# Spillway Leaks



## bcnu (May 4, 2009)

Have a small(acre or so) pond with concrete spillway. I use wooden 2x10's that fit in a concrete slot. Water is leaking under the bottom of the board where it meets the spillway bottom. I'm having trouble getting a tight seal. Wondering if u have any ideas for a barrier at the bottom. What about using a thick door gasket material for wood stoves and attaching it to board so that it forms a barrier at bottom(not under the board but on the pond side - would it remain watertight for the summer or would water pass right thru it? Would coating gasket material with tar or something improve water-tightness? How about somew other material? Oh, the board is about 40" long.


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## Highbeam (May 4, 2009)

Oooooh, that bottom board didn't pass the walrus test. 

Is the pond full? Are you going to have to swim to get this done?


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## velvetfoot (May 5, 2009)

Garage door bottom gasket?


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## Gooserider (May 5, 2009)

Can you put some sort of material against the board on the pond side?  I'm thinking something like a sandbag; possibly custom shaped - sort of an underwater version of those "draft stopper" tubes you will sometimes see people put in front of doors that have bad gaskets...  Maybe some sort of thin, flexible rubber hose (like sump pump discharge line) partially filled with sand?  Idea being that the sand would hold the hose in place while the water pressure jammed it into the crack.

Gooserider


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## bcnu (May 5, 2009)

No boards in yet - but raining cats and dogs right now so will have to wait awhile.  Tried sand bags last year and didn't conform enough to seal.  Thought about a garage door seal but wondered if it would make a tight seal.


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## woodsman23 (May 5, 2009)

try this site..   www.pondboss.com  great people with lots of knowledge.


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## gpcollen1 (May 5, 2009)

I'd second the garage door gasket or use some pool liner.  A pool store will sell you a piece of liner.


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## EatenByLimestone (May 6, 2009)

Beavers have good luck packing the holes with mud and grass.    I don't suppose it would be too bad to do a little shovel work when you want to use the spillway to drain it.  

Matt


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## JustWood (May 6, 2009)

Piece of doubled over rubber roofing or old inner tube nailed to the bottom of the board with roofing nails.


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## bcnu (May 6, 2009)

Used lots of mud last year and it never quite did the trick.  Thanks for all the good ideas so far.


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## johnn (May 6, 2009)

Is there a slot in the concrete bottom as in the sides?? Was this keyway of sorts , made during the pour, consistant in size?? If so,,,would a tightly fit board, swell up and make a better seal? I suppose if it worked too well you would no longer have a spillway that was operable.


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## bcnu (May 6, 2009)

Unfortunately there is no slot in the bottom.  With about 25 years of wear the concrete apron just in front of the boards isn't as good as it once was.  I made some repairs last year to that area.  I would, if possible, make the bottom board permanent.  The creek that fills the pond, while almost non existent in the summer becomes a torrent in the winter and I have to have all the boards removed - I've learned that by experience these past two winters.


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## Gooserider (May 6, 2009)

Might not be possible to get an absolute stop on the leakage, you might have to settle for slowing it down to a slow enough seepage that the pond stays full...  

That said, if you don't have a slot for the bottom board, I'd try building up some concrete (maybe with some rebar added)  on the downstream side to at least give the board a "step" to bear against...  

Maybe cover the bottom board in a tarp or something to give you a "mold release", and once you've slowed things down on the downstream side, pour in some hydraulic cement to make a slot on the upstream side....

Gooserider


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## Cutter (May 6, 2009)

I don't know all of the particulars but you might be able to creat the "slot" with bags of asphalt patch.  Put your board in place and they tamp the asphalt down and tight up against the board. You will have to do a good job of cleaning off the dirt or dust from the surface of the concrete before applying. The stuff works best on hot days.
Brad


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## bcnu (May 6, 2009)

I agree about creating a slot at the bottom for the board. I tried something temporary last year but wasn't sucessful.  One problem is that there is always some water moving thru the dam.  Goose, your idea about starting on the backside sounds interesting.  I know, from last year, that I can live with some seepage.  Just that it took a lot to get it to that point.


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