Making a weeping water feature out of a large boulder

[Dune]

I am new to this process and am not sure how to proceed. I would really appreciate any input your pond community could provide.

I have a boulder in my backyard approx 5' high x 6' wide and want to convert it to a water feature. I live in Mexico so I do not have access to the best of Home Depot/Lowe's to get supplies. As such, I need to be somewhat creative/resourceful in how I proceed as I do not have access to the best equipment.

What I foresee is digging a "pond" around the boulder (at the front/sides of the rock) approx 1' deep. Then filling the hole with some "base sand" followed by a pond liner. I would install a pond pump connected to 1/2" pvc pipe running around the back of the boulder attached to a Rain-Bird 180 degree spray head to provide low volume water spraying over the top of the rock to allow the volume of water to trickle down the rock face.

The desired result would be to have a low flow water feature trickling off the flat face of the boulder into the pond below. Not too much flow and no fish; just enough to provide the calming "trickle" effect water feature flowing off the boulder face to the pond below.

Questions:

1. What is the best way to attach the pond liner to the boulder face to avoid water leakage? My thought was to cut the pond liner as tight as possible to to the base of the boulder (form fitted) and then line it with some thin field stone in the 1' hole to hide the liner.

2. What capacity pump would be sufficient to move water up a 1/2" pvc pipe to a spray head approx 5' above the pond height.

Any thoughts/suggestions would be sincerely appreciated as I am still very much in the design phase. If anyone has suggestions beyond my basic concept I would really appreciate your input.

 

[RobAmy]

Welcome. You have a great rock there. I really do not see a good way of attaching the liner to the rock. Cutting it tight will not work with the texture and shape of the rock. I think for the cleanest look you really need to move that rock for the best leak proof way using a liner anyway. I think if you start attaching rocks it will change the simple beauty you have going on now. There are many ways to move the rock but with limited access to what you can get you hands on will be challenging. A machine is the simplest way but not sure if you have access to the boulder.

Something like this will work very well if you can get access to the parts. You do not need to lift it high at all. Just enough to get the liner and some sort of liner pad under and on top to protect the liner.

 

[Dune]

Thanks for the info and link. Unfortunately my backyard does not allow any heavy equipment access and I was really hoping not to have to attempt to move it. The size of the boulder is considerably larger than that in the video so I am not sure if I could use the mechanical setup shown in the video.

I was thinking if I excavated slightly under the boulder I might be able to put in a thin plywood fascia (which I could somewhat curve to match the curves of the boulder) on which I could then glue a pond liner. Not an ideal solution I agree but I'm not sure moving the boulder (which is the correct/ideal solution) is possible given it size.

 

[j.w]

@Dune Nice rock!

 

[Mmathis]

Hello and welcome! You may not know it, but we LOVE ROCKS on this forum, and that one is a beauty!

I agree that trying to attach a liner probably won’t work. I don’t know who it was, but someone on here a few years back did something similar. I don’t recall any details — all I remember is that they dug their pond to surround an island or something like that. IOW, it was a donut-pond. It sounded impossible, but I want to say that whatever they did, worked! I have no advice for you, sorry, but can only say that sometimes we have to just try something out to see if it will work or not work.

 

[Panzer13]

Welcome Dune.
Moving a boulder that we
Here is a thought, dig around the boulder and make trench 12-18 inches wide and deep. Depending on how much water you want your sump to hold. I would think the bigger the better, you will probably lose allot of water do to evaporation in Mexico. Make sure you dig an area large enough to house the pump behind the rock.
Ok so now we need to make a pump housing to surround the pump. The pump housing will fit in the sump in back of the rock. It must have a removable lid so we can access the pump. It also must allow water to flow into our pump housing but not allot rocks in. You could use a plastic milk crate for this. Cut the bottom of to make the lid. Zip tie weed barrier, or burlap to the walls of the milk crate and to the lid. This would allow water in and keep the gravel out. Maybe you could cover it with a piece of slate or two. The pump housing will also allow the pump to have the proper space around the pump so it can siphon water and function correctly.
Since you are not going to have plants or fish just use cement to line the sump. You could bring the cement rite up to the rock forming a good seal. Once the cement cures fill any cracks with a sealer. Put in your pump housing box attach the pump to your PVC. Fill the sump with gravel add water and away we go.
As to the pump, Amazon will have what you need. They should tell you what the maximum lift height for the pump is in the stats. If not go to the manufactures web site.
If you want a trickle effect you want a pump that is just strong enough to make it to the top of your rock. Given the rock is 5 feet tall and the sump would be a foot or so, six feet sounds rite.
I would check on the water level every couple of days or so till you get a feel for the rate of evaporation. If the water runs out the pump will overheat and be destroyed.

