Pond Boss Forums POND CONSTRUCTION Renovating a Pond or Lake? Old drain pipe leaking

Hi All,

Let me apologize in advance for the long post; but I am at my wits end fighting a leaking drain pipe and need all the advice I can get.

As I have posted previously, we bought a place last August with an existing 4.3 acre pond that was built in 1963. Thanks to many of you here, we have made significant improvements to the pond, ie liming, aeration, feeders, watershield treatment, etc. since we purchased it.

When the pond was first built, there was a 12" outflow pipe that ran under the dam. The dam is also the driveway into our and our neighbors property. There is also an emergency overflow "depression" in the drive in the event of a hard rain. The pond is fed predominantly by runoff.

Legend has it that about 10-15 years ago, beavers built a house around the vertical overflow (16"pipe that fed into the pipe running under the dam) and the pond continually flooded. In the process of removing the beaver house, they damaged the overflow stem and could not control the outflow of water through the 12" pipe under the dam.(more on that in a minute) So, they decided to try and plug both the vertical pipe and the 12" outflow pipe. Further, they dug about 6 feet through the top of the dam and installed another 12" pipe as the new outflow pipe.

So today, what I have is a 12" straight outflow pipe about 6 feet below the top of the dam, an emergency overflow area; and the remnants of 16" vertical stand pipe that once fed the overflow into a 12" pipe running through the bottom of the dam.

Back to plugging the original piping...it appears what they did was first was dropping X number of bags of concrete down the vertical pipe. I am told this stemmed the flow considerably but did not totally seal off the water so they went to the other side of the dam where the outflow was and crammed it with as much concrete, rocks, etc in an attempt to seal it off too.

When we inspected the property prior to purchase, we saw this, knew about it but really didn't worry about it because the leakage from this area, at the time was infinitesimal.

Three months ago, we started our fluoridone treatment for the watershield. Prior to doing the treatment, we reinspected the old outflow pipe to insure we had no major outflow. There was a little seepage, maybe 5GPH if that. I left a five gallon bucket there, meant to return in an hour but didn't get there until about an hour and half later and the bucket was barely overflowing.

In the last month or so, I noticed the pond level kept dropping. Stupidly, all of us around here wrote it off to evaporation. Earlier this week I was cutting the grass on the dam and noticed a fair amount of water below the old outflow pipe. Upon further inspection, there was a considerable amount of outflow, more like 5-10GPminute, coming out from under the pipe, not out the end and you could clearly hear the sounds of water moving.

Today, we were able to get a backhoe through the creek and up to the old drain pipe. We dug through all the roots and around the pipe and found the pipe had rusted through on the bottom, about two feet back from the end of the pipe. We believe this is the approximate area where the 'plugging' of the pipe ended. And we know the pipe is full of water, not just a small outflow. We came to that conclusion because while clearing away the roots with a pickax, about three feet back from the end, we accidentally punctured a hole in the top of the pipe and now have a steady, 1/8" stream of water, about 6" high, coming out of the top of the pipe. Also, in this area, we found the ground around the pipe to be dry so we believe the integrity of the dam is intact.

So, our current hypothesis is the pipe is full of water but not under alot of head pressure. We believe the entrance to the pipe on the pond side has to be at least partially blocked or the head pressure would be much higher forcing a much higher stream of water out of the top of the pipe where we accidentally punctured it. The 'plugging' exposed some of the pipe which eventually rusted through and since the water was never completely sealed off coming out of the pond, it is now coming out through the blowout.

Because we were fearful we would do something to dislodge the 'plugging' and cause the pond to totally drain, we stopped work in this area and decided to investigate the old overflow area of the pond.

Currently, the old overflow pipe is about 6" below the surface. We made a concoction of milky water out of lime and poured it around the edge of the overflow to see if we could see any of it being 'sucked' into the overflow. We saw none which lead us to the conclusion that the water was making its way into the outflow pipe somewhere besides the surface of theold vertical stem pipe, most probably around the joint somewhere. We put a person in the water and what we found was a) although visibility is about 4', once you stir up a little sediment, you can't see anything; and b) the bottom around the outside of the overflow is only about four feet. However, we dropped a brick on a string down into the overflow pipe and measured a depth of 7.6' from the top edge of the rim until the brick hit the bottom.

