Plugged Pond Overflow Pipe

[rekees]

I know this question doesn't relate directly to tractors but perhaps it qualifies as a rural living issue? Last Summer bought a farm that has a 2 acre pond. Unfortunately the previous owner didn't put a screen on the overflow drain pipe and now it appears to be about 90% plugged up. Water still flows thru it but so slowly that it takes weeks for the pond to return to a normal level after a heavy rain. I was wondering if anybody has experience/suggestions on unplugging such a pipe? The pipe is 4 inch PVC, 200 feet long and underground except for the ends. The ends would be difficult to access since the inlet requires standing in 3+ feet of water and the outlet is 1 foot below ground level in a hole. Is this a do-it-yourself project or will a plumber or pond professional be needed?

Chuck in IN

 

[Von]

How about blocking it off completely and then when the water is say 6"-12" over the top, open it up and let the water force clean it out. I don't know it this will work for you or not, but water is mighty powerful and will clean out a lot of rock and sticks that may be blocking.

Von

 

[rekees]

Von - Yes, I know the power of water. Just look at the Grand Canyon! The water gets over the top of the inlet whenever it rains heavily and the water pressure doesn't clean it out. I don't know what the plug(s) is composed of. Doubt rocks but could be sticks or fish, frogs, cattails, leaves and various other assorted pond related things that would fit into a 4" pipe.

Chuck in IN

 

[Von]

I would get in a boat and try to send a drain snake down and see if that helps.

Von

 

[Thomas]

rekees,
Maybe this will help.
Float a string or a rope thru the pipe,than tie a heavy rope on to that than pull that thru.
Now tie a old set of tire chains to the rope,but before you pull the tire chains thru,tie another rope to the other end of the tire chains.
Just pull the rope thru the pipe and should loosen up up things,but you may have to do this more than once.
If the tire chains should become stuck you can pull on the other end to free the chains.
I would always leave a rope in the pipe for future use,and maybe 4 or 5 times a year run the chain thru.


Thomas..NH /w3tcompact/icons/wink.gif

 

[gerard]

I think Thomas's idea has a lot of merit but I think the biggest problem is an undersized pipe. A 2 acre pond is pretty large and even an unobstructed 4 inch pipe is going to take a large time to drain off that much water. You may find you don't even have a blockage to speak of, just an undersized pipe. Just off the cuff I'd say you could have gone with a 12 inch pipe and still not be too large for that size pond. (With a little research you should be able to find the flow rate for 4inch pipe in gallons per hour for a specified head, then do a rough estimate on how much water is in your pond per inch. The only hard part is not knowing how much water runs into the pond from the adjacent ground. Lets say you get a 1/2 inch of rain. You would raise the pond level by that half inch plus the amount you get from the "watershed" for that pond. 1/2 inch for 2 acres equates to about 53,000 gal of water assuming zero runoff. That much water running through an unvented 4 inch pipe by gravity alone is going to take a l o n g time. Sounds like you have a great excuse to buy a backhoe attachment and lay some drain pipe!!)

 

[MarkV]

I think Gerard hit it on the head. I was going to say the same thing and I'm glad he got there first. He was much better with the math. We have a 3 acre pond at the inlaws house and over flow pipe is about 16". Might need to check with a pro.

MarkV

 

[rekees]

Thomas

Thanks for the suggestion. It may have some merit though I think it would be difficult to float the string or rope thru the pipe. Especially with the blockage in there somewhere. Have tire chains but pretty sure they wouldn't fit into the 4" pipe. Maybe I could use some other smaller object? Have to think about what.

Your approach is food for thought and I will consider it in the Spring.

Thanks.

Chuck in IN

 

[rekees]

gerard

Maybe a 4" pipe is too small but that's water over the dam (no pun intended). The last resort will be digging up the pipe and installing new pipe. A backhoe for my JD4300 would be $7000. For that kind of money I can live with the slow drainage.

There is definitely blockage because I've looked at the water coming out of the outlet and it's just about the rate you'd expect out of a garden hose! Also when the flow stops the level of the pond water is even with the top of the inlet. This tells me that maybe the blockage is near the inlet and may be relatively easy to reach?

Chuck in IN

 

[Harv]

Like Gerard and the others, 4 inches sounds a little small for any kind of outdoor drainage, but since it came that way and you're talking 200 feet, I guess you'd really like to make that work.

Since it's the size of household drainpipe, I would suggest you try household drain cleaning techniques. If you can't snake it out from the ends, you might get one of those rubber bladder things that attaches to the end of a hose (assuming you can get a hose to one end of the pipe). Can't remember exactly what they're called (plumbers affectionately refer to them as "douche bags", but this is a family-oriented message board so I will not use that term), but after you attach it to a hose, you shove it as far into the pipe as you can and then turn on the water full blast. The rubber bladder expands and seals itself inside the pipe so all the water pressure has to go out the other end. The downstream end of the thing has a relatively small aperture, so you get a pretty good "jet" of water.

If necessary, you might consider fashioning your own temporary pressure cap on the pipe. It wouldn't take much to put a cap on the end that you've adapted with some kind of hose fitting. The idea is to use hydraulic (how appropriate) pressure to get the job done. Even if you get it only partially cleared, you could then use this pressure system to force a "mouse" (something like a tennis ball) through, pulling a line. Once the line is through, you can try some of the methods that Thomas suggested.

If none of that works, it might be time to call Roto-Rooter (do they have those where you are?).

I guess all ponds are different. Mine, for example, has 3 main inlets which are fed from mountain runoff. The combined water flow can be tremendous at certain times of year, so our overflow is a tad larger than yours -- namely, four 36-inch diameter pipes (see attached). Of course, we only had to route it past the dam, which is about 20 feet at that point. /w3tcompact/icons/wink.gif