Pond Boss Forums POND CONSTRUCTION Renovating a Pond or Lake? Mystery water coming through dam pipe

I've been renovating my pond over the past 2 years. When I first started, I drained the pond down about 5 feet and extended the 4" outlet with a "temporary" corrugated black pipe using a heavily taped joint. I cut about 5 feet off the top riser pipe that governed the water level.

Now that I've mostly finished things, I plugged the riser and the pond filled back up using a new overflow (diagrammed). However, some water is still coming out of the temporary pipe. The water appears very clean. I'm trying to determine the source of the water and trying to figure out what, if anything, to do about it.

Iron level testing:

• out of the temporary pipe I see iron levels of at least 0.3 ppm (pictured right)
• from a well almost 150 ft away I see iron levels of 0.05 ppm (pictured left)
• from the pond itself I see iron levels of 0 ppm (not pictured, but the test strip was stark white)

Other notes:

• I'm getting a little seepage through the foot of the dam, and it looks rusty.
• The static water level in the well about 150 ft away is a about 10 feet higher than the foot of the dam.
• During construction the extended black pipe got clogged with debris. Water was flowing out a hole in the middle of new filled part of the dam at what seems like about the same rate it's coming out of the pipe now. I think it stopped when I removed the clog which turned out to be at the end of the temporary pipe.
• I've felt around the plug, and it doesn't seem like water is leaking there, but it's hard to tell
• I've thought about elevating the end of the temporary pipe to see what its static water level would be, but I haven't done this yet

Does the iron test definitely say the water is coming from a groundwater spring (or something) as opposed to pond water leaking? Or could the pond water absorb all the iron as it leaks? Thoughts?

Hey Crazyj, Nicely written post, I'm surprised you haven't gotten any feedback as your dilemma is interesting. I love your pond setting - you've got in-ground water sprinklers on the dam, I'm jealous...

My guess is that your old system was made from steel? If so, it is now rusty steel and probably has some rusted/rotted holes in it allowing water to seep into the now extended drain pipe. This rusted/rotted piping may be where you iron is coming from. Or it could be merely iron in the dam soil surrounding the old drain system. Did you take your pond water sample from the bottom of the pond near the old drain pipe or just off the surface? Iron levels might be different at the bottom, I'm guessing. Can you determine any water level changes. I'm no expert on the topic as my newly renovated pond is trying to fill up. Hopefully I don't have to worry about leaks, but you never know. I think there are only three possibilities here. One is that the old system is allowing water to seep from the pond out the old drain pipe (with extension). Another possibility is that natural ground water (water table or spring) is seeping into the old drain system. Or a combination of the two. I'd bet on the first. I like your approach using test kits to determine where the water is coming from and think other methods may be necessary as well to pinpoint the actual problem (like monitoring water drop in pond and comparing it to the output at the extension drain pipe, other water chemistry tests, ect.) As far a s fixing it...not sure at this point. Plugging the abandoned drain pipe might not totally stop the leak, but the leak may eventually slow to a stop as the leaking water carries dirt and debris and fills the crevasses kind of like "stop leak" for radiators. How was the old system plugged? Could it be seeping around that?

Hopefully my thoughts help you out and maybe this bump will get more to respond.

I think that elevating the line will answer where the water is coming from as long as the well and pond water elevations are sufficiently different.

Is the old riser pipe rusty? If yes, I suspect the leak is either the plug or through the pipe wall. Just a pin hole leak or two thru the pipe wall could easily provide 1 GPM flow. If the mystery water is flowing thru an old rusty pipe, that could explain the iron level being higher in the mystery flow.

The old pipe is rusty. Things I'm going to do:

- elevate the outlet to try and see the water level
- add some dye around the plug and old riser to see if comes through the outlet
- put a tshirt or something over the outlet to filter and see if any solids are coming through the outlet

I'll report back.

Your iron source could be from one or more of several sources. If your iron pipe has rusted enough to have thin areas, water can be seeping into it, and flowing over rusty surfaces. Also, if your water contacts iron soils, it can come from that. It can also be ground water. I bet your old pipe is the culprit. Since you blocked it, rather than fill or remove it, I'd bet it's providing a vehicle for seepage. So, the iron test does not prove the source is groundwater.

It finally got warm enough for me to put on a swimsuit and figure this thing out.

Elevating the pipe didn't help determine anything as water just leaked around the corrugated pipe ... must be a hole in it near where it comes out of the earth, which makes sense because it was supposed to be only temporary, and I think I nicked it with the excavator a couple times.

But based on y'alls thinking, I started messing around with my plug. Turns out it wasn't 100% plugged. I dove down 8 ft and put some plastic bags around the plug, and that slowed the flow from one beer mug ever 5 seconds to one beer mug every 14 seconds. So I started looking around for an even better sealer. I found some kitty litter in the cabin I had used to mix with Portland to grout my well. I mixed it with a little water, balled it up, and dove down to stuff it around the plug. Fixed. 100% sealed. Thanks for all the help.

Now I need to figure out whether I want to keep this as a way to drain the pond or if I want to abandon it. If I abandon it, I'll probably reconnect the old part of the riser to bring it above water level, then pour the mix of Portland and kitty litter until it's full.

I would plug it and use a siphon to drain if needed. I have a 4" PVC drain in my old pond which has never leaked, but the valve is also PVC and I fear it would break if I ever used it. Wish I had not installed it in the first place.

Ditto with plugging it.