Pond Boss Forums POND CONSTRUCTION Building a dam The Baird Method

Good question. I believe the name usually given to that is "whaleback" or "whalebacking". The number one way to avoid it is to have the liner be one perfect piece. I was getting water through the seam immediately. The other way to avoid the dreaded whaleback is to do exactly as you described and get the pond at least partially full before you begin the process of trenching in the liner. One good thing though, is that those liners are seriously tough. Almost untearable.

My bad! I do remember now that you said you had pieced some liner together and strongly discourage others from doing that from the negative experience you had.

My potential supplier encourages a different liner than the black stuff for some reason. Don't remember if he said why.

How 'bout this for a variation.

Why not make the base concrete, and the sidewalls out of cinder block?

I'm not experienced enough with this stuff to make a cost comparison, but the liner needs to be around triple the surface area of the pond, but concrete would only need to be exactly the surface area. The liner comes in at around 70 cents/s.f., and the concrete, with what my guy called a "broom finish?", would be under 3 bucks s.f. This is a virtual wash. Then the cinder block would only have to be six high, and 65 around the circumference, which my construction dude said would be only 450 dollars delivered. Maybe I'm oversimplifying, but it seems to me like you could put a really cheap plastic around the outside of the cinder block, and back fill to it. This amount of dirt work should be any tougher (maybe even easier?), so where would the extra expense be? You could even put some conduit in through the base of the concrete to support a pond light, like what n8ly had, and an aeration line.

I need somebody to tear this idea apart and bring me back to reality. Remember that I want a pond that my water will cycle through to my Dad's pond that is about 30 feet X 10 feet, and about 4 feet deep.

Basically with concrete base and cinder block walls you are talking about a raceway design. I have seen several to numerous fish holding tanks made this way (Bob Lusk has some holding tanks built this way). Insides are usually coated with water proofing paint/epoxy. The main structural problem that I envision with this is cracking of the side walls due to ground shift or freeze/thaw cycles. Ground shift and cracking can be reduced with proper reinforcing rods in the concrete base, and a properly built footer. Concrete blocks should be somehow tied to the concrete base to eliminate breaking away of the blocks from the base. Possibly pouring the top layer of concrete so it surrounds an inch or two of the bottom layer of concrete blocks, thus locking or sealing the blocks to the base. Additional reinforcing of blocks could be done by pouring concrete into the cavities of the blocks. I'm not sure how the ground embeded "raceway" will perform structually duing annual freezing and thawing cycles. Cement mason should be able to provide advice with this. I'd get 2-3 opinions about this.

Bruce, many of the smaller ponds here are built the way you have described. We have liners available, but the smaller ponds almost always use concrete slabs with block walls. However, almost all are above ground, eliminating the need for excavation. Many build in drain pipe and some use common wall construction and build several ponds.

Here they cover the bottom with a few inches of top soil to get a culture going and stock within a couple of weeks of completion.

Thanks Bill and Rad. I think this thread would greatly benefit from any comments made regarding stabilization of walls to prevent collapsing inward. Especially in a freeze/thaw climate. I'd like the pond to look as natural as possible, so of course I'd like the upper margin to be level with the surrounding terrain. My intuition tells me that the walls could be made stronger by intelligent use of surrounding soils. After all, they do this to build houses right?

Cracks in basement cement block walls are common. Cracks in the raceway side walls will leak water into the soil. A small amount of leakage may not be a big problem. A liner inside the "raceway" would prevent leakage after cracks form. Some basement sidewalls are poured concrete. Annual caulking of cracks may reduce leakage. Expanded insulation foam may be helpful to seal large cracks.

Cracks can have sharp edges, or produce sharp shards. Could these puncture a liner in combination with water pressure (minimal pressure with Bruce's shallow concept)?

Is there any reason I should be concerned about a small amount of leakage? Especially given that the pond would be a flow through with at least 10,000 gallons added each day?

Considering the leak water would end up in your Dad's pond (IIRC), where the overflow will go, the biggest problem would seem to be eroding/washing out something. Right?

Yes, that's correct.

For what its worth the pond book I have that shows how to build ornamental ponds warns against concrete in climates where there is freezing or thawing. It coincides with what Bill cody said.

