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Water feature advice needed

Started by Guest_Newt_* , Jun 12 2008 05:28 PM

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37 replies to this topic

#1 Guest_Newt_*

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Posted 12 June 2008 - 05:28 PM

I'm planning to install a water feature at my mother's place. There is a pre-existing erosion ditch about 3-5 feet deep with a 15-25% grade which has been used as a receptacle for fallen leaves and branches for decades (it's quite stable and no longer receives much runoff). I'm going to clear it out and line it to create a 20-30 foot long stream and two 10-15 foot long pools; I will build simple earthen dams to form the pools and they will be connected by a spillway. I hope the diagram below makes some kind of sense. The red represents the pump and pipe.

Posted Image

I've installed a few small lined ponds in the past, but never a more complex water feature such as this. So now the questions:

Where is the best place to lay the pipe from the pump to the top of the water feature? Should I place it in the bed of the water feature, or up along the bank?

What pump brands do you guys prefer? Are there any brands I should avoid?

How many GPH at the outflow will I need to get a stream about 24" wide of moderate flow? Just looking for a ballpark figure here.

Is there anything horrendously wrong with my overall plan? The dams will have spillways, the site is not a wetland, and no exotics will be stocked.

I'm sure I'll think of some more questions later. I appreciate any help you can give me!

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#2 Guest_mander_*

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Posted 12 June 2008 - 06:57 PM

Dang, where's my husband when I need him? He's the expert. My only experience is putting a pond where he told me not to and having all the problems he said I would. (Doesn't matter, I still like it!)

If I understand it correctly, it use to be a drainage ditch? What caused it to stop being a drainage ditch? My concern would be the amount of run off entering the stream. My guess would be you will need some rocks to stabilize the earthen dams. What are you using for lining?

I look forward to seeing this in progress.

Thanks,

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#3 Guest_Newt_*

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Posted 12 June 2008 - 07:25 PM

The ditch eroded out because it received runoff from a poorly graded driveway; eventually the driveway was regraded, and the ditch no longer receives such a high volume of water. It will be lined with a standard pond liner, probably 45 mil EPDM. I don't believe I will need rocks in the dams; they will be made of compacted clayey soil, and I think rocks would only interfere with the compacting process.

This is a long-term project. I'm cleaning the ditch out and developing plans now. Serious installation may not begin until well into the fall, and it will take a long time, as this will all be done with hand tools.

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#4 Guest_Irate Mormon_*

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Posted 13 June 2008 - 06:41 PM

Let's do some quick math here. Say you have a rectilinear section of stream which is 24" wide by 12" deep, and you want a current of about 3mph (that's walking speed). That translates into 190,000 inches per hour (round number). In cross section, your stream has 288 square inches, so let's take a 1-inch thick slice to make 288 cubic inches, which is roughly 1.25 gallons. Now, a pump which moves 1 gallon of water per hour (231 cubic inches) will move a 1" thick "slice" of water through your stream section at 1/1.25" , or .8" per hour. So, dividing 190,000 by .8 we get 237,500 gph.

If I've figured this correctly, then you need a 237,000 gph pump to produce a "moderate" current. Somebody help me out here - is that right or did I err grievously? I should check my self by using another method of calculating it, but it's time for supper.

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#5 Guest_Doug_Dame_*

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Posted 14 June 2008 - 10:34 AM

But the cross-section of a former drainage ditch won't be rectangular, it will be "squished U" shaped ... if we approximate that as triangular, then we have only half the cubic inches per slice.

And let's use granddad's walking speed, maybe 2 mph.

And figure that the deep center channel moves at full-speed, but its slower in the shallower edges.

Now we're down to only maybe 100,000 gph. MUCH more reasonable.

If noise isn't an issue, with the right plumbing a turbine off a decommissioned Boeing 737 might do the trick.

Astounding how much water moves in even a small cricklet, isn't it?

d.d.

Edited by Doug_Dame, 14 June 2008 - 10:37 AM.

