGardener]

I don't see the need to rock from the bottom of the pond to the top. You are taking up a lot of space with that and I'm sure the fish could use it. Also, fish can get hurt on sharp rocks and I have lost some females during spawning that got beaten up on rocks, and I don't have any on the walls like your illustration. Mine are like mmathis' and just from the shelf up.

The liner is not that visible, especially when algae covers it all. And the plants in the pond will be much more of a focus, not the liner. Personally, I would save the money and the effort and not use rocks that way. Just my 2 cents worth.

 

[DerekOR]

Mmathis – I guess you are correct there. Hopefully this will work for me. It will certainly look in no way, shape, or form as good as PondDigger’s mortar job .

WaterGardener – My original thinking was I needed to do the rock walls to help support the clay sides from caving in. The is largely my fault as I screwed up the excavation by trying to make more room for the fish. There is no real upper shelf for rocks in the current state ☹. So, if I don’t do the wall I won’t be able to do coping stones. If I had a time machine, I would probably dig the shelves properly like everyone is telling me, not do any rocks in the pond, and have a real nice top shelf for coping stones. I’m sort of trying to salvage what I’ve done here vs. rip everything out and start almost over from the beginning. Time will tell if the idea of pushing forward is a good one or a terrible idea. Plus I have ~14.5 tons of rock in my driveway and small backyard, so I have to put the rock somewhere ! Below is a picture of the rock pile as it was delivered. If it does work out and I end up rocking the whole pond, I will try to pick out rocks for under water which are as smooth as I can find from the pile.

 

[GBBUDD]

Should have asked to see what stone you had to work with i see many rock there 4 times the size i thought you had. you should be fine. if you put some medium sized on the bottom pulled out a little put gravel and concrete behind the first row and build from there your largest next mix and match as you go and you should be fine they do sell boulder baskets its a nylon weave with handles for a two man or four man lift you could use those or use some fabric.
good luck

 

[WaterGardener]

You could always build a nice waterfall with those rocks!

 

[DerekOR]

Thanks guys! That instills a bit more confidence !

The super big ones are simply too heavy to lower by hand (or sheet/tarp), but I think we can find a way to get the ~120lb ones down in the hole. We tried a couple using a tarp, and my wife and I can barely move them. Some are too heavy to move with a tarp at all, I had to use a dolly to get them from the driveway to the lagging area. The really big one (you cannot really see it in this picture) I calculated is about ~920 lbs! No idea what we'll do with that one - maybe put in the stream which will connect the swim pond to the fish pond (2021 work).

WaterGardener - we are thinking alike! I was thinking of saving the biggest ones for around the waterfall, but sounds like I had it bass ackwards. We can get a couple medium or medium/large down there like GBBUDD said and see what happens! Then we can do some of the ones which are too large to safely move down into the hole and muscle them in place for the waterfalls.

Here's a picture of the huge rock. I can just barely nudge it along half an inch at a time with a 5 foot long 2x4 board using it as a lever.

 

[GBBUDD]

[/QUOTE]
GO TO THE DEPOT AND RENT A MINI EXCAVATOR WITH A THUMB MONEY WELL SPENT

If i had to guess i would think that is basalt or very similar make sure you protect the liner that stuff can split and fracture very easy and it is extremely sharp when it does

 

[Jhn]

GO TO THE DEPOT AND RENT A MINI EXCAVATOR WITH A THUMB MONEY WELL SPENT

If i had to guess i would think that is basalt or very similar make sure you protect the liner that stuff can split and fracture very easy and it is extremely sharp when it does
[/QUOTE]

Was thinking the same thing with the excavator.

That load of rock is granite, fairly typical blue gray color. Would still protect the liner with 8oz non woven fabric, as when that stuff is dumped some of the rocks can chip causing very sharp edges just like the basalt you mentioned.

Derek one other suggestion is make sure all the rock especially the smaller stuff is actually rock and not compressed dirt. Fairly common to get a few of these with that size rock bought by the dump truck load. It looks just like the rock but it will crumble and fall apart over time. Just don’t want you using a rock like that to do anything structural in the pond. The compressed dirt looks slightly different color wise and edges can be a little rounded and if you aren’t sure about one of the rocks just bang it into another one, the granite rocks make a tinny sound almost like metal being banged together, if it is just hard dirt it won’t make that sound and may even crumble abit.

 

[GBBUDD]

One other mention for those who might decide to rent equipment where they have never done so before. The gas /throttle if you keep it low the machine has less power and speed and this is where you should start for several hours or until you get use to the controls and let no one in to the area of the swing of the machine you can easy hurt maim or kill someone very very quickly . thumbs on an excavator are a very useful tool but they do damage rock. What is called an endless sling is what you see the pond builders using. But make no mistake the rocks can slip out of that set up and you definitely don't want it to hit someone or the boulder poking a hole in the liner because it slipped. Left over fabrics old carpet sleeping bags what ever can help keep this from happening but the end result having larger stone is beyond worth the effort.

 

[CliffandJoann]

Try a rock shelf all around...but you’ll need flat rocks...my shelf goes down about 15” and is about 12”
wide...it’s filled up to the top with flat rocks and the rocks extend over the liner edge.

This drawing was made by a friend. I described our shelf and she drew this...our rocks are flatter
then the photo shows.

 

[DerekOR]

GBBUDD and JHN - thanks for all of the tips!

I have a coworker that has an excavator with a 20 foot reach that can fit through my gate. Trouble is we just need an equipment trailer to get it here. I am hoping I can rent it from him to set the largest rocks (perhaps for the waterfall) with that.

I tried out the mortar again yesterday, and it seems to be working well using some of the tips from folks here. Main thing is to keep the mortar wet. I probably sprayed it down 50 times yesterday. That seemed to do the trick and prevent it from cracking. Will post some more pics here soon.

Hoping I can use waterfall foam towards the end to adhere to the mortar and push in some small river rock to make it look a bit better so you're not staring at a grey wall of mortar !