So what we have is an old overflow stem that apparently has no integrity. The area around the outside of the stem has built up over the years either by beavers, sediment or a combination of both, where by no inspection of the 90 degree joint is possible. And most probably, a portion is covered in some concrete from the previous efforts to shut off the water.

Obviously, one option is to just let the pond drain until it quits leaking and then fix the leak. If its at the 7.6' level (where the brick stopped), that would basically empty the entire 4.3 acres; and for a variety of reasons, we need that to be our very last options.

I have thought about trying more concrete down into the vertical overflow but I am worried about its integrity and possibly breaking off entirely if I don't do it right.

Frankly, I am at a total loss right now and don't have the right answers. To make matters worse, all of our neighbors have taken an active interest in getting the pond right. All have been very supportive, financially, sweat equity, and otherwise and I would just hate for them to get up one morning to an empty pond.

Would appreciate all input and suggestions.

Warmest Regards to All,
Paul

Just a WAG here. There are companies that do hydraulic jacking with I believe a cement slurry. I wonder if they could pump cement into the culvert, displacing the water and sealing it up at the same time?

I've seen larger jobs where they pounded in "W" shaped long pieces of steel that interlocked, and kept the water at bay so excavation could be done on the outside of the steel. Once the work was completed, they had a vibrating grabber that lifted out the long pieces (an excavator was used for lifting power).

Can you extend the vertical standpipe above the water surface and pump it out? Maybe you can get a better idea where the leak is.

12" couplings are readily available.

Fernco Coupling

I see two options to keep from draining and do the repair.

Cofferdam the pond, dig out old and rebuild the dam. Cost of cofferdam rental & installation, continuous pumping of water while work is taking place. Can take a lot of time to get cofferdam to seal and a lot of labor installing.

Pump grout in and around the old pipe. May not have local. Hard to estimate how much it will take but probably more than you think. Cement grout isn't cheap.

The cheapest and probably best option will be draining, removing the old pipe and rebuiding the dam. Take the opportunity while water is low to make other improvements.

You might also look into flowable fill inside the standpipe. It's about the same price as regular concrete and most concrete plants should be able to provide it.

Thanks all for your input.

Ryan, in the long run, I would agree that letting the pond drain, removing the pipe and rebuilding the dam would be the best option. Our problem is the dam is our driveway and the only way in and out. We could move to a hotel for a week or so if necessary for the repairs; but, due to health reasons of a live-in in-law, our neighbors could not.

When you suggest pumping grout in, are you talking from the pond side or the drain end on the other side of the dam. What kind of grout should be used and what should I be looking for in a contractor?

Jsec, the water is now only a couple of inches above the rim of the vertical pipe. We are hoping we can pump it out once the water drops below the level of the rim but our hunch is the vertical pipe lost its integrity somewhere around the 90 joint down below so it may not pump out but we are going to give it a try.Thanks for the suggestion.

Essup, when you say 'culvert' are you talking about the old outflow 12" pipe or the vertical stand pipe?

Thanks again to all for your input.

Regards,
Paul

In reality the dam could be completely renovated in one day if properly planned..

Just doing a little google-ing.

I'd look for someone like this:

http://www.lincolnllc.com/earthen-dam-grouting.htm

Then contact a couple of others and compare notes.

Here's an engineer in VA who has done this:
http://www.linkedin.com/pub/john-pappas/8/60/1aa

Another engineer who may give you some leads
http://www.schnabel-eng.com/Company/People/BranchLeaders/ConnerBio.aspx

A lot of these get paid for advice so I'm not sure how much luck you'll have

About:
http://www.concreteconstruction.net/Imag...cm45-345784.pdf

Thanks Ryan. This is great info. I will do some more research.

Regards,
Paul