 

[GBBUDD]

You have given yourself a challenge for sure. the only way I could insure a water proof bond would be to cut a thin trench into the rock toward the bottom tuck the liner in and use lap seal or a polyurethane sealant and wedges. The best choice is as robamy suggested Rolling the boulder. if you dug your pit for the liner close to the finished size roll the boulder over where you already have your liner in place with LOTS of effort to remove any small rocks best to make a bed of sand. Have the liner folded in half , roll the boulder onto the liner. Unfold the liner and wala you have a waterproof liner under your boulder simple right!!! Yeah except that rock probably weighs about 9,000 pounds you will need a substantial piece of equipment. a dozer or excavator would be my choices in order. a smaller dozer could roll the rock but you'd need a good size excavator to do the same >
I have used epdm so create a boot around an 8 foot diameter circle . the ruber was cut in a diameter that was 2" smaller al the way around and then was stretched over the metal casing but i'm not so optimistic around a uneven rock.
GOOD LUCK

One last thing to consider the water fall foam they sell at every water garden web site is suppose to be expandable and makes for a water tight seal. food for thought.
Amazing how much your rock looks like concrete

 

[zeuspaul]

I would spray some water on the bolder and observe the path. Then carve the rock a bit with a hand grinder with a diamond blade to channel the water towards a common exit point. Then carve a lip at the exit to form a water fall that exits the rock. You may need to form an exit lip with a bit of concrete.

Then dig back a little under the spout and form the pool under the spout. Go back far enough to contain the splash in the pool.

 

[RobAmy]

water fall foam they sell at every water garden web site is suppose to be expandable and makes for a water tight seal.

The pond foam just helps redirect water flow, but it is not water tight

 

[Panzer13]

I have revision. You would probably need to build a form to fill the trench with concrete. So what if you used a liner in the trench and ran the liner to the base of the rock. Then mix some mortar to seal around the rock.
I just don't see lifting that boulder as a viable option. It would cost allot of money to hire a trackhoe or dozer to lift that thing. Not to mention the amount of damage a big piece of equipment like that is going to do to you're yard.
If you somehow managed to move it with a jack, winch or whatever and that thing broke loose it would squash someone like a bug. Unsafe is never an option in my book.

 

[GBBUDD]

I have revision. You would probably need to build a form to fill the trench with concrete. So what if you used a liner in the trench and ran the liner to the base of the rock. Then mix some mortar to seal around the rock.
I just don't see lifting that boulder as a viable option. It would cost allot of money to hire a trackhoe or dozer to lift that thing. Not to mention the amount of damage a big piece of equipment like that is going to do to you're yard.
If you somehow managed to move it with a jack, winch or whatever and that thing broke loose it would squash someone like a bug. Unsafe is never an option in my book.

The dozer is to only roll the boulder. This would be the best option I could think of. Dig the containment area off to one side place the rubber in a thick bed of sand both above and below the liner. Roll the boulder into the containment area possibly onto some lumber to help it roll and not bed into the sand.
if you want the boulder right where it is dig half of the containment area roll the boulder into and onto the liner that's rolled up or folded. then dig the other half of the containment, unroll the folded up liner and roll the boulder back. no lifting involved. If you go through all this for your water feature I'd go further and have a hole drilled through it for your water source.

not water proof?glad a changed gears on the patio to the pond seal idea on my project and built the retaining walls.

trying to seal to a boulder with concrete will eventually crack and loose it's seal. two different planes two similar but different materials that will expand and contract and different rates. Thus cracks, could it be sealed with a urethane caulking or grout that's a possibility.

 

[Mmathis]

@Dune You know, I was thinking about something.......it’s been bothering me from the beginning. With the size of that rock, if you were to figure out a way to make your plan work — have you considered evaporation? That’s a huge surface area. You are in Mexico where [I assume] it gets pretty hot — and the rock will be hot. Wouldn’t you lose a lot of water simply due to evaporation?

It may not be a consideration for you, but in the past we’ve had members report water loss, assumed to be from a leak. Some of these ponders had heavily rocked ponds (exposed rocks on the outer edges). But when a leak would never be found, it was sometimes concluded/assumed that the water loss was perhaps due to water evaporating. IDK, but something to think about.

LOVE THAT ROCK!

 

[Mmathis]

@Panzer13 and @GBBUDD OP has stated that getting equipment into the yard isn’t possible.

 

[Panzer13]

@Dune You know, I was thinking about something.......it’s been bothering me from the beginning. With the size of that rock, if you were to figure out a way to make your plan work — have you considered evaporation? That’s a huge surface area. You are in Mexico where [I assume] it gets pretty hot — and the rock will be hot. Wouldn’t you lose a lot of water simply due to evaporation?

It may not be a consideration for you, but in the past we’ve had members report water loss, assumed to be from a leak. Some of these ponders had heavily rocked ponds (exposed rocks on the outer edges). But when a leak would never be found, it was sometimes concluded/assumed that the water loss was perhaps due to water evaporating. IDK, but something to think about.

LOVE THAT ROCK!

Turtlemommy is rite evaporation is a big factor. Even if you could move the rock or seal around it with something you would still need a large sump for water in order to run the fountain for any length of time.
I am going to finish with this. Anything is possible it's just a question of money, how much are you willing to spend?
It was my impression that Dune was wanting to keep this project on the lite side.

 

[GBBUDD]

Know anybody in the wrecker/ towing business ? air bags could do the job to roll it. With the epoxy based materials today I'm sure someone has a product that they would guarantee a water proof bond. Or like in the roofing trades epdm around the rock place a termination strip anchoring to the rock and then pour a pitch pocket to seal the joint.