Today we were looking at another pond to dredge out, the owner said before we left. "by the way, the pipe has a leak in it, can you look at it" Walked behind the dam and found this. Sir... you have a problem! Video of it: http://s228.photobucket.com/albums/ee145/Letsdig18/?action=view¤t=004-51.flv 30 years of rust. 36" pipe 15' off the ground, held up by a light pole and some rebar, oh yeah For the fix I'm going to dig back 45 feet to where the metal joins to concrete and replace all the metal back with concrete. When It get to about where the water is pouring out now I'm going to stack a few of the concrete man holes and have a 36" hole cut in the side of the top one. Slide it over the pipe comming out of the back, that way the water can pour down to the bottom of the man hole. Then I'll have another pipe at the bottom of the man hole to release the water into the stream. This way the water does not have to pour down 15' and wash out a huge hole in the backside of the dam. how does my idea sound? If you can understand what I said
sounds like THE fix to me!!! That is exactly what i would design!
Chris, What about moving the manhole closer to where the concrete is right now so that you can completely bury it and then the only thing you'll see is the end of the outlet pipe?
It'll be a little further back than the water pouring out now that I look at the picture. I plan on covering the manhole with dirt. The main issue that will determine how far back it goes is the solid rock that's in the ground below it. I really don't want to do any hammering.
Why not, build a rock spill way let the rock support the pipe, excavate back to the concrete pipe, add plastic pipe pour a collar at the joint. Might be cheaper then man holes, and take less time. Telescooper
You dont think you could fix that leaking CMP with a can of great stuff?
Ya that great stuff works wonders! LOL
Seems to work when fixing leaking joints
I'm wondering how high that creek gets when it's glowing real good? If you do anything to direct the water down from height of the current pipe, will it be protected from the creek if there's a heavy rain and the water rises to the edge of the bank? Could you just pour concrete against the edge of the embankment and create a ramp of sorts for the water to flow down that will eliminate the erosion, but not be affected by the creek when it's full? Or maybe a massive amount of some very large rip-rap? Eddie
Why not cement the rip rap together with great stuff foam. ;-)
Sounds like a lot of unnecessary work that will ultimately create other problems down the road. Cant say for sure what I would do,I cant tell from the video. If that were a river up here in pa you would need a permit to do anything within 50' of the river. Now personally if it was me I would propose rip-rap under the pipe and all along the river bank. Under the pipe is not the only location of an erosion problem. There has to be an even plain on the river bank or it will just create "eddy's" during high flow. (Wash out behind what ever is creating the "eddy"). That's probably why there is a much larger erosion issue behind the big rock under the pipe. That is where the problem down the road comes into play. You would have to have a great foundation for the manholes as the water passing around it will eat out the back side and compromise the outflow structure.As far as the pipe is concerned there is not really a good view showing the invert of the pipe. If you are going to draw the pond down then put a new pipe in. Rip-rap in cheaper, faster,more aesthetically pleasing and more stable.
You may look into some turf reinforcement mat and posibly some scour stop. They are some erosion control products. I know that North American Green makes some trm that when full vegitated is the equalivent to 48" rip rap. Here in Northern Indiana it cost more for trucking than the rip rap so I find that trm is a good alternative to rip rap and it is also "green"
Chris, Let me start by saying I have, like... no experience in this situation, but just looking at it and reading what you and others have said, I think that Reuben has a point about no matter what, you'll wanna rip-rap the heck out of the bank for a ways in both directions from the pipe at least as high as typical flood waters would reach. This will protect the bank, which we have to assume is the other side of the pond's bank as well, and any outflow structure. Something else I'm wondering, is part of the idea of the manhole to slow the flow of the pond water before it's released to the stream? If it is, then a manhole makes sense, but it would be a good idea to leave a bit of a trap in it (ie. don't have the invert of the exit pipe flush with the bottom of the manhole). Keep us updated, hope my lack of real experience is any help, haha :notworthy
How about: Slip line new 30" double wall plastic pipe inside of 36" pipe. Concrete pump between new pipe and old pipe. Concrete erosion mat at discharge to stream edge. Alan
Can't replace all the pipe as the dam is a main road, so no digging up the road. But the good news is under the road it is concrete pipe, so I'll just tap into the and replace all 45' of rotton metal pipe. Now I'm thinking about just using 36" ADS plastic pipe, just using single wall and slope it down the creek. Cover it up and rip rap around the outlet pipe. Everyone Else: Thanks for all the helpful replys!
that sounds much more practical