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#6 Guest_Irate Mormon_*

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Posted 14 June 2008 - 11:14 PM

Jan Hoover once told me that nobody has ever been able to measure the water velocity at the bottom of the Mississippi River. After thinking about it, I understand how difficult this would be. I have yet to figure out a realsitic way to do it.

Anyway, it seems nobody is going to argue with my numbers (Doug's parameters don't really contradict my set of assumptions, but they're probably more realistic), so good luck with the stream thing!

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#7 Guest_Newt_*

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Posted 15 June 2008 - 02:25 PM

I was thinking more along the lines of 1", not 1', deep.

So, if I'm looking at your calculations correctly, that means a 1" slice will be 24 cubic inches, which is 0.1 gallons. So a pump that moves 231 gph will move that water 1/.1, or 10", per hour. Divide 190,000 by 10 and I get about 19,000 gallons per hour. That still seems a bit high....

I know I've seen this done, and there were no decommissioned turbines involved. I must be missing something.

Edited by Newt, 15 June 2008 - 02:26 PM.

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#8 Guest_Newt_*

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Posted 15 June 2008 - 02:27 PM

Y'know, maybe 1" is still more than I really want. I'd be happy with enough water to provide laminar flow.

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#9 Guest_Irate Mormon_*

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Posted 15 June 2008 - 03:45 PM

Just stick with a 4000gph water circulating pump - they have them at Home Depot for less than $200.

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#10 Guest_Irate Mormon_*

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Posted 15 June 2008 - 03:48 PM

I really would be much happier if Ed Bihary checked my figures. It just doesn't feel right.

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#11 Guest_mander_*

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Posted 16 June 2008 - 10:51 PM

Where is the best place to lay the pipe from the pump to the top of the water feature? Should I place it in the bed of the water feature, or up along the bank?

If I understand your question correctly, I believe the way you have drawn it, with the pipe on the outside of the pond, would be preferred to running it up the inside of the creek bed, at least, I do believe that is the standard way, easier to hide, less likely to be damaged . So is it 20-30 feet over all, or 20-30 feet plus two 10-15? Are you looking at 40 feet or 90 feet? How far away is the electrical source going to be from the pump? You might want to rent a trencher for a few hours rather than hand dig the trenches for the pipes, I mean, you'll be running the wiring through a pipe as well, won't you? To protect it from shovels? I would be inclined to think it best to have the pipe running on which ever side will get the least amount of foot traffic.

Keep us posted!

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#12 Guest_Newt_*

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Posted 17 June 2008 - 10:03 AM

Thanks, Mander. Running the pipe on the bank was my inclination, I just wasn't sure. The pump will be in the lower pool, so the distance from pump to outflow will be about 60 feet, with a head of about 12 feet (haven't measured this yet, just approximating). The electrical source is a GFCI outlet about 100 feet away and up the hill; I will bury an extension cord inside some conduit; I was not planning on using the same trench as the pipe, as that would require a more cicuitous route for the cord, but it's worth considering.

I'm not going to rent a trencher, for three reasons: the area can only be accessed through my mother's gardens, which I do not wish to trample; I'm a cheapskate; and I've already settled on doing it all by hand (I'm stubborn). I know it'll take a lot longer, but I think it'll be worthwhile.

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#13 Guest_choupique_*

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Posted 17 June 2008 - 10:16 AM

I have two pumps running in my Gar River pond. One is 2400 gph and the other is an 1800 gph. These are the mag drive pumps.

In the middle pool, I have a falls above it and below it in a line. This is the deepest section of that pond along the west shore. On the east shore I have a spring, which has half the flow of the 2400 gph. That shoots along the north shore of the pond and combines with the flow of the upper pond in the NW corner. The rest of the 2400 pump and the 1800 gph all flow to the upper pond.

That combines and is "sucked" on in the SW corner over a falls into the lower pond.

The design makes a very serious flow in water knee deep for twelve feet, and the rest of the middle pool is calf deep. The current is strong enough to bend over plants and if you drop food in there is an obvious flow as it sinks - plus the fish act just as they would in an ordinary stream flow.

