Pond Boss Forums INTRO Questions & Observations overflow pipe screen HELP!

I have only 7 more inches to go.

Now I have a new problem. What is the best way to screen your overflow pipe? My pipe is 14" in diameter.

I don't want to see all those fat heads on the back side of the dam.

There was another thread about this a little while ago. It had some pictures of what people had made. If they are horizontal pipes you can use some type of fencing, like goat fence, and t-posts to hold it in place. Then just put in a semi circle around the pipes. If you want it to keep fish in, use the smallest grating you can buy. Hopefully somebody else will elaborate.

start here
outlet config. thread

I would assume that, with a 14 inch overflow pipe, you expect a lot of runoff into the pond. A lot of runoff might mean a lot of junk coming into the pond. Unless I were there to monitor it, I wouldn't constrict an overflow in any way. If the screen stops up it could keep the pipe from doing its job of protecting the dam. You could lose a lot more than minnows. However, you should lose a small percentage and they are extremely prolific.

Look at the link Brettski has provided. I like what Theo is doing. However, for safetys sake, you have to monitor it.

JMO

I agree with Dave. If you clog up that pipe more than just the fish will escape. Maybe you could build a fence out away from it that would stop the fish but not clog the pipe.

I think MOST of us can safely put up a fence of some sort that will stop MOST of the fish from leaving our pond MOST of the time. Change any of those three MOSTs to an ALL and you're looking for trouble.

I believe my barrier, that is shown in the thread Brettski linked to, will stop almost all fish exceeding the 1/2" screen size from being washed out of my pond in anything short of a once in 5-10 year rain event. I put it in so that it only takes perhaps 8" of water level rise to by-pass the fence. This is at about 18" below the point where the secondary spillway (overflow) starts to pass water, which in turn is at least 18" below the top of the dam.

So that all the qualifiers and provisos (that I can think of) are in the open, the pond has a 10-11 acre watershed feeding it and has only required an 8" drain pipe to handle all drainage. The secondary spillway has only had water once, when the pond was new. Before I cut the thin upper end collar off the drainpipe, it collapsed during a heavy flow and blocked probably 2/3 of the hole. Since the collar was removed, all flows have fit down the 8" drain without any overflow.

One additional important fact is that my pond has a very small amount of vegetation in it to possibly block the screen. Most of what it does have is FA, which seems to float if loose and has only blocked the screen at the surface level. When that happens, the water keeps on flowing out through the submerged part of the screen.

P.S. I put the screen in when the pond was new, my fish were small, and my amazement at the sheer numbers of fry, fingerlings, and juvenile fish produced by spawning had not yet been established. If I hadn't have done it then, I wouldn't bother to do it now.

Oops I think this is where I meant to post this message in the first place.
In Washington I am required to have a 1/4 inch screen on my outlet to prevent larger bluegill and bass from entering the river system nearby. I've also been concerned with the fact that debris will quickly clog the screen. I've been toying with two ideas to combat this problem.

1. Use a multi screen approach. Like above, but start with a 2 inch mesh wire fence to catch bigger debris and then follow it up with my 1/4 inch mesh. before the water enters an 18 inch culvert.

2. Use a pvc Y to lower the intake a couple feet or so below the bottom level of the culvert. This will prevent most of the clogging due to the fact that the debris is usually near the surface. Then I will build a sort of cage around the intake to maximize surface area for intake if some clogging does occur.

Any comments or suggestions?

Just got another idea. What about using a brushpile as a sort of debris blocker in front of the outflow pipe?

Altho this is not what the intended purpose is for, maybe this engineering will ignite "out of the box" thinking...
When I spoke with Mike Otto about a thru-dam drainpipe, we also discussed a filter at the intake (pond side) of the drain. Our discussion was based on 6" dia PVC. He said that his normal procedure for a strainer is to put a 90 degree elbow on the intake of the pipe, pointing upward (don't glue the 90 to the horz drain pipe...just twist it on snug using the natural pipe-fit to hold it together. This way the entire strainer assy can be removed, if need be, to by-pass an unexpected severe clog). He then takes a 5' - 6' section of the same pipe and drills 3/4" -1" holes all up, down, and around, about 1" spacing between holes (I think he said that the 1" will allow the leaves to get thru...had probs with .750" choking with leaves). He attaches this to the up-ward facing 90 and puts a cap over the top of the filter pipe. He pounds in a T-bar next to and parallel to the vert strainer pipe. Attach the strainer pipe to the T-bar with removeable pipe strap, galv. bailing wire, or some similar non-corrosive "reasonably easy to remove" fastener.
So...I share this with my contractor who, as always, listens intently allowing me to present my case. "OK...yep....yep.....uh huh....yep" When I finish, he looks at me and says "and....?". That's it (I think). He responds by adding: I do the same type thing, but we add a little more. He drops a vert pc of 12" or 15" corrugated pipe over the entire vert PVC strainer described above. The corr pipe has the same gazillion holes drilled thru it. Then they drop gravel into the corr pipe, filling the gap between the PVC and corr and a foot or two over the top of the PVC cap.
It makes sense to me. The only thing I did not address with my guy was the "not gluing the 90 to the drain" decision. I presume that he does glue it, assuming there should never be a clog scenario with his "double filter" design.
I like Mike...I like my guy, too.