I built a wood foundation for my log home specifically because all concrete foundations crack. They are also damp to some extent. My specially treated wood foundation with a pea gravel exterior is dry as a bone. No leaks whatsoever in 12 years.

Do you really need a liner or concrete? If your soil is not too porous, and you alter your banks to keep them from caving in, why bother? One added benefit of a natural soil pond is more natural conversion of nitrites to nitrates etc. And although I find my Chara growth annoying, and try to keep it thinned out, I have no doubt it provides addtional surface for nitrification and produces some oxygen during the day. And friend in the know says it provides a lot of habitat for forage insects also.

Could a wood foundation be built for a pond? Like a pole barn?

Couple of things I would consider here, first, if the water flow is constant the pond walls could be reduced to 3 feet. Three foot walls require a lot less re-enforcing than 4. So with Bill Cody's rebar from slab to wall idea the strength problem is solved. Next you cold weather basement guys know that there are coatings that waterproof basement walls, which if applied to the outside of the pond walls would solve many of the leak problems, especially if you planned on another coating on the inside.
Concrete has come a long ways and adding the right supplements will increase the elasticity a great deal so freeze/thaw factors can be reduced.
The biggest problem I see is in making a silk purse out of a sow's ear and I am wondering why that is a goal? Wouldn't an above ground pond work as well? Plus it would give you an opportunity to evaluate an entirely different way of managing a pond.
I believe that you could grow some big fish really fast in a high water flow system, but that type of system would require a lot of management and better to do it standing up than bending over. Just a thought.

How committed are you to trying to make it look "natural", Bruce?

100% committed. I know this makes it a lot tougher, but I've already created some eyesores on my property. I'd hate to do it again.

I've had the same experiences with the GBH on my dock as CB does. A solar powered electric fence my discourage repeat attempts to defeat your defenses. I saw in a pond catalog that they make stakes for a low fence that extends over the water at a 45 deg angle.

I could make a good estimate that coating concrete and will cost as much or more than a liner. How about using railroad ties and/or retaining wall blocks covered with a liner? They can handle some heaving and movement but wouldn't move so much to compromise the liner. They look pretty natural, at least as much as pavers do. Here's a rough sketch.

Thanks, Ryan. Your depiction is more legible than some.

Is there a way that I could buy some of that inexpensive plastic sheeting that painters use and put it under the concrete before it's poured, and then lift it up and around the outside of the cinder block, then backfill it? Would that kind of plastic keep most of the dirt out and the water in? Would it degrade over time if it is completely packed between soil and concrete?

You guys have been fantastic at participating in this thread. I really believe that it will come in handy for a few others as well.

Visquilene? It degrades big time in sun and weather. I think it will hold up much longer buried, but it's been 10 years or more since I've seen any that was underground for a few years. And that stuff was wadded up - I don't know if it would still hold water.

Maybe try it as a low cost attempt, with aback-up plan if needed.

i wouldnt go for visqueen, we use it in my business alot, and i have some layin around that has deteriorated pretty quickly, granted its not buried, but i would still get a thick durable geotextile fabric for purposes of long term "keeping water in".

Any ideas on how to price "thick durable geotextile fabrics"?

not specifically. i used to get free samples all the time from vendors, target audience being environmental remediation folks and landfills. i'll see if i can dig up a couple names and send you a PM..might be a day or two, you in a hurry? my older files are archived in the attic otherwise try some internet searches for "geotextile(s)", "landfill liner(s)"...probably point you in the right direction.

Definitely not in a hurry. I was just trying to crunch numbers of the various possibilities. Thank you.

Making it look nice is a lot easier/cheaper with a polyvinyl chloride (PVC) liner. Using Ryan's diagram you can dig a free form hole. DIY retaining wall blocks can be used to follow the design, as well as dress up the edge(nice work Ryan).
The fish farmers here are starting to use liners, not necessarily for leakage problems but, because they are easily cleaned after they are drained. Allowing faster turn around.

You have probably looked at liner sites but here is one in case you have not.
http://www.pondliners.com/installation.html

OK, I'm a little slow--but maybe I'm getting it now.

You guys are saying that I could do the retaining wall, and skip the concrete floor, and place the PVC liner. That would be interesting. Is PVC liner the same as EPDM liner. The EPDM is what I've used in the past.