4200 gph rating on the pumps, and the flow is quite nice. With a narrow area that is shallow and rocky I am sure there would be some nice riffles if I had designed it that way.

I know the mag drive pumps come in 3600 gph, maybe larger now. That and proper design I think can get the current to do what you want without using a jet engine to accomplish it. :biggrin:

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#14 Guest_Newt_*

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Posted 17 June 2008 - 11:03 AM

Thanks, Choupique, that's reassuring!

I like the secondary spring you describe; I had considered adding one to my design, but didn't want to get too ambitious.

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#15 Guest_mander_*

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Posted 17 June 2008 - 08:05 PM

I'm a cheapskate.

Oh my goodness! There's nothing more amusing than a cheapskate! Mind if I set up a popcorn stand and sell to all the neighbors who come to watch? :biggrin:

I was thinking you were old like me, but I'm going to have to revamp your age to under 35. 160 feet of trench digging. You stud you. :biggrin:

Enjoy!

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#16 Guest_choupique_*

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Posted 17 June 2008 - 09:49 PM

You could probably add several springs to jet water and get the flow going the way you want. Kind of like how people do with power heads and tubing in their stream tanks.

I used PVC pipe. Set up valves and its really easy to punch through the EPDM. Just cut a hole half the size of the pipe, push the pipe through that hole carefully not to tear the liner, then put a pipe clamp on the liner stretched around the pipe. You can then cut a ring of EPDM with a hole the half the size the pipe and about an inch wide. This can slip down over the pipe clamp and cover it from cutting anyone or thing, plus dresses it up nice. I think that is called a pipe boot something or other.

Don't worry too much about how the angle the pipe comes through. You can modify that later with more pipe fittings and pipe inside the pond - play around with it until you get the desired effect. You can then stack rocks and gravel around that to hide the pipe and divert the water even more if nessacary.

I will have to try to get some pictures sometime, maybe explain it a little better.

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#17 Guest_Newt_*

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Posted 18 June 2008 - 02:59 PM

Oh my goodness! There's nothing more amusing than a cheapskate! Mind if I set up a popcorn stand and sell to all the neighbors who come to watch?

I was thinking you were old like me, but I'm going to have to revamp your age to under 35. 160 feet of trench digging. You stud you.

Enjoy!

Heh. I'm still practically a young'un. I'm an experienced ditch digger (looks great on a resume), so I know what I'm in for.

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#18 Guest_Newt_*

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Posted 18 June 2008 - 03:02 PM

You could probably add several springs to jet water and get the flow going the way you want. Kind of like how people do with power heads and tubing in their stream tanks.

I used PVC pipe. Set up valves and its really easy to punch through the EPDM. Just cut a hole half the size of the pipe, push the pipe through that hole carefully not to tear the liner, then put a pipe clamp on the liner stretched around the pipe. You can then cut a ring of EPDM with a hole the half the size the pipe and about an inch wide. This can slip down over the pipe clamp and cover it from cutting anyone or thing, plus dresses it up nice. I think that is called a pipe boot something or other.

Don't worry too much about how the angle the pipe comes through. You can modify that later with more pipe fittings and pipe inside the pond - play around with it until you get the desired effect. You can then stack rocks and gravel around that to hide the pipe and divert the water even more if nessacary.

I will have to try to get some pictures sometime, maybe explain it a little better.

Thanks, Choupique. I can sort of picture what you're talking about, but photos would be great. Do you use any sealant around the pipes where they pierce the liner, or is the clamp sufficient to make it watertight?

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#19 Guest_mander_*

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Posted 18 June 2008 - 06:37 PM

Thanks, Choupique. I can sort of picture what you're talking about, but photos would be great. Do you use any sealant around the pipes where they pierce the liner, or is the clamp sufficient to make it watertight?

Are you using the liner alone? Or are you adding cement and rocks?

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#20 Guest_Newt_*

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Posted 18 June 2008 - 07:00 PM

Are you talking about the outflows? I imagine they will just be stacked stone and perhaps some caulk to control water flow, no cement. I haven't really thought about them in detail yet, as I'm trying to figure out the overall layout first.